Li Dandan, Yu Fushun, Zhang Yanzhao, Hu Kaihong, Dai Dongyang, Song Siwen, Zhang Fan, Sa Rina, Lian Hua, Sheng Yunyan
College of Horticulture and Landscape Architecture, Heilongjiang Bayi Agriculture University, Daqing, Heilongjiang, China.
Front Plant Sci. 2023 Jan 18;13:1093859. doi: 10.3389/fpls.2022.1093859. eCollection 2022.
Low light stress inhibits plant growth due to a line of physiological disruptions in plants, and is one of the major barriers to protected cucumber cultivation in northern China.
To comprehensively understand the responses of cucumber seedlings to low-light stress, the low-light-tolerant line (M67) and The low-light-sensitive line (M14) were conducted for the analysis of photosynthetic phenotype, RNA sequencing (RNA-seq) and the expression level of photosynthesis-related genes in leaves under low-light stress and normal light condition (control).
The results showed that there was a sharp decrease in the photosynthate accumulation in the leaves of the sensitive line, M14, resulting in a large decrease in the photosynthetic rate (Pn) (with 31.99%) of leaves compared to that of the control, which may have been caused by damage to chloroplast ultrastructure or a decrease in chlorophyll (Chl) content. However, under the same low-light treatment, there was no large drop in the photosynthate accumulation and even no decrease in Pn and Chl content for the tolerant line, M67. Moreover, results of gene expression analysis showed that the expression level of genes (the photosystem II oxygen-evolving enhancer protein 3 gene) and (ATPase, F1 complex gene) in the M14 leaves decreased sharply (by 35.04% and 30.58%, respectively) compared with the levels in the M67 leaves, which decreased by 14.78% and 23.61%, respectively. The expression levels of genes involved in Chl synthesis and carbohydrate biosynthesis in the leaves of M14 decreased markedly after low-light treatment; in contrast, there were no sharp decreases or changes in leaves of M67.
Over all, the ability of cucumber to respond to low-light stress, as determined on the basis of the degree of damage in leaf structure and chloroplast ultrastructure, which corresponded to decreased gene expression levels and ATP phosphorylase activity, significantly differed between different low-light-tolerant lines, which was manifested as significant differences in photosynthetic capacity between them. Results of this study will be a reference for comprehensive insight into the physiological mechanism involved in the low-light tolerance of cucumber.
弱光胁迫会因一系列植物生理紊乱而抑制植物生长，是中国北方保护地黄瓜栽培的主要障碍之一。
为全面了解黄瓜幼苗对弱光胁迫的响应，以耐弱光品系（M67）和弱光敏感品系（M14）为材料，分析了弱光胁迫和正常光照条件（对照）下叶片的光合表型、RNA测序（RNA-seq）及光合作用相关基因的表达水平。
结果表明，敏感品系M14叶片光合产物积累急剧下降，导致叶片光合速率（Pn）较对照大幅降低（降低31.99%），这可能是由于叶绿体超微结构受损或叶绿素（Chl）含量降低所致。然而，在相同的弱光处理下，耐弱光品系M67的光合产物积累没有大幅下降，甚至Pn和Chl含量也没有降低。此外，基因表达分析结果显示，M14叶片中基因（光系统II放氧增强蛋白3基因）和基因（ATP酶，F1复合体基因）的表达水平与M67叶片相比急剧下降（分别下降35.04%和30.58%），而M67叶片中这两个基因的表达水平分别下降了14.78%和23.61%。弱光处理后，M14叶片中参与Chl合成和碳水化合物生物合成的基因表达水平显著下降；相比之下，M67叶片中没有急剧下降或变化。
总体而言，基于叶片结构和叶绿体超微结构的损伤程度确定的黄瓜对弱光胁迫的响应能力，与基因表达水平和ATP磷酸化酶活性的降低相对应，在不同耐弱光品系之间存在显著差异，表现为它们之间光合能力的显著差异。本研究结果将为全面深入了解黄瓜耐弱光生理机制提供参考。
