Soybean (Glycine max) is an important legume crop that was domesticated in temperate regions. Soybean varieties from these regions generally mature early and exhibit extremely low yield when grown under inductive short-day (SD) conditions at low latitudes. The long-juvenile (LJ) trait, which is characterized by delayed flowering and maturity, and improved yield under SD conditions, allowed the cultivation of soybean to expand to lower latitudes. Two major loci control the LJ trait: J and E6. In the current study, positional cloning, sequence analysis, and transgenic complementation confirmed that E6 is a novel allele of J, the ortholog of Arabidopsis thaliana EARLY FLOWERING 3 (ELF3). The mutant allele e6^PG, which carries a Ty1/Copia-like retrotransposon insertion, does not suppress the legume-specific flowering repressor E1, allowing E1 to inhibit Flowering Locus T (FT) expression and thus delaying flowering and increasing yields under SD conditions. The e6^PG allele is a rare allele that has not been incorporated into modern breeding programs. The dysfunction of J might have greatly facilitated the adaptation of soybean to low latitudes. Our findings increase our understanding of the molecular mechanisms underlying the LJ trait and provide valuable resources for soybean breeding.

中文翻译：

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最近 J 的逆转录转座子插入导致 E6 基因座促进大豆适应低纬度

大豆（Glycine max）是温带地区驯化的重要豆类作物。这些地区的大豆品种通常早熟，在低纬度诱导性短日照 (SD) 条件下生长时产量极低。长幼苗 (LJ) 性状以开花和成熟延迟为特征，在 SD 条件下提高产量，使大豆的种植范围扩大到低纬度地区。两个主要位点控制 LJ 性状：J和E6。在目前的研究中，定位克隆，序列分析，和转基因互补证实E6是一种新颖的等位基因Ĵ，的直向同源物拟南芥早期开花3（ELF3 )。携带Ty1/Copia样逆转录转座子插入的突变等位基因e6 ^PG不抑制豆科植物特异性开花抑制因子E1，允许E1抑制开花位点 T ( FT ) 表达，从而延迟开花并增加 SD 条件下的产量。在E6 ^PG等位基因是尚未纳入现代育种计划罕见的等位基因。J的功能障碍可能极大地促进了大豆对低纬度的适应。我们的发现增加了我们对 LJ 性状潜在分子机制的理解，并为大豆育种提供了宝贵的资源。