Non-photochemical Quenching Plays a Key Role in Light Acclimation of Rice Plants Differing in Leaf Color

Abstract

Non-photochemical quenching (NPQ) is an important photoprotective mechanism in rice; however, little is known regarding its role in the photosynthetic response of rice plants with differing in leaf color to different irradiances. In this study, two rice genotypes containing different chlorophyll contents, namely Zhefu802 (high chlorophyll) and Chl-8 (low chlorophyll), were subjected to moderate or high levels of light intensity at the 6-leaf stage. Chl-8 possessed a lower chlorophyll content and higher chlorophyll a:b ratio compared with Zhefu802, while Pn, Fv/Fm, and ΦPSII contents were higher in Chl-8. Further results indicated that no significant differences were observed in the activities of Rubisco, Mg2+-ATPase, and Ca2+-ATPase between these genotypes. This suggested that no significant difference in the capacity for CO2 assimilation exists between Zhe802 and Chl-8. Additionally, no significant differences in stomatal limitation were observed between the genotypes. Interestingly, higher NPQ and energy quenching (qE), as well as lower photoinhibitory quenching (qI) and production of reactive oxygen species (ROS) was observed in Chl-8 compared with Zhefu802 under both moderate and high light treatments. This indicated that NPQ could improve photosynthesis in rice under both moderate and high light intensities, particularly the latter, whereby NPQ alleviates photodamage by reducing ROS production. Both zeaxanthin content and the expression of PsbS1 were associated with the induction of NPQ under moderate light, while only zeaxanthin was associated with NPQ induction under high light. In summary, NPQ could improve photosynthesis in rice under moderate light and alleviate photodamage under high light via a decrease in ROS generation.

Physiological, Biochemical and Chlorophyll Fluorescence Parameters of Physalis Peruviana L. Seedlings Exposed to Different Short-Term Waterlogging Periods and Fusarium Wilt Infection

“…Lower Fv/Fm and qP under stress conditions (waterlogging and Foph) may be due to the fact that these factors cause leaf photosynthetic pigments degradation, a high ethylene and reactive oxygen species (ROS) production which affect the biochemical function of chloroplasts [24,91,92]. Likewise, NPQ is an important plant photoprotective mechanism to abiotic and biotic stress conditions [95]. In this study, high NPQ values were mainly observed in cape gooseberry plants inoculated with Foph and subjected to waterlogging periods.…”

Transcription analysis of chlorophyll biosynthesis in wildtype and chlorophyll b-lacking rice (Oryza sativa L.)

“…This finding was strongly supported by differences in the chloroplast ultrastructure and leaf coloration of wt and ch1 rice, thereby suggesting that the lower accumulation of Chl contents was responsible for the lower Chl b content and higher Chl a/b ratio of the ch1 rice. During photosynthesis, light energy is captured by pigments in the LHC proteins, which then transfer absorbed light energy to PSI and PSII reaction center complexes (Goral et al 2012, Zhao et al 2017. In a previous study of a Chl-deficient A. thaliana mutant, LHC protein was strongly reduced, or even completely absent, thereby impairing the grana stacking of the plant's chloroplast (Kim et al 2009).…”

Effects of Light and Daytime on the Regulation of Chitosan-Induced Stomatal Responses and Defence in Tomato Plants

“…In case of our experiments, NPQ also increased in the CHT-treated tomato leaves at dawn. NPQ could alleviate photodamage by reducing ROS production and could improve photosynthesis at this crucial daytime [56]. These results suggest that CHT perception on the epidermis of intact leaves, which provides the first line of plant defence system, induces significant changes in the photosynthetic activity and in the signalling and metabolism of mesophyll cells in the early light phase thus can contribute to promote defence responses in leaves and plants.…”