Abstract:Pleione is a genus of the Orchidaceae with great ornamental value, including 24 species and nine natural hybrids, and having 431 grexes registered with the Royal Horticultural Society in the UK. The plants of this genus are very popular and are of great potential for market development. China is the center of distribution and species diversity of Pleione, but lags behind Europe in resources development and breeding of the genus. In order to strengthen the conservation and sustainable development and utilization of Pleione, its germplasm resources and crossbreeding were reviewed, focusing on the achievements of crossbreeding in the past 50 years aiming at different breeding goals, and summarizing the problems in and prospects for the germplasm resources, crossbreeding, and industry, to provide some insights and directions for Pleione breeding.

Abstract:Leaf color mutants in rice are important materials for deciphering the photosynthesis, chlorophyll synthesis and degradation, and plant growth and development, and they are also with high practical value in producing hybrid seeds and improving biomass. To date, over 120 genes modifying the leaf color have been molecularly cloned on 12 chromosomes, including chromosome 3 where the most number of genes were reported. In this paper, the genetic mechanism and molecular isolation of leaf color genes, the regulation mechanism and the practical use in rice breeding were summarized and prospected. This might provide a basis for high photosynthetic breeding and the exploitation of leaf color germplasm resources suitable for hybrid seed production in rice.

Abstract:Imidazolinones, which target the acetolactate synthase, are deployed as broad spectrum and high-efficiency herbicides in order to control the weeds in agriculture. Breeding for rice varieties with resistant to imidazolinone herbicides is one of the economically effective strategies to control weeds in rice fields. In this study, a new rice germplasm resistant to imidazolinone herbicides was identified from 30,570 rice germplasm accessions by spraying imidazolinone herbicides. Testing for resistance in its progeny indicated that this resistance was inheritable. Furthermore, a PCR amplification and sequencing of ALS gene encoding sequence revealed a G/A mutation at position 1880 bp position, which lead to an amino acid alteration from serine (S627) to asparagine (N627) and which might be the causal agent for herbicide resistance. Taken together, this study described an elite germplasm with a practical potential in breeding for new herbicide-resistant rice varieties.

Abstract:Rice blast is one of the most devastating diseases in rice production. Although the commercially-released resistant cultivars often become susceptible in 3-5 years due to the rapid evolution of M. oryzae isolates, breeding for resistant variety is still the most economical and effective approach to control blast disease. In this study, the donor line R6, which harbors rice blast resistance gene Pi25, was crossed with the super early-season rice Zhongzao39 (the receptor and recurrent parent), followed by generations of backcrossing, self-pollination and molecular marker-assisted selection. The offspring lines were tested for rice blast resistance by spray inoculation in the greenhouse, injection inoculation in the field and natural infection in the disease nursery. Remarkably, four lines (i.e. FY82, FY90, FY125 and FY137) carrying Pi25 showed the elevation of resistance on leaf blast and neck blast. In addition, investigation of the genealogical composition and other resistance loci provided a preliminary dataset in order to decipher the genetic basis of rice blast resistance.

Abstract:the relative Cd-reduction rate of polished rice and screened the resources with no significant difference in the annual relative Cd-reduction rate. In addition, 45 SSR markers were used to detect the genetic diversity of 15 rice accessions, in order to identify the resources available for breeding with a great genetic distance and high relative Cd-reduction rate. The results showed that in 2018, Cd content in 15 low-Cd polished rice was lower than cv. Xianwanxian 12. Ten samples represented relative Cd-reduction rate of more than 50%, ranging from 50.8% to 83.5%, while 5 samples were less than 50%, ranging from 1.9% to 49.8%. In 2019, the relative Cd-reduction rate in 7 rice samples with similar growth period was higher than 50%, variable from 60.1% to 78.7%. Based on the two-year test results, no significant difference was found among four low-Cd rice samples 7 (BS82), 14 (X211), 19 (7W172), 20 (7W216), and the relative Cd-reduction rate was higher than 50%. The overall genetic diversity in 15 low Cd-accumulating rice population indicated relatively abundant (Na=4.311, Ne=3.257, Ho=0.041, He=0.657, I=1.207, Nei's=0.639, PIC=0.612). The mean genetic similarity (GS) was 0.377, suggesting distant genetic relationship. For examples, the GS in pairs of samples 7 and 14, samples 7 and 19 (20) as well as samples 14 and 19 (20) were 0.319, 0.447 and 0.426, respectively. Therefore, four rice germplasm resources

