Institute for Sustainable Plant Protection (IPSP), The National Research Council of Italy (CNR), 50019 Sesto Fiorentino (Florence), Italy.
Department of Agriculture, Food, Environment and Forestry, University of Florence, 50019 Sesto Fiorentino (Florence), Italy.
Int J Mol Sci. 2019 Jul 23;20(14):3599. doi: 10.3390/ijms20143599.
Molecular mechanisms that are the base of the strategies adopted by Mediterranean plants to cope with the challenges imposed by limited or excessive solar radiation during the summer season have received limited attention. In our study, conducted on plants growing in the shade or in full sunlight, we performed measurements of relevant physiological traits, such as leaf water potential, gas exchange and PSII photochemistry, RNA-Seq with assembly, and the analysis of differentially expressed genes. We also identified and quantified photosynthetic pigments, abscisic acid, and flavonoids. Here, we show major mechanisms regulating light perception and signaling which, in turn, sustain the shade avoidance syndrome displayed by the 'sun loving' . We offer clear evidence of the detrimental effects of excessive light on both the assembly and the stability of PSII, and the activation of a suite of both repair and effective antioxidant mechanisms in sun-adapted leaves. For instance, our study supports the view of major antioxidant functions of zeaxanthin in sunny plants concomitantly challenged by severe drought stress. Finally, our study confirms the multiple functions served by flavonoids, both flavonols and flavanols, in the adaptive mechanisms of plants to the environmental pressures associated to Mediterranean climate.
地中海植物为应对夏季有限或过量太阳辐射带来的挑战而采用的策略的基础分子机制尚未得到充分关注。在我们对生长在阴凉处或全日照下的植物进行的研究中，我们进行了相关生理特征的测量，如叶片水势、气体交换和 PSII 光化学、组装的 RNA-Seq 和差异表达基因的分析。我们还鉴定和量化了光合色素、脱落酸和类黄酮。在这里，我们展示了调节光感知和信号转导的主要机制，这反过来又维持了“喜爱阳光”的植物的避荫综合征。我们提供了明确的证据，证明过量的光对 PSII 的组装和稳定性以及在适应阳光的叶片中激活一系列修复和有效的抗氧化机制都有不利影响。例如，我们的研究支持叶黄素在同时受到严重干旱胁迫的阳光充足的植物中具有主要抗氧化功能的观点。最后，我们的研究证实了类黄酮（黄酮醇和黄烷醇）在植物适应与地中海气候相关的环境压力的适应机制中的多种功能。
