燕麦不同组合正、反交杂种后代的表型及遗传参数分析

Phenotype and genetic variation analysis of forward and reverse hybrid progeny from different oat crosses

为了明确燕麦不同组合正、反交杂种后代的表型差异及遗传变异情况,本研究以福瑞至(F709)与709(709F)、牧乐思(ML2)与陇燕2号(L2M)为亲本配制正、反交组合,用简单序列重复分子标记对杂种F1代进行了鉴定,比较了正、反交杂种的表型差异,并分析了杂种F_(2)代的遗传变异及多样性。结果表明:用SSR分子标记从37个F_(1)单株中共鉴定出32个真杂种,占比86.5%。福瑞至和709、牧乐思和陇燕2号组合的F_(1)真杂种率分别为88.9%和84.2%。正、反交对杂种后代的表型有显著影响。F709-F_(1)的旗叶比反交的窄19.4%;ML2-F_(1)的主穗粒数比反交少12.2%。F_(2)群体遗传变异幅度较大。同一性状在正、反交F_(2)中的遗传变异系数(G_(cv))、广义遗传力(Hb)和相对遗传进度(ΔGt)存在显著差异。F_(2)群体株高的遗传变异系数较小(4.50%~10.27%)、广义遗传力较高(33.12%~85.41%),分蘖数和有效分蘖数的相对遗传进度较大。福瑞至和709的正、反交F2群体的穗下节长的广义遗传力是所有指标中最低的,分别为14.13%和23.81%,相对遗传进度也最小。主穗粒数的Gcv在其正、反交F_(2)中的差异最显著,在F709-F_(2)中为7.09%,反交中增至19.03%;F709-F_(2)的Hb为22.54%,反交则为66.01%。牧乐思和陇燕2号的正、反交F_(2)群体叶片数的广义遗传力最高(99.53%),几乎不受环境的影响。ML2-F_(2)旗叶宽的Hb为9.07%,其ΔG_(t)为2.79,反交中旗叶宽的Hb为30.23%,ΔGt为9.77。10对SSR引物对F2群体扩增的多态性比率达73.5%,实际杂合度为0.35~0.99,远高于期望杂合度;Nei’s基因多态性、香农指数分别为0.29~0.50和0.53~0.71,F_(2)群体分离现象明显,遗传变异幅度大,具有较大的选择空间。

In order to clarify the phenotypic and genetic variation differences of F_(1) and backcross hybrid progenies in oat(Avena sativa),crosses were made in this study between four oat varieties:Forage(F709),709(709F),Molass(ML2)and Longyan No.2(L2M).Molecular identification of hybrid F_(1) plants was conducted by simple sequence repeat(SSR)and their phenotypic differences were compared.The genetic variation and diversity of the F2 generation were also analyzed.It was found that 32 from 37(86.5%)of F1 plants were identified as true hybrids based on SSR.True hybrid rates of up to 88.9% were obtained for the Forage and 709 crosses,and rates of up to 84.2%were obtained for Molass and Longyan No.2.The cross mode significantly affected hybrid phenotype.The flag leaf width of F709-F1 was 19.4% narrower than that of 709F-F1.The grain number of the main panicle of ML2-F1 was 12.2%less than that of L2M-F1.The genetic variation of the F2 population was remarkable.Significant differences were observed in the F2 genetic variation coefficient(Gcv),generalized heritability(Hb)and relative genetic progress(ΔG_(t))of the same trait in F_(1) and backcrosses.Among the F_(2 )population,plant height had the lowest G_(cv)(4.50%-10.27%)and higher Hb(33.12%-85.41%)while tiller number and effective tiller number had the greatest relative genetic progress.The Hb of peduncle length of the F_(2) population from Forage and 709 was the lowest(14.13%for the F_(1) cross and 23.81%for the backcross),with the least relative genetic progress.Significant G_(cv) and Hb differences between the F1 and backcrosses,were observed for grain number of the main panicle with values of 7.09%and 22.54%,respectively in F709-F_(2),and 19.03% and 66.01%in the backcross.The leaf number of the F_(2) population from Molass and Longyan No.2 had the highest Hb(99.53%),indicating little environmental effect.The Hb of flag leaf width of ML2-F_(2) was 9.07%,and ΔG_(t) was 2.79,while in L2M-F_(2),Hb was 30.23% andΔGt was 9.77.Ten polymorphic SSR primers resulted in 73.5%polymorphism rate in the F_(2)population.Actual heterozygosity(0.35-0.99)was much higher than the expected heterozygosity.The Nei’s gene polymorphism and Shannon index were 0.29-0.50 and 0.53-0.71,respectively,indicating an obvious segregation and greater variation with great selection potential.