Abstract:Rice ‘Yuenong Simiao’ recently bred in Guangdong Province, China, with a strong resistance to rice blast, is a leading high-quality cultivar for regular cultivation, which can also be used as a hybrid rice restorer line. In this study, it has been revealed that ‘Yuenong Simiao’ has a broad spectrum of resistance against rice blast strains from South China. Genetic analysis of genetically segregated F2 population of ‘Yuenong Simiao’ × ‘LTH’ showed that the broad resistance spectrum of ‘Yuenong Simiao’ may be controlled by multiple genes. Using the molecular markers of major resistance genes Pi1, Pi2, Pi9, Pib and Pita, we have detected that ‘Yuenong Simiao’ contains at least Pi2 and Pib resistance loci. These results have revealed the cultivar’s genetic basis of high resistance to rice blast, and provides important molecular basis for extending the cultivation of disease-resistant cultivars.

Abstract:Chromosome addition lines of wheat-wild species have excellent traits such as disease resistance and stress tolerance, which is an important bridge material for the introgression of elite characters to wheat. Many studies have reported the increasing of disease resistance or stress tolerance when the wild relatives derived segments are present in wheat. However, the effects on agronomic traits caused by introgressions of alien chromosomes remain to be rarely reported. In this study, several agronomic traits consisting of plant height, spike length, flag leaf length and width, effective tiller number, spikelet number, grain number per spike and thousand-kernel weight in a set of chromosome addition lines were investigated at four field trials experiments. In relative to wheat control lines, the presence of introduced chromosomes Aegilops searsii 4Ss#1, Elymus ciliaris 5Yc and 7Yc, Dasypyrum villosum 2V#3, Lophopyrum elongatum 3E, 5E and 6E resulted in significant increase on spike length. When E. ciliaris 5Yc chromosome is present, the wheat-wild addition lines showed markedly decrease on the size of flag leaf. The chromosomes of E. ciliaris 7Sc and 7Yc were found to be associated with the increase of thousand-kernel weight. Thus, these chromosome addition lines in conjunction with future chromosome engineering and (/or) physicochemical mutagenesis induced structural variants become of interest to localize the agronomically-important genes.

Abstract:Exploring new sources of resistance and widening genetic resources of disease resistance are important strategic reserves to ensure the sustainable development of agricultural production. In order to get it clear about the resistance to stripe rust and the distribution of stripe rust resistance genes in 400 wheat varieties (lines), the resistance to stripe rust was identified on adult plants in the field by using the dominant mixed races (CYR31,CYR32 and Su11-14) in Guanzhong area, and Yr5, Yr9, Yr10, Yr15, Yr17, Yr18 and Yr26 which are known as stripe rust resistance genes were detected and screened by molecular markers in this study for comprehensive analysis of resistance genes that may be carried by tested materials. The results showed that out of the 400 materials, 177 (44.25%) were highly resistance to immunity (IT=0~1) to mixed races at adult stage, 62 (15.5%) were moderate resistance (IT=2) and 162 (40.25%) were medium or high susceptible (IT=3/4). Combined with disease resistance performance and molecular analysis of known Yr gene, the results showed that Yr5 was carried by 121 (32.5%) wheat materials, Yr9 was carried by 96 (24%) materials,Yr10 was carried by 10 (2.5%) materials, Yr15 was carried by 19 (4.75%) materials, Yr17 was carried by 150 (37.5%) materials, Yr18 was detected in 15(3.75%) materials, and Yr26 was detected in 127 (31.75%) materials, respectively. But Yr5, Yr9, Yr10, Yr15, Yr17, Yr18 and Yr26 were not found in 25 materials such as Dingxi 24 and N7187 among the 400, they might contain other unknown resistance genes or new genes. The results of the study established the identification and evaluation system of resistance to wheat stripe rust, and 177 resistant materials with different resistance characteristics were selected out, of which 25 might contain new resistance sources, which laid a foundation for further cultivation of new varieties resistant to stripe rust

