A recessive allele for delayed flowering at the soybean maturity locus E9 is a leaky allele of FT2a, a FLOWERING LOCUS T ortholog.
A recessive allele for delayed flowering at the soybean maturity locus E9 is a leaky allele of FT2a, a FLOWERING LOCUS T ortholog.
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大豆成熟基因座 E9 延迟开花的隐性等位基因是 FT2a（开花基因座 T 直系同源物）的泄漏等位基因
DOI：
10.1186/s12870-016-0704-9
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发表时间：
2016-01-19
影响因子：
5.3
通讯作者：
Abe J
中科院分区：
文献类型：
--
作者：
Zhao C;Takeshima R;Zhu J;Xu M;Sato M;Watanabe S;Kanazawa A;Liu B;Kong F;Yamada T;Abe J
了解种子开花和成熟的分子机制，对于提高种子作物在不同环境中的适应性和产量具有重要意义。在大豆这一兼性短日照植物中，四个成熟基因E1到E4的遗传变异在适应不同光周期的环境中起着重要作用。然而，人们对开花和成熟过程中自然变异的分子基础了解甚少。利用早熟大豆品种间的杂交，对开花基因进行了遗传和分子研究。该杂交后代分离出两个成熟度基因座：E1和E9。对后一个基因座进行了详细的分子分析，以确定致病基因。精细定位、测序和表达分析表明，E9是拟南芥开花基因T的同源基因FT2a，与E9相比，E9等位基因转录水平很低，开花延迟。尽管编码序列相同，但在两个品种之间的启动子、非翻译区和内含子中检测到了许多单核苷酸多态和插入/缺失。此外，E9等位基因在第一内含子中插入了一个Ty1/Copia样反转录转座子sore-1。比较不同等位基因在近等基因系和光周期不敏感品种中的表达水平表明，SORE-1的插入通过其等位基因特异性转录抑制而减弱了FT2a的表达。SORE-1高度甲基化，似乎没有中断FT2a RNA的加工。大豆成熟基因E9是FT2a，它的隐性等位基因由于SORE-1的插入导致等位基因特异性转录抑制而导致转录丰度降低而延迟开花。因此，FT2a转录本的丰度与大豆开花时间的变化直接相关。E9等位基因可能在早花遗传背景下维持营养生长，也可作为在低纬地区短日照条件下导致晚花的长幼等位基因。本文的在线版本(doi：10.1186/s12870-0160704-9)包含补充材料，授权用户可以使用。
Understanding the molecular mechanisms of flowering and maturity is important for improving the adaptability and yield of seed crops in different environments. In soybean, a facultative short-day plant, genetic variation at four maturity genes, E1 to E4, plays an important role in adaptation to environments with different photoperiods. However, the molecular basis of natural variation in time to flowering and maturity is poorly understood. Using a cross between early-maturing soybean cultivars, we performed a genetic and molecular study of flowering genes. The progeny of this cross segregated for two maturity loci, E1 and E9. The latter locus was subjected to detailed molecular analysis to identify the responsible gene. Fine mapping, sequencing, and expression analysis revealed that E9 is FT2a, an ortholog of Arabidopsis FLOWERING LOCUS T. Regardless of daylength conditions, the e9 allele was transcribed at a very low level in comparison with the E9 allele and delayed flowering. Despite identical coding sequences, a number of single nucleotide polymorphisms and insertions/deletions were detected in the promoter, untranslated regions, and introns between the two cultivars. Furthermore, the e9 allele had a Ty1/copia–like retrotransposon, SORE-1, inserted in the first intron. Comparison of the expression levels of different alleles among near-isogenic lines and photoperiod-insensitive cultivars indicated that the SORE-1 insertion attenuated FT2a expression by its allele-specific transcriptional repression. SORE-1 was highly methylated, and did not appear to disrupt FT2a RNA processing. The soybean maturity gene E9 is FT2a, and its recessive allele delays flowering because of lower transcript abundance that is caused by allele-specific transcriptional repression due to the insertion of SORE-1. The FT2a transcript abundance is thus directly associated with the variation in flowering time in soybean. The e9 allele may maintain vegetative growth in early-flowering genetic backgrounds, and also be useful as a long-juvenile allele, which causes late flowering under short-daylength conditions, in low-latitude regions. The online version of this article (doi:10.1186/s12870-016-0704-9) contains supplementary material, which is available to authorized users.