芝麻栽培种与野生种(Sesamum indicatum)杂种F_1的获得及特性鉴定

Production and Identification of F_1 Interspecific Hybrid Between Sesamum indicum and Wild Relative S. Indicatum

【目的】通过远缘杂交获得芝麻栽培种与野生种的杂交后代,改良芝麻栽培种对茎点枯病的抗性。【方法】对野芝3号(S.indicatum)(P_3)和芝麻栽培种中芝14(P_1)、中芝14同源四倍体(P_2)进行正反种间杂交,通过幼胚培养技术获得杂种F1植株。首先利用SSR分子标记、细胞学、形态学方法进行后代真实性鉴定,筛选出真杂种。后对种间杂交的3个亲本(野芝3号、中芝14及其同源四倍体)以及杂种后代F1株系进行茎点枯病人工接种鉴定。【结果】种间正反交组合后代的幼胚成苗率有明显差异,在接种的773个幼胚中,有155个幼胚发育成苗,平均幼胚成苗率为20.05%。种间正交组合(P_3×P_1、P_3×P_2分别为32.75%和21.11%),高于反交组合(P_1×P_3、P_2×P_3分别为8.84%和13.41%)。说明亲本的基因型在很大程度上影响远缘杂交的成苗率。P_3×P_1、P_1×P_3组合F1植株染色体数目为42条;P_3×P_2、P_2×P_3组合F1染色体数目为55条,正反交杂种F1株系大部分花粉粒形态独特,形状规则但多无内含物,为高度不育类型;部分F1株系有少量的可育花粉,为部分不育型。选用多态性较好的HS142引物在亲本中芝14中能清晰的扩增出2条特异性条带(约460和500 bp),在野芝3号则扩增出1条特异性条带(约380 bp)。然后对12个后代进行鉴定,其中有10个杂种F1植株同时具有3条父、母本特异条带,另2株仅出现母本或父本带为假杂种。以高抗种质野芝3号为母本的种间杂交P_3×P_1、P_3×P_2后代染病的病斑长度分别为9.35和6.65 cm,反交组合后代的病斑长度分别为9.90和8.90 cm;所有杂交组合的后代对茎点枯病抗性均高于其栽培种亲本(P_1 14.30 cm和P_2 11.46 cm),但低于野生种亲本(P_3 4.80 cm)。【结论】通过种间杂交结合幼胚培养可以筛选出茎点枯病抗性明显高于芝麻栽培亲本的新种质。

[Objective] The progenies ofSesamum indicum and wild species were obtained by interspecific hybridization in order to improve charcoal rot disease （Macrophominaphaseolina） resistance of sesame cultivars. [Method] No.3 wild sesame （S. indicatum） （P3）, Zhongzhi 14 （P1） and autotetraploid of Zhongzhi 14 （P2） were used as reciprocal cross parents, the Fx plants of interspecific hybrids were obtained using the immature embryo culture technique. First, the authenticity of FI progenies were confirmed by using phenotypic, cytological and SSR marker methods in order to screen out the true hybrids. Then the three parents of the interspecific hybrids （No.3 wild sesame, Zhongzhi 14 and autotetraploid of Zhongzhi 14 ）and hybrids of F1 lines resistance to Macrophomina phaseolina was identified by artificial inoculations. [Result] The seedling ratios of immature embryos between reciprocal combinations existed significant difference. The 773 immature embryos were inoculated of which 155 embryos developed into seedlings and the average seedling rate was 20.05%. The seedling ratios of combinations （P3×P1 32.75%, P3×P2 21.11%） were higher than those of reciprocal combinations （P1×P3 8.84%, P2×P3 13.41%）. This indicates that the genotype of the parent affects the seedling rate of distant hybridization to a large extent. The number of chromosomes in the F1 plants of （P3 ×P1, P1 × P3） was 42 and in the F1 plants of （P3 × P2, P2 × P3） was 55. The majority of the pollen grains of the F1 hybrids were regular but no inclusions, all of which were highly sterile. HS142 primer with a better polymorphism could be clearly amplified two specific types in Zhongzhil4 （about 460 bp and 500 bp） and the one in No.3 wild sesame（about 380 bp） .Then, it could be used to identify twelve hybrid progenies and their parents. There are ten of F1 progenies with three male and female-specific markers of the parents, the other two plants only appeared in the female parent or male parent type which was the fake hybrids. The infected lesion length of progenies from interspecific hybridization P3×P1, P3×P2, using No.3 wild sesame with high charcoal rot resistance as female parent, was 9.35 cm and 6.65 cm, respectively, while 9.90 cm and 8.90 cm from reciprocal combinations. The resistance to resacrophomina phaseolina of progenies from all combinations was higher than their cultivated parents （P1 14.30 cm and P2 11.46 cm）, but weaker than wild relative （P3 4.80 cm）. [Conclusion] New germplasms with high charcoal rot resistance can be created through interspecific hybridization combined with immature embryo culture, which provides important materials for genetic improvement of sesame with charcoal rot resistance.