Abstract:In order to breed for elite Elymus sibiricus L. varieties suitable for the high yield and high quality in Qinghai-Tibet Plateau, we conducted a three-year field trials for investigating the seed production performance. Eleven E. sibiricus L. germplasm resources collected in different ecological regions of the Qinghai-Tibet Plateau as well as two the nationally-registered varieties Qingmu NO.1 and Tongde were applied. The results showed that: (1) There were significant difference on seed yield production among different genotypes in different years (P<0.05). Two genotypes I-1-5-13 and I-1-5-19 showed the best yield performance, with an average of 1494.93 kg/hm2 and 1386.82 kg/hm2, 81.49% and 68.36% higher than that of Qingmu NO.1, and 90.92% and 77.11% higher than that of Tongde. (2) The seed yield generally became declined constantly in a manner of continuous cropping. Attractively, both I-1-5-47 and I-1-5-50 showed high and stable yield production within 3 years. Based on the production performance, both genotypes showed a potential in future breeding for seed-type E. sibiricus L. (3) The yield traits, i.e. the seed number per inflorescence, seed length, number of spikelet, length of spike and seed weight per inflorescence were significantly positively correlated with seed yield (P<0.05). Especially, the seed number per inflorescence showing an correlation coefficient of 0.809, in relative to seed yield, can be used as a key indicator in predicting the seed yield. (4) The cluster analysis of seed yield and yield traits suggested three categories: group-I that represented the genotypes which were originated from areas with higher altitudes with an average altitude of 3967m, and showed a moderate yield performance; group-II that represented the genotypes which were originated from low-altitude areas with an average altitude of 3244m, and showed a high seed yield; group-III that represented the genotypes which showed a low seed yield and were originated from higher altitudes areas with an average altitude of 4392m.

Abstract:Elite germplasm resources is the important foundation for the breeding of maize elite hybrid, and germplasm suitable for mechanical grain-harvesting is an urgent need in China. It is an important way to solve the problem by introducing European early maturity germplasm in domestic germplsm to develop Huanglv-European (HE) lines. In this study, the 258 HE lines were crossed with the tester lines Jing MC01 and Zheng 58 to evaluate the yield and grain moisture performances of the hybrids. The results indicated that: (1) the hybrids of Jing MC01 had lower grain moisture and higher grain yield as compared with the tester Zheng 58; (2) the Huanglv-European lines with different domestic background had much different performances in test crosses, Huangzao4 and Jing2416 derived lines had lower grain moisture and higher yield in both spring and summer maize, while the lines from Chang7-2 showed higher moisture and yield;(3) The hybrid from the HE lines with the percentage of 25% early maturity donors performed better in the target traits. Thus, the conclusion is that it would be an effective way to develop elite HE lines by backcrossing once with the domestic lines in practical breeding.

Abstract:In this study, 13 agronomic traits of 160 chickpea germplasm resources induced from ICRISAT were evaluated. The results showed that these chickpea germplasms represented abundant genetic diversity. The variable coefficients of 7 quantitative traits were branches per plant(70.1%)>pods per plant(46.1%) > 100-seed weight(27.5%) > yield(23.7%) > plant height(20.5%) > seeds per pod(18.3%) > growth period(5.8%), and the genetic diversity index of 6 quality traits were seed color(1.385) > plant type(1.119) > flower color(0.905) > seed surface(0.772) > seed shape(0.412) > leaf type(0.000). The cumulative contribution of the top 4 principal factors reached 63.417% in the principal factors analysis, as well as the first principal factor was mainly related to the yield traits and yield; the second principal factor was mainly related to the growth period; the third principal factor was mainly related to the plant height and seed shape. With cluster analysis, 160 chickpea germplasm resources were classified into 3 groups, the group Ⅰ showed the highest plant height, the group Ⅱ showed the highest yield, the group Ⅲ showed the biggest seed. 63 chickpea germplasm resources with elite agronomic traits were screened, which were early maturing, short stem, unbranching, more pods per plant, more seed per pod, large seed and high yield.

Abstract:Fifty five F1 populations were obtained by crossing 56 fuzzless mutant accessions of Gossypium arboreum (female parents) with G. arboreum ‘Shixiya 1 Hao’ (male parent) for analysis of the dominant and recessive inheritance of fuzzless trait in cotton. Fifteen F2 populations were obtained for further analysis of fuzzless trait inheritance pattern. The results showed that the genetic mechanism of fuzzless trait inheritance was complex, with 37.5% of dominant inheritance and 62.5% of recessive inheritance. The fuzzless trait was controlled by a single dominant gene in acc. ‘GA0149’ and acc. ‘Hengfeng Tiezi’, while a single recessive gene was responsible for the mutation in ‘Changzi 1 Hao’. However, in most of the accessions, the fuzzless trait was controlled by two pairs of genes with dominant and epistatic effects. Particularly, eight accessions carried two dominant epistatic inhibition gene and 4 accessions had a pair of genes with complementary effects responsible for fuzzless trait. The correlation analysis showed that the fuzzless trait was positively correlated with leaf hair but had no relationship observed with lint percentage. In some cross combinations, it was positively correlated with the leaf area but negatively with the gossypol number. The phenotypic traits in Asian cotton populations showed significant genetic diversity. The flower color, leaf shape, presence or absence of petal base spot and the color of stem were significantly different among different accessions.

