Photoinhibition of Leaves with Different Photosynthetic Carbon Assimilation Characteristics in Maize (&amp;lt;i&amp;gt;Zea mays&amp;lt;/i&amp;gt;)

Yanye Ruan,Bo Song,Lijun Zhang,Zhenhai Cui,Xiaoyang Li,Siqi Jiang,Yanpeng Wang,Yixin Guan,Qi Qi,Zhiyou Guo,Jinjuan Fan,Ao Zhang,Yanshu Zhu

doi:10.4236/ajps.2017.83023

Photoinhibition of Leaves with Different Photosynthetic Carbon Assimilation Characteristics in Maize (&lt;i&gt;Zea mays&lt;/i&gt;)

Yanye Ruan, Bo Song + Show 11 more

Open Access

https://doi.org/10.4236/ajps.2017.83023

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Abstract

Strong light decreases the rate of photosynthesis and assimilates production of crop plants. Plants with different carbon reduction cycles respond differently to strong light stress. However, variation in photoinhibition in leaves with different photosynthetic characteristics in maize is not clear. In this experiment, we used the first leaves (with an incomplete C4 cycle) and fifth leaves (with a complete C4 cycle) of maize plants as well as the fifth leaves (C3 cycle) of tobacco plants as a reference to measure the photosynthetic rate (PN) and chlorophyll a parameters under strong light stress. During treatment, PN, the maximal fluorescence (Fm), the maximal quantum yield of PSII photochemistry (Fv/Fm), and the number of active photosystem II (PSII) reaction centers per excited cross-section (RC/CSm) declined dramatically in all three types of leaves but to different degrees. PN, Fm, Fv/Fm, and RC/CSm were less inhibited by strong light in C4 leaves. The results showed that maize C4 leaves with higher rates of photosynthesis are more tolerant to strong light stress than incomplete C4 leaves, and the carbon reduction cycle is more important to photoprotection in C4 leaves, while state transition is critical in incomplete C4 leaves.

Highlights

The results showed that maize C4 leaves with higher rates of photosynthesis are more tolerant to strong light stress than incomplete C4 leaves, and the carbon reduction cycle is more important to photoprotection in C4 leaves, while state transition is critical in incomplete C4 leaves
C4 photosynthetic enzymes are distributed in mesophyll cells (MC) and bundle sheath cells (BSC), which cooperate during C4 photosynthesis
M5 maintained a consistently higher photosynthetic rate (PN) than did M1 and T5. These results suggested that C4 leaves (M5) were more tolerant to strong light stress than leaves with an incomplete C4 (M1) and C3 leaves (T5)

Summary

Introduction

The longer the exposure to excess excitation energy, the more damage to the photosynthetic apparatus To avoid this damage, plants have evolved a series of protective mechanisms [2] [3] [4] [5], including photochemical quenching, fluorescence quenching, and thermal dissipation of excess excitation energy. Photochemical quenching is related to the activity of photosystem II (PSII) reaction centers (RC), the efficiency of the electron transfer chain, and the capacity of the photosynthetic carbon cycle. Based on the pathway of photosynthetic carbon fixation, higher plants are classified into three types: C3, C4, and CAM. MC chloroplasts have higher PSII activity and lower Rubisco activity. BSC chloroplasts have lower PSII activity and higher Rubisco activity [7] [8]. C4 photosynthetic enzymes are distributed in MC and BSC, which cooperate during C4 photosynthesis

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