摘要
qCTS-9是在多种苗期低温条件下稳定发挥作用的水稻耐冷基因,研究其耐冷优异单倍型及适应性进化模式,有利于为水稻耐冷育种提供基因资源和技术支撑。本研究利用116份栽培稻(Oryza sativa L.)和37份普通野生稻(Oryza rufipogon Griff.),对qCTS-9基因的核苷酸多样性及单倍型进行了分析。结果表明,qCTS-9基因编码区内的14个SNPs组成了8种单倍型,其中的4个非同义SNPs组成3种功能单倍型,这3种功能单倍型之间表现出显著的耐冷性差异,编码区的第1535 bp处SNP可能是qCTS-9基因的关键变异位点。对qCTS-9基因启动子区顺式作用元件进行分析后发现,相比于野生稻和粳稻,低温敏感籼稻Hap4单倍型材料中-1107 bp有一个SNP (G→A),导致该处的MYB识别位点缺失,这个自然变异可能与籼稻耐冷性下降相关。野生稻包含栽培稻中qCTS-9基因的大部分变异,但在编码区及启动子顺式作用元件中无独有的变异位点;从野生稻向籼粳分化的过程中,耐冷相关等位或突变被固定和扩展,进而增强了其区域适应性。
水稻(Oryza sativa L.)是世界上最重要的粮食作物之一,为世界一半以上的人口提供主
水稻的耐冷性是一种由数量性状位点(QTL,quantitative trait locus)控制的复杂性
本研究选择116份栽培稻(Oryza sativa L.)和37份普通野生稻(Oryza rufipogon Griff.),分析水稻苗期耐冷基因qCTS-9变异位点的多样性,挖掘苗期耐冷的优异单倍型及适应性进化模式,为通过分子育种提高水稻耐冷性提供支撑。
本研究共使用116份栽培稻(材料信息详见https://doi.org/10.13430/j.cnki.jpgr.20240103001,
单倍型分组 Haplotype group | 粳稻 Japonica | 籼稻 Indica | Aro | Aus | ||||
---|---|---|---|---|---|---|---|---|
数量 Number | 比例(%) Proportion | 数量 Number | 比例(%) Proportion | 数量 Number | 比例(%) Proportion | 数量 Number | 比例(%) Proportion | |
Hap1 | 74 | 83.15 | 0 | 0 | 0 | 0 | 0 | 0 |
Hap2 | 13 | 14.61 | 5 | 22.73 | 0 | 0 | 0 | 0 |
Hap3 | 1 | 1.12 | 6 | 27.27 | 1 | 50.00 | 1 | 33.33 |
Hap4 | 0 | 0 | 6 | 27.27 | 0 | 0 | 0 | 0 |
Hap5 | 0 | 0 | 2 | 9.09 | 0 | 0 | 1 | 33.33 |
Hap6 | 0 | 0 | 1 | 4.55 | 1 | 50.00 | 1 | 33.33 |
FHap1 | 74 | 83.15 | 0 | 0 | 0 | 0 | 0 | 0 |
FHap2 | 14 | 15.73 | 7 | 31.82 | 1 | 50.00 | 1 | 33.33 |
FHap3 | 1 | 1.12 | 15 | 68.18 | 1 | 50.00 | 2 | 66.67 |
qCTS- | 74 | 83.15 | 0 | 0 | 0 | 0 | 0 | 0 |
qCTS- | 14 | 15.73 | 20 | 90.91 | 2 | 100 | 3 | 100 |
对栽培稻群体进行耐冷性鉴定,幼苗培养与苗期低温黄叶率鉴定参考宋佳
使用SPAD-502型叶绿素仪测定苗期叶绿素含量,测定位置选取两叶一心期水稻幼苗第二叶的中上部,每个水稻品种取3次SPAD值的平均值为处理前SPAD终值,测定完成后将水稻幼苗置于10℃下胁迫48 h(12000 Lux,12 h光照/12 h黑暗)。胁迫完成后的水稻幼苗再次测定SPAD值,重复3次,取3次SPAD值的平均值为胁迫后终值。
本研究重测序数据来源于Zheng
使用R包geneHap
qCTS-9基因(Os09g0410300)位于第9染色体,其编码区序列(CDS,coding sequence)在14531190 bp到14547560 bp之间(+链),CDS全长为4614 bp,共包含26个外显子,编码蛋白共有1537个氨基酸,包含保守的谷氨酸锌化氨肽酶(Gluzincin)结构域。116份栽培稻的重测序数据结果显示(

图 1 qCTS-9基因编码区的核苷酸多样性
Fig.1 Nucleotide polymorphisms in the qCTS-9 coding region
红色的SNPs代表非同义突变位点
SNPs marked in red represent non-synonymous mutation sites
编码区的14个SNPs在116份栽培稻材料中共具有8个单倍型(

图2 qCTS-9基因编码区单倍型分析
Fig. 2 Haplotypes analysis of qCTS-9 coding region
A:所有单倍型的分类图;B:所有单倍型的Network图,图例上方弧线按比例对应单倍型饼图不同样本数量,单倍型间连线上点的数量代表两单倍型间的差异位点数量;C:功能单倍型分类图;D:功能单倍型低温处理后黄叶率,不同小写字母代表P<0.05水平上的差异显著性;E:功能单倍型低温处理前后叶绿素含量(SPAD), * 代表P<0.05水平上的差异显著性
A: The classification of all haplotypes for qCTS-9; B: The Network of all haplotypes for qCTS-9, the arc above the legend corresponds proportionally to the different sample sizes in the haplotype pie chart,the number of points on the line connecting haplotypes represents the number of differential sites between two haplotypes; C: The classification of functional haplotypes for qCTS-9; D: The value of yellow leaf rate of functional haplotypes for qCTS-9,different lowercase letters represent significant differences at the P<0.05 level; E:The changes of SPAD value in chlorophyll content of functional haplotypes before and after low temperature treatment,*: Significant differences at the level of P<0.05
为了进一步探究不同单倍型对耐冷表型的影响,对qCTS-9基因编码区的变异位点进行筛选,编码区发生变化的14处核苷酸中只有7处是非同义突变,筛去变异样本量少于3个的变异位点,最终得到4个功能SNPs:1535 bp (A→G, Asn→Ser)、1746 bp (G→T, Leu→Phe)、1847 bp (G→A, Cys→Tyr)、4514 bp (T→C, Ile→Thr)。这4个SNPs构成的3种功能单倍型FHap1(包括Hap1)、FHap2(包括Hap2、Hap6和Hap7)及FHap3(包括Hap3、Hap4、Hap5和Hap8),样本数分别为74个、23个和19个(
3种功能单倍型在不同类型材料中的频率有明显差异(
顺式作用元件包括脱水响应元件核心基序DRE cor

图3 qCTS-9基因启动子低温响应顺式作用元件
Fig. 3 The low-temperature responsive cis-acting elements analysis of qCTS-9 gene promoter
标尺代表序列长度
The ruler represents the sequence length
种群间的遗传变异是育种中有用突变的最终来
在栽培稻驯化过程中,低温适应能力逐渐分化,以适应不断变化的生态环
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