Abstract:In order to catalog and preserve 63 tobacco germplasm accessions, which were collected by Chongqing Project Group in a frame of the Third National Survey and Collection Action on Crop Germplasm Resources, we conducted the field experiments for identifying the phenotypic and marker-assisted genetic diversity. Morphological characteristics and main agronomic traits were surveyed and analyzed. These tested germplasm accessions represented abundant genetic diversity at both quantitative traits and qualitative traits. Specially for qualitative traits, leaf shape had the highest diversity index, followed by Leaf length, leaf width and stem girth. Clustering analysis suggested four groups of these newly-collected tobacco germplasm accessions. The germplasms resided to the first group were mainly rustica, while the germplasms from the third group showed higher plant height and bigger leaves with a potential for high-yield breeding. Tests for disease resistance indicated that 11 accessions were resistant to TMV and CMV. Particularly, two of them were free of TMV infection and highly resistant to CMV, which could be used for disease resistance breeding. By taking use of field phenotypic datasets and genotyping results using SSR markers, the germplasm accessions showing identical were excluded for cataloglization and conservation into the National Bank of Tobacco Germplasm Resources. Therefore, survey and collection of tobacco germplasm resources is of great significance, in order to enrich the genetic diversity of Tobacco Germplasm Resources and benefit for tobacco breeding.

Abstract:From 2015 to 2018, the survey and germplasm collection of pepper germplasm resources were conducted in 80 townships (towns) from 44 counties (districts) in Guangxi province, China. The distribution, morphological types, agronomic trait and excellent characters of the collected resources were analyzed. As a result, 144 pepper germplasm resources were collected and they were mainly distributed in the west and north regions of Guangxi. These germplasm accessions were mainly found to grow at an altitude from 0 to 300 metres. Two morphological types consisting of finger shape pepper and horn shape pepper accounted from the large proportion in pepper germplasm of Guangxi. Moreover, six pepper germplasm resources with excellent characteristics were identified, including Shangsi color pepper, Zhongshan bell pepper, Huangping pepper, Xilin pickled rod chilli, Lipu pod pepper and Ningming pepper. The elite germplasm resources might lay a foundation for future use in breeding and innovation of new materials.

Abstract:Recombinant inbred lines (RIL), which were generated by single seed descend method (SSD) with multiple generations from the F2 population, are commonly used in studies of the genetic mapping and the quantitative trait locus (QTL) mapping. Tracking and analyzing the genetic differences in generations of RILs might be of significance to assist the RIL population construction. In this study, 18 SSR markers being polymorphic with parents were used to track the genetic diversity of F1 to F10 population during the RIL construction in sesame. With the increase of RIL population generations, the levels of polymorphism became decreased constantly from 87.54% of F2 to 3.33% of F10. The percentage of loci showing heterozygous decreased from 100% of F1 to 0.19% of F10, and the coefficient of genetic similarity increased from 0.6669 of F2 to 0.9908 of F10, and the genetic distance decreased from 0.2592 of F2 to 0.0094 of F10. The percentage of the polymorphism, the heterozygous loci, the genetic similarity coefficient as well as the genetic distance were variable in F2 to F6, while the level of variations became smaller in generations of F6 to F10. The clustering results showed that F2 plants were randomly classified, while in F3 to F10 generations the plants derived from the same line were clustered together. F5 to F7 populations are ideal to select residual heterozygous lines. The high-generation populations (>7 generations, i.e. F8) are qualified for the genetic mapping and QTL mapping. The genetic background of F8 population tends to be consistent, which provides theoretical reference for the determination of self-crossing generation in sesame hybridization breeding.

Abstract:This study investigated tar content of 205 flue-cured tobacco germplasm accessions which were collected from Shandong province and Sichuan province, China. Seventeen low-tar flue-cured tobacco germplasms such as Wolihuang 0782, P3, Qiannan No.7, 82-3041 and Jiyan No.10 were identified by deployment of multiyear and multiple location experiments. Furthermore, the agronomic traits including plant height, leaf number and stem diameter were scored, and six conventional chemical components in the cured tobacco leaves were examined. The correlation between agronomic traits, chemical composition and tar release was investigated by using simple correlation analysis, path analysis and regression analysis. An extremely significant positive correlation was revealed between tar release and any of nicotine, total sugar and reducing sugar. An extremely significant negative correlation was detected between potassium and tar release, while Chlorine was significantly and negatively correlated with tar release. No significant correlation was observed between other factors and tar release. The tar release were contributed by potassium, followed by total sugar, nicotine, middle leaf length, chlorophyll, stem diameter as well as plant height. Potassium and total sugar mainly affect tar content through direct action. The direct and indirect effects of nicotine to tar release are similar. Agronomic traits including waist length, chlorophyll and stem diameter can indirectly affect tar release, and other factors showed no obvious effect on tar content. Finally, a regression model between agronomic traits, chemical composition and tar release was proposed, which is of importance for the screening and utilization of low-tar flue-cured tobacco germplasm.

