Mature leaf degradation for supporting the younger leaf growth is a survival strategy for plants under waterlogging stress, but its molecular mechanism is rarely known. In this study, two barley cultivars Laurikka (B1) and Evergreen (B2), differing in waterlogging tolerance, were subjected to 6- or 10- day waterlogging stress during tillering stage. B1 was found more sensitive to waterlogging stress than B2, showing a more rapid leaf chlorophyll loss, but the elongation rate of the youngest leaf had little difference between the two cultivars. The youngest and mature leaves were sampled for dynamic transcriptome analysis. The results showed that 4384 genes were differentially expressed (DEGs) in the two cultivars, displaying significant enrichment of ATP binding, oxidoreductase and hydrolase activity and iron transport. More DEGs were identified between the waterlogging durations and leaf ages, whereas leaf age-specific DEGs were additionally enriched in the photosystem II, thylakoid membrane and carbohydrate binding pathways. A weighted gene co-expression network analysis (WGCNA) of 17669 highly expressed genes was performed to identify hub genes and construct regulatory networks. A cultivar-specific network was dominated by HST1, MLH1 and SYP22 etc., while leaf age-specific networks were largely regulated by chlorophyll metabolism related hub genes CURT1B, PNSL4, and PSY1 etc. This study provided a new insight into deciphering the role of hub genes, networks and pathways with relevance to whole leaves responses to waterlogging stress.

支持年轻叶片生长的成熟叶片降解是植物在涝渍胁迫下的生存策略，但其分子机制鲜为人知。在本研究中，耐涝性不同的两个大麦品种 Laurikka (B1) 和 Evergreen (B2) 在分蘖期经受 6 天或 10 天的涝渍胁迫。发现B1比B2对淹水胁迫更敏感，表现出叶片叶绿素损失更快，但两个品种之间最年轻的叶片伸长率几乎没有差异。对最年轻和成熟的叶子进行采样以进行动态转录组分析。结果表明，4384个基因在两个品种中差异表达（DEGs），显示出显着富集的ATP结合、氧化还原酶和水解酶活性以及铁转运。在涝渍持续时间和叶龄之间发现了更多的 DEG，而叶龄特异性 DEG 在光系统 II、类囊体膜和碳水化合物结合途径中也富集。对 17669 个高表达基因进行加权基因共表达网络分析 (WGCNA)，以确定枢纽基因并构建调控网络。一个品种特定的网络由HST1、MLH1和SYP22等，而叶龄特异性网络主要受叶绿素代谢相关枢纽基因CURT1B、PNSL4和PSY1等调控。本研究为破译相关枢纽基因、网络和通路的作用提供了新见解全叶对涝渍胁迫的反应。