National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, 430070, Wuhan, China.
Global Institute for Food Security, University of Saskatchewan, Saskatoon, SK, S7N 4J8, Canada.
Commun Biol. 2022 Dec 23;5(1):1412. doi: 10.1038/s42003-022-04374-w.
Production of viable progeny from interploid crosses requires precise regulation of gene expression from maternal and paternal chromosomes, yet the transcripts contributed to hybrid seeds from polyploid parent species have rarely been explored. To investigate the genome-wide maternal and paternal contributions to polyploid grain development, we analyzed the transcriptomes of developing embryos, from zygote to maturity, alongside endosperm in two stages of development, using reciprocal crosses between tetraploid and hexaploid wheats. Reciprocal crosses between species with varied levels of ploidy displayed broad impacts on gene expression, including shifts in alternative splicing events in select crosses, as illustrated by active splicing events, enhanced protein synthesis and chromatin remodeling. Homoeologous gene expression was repressed on the univalent D genome in pentaploids, but this suppression was attenuated in crosses with a higher ploidy maternal parent. Imprinted genes were identified in endosperm and early embryo tissues, supporting predominant maternal effects on early embryogenesis. By systematically investigating the complex transcriptional networks in reciprocal-cross hybrids, this study presents a framework for understanding the genomic incompatibility and transcriptome shock that results from interspecific hybridization and uncovers the transcriptional impacts on hybrid seeds created from agriculturally-relevant polyploid species.
从不同倍性的杂交中产生有活力的后代需要精确调控来自母本和父本染色体的基因表达，但来自多倍体亲本物种的杂种种子的转录本很少被探索。为了研究多倍体谷物发育过程中基因组范围的母本和父本贡献，我们使用四倍体和六倍体小麦的正反交，分析了从合子到成熟的发育胚胎以及两个发育阶段的胚乳的转录组。不同倍性物种之间的正反交广泛影响基因表达，包括在特定杂交中选择性剪接事件的变化，如活跃的剪接事件、增强的蛋白质合成和染色质重塑所示。在五倍体中，同源基因在单价 D 基因组上被抑制，但在与更高倍性母本的杂交中这种抑制被减弱。在胚乳和早期胚胎组织中鉴定了印迹基因，支持早期胚胎发生中主要的母本效应。通过系统研究正反交杂种中的复杂转录网络，本研究为理解种间杂交导致的基因组不兼容性和转录组冲击提供了一个框架，并揭示了来自农业相关多倍体物种的杂种种子的转录影响。
