Developmental signals and environmental stresses regulate carbon distribution in the vegetative and reproductive organs of plants and affect seed yield. Cleistogenes songorica is a xerophytic grass with great potential application value in ecological restoration. However, how carbohydrate transport and distribution during grain filling affect the seed yield of C. songorica under water stress is not clear. The present study showed that the soluble sugar and starch contents of cleistogamous (CL) spikes and chasmogamous (CH) spikes were significantly higher at the milk stage, which was attributed to a significantly higher seed number and seed yield per spike under water stress conditions than under well-watered conditions (P < 0.01). RNA-seq data revealed a total of 54,525 differentially expressed genes (DEGs) under water stress conditions, but only 3744 DEGs were shared among all comparison groups. Weighted gene co-expression network analysis showed that the transport and distribution of carbohydrates were regulated by ABA-responsive genes (CsABA8OX1_1, CsABA8OX1_2, CsABA8OX2_1, CsABA8OX2_2, CsNCED3, CsNCED1_1, CsNCED1_2 and CsNCED4_1) and sugar transport and starch synthesis genes (CsSUS1, CsSUS2, CsSUS3, CsAGP1, CsAGP4, CsAGP5, CsSSS1 and CsSBE5) under water stress conditions. These genes jointly regulated carbohydrate remobilization in sources (stems, leaves and sheaths) to promote grain filling and improve seed yield. The present study helped to clarify the phenotypic, metabolic and transcriptional response mechanisms of vegetative organs, such as stems and leaves, and reproductive organs, such as CL spikes and CH spikes, to promote carbohydrate redistribution under water stress, and it provides theoretical guidance for improving seed yields.

发育信号和环境胁迫调节植物营养和生殖器官中的碳分布并影响种子产量。Cleistogenes songorica是一种旱生草，在生态修复中具有巨大的潜在应用价值。然而，在水分胁迫下，灌浆过程中碳水化合物的运输和分配如何影响松果的种子产量尚不清楚。本研究表明，在泌乳期，cleistogamous (CL) 穗和 chasmogamous (CH) 穗的可溶性糖和淀粉含量显着升高，这归因于水分胁迫条件下种子数和每穗的种子产量显着高于在充分浇水的条件下（P< 0.01)。RNA-seq 数据显示，在水分胁迫条件下，共有 54,525 个差异表达基因 (DEG)，但所有对照组仅共享 3744 个差异表达基因 (DEG)。加权基因共表达网络分析表明，碳水化合物的转运和分布受ABA反应基因（CsABA8OX1_1、CsABA8OX1_2、CsABA8OX2_1、CsABA8OX2_2、CsNCED3、CsNCED1_1、CsNCED1_2和CsNCED4_1）和糖转运和淀粉合成基因（CsSUS1、CsSUS2 ）的调控。 , CsSUS3 , CsAGP1 , CsAGP4 ,CsAGP5，CsSSS1和CsSBE5）在水分胁迫条件下。这些基因共同调节来源（茎、叶和鞘）中的碳水化合物再活化，以促进籽粒灌浆并提高种子产量。本研究有助于阐明植物茎叶等植物器官和 CL 尖峰和 CH 尖峰等生殖器官的表型、代谢和转录反应机制，以促进水分胁迫下碳水化合物的再分配，并提供理论指导。提高种子产量。