College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China.
Genes (Basel). 2021 Oct 29;12(11):1735. doi: 10.3390/genes12111735.
Excessive aluminum ions (Al) in acidic soil can have a toxic effect on watermelons, restricting plant growth and reducing yield and quality. In this study, we found that exogenous application of nitric oxide (NO) could increase the photochemical efficiency of watermelon leaves under aluminum stress by promoting closure of leaf stomata, reducing malondialdehyde and superoxide anion in leaves, and increasing POD and CAT activity. These findings showed that the exogenous application of NO improved the ability of watermelon to withstand aluminum stress. To further reveal the mitigation mechanism of NO on watermelons under aluminum stress, the differences following different types of treatments-normal growth, Al, and Al + NO-were shown using de novo sequencing of transcriptomes. In total, 511 differentially expressed genes (DEGs) were identified between the Al + NO and Al treatment groups. Significantly enriched biological processes included nitrogen metabolism, phenylpropane metabolism, and photosynthesis. We selected 23 genes related to antioxidant enzymes and phenylpropane metabolism for qRT-PCR validation. The results showed that after exogenous application of NO, the expression of genes encoding and increased, consistent with the results of the physiological indicators. The expression patterns of genes involved in phenylpropanoid metabolism were consistent with the transcriptome expression abundance. These results indicate that aluminum stress was involved in the inhibition of the photosynthetic pathway, and NO could activate the antioxidant enzyme defense system and phenylpropane metabolism to protect cells and scavenge reactive oxygen species. This study improves our current understanding by comprehensively analyzing the molecular mechanisms underlying NO-induced aluminum stress alleviation in watermelons.
土壤酸化会导致过量的铝离子（Al）对西瓜产生毒害作用，抑制植物生长，降低产量和品质。在本研究中，我们发现外源一氧化氮（NO）的施加可以通过促进叶片气孔关闭、减少叶片丙二醛和超氧阴离子的积累，以及增加 POD 和 CAT 活性，提高铝胁迫下西瓜叶片的光化学效率。这些结果表明，外源 NO 提高了西瓜耐受铝胁迫的能力。为了进一步揭示 NO 对铝胁迫下西瓜的缓解机制，我们采用转录组从头测序技术，比较了正常生长、铝处理和铝+NO 处理三种不同处理方式下的差异。共鉴定到 511 个差异表达基因（DEGs）。显著富集的生物过程包括氮代谢、苯丙烷代谢和光合作用。我们选择了 23 个与抗氧化酶和苯丙烷代谢相关的基因进行 qRT-PCR 验证。结果表明，外源施加 NO 后，编码 和 的基因表达增加，与生理指标的结果一致。苯丙烷代谢相关基因的表达模式与转录组表达丰度一致。这些结果表明，铝胁迫抑制了光合作用途径，而 NO 可以激活抗氧化酶防御系统和苯丙烷代谢，以保护细胞并清除活性氧。本研究通过综合分析 NO 缓解西瓜铝胁迫的分子机制，加深了我们对这一过程的理解。
