College of Resources and Environmental Engineering, Yangzhou Polytechnic College, Yangzhou, China.
Jiangsu Safety & Environment Technology and Equipment for Planting and Breeding Industry Engineering Research Center, Yangzhou, China.
Plant Signal Behav. 2023 Dec 31;18(1):2186640. doi: 10.1080/15592324.2023.2186640.
Zinc (Zn) is an important element in plants, but over-accumulation of Zn is harmful. The phytohormone brassinosteroids (BRs) play a key role in regulating plant growth, development, and response to stress. However, the role of BRs in watermelon ( L.) under Zn stress, one of the most important horticultural crops, remains largely unknown. In this study, we revealed that 24-epibrassinolide (EBR), a bioactive BR enhanced Zn tolerance in watermelon plants, which was related to the EBR-induced increase in the fresh weight, chlorophyll content, and net photosynthetic rate (Pn) and decrease in the content of hydrogen peroxide (HO), malondialdehyde (MDA), and Zn in watermelon leaves. Through RNA deep sequencing (RNA-seq), 350 different expressed genes (DEG) were found to be involved in the response to Zn stress after EBR treatment, including 175 up-regulated DEGs and 175 down-regulated DEGs. The up-regulated DEGs were significantly enriched in 'phenylpropanoid biosynthesis' pathway (map00940) using KEGG enrichment analysis. The gene expression levels of , , , and , key genes involved in phenylpropanoid pathway, were significantly induced after EBR treatment. In addition, compared with Zn stress alone, EBR treatment significantly promoted the activities of PAL, 4CL, and POD by 30.90%, 20.69%, and 47.28%, respectively, and increased the content of total phenolic compounds, total flavonoids, and lignin by 23.02%, 40.37%, and 29.26%, respectively. The present research indicates that EBR plays an active role in strengthening Zn tolerance, thus providing new insights into the mechanism of BRs enhancing heavy metal tolerance.
锌（Zn）是植物中的一种重要元素，但过量积累会对植物造成伤害。植物激素油菜素内酯（BRs）在调节植物生长、发育和应对胁迫方面起着关键作用。然而，BRs 在西瓜（L.）中的作用在 Zn 胁迫下，作为最重要的园艺作物之一，仍然知之甚少。在这项研究中，我们揭示了 24-表油菜素内酯（EBR），一种生物活性 BR，增强了西瓜植株对 Zn 的耐受性，这与 EBR 诱导的西瓜叶片鲜重、叶绿素含量、净光合速率（Pn）增加以及过氧化氢（HO）、丙二醛（MDA）和 Zn 含量降低有关。通过 RNA 深度测序（RNA-seq），发现 350 个不同表达的基因（DEG）参与了 EBR 处理后对 Zn 胁迫的反应，包括 175 个上调的 DEG 和 175 个下调的 DEG。KEGG 富集分析表明，上调的 DEG 显著富集在‘苯丙烷生物合成’途径（map00940）中。苯丙烷途径关键基因 、 、 、 的基因表达水平在 EBR 处理后显著诱导。此外，与单独的 Zn 胁迫相比，EBR 处理分别显著促进了 PAL、4CL 和 POD 的活性，提高了 30.90%、20.69%和 47.28%，并增加了总酚类化合物、总类黄酮和木质素的含量，分别提高了 23.02%、40.37%和 29.26%。本研究表明，EBR 在增强 Zn 耐受性方面发挥了积极作用，从而为 BRs 增强重金属耐受性的机制提供了新的见解。
