Puglielli Giacomo, Redondo-Gómez Susana, Gratani Loretta, Mateos-Naranjo Enrique
Department of Environmental Biology, Sapienza University of Rome, P.le A. Moro 5, 00185 Rome, Italy.
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, 1095, 41012, Sevilla, Spain.
J Plant Physiol. 2017 Jun;213:199-208. doi: 10.1016/j.jplph.2017.02.015. Epub 2017 Mar 25.
The differential degree by which paraheliotropism may counterbalance the deleterious impact of high irradiance between congeneric species in relation to different water availabilities has been poorly investigated. We followed the evolution of gas exchange, quenching analysis and OJIP parameters in restrained (R) and free (F) to move leaves of Cistus monspeliensis (CM) and Cistus salvifolius (CS) under drought stress (WS) and well-watered conditions (WW). Concerning gas exchange parameters, leaf restriction effect was overall not significant in CM except in apparent carboxylation efficiency (C) under WS, while CS showed a significant sensitivity of maximum net photosynthetic rate (A), stomatal conductance (gs) and C even under WW. The recovery analysis highlighted also a faster gs recovery in F leaves. Furthermore, in both the species, restriction affected photon allocation pathways especially in terms of light-regulated and light-independent constitutive non-photochemical energy dissipation under WW, ultimately affecting electron transport rate (ETR). Nevertheless, the OJIP analysis provided us evidences that CM was characterized by a down-regulation of ETR while an impairment occurs in CS. In CM this was due to its ability to modify a certain fraction of reaction centers thus resulting in a higher capability for dissipation of excess light energy under well-watered conditions, not affecting electron transport efficiency. This response was not observed in CS. Overall, we demonstrated that congeneric species, even mostly sharing the same physiological targets, differ in the degree by which leaf movements help to counterbalance the negative effect of the high irradiance in relation with the amount of water available.
关于不同水分可利用性条件下，同属物种间向日性抵消高辐照度有害影响的差异程度，目前研究较少。我们追踪了在干旱胁迫（WS）和水分充足条件（WW）下，蒙氏岩蔷薇（CM）和鼠尾草叶岩蔷薇（CS）受限制（R）和自由（F）移动叶片的气体交换、猝灭分析和OJIP参数的变化。关于气体交换参数，除了在干旱胁迫下的表观羧化效率（C）外，叶片限制效应在蒙氏岩蔷薇中总体不显著，而鼠尾草叶岩蔷薇即使在水分充足条件下，最大净光合速率（A）、气孔导度（gs）和C也表现出显著的敏感性。恢复分析还突出显示了自由移动叶片中gs恢复更快。此外，在这两个物种中，限制影响了光子分配途径，特别是在水分充足条件下光调节和光非依赖性组成型非光化学能量耗散方面，最终影响了电子传递速率（ETR）。然而，OJIP分析为我们提供了证据，表明蒙氏岩蔷薇的特征是ETR下调，而鼠尾草叶岩蔷薇则发生了损伤。在蒙氏岩蔷薇中，这是由于其能够改变一定比例的反应中心，从而在水分充足条件下具有更高的能力来耗散过剩光能，而不影响电子传递效率。在鼠尾草叶岩蔷薇中未观察到这种反应。总体而言，我们证明了同属物种，即使大多共享相同的生理目标，但在叶片运动帮助抵消高辐照度负面影响的程度上，因可用水量的不同而存在差异。
