College of Grassland Science and Technology, Sichuan Agricultural University, Chengdu, 611130, China.
Sichuan Provincial Forestry and Grassland Development Research Center, Chengdu, 610081, China.
BMC Genomics. 2024 Oct 8;25(1):947. doi: 10.1186/s12864-024-10844-8.
Elephant grass (Cenchrus purpureus) is a perennial forage grass characterized by tall plants, high biomass and wide adaptability. Low-temperature stress severely limits elephant grass biomass and geographic distribution. WRKY is one of the largest families of plant-specific transcription factors and plays important roles in plant resistance to low-temperature. However, the understanding of the WRKY family in grasses is limited. In this study, we conducted a genome-wide characterization of WRKY proteins in elephant grass, including gene structure, phylogeny, expression, conserved motif organization, and functional annotation, to identify key CpWRKY candidates involved in cold tolerance.
In this study, a total of 176 WRKY genes were identified in elephant grass. It was found that 172 were unevenly distributed across its 14 chromosomes, while the remaining 4 genes were not anchored to any chromosome. The genes were classified into three groups based on their WRKY conserved domains and zinc finger motifs. There were 12, 8, 19, 27, 12, 18 and 80 CpWRKYs belonging to group I, group IIa, group IIb, group IIc, group IId, group IIe and group III, respectively. We hypothesized that the ancient subgroup IIc WRKY gene is the ancestor of all WRKY genes in elephant grass. Most CpWRKYs in the same group have similar structure and motif composition. A total of 169 duplicate gene pairs were identified, suggesting that segmental duplication might have contributed to the expansion of the CpWRKY gene family. Ka/Ks analysis revealed that most of the CpWRKYs were subjected to purifying selection during the evolution. It was also found that six genes (CpWRKY51, CpWRKY81, CpWRKY100, CpWRKY101, CpWRKY140 and CpWRKY143) exhibited higher expression in roots compare to leaves, and were significantly induced by low temperature stress. Among them, CpWRKY81 had the highest expression under low-temperature stress, and its over-expression significantly enhanced the cold tolerance in yeast.
In this study, we characterized WRKY genes in elephant grass and further investigated their physicochemical properties, evolution, and expression patterns under low-temperature stress. This research provides valuable resources for identifying key CpWRKY genes that contribute to cold tolerance in elephant grass.
象草（Cenchrus purpureus）是一种多年生饲料草，具有植株高大、生物量大和适应性广的特点。低温胁迫严重限制了象草的生物量和地理分布。WRKY 是植物特有的转录因子家族中最大的家族之一，在植物对低温的抗性中发挥着重要作用。然而，人们对禾本科植物 WRKY 家族的了解有限。在本研究中，我们对象草中的 WRKY 蛋白进行了全基因组特征分析，包括基因结构、系统发育、表达、保守基序组织和功能注释，以鉴定参与耐冷性的关键 CpWRKY 候选基因。
本研究在象草中共鉴定出 176 个 WRKY 基因。结果发现，172 个 WRKY 基因不均匀分布在其 14 条染色体上，而其余 4 个基因没有锚定到任何染色体上。根据 WRKY 保守结构域和锌指基序，这些基因被分为三组。分别有 12、8、19、27、12、18 和 80 个 CpWRKY 属于 I 组、IIa 组、IIb 组、IIc 组、IId 组、IIe 组和 III 组。我们假设古老的 IIc WRKY 基因亚组是象草中所有 WRKY 基因的祖先。同一组中的大多数 CpWRKY 具有相似的结构和基序组成。共鉴定出 169 对重复基因对，表明片段复制可能导致 CpWRKY 基因家族的扩张。Ka/Ks 分析表明，大多数 CpWRKY 在进化过程中受到了纯化选择。还发现，在低温胁迫下，6 个基因（CpWRKY51、CpWRKY81、CpWRKY100、CpWRKY101、CpWRKY140 和 CpWRKY143）在根中比叶中的表达更高，且受到低温胁迫的显著诱导。其中，CpWRKY81 在低温胁迫下表达最高，其过表达显著增强了酵母的耐寒性。
本研究对象草中的 WRKY 基因进行了特征分析，并进一步研究了它们在低温胁迫下的理化性质、进化和表达模式。这项研究为鉴定参与象草耐冷性的关键 CpWRKY 基因提供了有价值的资源。
