水稻剑叶形态QTL定位及候选基因分析

QTL mapping and analysis of candidate genes in flag leaf morphology in rice

叶片是水稻的重要器官,是进行光合作用的主要场所,而叶长、叶宽、叶面积等剑叶形态相关性状能够直接影响叶片的光合效率.研究水稻剑叶形态相关性状的QTL(quantitative trait loci)位点,并通过遗传育种的手段对水稻剑叶形态进行改良,可以为培育理想株型的水稻提供理论依据.本研究以籼稻品种华占(HZ)为父本,粳稻品种热研2号(Nekken2)为母本,杂交获得F1代后,连续自交多代得到120个重组自交系(recombinant inbred lines,RIL)群体,将其作为实验材料.在相同且适宜的条件下培养后,对水稻分蘖期和成熟期剑叶叶长、叶宽、叶面积等性状进行考察分析,同时利用该RIL群体构建遗传图谱,对水稻分蘖期和成熟期剑叶叶长、叶宽、叶面积性状的QTL进行定位分析,共检测到35个剑叶形态相关性状的QTL.其中包含6个与剑叶叶长相关的QTL(分蘖期5个、成熟期1个),其中一个的LOD值高达6.92;8个与剑叶叶宽相关的QTL(只在分蘖期检测到),其中一个的LOD值高达4.51;21个与剑叶叶面积相关的QTL(分蘖期12个、成熟期9个),其中两个的LOD值分别高达6.37和4.06.对这些QTL区间内与剑叶叶长、叶宽、叶面积相关的候选基因进行定量分析,发现LOCOs02g52040,LOCOs03g46610,LOCOs04g52230,LOCOs04g44150,LOCOs04g52479,LOCOs09g37400,LOCOs12g42020这7个基因在双亲间的表达量差异显著,结合亲本剑叶叶长、叶宽、叶面积的数据结果,推测LOCOs04g52230,LOCOs04g44150,LOCOs09g37400,LOCOs12g42020的高表达可能会促进水稻剑叶的增宽增长,叶面积增大,而LOCOs02g52040,LOCOs03g46610,LOCOs04g52479的高表达可能抑制水稻剑叶的生长.本研究通过QTL分析,挖掘了调控水稻剑叶叶长、叶宽及叶面积的QTL位点,为培育株型优良的水稻新品种提供了参考.

Leaf is an important organ of rice,and it is the main place for photosynthesis.Leaf morphology related traits such as leaf length,leaf width and leaf area can directly affect leaf photosynthetic efficiency.The study of quantitative trait loci(QTL)sites for morphological characters of rice flag leaf and the improvement of morphological characters of rice flag leaf by means of genetic breeding can provide theoretical basis for the cultivation of ideal plant type rice.In this study,an indica rice variety HZ was used as the male parent,and a japonica rice variety Nekken2 was used as the female parent.After F1 generation was obtained by cross-breeding,120 recombinant inbred lines(RIL populations)were obtained from successive generations of self-crossing,which were used as experimental materials in this study.Leaf length,leaf width,leaf area of rice at tillering stage and mature stage were studied and analyzed after incubation under the same and appropriate conditions.At the same time,the genetic map was constructed by using the RIL population to locate the QTLs for the traits of leaf length,leaf width and leaf area in rice at tillering stage and mature stage,35 QTLs related to leaf morphology were detected.There were 6 QTLs related to blade length(5 at tillering stage,1 at maturation stage),LOD value of one of them was as high as 6.92;8 QTLs related to blade width(detected only at tillering stage),LOD value of one was as high as 4.51;21 QTLs related to blade area(12 at tillering stage,9 at mature stage),LOD values of two of them were as high as 6.37 and 4.06 respectively.Through quantitative analysis of the candidate genes related to leaf length,leaf width and leaf area in these QTL regions,it was found that LOCOs02g52040,LOCOs03g46610,LOCOs04g52230,LOCOs04g42230,LOCOs04g44150,LOCOs04g52479,LOCOs09g37400 and LOCOs12g42020 were significantly different in expression levels between the parents.Combined with the data of leaf length,leaf width and leaf area of the parents,we speculated that The high expressions of LOCOs04g52230,LOCOs04g44150,LOCOs09g37400 and LOCOs12g42020 may promote the growth of leaf width and leaf area,while the high expressions of LOCOs02g52040,LOCOs03g46610 and LOCOs04g52479 may inhibit the growth of rice flag leaves.Through the analysis of QTL in this study,QTL regulating leaf length,leaf width and leaf area of rice flag leaf were excavated,which provided a reference for cultivating new rice varieties with excellent plant type.