Abstract:Through interspecific hybridization, the gene for the trait of yellow skin of the fruit, which exists only in Cucurbita pepo, was transferred to C. moschata and C. maxima. Genetic analysis showed that the inheritance pattern in interspecific progenies was in line with the Mendelian law. Genetic performances of the yellow skin gene were compared among the three species in Cucurbita. The results showed that trait expression of this gene was affected by multiple factors including species, parental fruit shape and color. New Cucurbita germplasms with novel yellow skin can be created by transferring the gene from C. pepo to C. moschata and C. maxima through interspecific hybridization.

Abstract:Duckweed, a family of aquatic plants, has the characteristics of fast growth and reproduction, strong nitrogen and phosphorus absorption capacity, and high protein and starch content. Therefore it has great potential in feed and bioenergy production. However, the information of duckweed germplasm collection and diversity analysis in the middle reaches of Changjiang River has not been systematically reported. In this study, 112 duckweed germplasm were collected from 34 representative natural aquatic habitats in three provinces of the middle reaches of the Changjiang River. These germplasm resources were classified into 4 genera and 6 species by morphological and molecular biological identification. Lemna contained 3 species and 34 accessions. Spirodela, Landoltia and Wolffia contained only 1 species, and their collected germplasm number was 33, 19 and 6, respectively. Genetic diversity analysis showed that the number of haplotypes of their AtpF-AtpH spacer sequences and rpS16 intron sequences were 11 and 18, the haplotype diversity was 0.748 and 0.892, the population mutation rates were 0.03439 and 0.03507, nucleotide differences per Kb were 31.386 and 61.263 and nucleotide diversity was 0.04713 and 0.06623, respectively. This study plays a key role for the utilization of duckweed in the middle reaches of the Changjiang River.

Abstract:The recombinant inbred line population, which was derived from a hybridization of the japonica variety Asominori and the indica variety IR24, was deployed for the quantitative trait locus (QTL) mapping for the genetic components underlying the heading date (HD) in two environments (Nanjing and Hainan, both from China). As a result, five and six QTLs were detected from both locations respectively. Of them, this locus qDTH-6 on chromosome 6 could be simultaneously detected with LOD values of 6.28 and 12.93, and with the contribution rates of 12.26 and 17.18, respectively. Moreover, this line CSSL45, which is one of IR24 chromosome segment substitution lines (CSSL) and which contains qDTH-6, and its background parental line were treated under short-day (SD) condition. The qDTH-6 allele from IR24 showed dominant photo-inhibition. By analyzing a set of heading date tester lines and some tester cultivars crossed with CSSL45, we speculated that the qDTH-6 allele from IR24, which names Su-E1(t), inhibited the function of photoperiod-sensitive gene E1 (Ghd7). Using CSSL45 × Asominori secondary F2 population, Su-E1(t) was further localized close to SSR marker RM527. Taken together, the results might be of significance in order to shorten the heading date of indica-japonica hybrid.

Abstract:In order to explore the physiological characteristics and the transcriptional regulation of OsDSR2 RNAi transgenic rice under salt stress, we analyzed the physiological indicators and the transcriptome profiles of OsDSR2 RNAi transgenic rice seedlings compared to wild type Zhonghua 11(ZH11) plants. Analysis of the various physiological indexes under normal conditions revealed no significant difference in OsDSR2 RNAi transgenic line and ZH11. Under salt stress treatments, no significant difference on the content of chlorophyll, soluble sugar (SS), superoxide dismutase (SOD) activity and catalase (CAT) activity of OsDSR2 RNAi transgenic rice to ZH11 was detected, while the content of cell membrane permeability, malondialdehyde (MDA) and Na+/K + in transgenic rice were detected to be significantly lower; the content of Proline (Pro) and peroxidase (POD) activity were significantly higher than those of ZH11. The transcriptome analysis revealed 68 differentially expressed genes in OsDSR2 RNAi transgenic plants before and after salt stress treatment, 55 genes of which were up-regulated and 13 genes of which were down-regulated. GO analysis showed that the differentially expressed genes were enriched in stress response, catabolism and other biological processes. KEGG analysis showed that the differentially expressed genes were mainly involved in the biosynthesis of carotenoids, brassinolactone and the biosynthesis of epidermal, cork and wax biosynthesis pathways. The differential expression of OsbZIP16, OsLEA3, RAB21 and other stress-related genes under treatments was further verified by RT-qPCR. Taken together, the OsDSR2 RNAi transgenic rice plants showed the salt tolerance which might be associated with the reduction of the cell membrane permeability, the content of MDA and Na+/K +, the Pro and POD activities as well as the inhibition of the chlorophyll degradation. Furthermore, OsDSR2 gene might be also involved in the transcriptional regulation of OsLEA3, RAB21, OsbZIP16 and plant cuticular wax biosynthesis gene (LOC_Os04g28620).

