Abstract:Loose-curd cauliflower is currently the main type of cauliflower consumed in China. Clubroot andblack spot diseases are improtant diseases that directly and adversely affect the yield and quality of cauliflower. Therefore, to select varieties of good commercial quality with high and multiple resistance is one of the major goalsin cauliflower breeding. In this study, we for the first time established the evaluation system of curd traits forloose-curd cauliflower germplasm resources. Sixty-six accessions of loose-curd cauliflower inbred lines wereevaluated for eight characters of curd compactness, curd shape, surface smoothness, surface color, buds size, lengthof secondary lateral branch, pedicel color and curd hairiness. Each character was assigned a value for statistics andcomparison. Eleven inbred lines were selected for excellent traits based on the evaluation system. With artificialinoculation at seedling stage, we identified and evaluated the resistance to clubroot and black spot of loose-curdcauliflower respectively. The results showed that none of the accessions were immune to clubroot, with 2 of highresistance, 9 of fair resistance, 16 of medium resistance, and none of the accessions were immune or highlyresistant to black spot, with 4 of fair resistance, 10 of medium resistance. Only a few accessions were found to havedual resistance to clubroot and black spot diseases. Among them, ‘GY-40’ showed relatively high resistance to bothdiseases, ‘GY-21’ showed fair resistance to clubroot and medium resistance to black spot, and ‘GY-21’ showedmedium resistance to both diseases. ‘GY-40’ is therefore an ideal parent line for breeding cauliflower varieties, dueto its excellent traits and relatively high dual resistance to both clubroot and black spot diseases. The study willprovide reference for evaluating curd traits of cauliflower germplasm resources, be of great significance forstandardization of resources collection, sorting and preservation, and provide excellent accessions for breeding ofloose-curd cauliflower varieties with dual resistance to clubroot and black spot diseases.

Abstract:Studies of the genetic relationship could provide reference for the excellent germplasm innovation and new varieties breeding. Within this study, we investigated the genetic diversity by SSR markers using capillary electrophoresis fluorescence detection technology, in 187 accessions that include cauliflower, broccoli, Roman cauliflower, landraces and wild species. A total of 313 alleles were amplified from 30 pairs of SSR primers, with an average of 10.43. According to the curd phenotypic characters of the materials, these genotypes were composed of four subgroups: cauliflower (subgroup 1, P1-81), broccoli (subgroup 2, P82-147), Roman cauliflower (subgroup 3, P148-154), wild and local species (subgroup 4, P155-187). The narrowed genetic diversity was observed among subgroups 1, 2 and 3, except subgroup 4 that showed abundant diversity. The phylogenetic tree and population structure analysis assigned these genotypes into three groups. Cauliflower (G1) and broccoli (G2) were grouped independently, while Roman cauliflower together with wild species and landraces assembled the third group (G3).

Abstract:Classification of cauliflower resource was useful for heterosis and hybridization selection. 54 cauliflower inbred lines were analyzed with statistical methods of cluster analysis and the principal component analysis (PCA). The PCA results showed that, the six eigenvalues of cumulative variance proportion 70.024% were selected for evaluation of inbred line of cauliflower; Days to curd appearing, days to curd harvesting, leaf length, leaf width, plant height, lengthways diameter of curd, transverse diameter of curd, curd weight, curd shape, tight degree, leaf color, wax powder, leaf number inside, days to flowering and plant extent were morphological characteristics for parents screening. By cluster analysis under the results of PCA, 54 cauliflower inbreed lines were classified into 3 clusters. Characters of clusterⅠwere early maturity, little plant extent, narrow leaf with less wax, moderate weight and tight degree of curd; Cluster Ⅱ had the characters of middle maturity, moderate plant extent, sage green leaves with thick wax, and weighty curd with tight semicircular; Cluster Ⅲ was type of late maturity, high stalk, large plant extent, more length and width leaves with moderate wax, and oblate curd. Three clusters had obvious feature, so that it would be helpful for parent materials selection in breeding.

Abstract:An Agrobacteriummediated transformation system,using transient and stable transformation assays,was used to evaluate some factors influencing transformation in cauliflower.These included the precultivation time,the bacterial density,the inoculation duration time with Agrobacterium tumefaciens,the concentration of acetosyringone,the delay selection and the concentration of kanamycin in selection.Using cotyledons with 12mm petioles as explants,the best transformation parameters were:twoday precultivation,OD6000.30.4 of bacterial density,eightminute infection with Agrobacterium tumefaciens,twoday cocultivation,100μmol/L acetosyringone in the cocultivaiton medium and sevenday delay selection in kanamycin of 5mg/L.By optimizing the parameters on the procedure of Agrobacteriummediated transformation,a high transformation efficiency(35.7%)was demonstrated.The GUS transient expression could be an important indicator for cauliflower transformation.The development of an efficient Agrobacteriummediated transformation system opens up new opportunities for the functional characterization of genes and promotes the development of novel germplasm of Brassica vegetable genus.