Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Japan.
Theor Appl Genet. 2011 Aug;123(3):475-82. doi: 10.1007/s00122-011-1600-1. Epub 2011 May 5.
Brassica napus, an allopolyploid species having the A genome of B. rapa and the C genome of B. oleracea, is self-compatible, although both B. rapa and B. oleracea are self-incompatible. We have previously reported that SP11/SCR alleles are not expressed in anthers, while SRK alleles are functional in the stigma in B. napus cv. 'Westar', which has BnS-1 similar to B. rapa S-47 and BnS-6 similar to B. oleracea S-15. This genotype is the most frequent S genotype in B. napus, and we hypothesized that the loss of the function of SP11 is the primary cause of the self-compatibility of 'Westar'. To verify this hypothesis, we transformed 'Westar' plants with the SP11 allele of B. rapa S-47. All the transgenic plants and their progeny were completely self-incompatible, demonstrating self-compatibility to be due to the S haplotype having the non-functional SP11 allele in the A genome, which suppresses a functional recessive SP11 allele in the C genome. An artificially synthesized B. napus line having two recessive SP11 alleles was developed by interspecific hybridization between B. rapa and B. oleracea. This line was self-incompatible, but F(1) hybrids between this line and 'Westar' were self-compatible. These results suggest that the self-compatibility mechanism of 'Westar' is applicable to F(1) seed production in B. napus.
甘蓝型油菜（Brassica napus）是一种异源多倍体物种，其 A 基因组来自白菜（B. rapa），C 基因组来自甘蓝（B. oleracea），尽管白菜和甘蓝都是自交不亲和的。我们之前报道过，SP11/SCR 等位基因在油菜‘Westar’的花药中不表达，而 SRK 等位基因在柱头中是有功能的，‘Westar’具有与白菜 S-47 相似的 BnS-1 和与甘蓝 S-15 相似的 BnS-6。这种基因型是油菜中最常见的 S 基因型，我们假设 SP11 功能的丧失是‘Westar’自交亲和性的主要原因。为了验证这一假设，我们用白菜 S-47 的 SP11 等位基因转化了‘Westar’植株。所有转基因植株及其后代都是完全自交不亲和的，这表明自交亲和性是由于 A 基因组中的 S 单倍型具有无功能的 SP11 等位基因，从而抑制了 C 基因组中隐性 SP11 等位基因的功能。通过白菜和甘蓝的种间杂交，我们开发了一个具有两个隐性 SP11 等位基因的人工合成油菜品系。这个品系是自交不亲和的，但这个品系与‘Westar’的 F1 杂种是自交亲和的。这些结果表明，‘Westar’的自交亲和机制适用于油菜 F1 种子的生产。
