Viruses can interfere with the ability of plants to overcome abiotic stresses, indicating the existence of common molecular networks that regulate stress responses. A begomovirus causing the tomato yellow leaf curl disease was recently shown to enhance heat tolerance in tomato and drought tolerance in tomato and Nicotiana benthamiana and experimental evidence suggested that the virus-encoded protein C4 is the main trigger of drought responses. However, the physiological and molecular events underlying C4-induced drought tolerance need further elucidation. In this study, transgenic tomato plants expressing the tomato yellow leaf curl Sardinia virus (TYLCSV) C4 protein were subjected to severe drought stress, followed by recovery. Morphometric parameters, water potential, gas exchanges, and hormone contents in leaves were measured, in combination with molecular analysis of candidate genes involved in stress response and hormone metabolism. Collected data proved that the expression of TYLCSV C4 positively affected the ability of transgenic plants to tolerate water stress, by delaying the onset of stress-related features, improving the plant water use efficiency and facilitating a rapid post-rehydration recovery. In addition, we demonstrated that specific anatomical and hydraulic traits, rather than biochemical signals, are the keynote of the C4-associated stress resilience. Our results provide novel insights into the biology underpinning drought tolerance in TYLCSV C4-expressing tomato plants, paving the way for further deepening the mechanism through which such proteins tune the plant-virus interaction.

中文翻译：

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番茄黄卷叶撒丁岛病毒的 C4 蛋白通过形态调整启动番茄的耐旱性

病毒可以干扰植物克服非生物胁迫的能力，表明存在调节胁迫反应的共同分子网络。导致番茄黄叶卷曲病的 begomovirus 最近被证明可以增强番茄的耐热性和番茄和本塞姆氏烟草的耐旱性，实验证据表明，病毒编码的蛋白质 C4 是干旱反应的主要触发因素。然而，C4 诱导的耐旱性背后的生理和分子事件需要进一步阐明。在这项研究中，表达番茄黄卷叶撒丁岛病毒 (TYLCSV) C4 蛋白的转基因番茄植物受到严重干旱胁迫，然后恢复。测量了叶片中的形态学参数、水势、气体交换和激素含量，结合参与应激反应和激素代谢的候选基因的分子分析。收集的数据证明，TYLCSV C4 的表达通过延迟胁迫相关特征的发生、提高植物水分利用效率和促进补水后的快速恢复，对转基因植物耐受水分胁迫的能力产生积极影响。此外，我们证明了特定的解剖学和水力学特征，而不是生化信号，是 C4 相关应激恢复力的基调。我们的研究结果为支持表达 TYLCSV C4 的番茄植株耐旱性的生物学提供了新的见解，为进一步深化此类蛋白质调节植物-病毒相互作用的机制铺平了道路。