Abstract:With the frequent use and increasing growing area of transgenic crops on a global scale, gene flow in transgenic crops has aroused great biosafety concerns. Pollen dispersal is the primary mode of gene transfer from a cultivated crop to the wild relatives.In our investigation it was found that wild relatives of wheat occur in sympatry with cultivated wheat in China and some wild relatives in wheat-growing region of Huanghuaihai flower synchronously with cultivated wheat. We collected and grew the seeds of these wild relatives and made hybridization with transgenic wheat MG176. The rates of successful artificial hybridization were 2.18-68.61%.However, it was difficult for the hybrids to reproduce naturally on account of low seedling emergence rates (0-2.86%) and pollen abortion. Backcrosses of the hybrids with either wheat MG176 or wild relative parent failed to produce seed except (Aegilops columnaris × MG176) × MG176 which had a seed set of 0.24% with zero seedling emergence when planted in the field. In simulated natural condition, no gene flow events were detected in the related wild relatives of wheat through 5 years of continuous monitoring.We concluded that the risk of exogenous gene flow from transgenic wheat to wild relatives was extremely low.

Abstract:The root system architecture (RSA) determines the composition of the root system and plays an irreplaceable role in crop growth and development. It is of great significance to analyze the genetic mechanism of wheat root architecture and the selection of varieties with better RSA traits in breeding for elite wheat varieties. Genome-wide association study (GWAS) is an effective method to analyze the genetic mechanism of complicated quantitative traits (i.e. RSA) in wheat. In the study, GWAS for RSA-related traits(total root length, total root surface area, total root volume, average root diameter and number of root tips) were conducted in 160 wheat accessions from Henan and Shandong, which were previously genotyped by wheat 660K SNP chip. Twenty-three loci associated with RSA related traits were detected from chromosomes 1A, 2A, 2B, 3B, 4A, 5A, 5B, 5D, 6A, 6B and 7B, and each explained the phenotypic variation variable from 7.2% to 12.8%. Among them, eleven loci are found to coincide with the formerly-reported loci, and the remaining 12 loci are newly identified. Taken together, this study is of significance to uncover the genetic structure of the root architecture with a potential in future breeding of high-yield and stress-resistant wheat cultivars.

Abstract:Transforming resistance genes of wild relatives into elite cultivars is an effective approach to improve the wheat disease resistance. Identification of the alien chromosomes by deployment of a rapid and precise method becomes important in order to simplify the process on selection and utilization of the favorable genes. In this study, CH357, a new wheat germplasm resource which was derived from wheat-Thinopyrum intermedium partial amphiploid TAI7047, was subjected for tests upon infections of Powdery mildew and Stripe rust, as well as the evaluation by fluorescent in situ hybridization (FISH) and molecular markers detection. The results showed that CH357 contained a wheat-Th. intermedium 6JS/6B chromosome substitution. This genotype was tested to be resistant against wheat powdery mildew and stripe rust, and the resistances were likely caused by 6JS chromosome of Th. Intermedium, thus raising a potential for wheat resistance breeding. Furthermore, 160 STS markers were developed based on the Contigs sequences of Th. intermedium group 6 genome. Out of that, eight markers were found to specifically amplify the alien chromosome of CH357. The PCR-based assay will provide a user-friendly method for identifying the 6JS chromosome or fragments of Th. intermedium in wheat.

Abstract:The lack of available phosphorus in soil has become the major restricted factor for yield and quality of soybean (Glycine max). Therefore, the mining of genetic loci at crucial phosphorus requirement stages becomes very important for genetic improvements of phosphorus efficiency in soybean. In view of this, the association analysis based on the SoySNP6K (5403 SNP markers) was used in this study to find 10 genetic loci controlling phosphorus related traits of soybean at the crucial stages, with the result that 78 SNPs were detected under normal phosphorus condition at T1 stage (four-leaf stage), of which relatively more were associated with root and total dry weights, and 134 SNPs were detected under low phosphorus condition at T1 stage, of which relatively more were associated with total dry weight, with SNP clusters on chromosomes 8, 13 and 20 detected controlling shoot and total dry weights, shoot fresh and dry weights, and total dry weight. At T2 stage (six-leaf stage), 83 SNPs were detected under normal phosphorus condition, of which relatively more were associated with plant height and shoot dry weight, and 53 SNPs were detected under low phosphorus condition, of which relatively more were associated with plant height and root/shoot ratio, with an SNP cluster on chromomsome 18 detected controlling root and total dry weights, and 3 SNPs on chromomsomes 11, 16 and 18 detected associated with pleiotropism. More importantly, 9 SNPs were detected controlling shoot fresh and dry weights, root/shoot ratio, and plant height at T1 and T2 stages simultaneously, which provided some selected molecular markers for soybean phosphorus efficiency genetic improvements in future.

