Yu Zhe-Ping, Lv Wen-Huan, Sharmin Ripa Akter, Kong Jie-Jie, Zhao Tuan-Jie
National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
Plants (Basel). 2023 Jun 10;12(12):2266. doi: 10.3390/plants12122266.
Seed-flooding stress is one of major abiotic constraints that adversely affects soybean production worldwide. Identifying tolerant germplasms and revealing the genetic basis of seed-flooding tolerance are imperative goals for soybean breeding. In the present study, high-density linkage maps of two inter-specific recombinant inbred line (RIL) populations, named NJIRNP and NJIR4P, were utilized to identify major quantitative trait loci (QTLs) for seed-flooding tolerance using three parameters viz., germination rate (GR), normal seedling rate (NSR), and electrical conductivity (EC). A total of 25 and 18 QTLs were detected by composite interval mapping (CIM) and mixed-model-based composite interval mapping (MCIM), respectively, and 12 common QTLs were identified through both methods. All favorable alleles for the tolerance are notably from the wild soybean parent. Moreover, four digenic epistatic QTL pairs were identified, and three of them showed no main effects. In addition, the pigmented soybean genotypes exhibited high seed-flooding tolerance compared with yellow seed coat genotypes in both populations. Moreover, out of five identified QTLs, one major region containing multiple QTLs associated with all three traits was identified on Chromosome 8, and most of the QTLs within this hotspot were major loci ( > 10) and detectable in both populations and multiple environments. Based on the gene expression and functional annotation information, 10 candidate genes from QTL "hotspot 8-2" were screened for further analysis. Furthermore, the results of qRT-PCR and sequence analysis revealed that only one gene, (), was significantly induced under flooding stress and displayed a TTC tribasic insertion mutation of the nucleotide sequence in the tolerant wild parent (PI342618B). encodes an ERF transcription factor, and the subcellular localization analysis using green fluorescent protein (GFP) revealed that protein was localized in the nucleus and plasma membrane. Furthermore, overexpression of significantly promoted the growth of soybean hairy roots, which might indicate its critical role in seed-flooding stress. Thus, was considered as the most possible candidate gene for seed-flooding tolerance.
种子淹水胁迫是影响全球大豆生产的主要非生物胁迫之一。鉴定耐淹种质并揭示种子耐淹性的遗传基础是大豆育种的重要目标。在本研究中，利用两个种间重组自交系（RIL）群体NJIRNP和NJIR4P的高密度连锁图谱，通过发芽率（GR）、正常幼苗率（NSR）和电导率（EC）三个参数来鉴定种子耐淹性的主要数量性状位点（QTL）。通过复合区间作图（CIM）和基于混合模型的复合区间作图（MCIM）分别检测到25个和18个QTL，两种方法共鉴定出12个共同的QTL。所有耐淹的有利等位基因均显著来自野生大豆亲本。此外，鉴定出4对双基因上位性QTL，其中3对无主效应。此外，在两个群体中，有色大豆基因型比黄种皮基因型表现出更高的种子耐淹性。此外，在鉴定出的5个QTL中，在第8号染色体上发现了一个包含与所有三个性状相关的多个QTL的主要区域，该热点区域内的大多数QTL是主效位点（>10），并且在两个群体和多个环境中均可检测到。基于基因表达和功能注释信息，从QTL“热点8-2”中筛选出10个候选基因进行进一步分析。此外，qRT-PCR和序列分析结果表明，在淹水胁迫下只有一个基因（）被显著诱导，并且在耐淹野生亲本（PI342618B）的核苷酸序列中显示出TTC三碱基插入突变。编码一种ERF转录因子，使用绿色荧光蛋白（GFP）进行的亚细胞定位分析表明，蛋白定位于细胞核和质膜。此外，的过表达显著促进了大豆毛状根的生长，这可能表明其在种子淹水胁迫中起关键作用。因此，被认为是种子耐淹性最有可能的候选基因。
