宁春4号与河东乌麦杂交F_2代穗部性状分析及其重要QTL发掘

Analysis on panicle traits and important QTL discovery of F_2 hybrids from Ningchun No.4 and Hedong black wheat

【目的】分析宁春4号与河东乌麦杂交F_2代的穗部性状,并利用SSR分子标记发掘其重要QTL,为宁夏小麦穗部性状改良提供理论参考。【方法】以宁春4号与河东乌麦杂交F_2代的331个单株为材料,利用方差分析、相关性分析、聚类分析和单标记回归分析等方法对5个穗部性状及其重要QTL进行定位研究。【结果】5个穗部性状在F_2代呈连续正态分布,符合多基因控制的数量性状的遗传特点。F_2代出现许多具有超亲性状的单株,穗长、总小穗数、结实小穗数、穗粒数和穗粒重的平均值分别为8.69 cm、18.01个、16.71个、33.07粒和1.19 g,超中亲比例分别达20.24%、44.71%、41.99%、34.14%和33.84%,超高亲比例依次为6.64%、18.73%、17.22%、34.14%和26.88%。5个穗部性状间均呈极显著正相关(P<0.01),表明这些性状对产量的贡献均较大。基于穗部性状测定结果,在遗传距离为5 c M时,可将F_2代331个单株分为八大类群,其中,类群Ⅰ平均穗长最长(为9.96 cm)、穗粒数最多(49.25粒)、穗粒重最重(1.61 g),类群Ⅷ平均总小穗数和结实小穗数最多,分别为21.40和19.57个,表明类群Ⅰ和Ⅷ为穗部性状优异类群。利用19个SSR分子标记共发掘出36个与穗部性状相关的QTL,其中,穗长、总小穗数、结实小穗数、穗粒数和穗粒重QTL数量分别有15、6、6、5和4个,分布在2A、4A、5A、1B、2B、3B、5B、7B、5D、6D和7D等11条染色体上,加性效应为-0.72～1.57,表型贡献率为2%～9%,LOD最大值为23.90,其中,4A染色体上检测到穗长、穗粒数和穗粒重QTL,5A染色体上检测到穗长、总小穗数和结实小穗数QTL,1B和5D染色体上均检测到穗长、总小穗数、结实小穗数、穗粒数和穗粒重QTL,2B染色体上检测到穗长、总小穗数、结实小穗数和穗粒重QTL,7B染色体上检测到穗长和总小穗数QTL,表明4A、5A、1B、2B、7B和5D等6条染色体存在QTL富集区。【结论】小麦杂交F_2代遗传性状处于高度分离,蕴藏着最大的数量遗传信息,为相关穗部性状分析及QTL发掘提供了可靠的遗传群体,检测到的36个QTL可用于小麦穗部性状的遗传改良。

【Objective】Panicle traits of F2 hybrids from Ningchun No.4 and Hedong black wheat were analyzed and their important QTLs were discovered by SSR molecular markers. It would provide reference for panicle traits improvement of Ningxia wheat.【Method】Three hundred and thirty-one individual plants of F2 hybrids from Ningchun No.4 and Hedong black wheat were as materials. By means of variance analysis,correlation analysis,cluster analysis and single marker regression analysis,five panicle traits and their important QTLs were studied.【Result】The five panicle traits showed continuous normal distribution in F2 hybrids,that conformed to the genetic characteristics of quantitative traits controlled by polygenes. There appeared many individual plants with superparental traits in F2 hybrids,the average values of panicle length,gross spikelet number,bearing spikelet number,kernels per spike and kernel weight per spike were 8.69 cm,18.01,16.71,33.07 and 1.19 g,respectively. The proportions of over mid-parents were 20.24%,44.71%,41.99%,34.14% and 33.84%,respectively,and their ultra-high parents were 6.64%,18.73%,17.22%,34.14% and 26.88%,respectively. The five panicle traits were in extremely significant positive correlation among each other(P<0.01),which showed that the contributions of these traits to yield were large. Based on the panicle traits,three hundred and thirty-one individual plants were divided into eight clusters at genetic distance being 5 cM. Group Ⅰ had the longest average panicle length (9.96 cm),the largest kernels per spike number(49.25 kernels)and largest kernel weight per spike(1.61 g). Group Ⅷ had the largest average gross spikelet number and bearing spikelet number,which were 21.04 and 19.57. It showed that group Ⅰ and group Ⅷ were groups with excellent panicle traits. Thirty-six panicle related QTL were discovered by nineteen SSR molecular markers. Among them,QTLs of the panicle length,gross spikelet number,bearing spikelet number, kernels per spike number and kernel weight per spike were 15,6,6,5 and 4,respectively. They were located on 11 chromosomes including 2A,4A,5A,1B,2B,3B,5B,7B,5D,6D and 7D. Their additive effects were -0.72 to 1.57,the contribution rates to phenotype were 2% to 9%,maximum LOD score was 23.90. QTLs of the panicle length,kernels per spike number and kernel weight per spike were detected on chromosome 4A. QTLs of the panicle length,gross spikelet number and bearing spikelet number were detected on chromosome 5A. QTLs of the panicle length,gross spikelet number,bearing spikelet number,kernels per spike and kernel weight per spike were all detected on chromosomes 1B and 5D. QTLs of the panicle length,gross spikelet number,bearing spikelet number,kernel weight per spike were detected on chromosome 2B. QTLs of the panicle length and gross spikelet numbers were detected on chromosome 7B. The results showed that QTL enrichment regions existed in chromosomes 4A,5A,1B,2B,7B and 5D.【Conclusion】The genetic characteristics in F2 hybrids of wheat are highly separated,and contain the maximum amount of genetic information,which provide the reliable genetic population for the panicle traits analysis and QTLs discovery. The detected 36 QTLs may be used for genetic improvement of panicle traits for wheat.