Abstract:On the basis of low-glucosinolate and low-erucic rapeseed (Brassica napus), stable high-oleic rapeseed is one of the most important breeding objectives. In this study, CRISPR/cas9 system was used to improve the variety XY15 selected by Hunan Agricultural University. BnaFAD2 and BnaFAE1 are two key genes for the conversion of oleic acid to unsaturated fatty acids and ultra-long-chain fatty acids. The CRISPR/Cas9 system was introduced into XY15 by using highly efficient rapeseed transformation technology. The results of target gene cloning and sequencing showed that none of the seven T0 transgenic plants obtained were edited. However, gene editing was found and detected in T1 plants. The total gene editing efficiency of BnaFAD2.A05, BnaFAD2.C05, BnaFAE1.A08 and BnaFAE1.C03 were 38.89%, 27.78%, 22.22% and 30.56%, respectively. Among the T2 plants, 5 plants and 4 target genes were all mutated, and the relative oleic acid content of the mutants Cas9-1-12-4, Cas9-1-12-5, Cas9-2-7-11, Cas9-5-5-3 and Cas9-6-6-1 without foreign genes was 68.69%, 80.16%, 75.82%, 75.97% and 74.37%, respectively, which were significantly higher than that of the wild type XY15 (62.04%).

Abstract:In order to investigate the effect of aquaporin in tea plant under water stress, two aquaporin genes (AQPs, aquaporins) were cloned from Camellia sinensis ‘Fuding Dabai’, and their expression patterns under simulated drought, exogenous application of ABA, natural drought and rehydration were analyzed. Amino acid sequence analysis showed that both aquaporins contained SGGHINPAVT, a conserved signal sequence of MIP protein family, and two highly conserved NPA (Asn-Pro-Ala) units, both of which contained six transmembrane regions. Based on the results of homologous alignment and the prediction of cell localization, they were assigned to the plasma membrane aquaporin (PIPs, plasma membrane intrinsic proteins) subfamily. The results of real-time fluorescence quantitative PCR showed that the gene expression of the two CsPIPs was tissue-specific, the expression level of CsPIP2;7 was the highest in leaves, and CsPIP2;8 was the highest in flowers and leaves. After 20% PEG simulated drought stress,CsPIP2;7 was significantly down-regulated, CsPIP2;8 fluctuated, and was slightly up-regulated 24 hours later. After exogenous application of ABA, CsPIP2;7 was significantly down-regulated, while CsPIP2;8 was significantly up-regulated. In addition, experiments of natural drought and rehydration showed that the expression of the two aquaporin genes was up-regulated by drought stress and reached the maximum 24 days after irrigation stopped, CsPIP2;7 and CsPIP2;8 were up-regulated by 7.13 times and 3.68 times respectively, and the two genes were down-regulated 29 days after irrigation stopped, and were down-regulated or remained stable after rehydration. Different from the expression pattern of leaves, CsPIP2;7 decreased slowly in the process of slow drought and was up-regulated significantly after rehydration, and CsPIP2;8 fluctuated as with PEG treatment, but was down-regulated after rehydration.

Abstract:In order to explore the genetic relationship among Lagerstroemia, Heimia and Lythrum of the family Lythraceae, the genome sizes of eight species and two cultivars of Lagstroemia, of two species of Heimia and of Lythrum salicaria L. were estimated by flow cytometry method with Brassica rapa Rupr. and Cucumis sativus L. as inner calibration. The chromosome number and karyotype parameters of the two Heimia species and of Lythrum salicaria L. were obtained using traditional chromosome tableting. The results showed that the average genome size of Lagerstroemia species and cultivars ranged from 341.00±2.00 to 370.00±8.89 Mbp. The average genome size of Heimia myrtifolia Cham. et Schlechtend. and H. salicifolia Link were 414.67±5.77 Mbp and 420.00±7.00 Mbp respectively, and the karyotype formulas of the two species were 2n=16=6sm+8m+2st and 2n=16=2sm+14m. The average genome size of Lythrum salicaria L. was 1294.00±30.32 Mbp, and the karyotype formula was 2n=54=31sm+15m+8st. In this study, the genome size of 13 taxa in the Lythraceae, and the karyotypes of two Heimia species and of L. salicaria L. were reported for the first time. The results of our research laid a foundation for research on genomics and genetics of the Lythraceae.

