Department of Plant Sciences, Rothamsted Research, Harpenden AL5 2JQ, UK.
Plant J. 2012 Aug;71(3):503-16. doi: 10.1111/j.1365-313X.2012.05015.x. Epub 2012 Jun 8.
Interploidy crosses fail in many plant species due to abnormalities in endosperm development. In the inbreeding species Arabidopsis thaliana, both paternal and maternal excess interploidy crosses usually result in viable seed that exhibit parent-of-origin effects on endosperm development and final seed size. Paternal excess crosses result in extended proliferation of the endosperm and larger seeds, while conversely maternal excess crosses result in early endosperm cellularisation and smaller seeds. Investigations into the effect of parental gene dosage on seed development have revealed that MADS box transcription factors, particularly the AGAMOUS-like family, play important roles in controlling endosperm proliferation. The important crop genus Brassica contains self-incompatible outbreeding species and has a larger and more complex genome than the closely related Arabidopsis. Here we show that although Brassica oleracea displays strong parent-of-origin effects on seed development, triploid block due to lethal disruption of endosperm development was restricted to paternal excess, with maternal excess crosses yielding viable seed. In addition, transcriptome analyses of Brassica homologues of Arabidopsis genes linked to parent-of-origin effects revealed conservation of some mechanisms controlling aspects endosperm behaviour in the two species. However, there were also differences that may explain the failure of the paternal excess cross in B. oleracea.
在许多植物物种中，由于胚乳发育异常，异倍性杂交失败。在自交物种拟南芥中，父本和母本过量的异倍性杂交通常会产生有活力的种子，这些种子在胚乳发育和最终种子大小上表现出亲本来源效应。父本过量杂交导致胚乳的延长增殖和更大的种子，而相反的母本过量杂交导致早期胚乳细胞化和更小的种子。对亲本基因剂量对种子发育影响的研究表明，MADS 盒转录因子，特别是 AGAMOUS 样家族，在控制胚乳增殖中发挥重要作用。重要的作物属芸薹属包含自交不亲和的杂交种，其基因组比密切相关的拟南芥更大、更复杂。在这里，我们表明，尽管甘蓝型油菜在种子发育上表现出强烈的亲本来源效应，但由于胚乳发育致死破坏导致的三倍体阻断仅限于父本过量，而母本过量杂交则产生有活力的种子。此外，对与亲本来源效应相关的拟南芥基因的芸薹属同源物的转录组分析揭示了一些控制两个物种胚乳行为的机制的保守性。然而，也存在一些差异，这可能解释了父本过量杂交在甘蓝型油菜中的失败。