Abstract:In order to provide better guarantee on technical support for the future innovation of common buckwheat resources and new variety breeding, this study investigated the effective method of isostyle resources in innovation of common buckwheat. The positive and negative hybridization tests by using isostyle germplasm resource crossing with common buckwheat cultivars showing different flower types were carried out. Six hybridization combinations (isostyle × cultivar, isostyle × long style, isostyle × short style,cultivar × isostyle, long style × isostyle, short style × isostyle) were achieved, and they were subjected for analyzing the seed-fertility and the inheritance segregation. The results showed that the fertility rate of isostyle common buckwheat resources was observed up to 22.6%, significantly higher than that of common buckwheat. Regarding to the hybrids for selecting the new isostyle pure lines, the "long style × isostyle" hybrid pattern was the best pattern. Otherwise, the "isostyle × cultivar" was optimal for the selection of new strains. Taken together, this study suggested the feasibility on hybridization techniques in order to meet the demand of the resource innovation. The offspring plants were observed with obvious phenotypic variation, which might suggest a possibility to effectively solve the bottleneck problem in common buckwheat cross breeding.

Abstract:In order to promote the development and utilization of wild Allium resources in the Tibetan Plateau, the volatile components of eight wild Allium species in Tibet were measured by dynamic headspace gas chromatography / mass spectrometry. The components identified were determined by NIST 11 and Wiley 7n standard library, and the quantities were calculated by peak area normalization. Twenty-five volatile compounds were detected in the leaves of Allium cyathophorum, A. macranthum, A. rude, A. chrysanthum, A. prattii, A. cyaneum, A. fasciculatum and A. wallichii. Fourteen volatile components were detected in A. rude, three in A. prattii, approximately ten in other species. The diethyl ether and dimethyl disulphides were found in eight wild Allium species with variable levels on content. The propyl mercaptan was specifically detected in A. cyathophorum and A. rude, and the compounds including propanal, methylsulfur heterocyclic ring, dipropyl trithiolides, 2,4-dihydro-4-methyl-3H-1,2,4-triazole-2-thionone, 3-amino-2-thiazolinone, and 1-chloro-1-propylene were extensively detected in A. rude. The trimethylamine and diallyl thioether were detected in A. macranthum, methylpropyl thioether in A. cyathophorum, hexaldehyde in roots of A. fasciculatum, as well as positive octane and 2-fluoropropene in stems of A. chrysanthum. In A. rude, two and fourteen volatile components were detected in underground stems and leaves, respectively. 15 and 12 volatile components in underground stems and leaves of A. chrysanthum were identified. The volatile substances in different parts of the same wild Allium are as follows: there are 2 kinds and 14 kinds in the underground stems and leaves of A. rude; 15 kinds and 12 kinds in the underground stems and leaves of A. chrysanthum; 6 kinds and 3 kinds in the underground stems and leaves of A. prattii; as well as there are 10, 9 and 8 kinds in the Stem (both above and below ground) , fleshy roots and leaves of A. fasciculatum respectively.

Abstract:Bretschneidera sinensis Hemsl., a monotypic species and Tertiary relict tree, is listed in the State First-Class Protection Tree Species of China. The natural population is decreasing nowadays with a sparse distribution ranged from south China to northern Vietnam. Within this study, we investigated the flowering behavior, pollen type, dynamic viability and storage method of pollen and receptivity of stigma. The elongation of the stigma at initial flowering stage was observed, which leads to the physical barrier compromising the self-pollination effectively. The receptivity of stigma developed form little bud to full-bloom stage, and mucilage was secreted by stigma only at full-bloom stage. Pollen grains were starchless which indicate a typical insect pollination. The viability of pollen was very low at bud stage, and then reached high at full-bloom stage. The optimal concentration of sucrose solution for in vitro germination was 20%. Pollen grains were observed to be sensitive responding to storage treatments. Pollen viability could be maintained up to 190 h under freeze storage (- 20 ℃), suggesting that low temperature is the key factor to reserve the pollen viability. The resistance of the wild population upon climate change was quite fragile because the time-frame on the flowering of natural populations of B. sinensis was short. Thus, collection and low-temperature storage of mature pollen in combination with artificial pollination are recommended in B. sinensis.