Non-Photochemical Quenching Involved in the Regulation of Photosynthesis of Rice Leaves under High Nitrogen Conditions

Abstract

Excess and deficient nitrogen (N) inhibit photosynthesis in the leaves of rice plants, but the underlying mechanism is still unclear. N can improve the chlorophyll content and thus affect photon absorption, but the photosynthetic rate does not increase accordingly. To investigate this mechanism, three concentrations of N treatments were applied to two rice varieties, Zhefu802 and Fgl. The results indicated increased chlorophyll content of leaves with an increased N supply. Little discrepancy was detected in Rubisco enzyme activity and Non-photochemical quenching (NPQ) in the high nitrogen (HN) and moderate nitrogen (MN) treatments. The model that photoinhibition occurs in Zhefu802 due to a lack of balance of light absorption and utilization is supported by the higher malondialdehyde (MDA) content, higher H 2 O 2 content, and photoinhibitory quenching (qI) in HN treatment compared with MN treatment. A lower proportion of N in leaf was used to synthesize chlorophyll for Fgl compared with Zhefu802, reducing the likelihood of photoinhibition under HN treatment. In conclusion, HN supply does not allow ideal photosynthetic rate and increases the likelihood of photoinhibition because it does not sustain the balance of light absorption and utilization. Apart from Rubisco enzyme activity, NPQ mainly contributes to the unbalance. These results of this study will provide reference for the effective N management of rice. Int. J. Mol. Sci. 2020, 21, 2115 2 of 17 reaction center, resulting in 3P680 * , a triple state of the chlorophyll molecules [11]. The triple molecules can react with O 2 to generate deleterious singlet O 2 ( 1 O 2 ) [12], degrade the PSII reaction center protein D1, inactivate PSII and inhibit photosynthesis [13]. To eliminate damage from excessive light, plants have evolved some photoprotective mechanisms [7]. One mechanism is to dissipate the excessive excitation energy as heat in PSII antenna complex, which is known as non-photochemical quenching (NPQ) of chlorophyll fluorescence [14,15]. Although ubiquitous, the role of NPQ in plant productivity remains uncertain because it momentarily reduces the quantum efficiency of photosynthesis. Hubbart et al. [16] assessed photoprotection in rice at the whole canopy scale, and demonstrated that compared to wild-type plants, the overexpression of PsbS resulted in higher NPQ, increased canopy radiation use efficiency, and grain yield in fluctuating light. Genotypic variation of NPQ in rice was observed under natural solar radiation [17]. Wang et al. [8] reported that OsPsbS1 explains more than 40% of the NPQ variation. According to the induction speed of the relaxation kinetics curve in the dark, NPQ can be divided into three main components: qE, energy-dependent quenching, or fast NPQ, which is induced in seconds and is based on the proton gradient across the thylakoid membrane; qT, state transition quenching, or middle NPQ, which is induced in minutes; and the third component, qI, photo-inhibition quenching, or slow NPQ, which is induced very slowly [18,19]. The ...

Retrieving rice (Oryza sativa L.) net photosynthetic rate from UAV multispectral images based on machine learning methods

“…The ground sample results showed that the SPAD and Pn generally increased with nitrogen application (N1–N3 levels), then decreased at the N4 level, and finally recovered at the N5 level under the same leakage treatment at the jointing–booting stage, which also indicated that proper N application could improve the photosynthesis, while excessive N application not only had a poor effect on photosynthesis, but also affected plant growth and increased risk of contamination during leakage and drainage. This phenomenon was similar to that found by Cisse et al. (2020) .…”

“…The ground sample results showed that the SPAD and Pn generally increased with nitrogen application (N1-N3 levels), then decreased at the N4 level, and finally recovered at the N5 level under the same leakage treatment at the jointing-booting stage, which also indicated that proper N application could improve the photosynthesis, while excessive N application not only had a poor effect on photosynthesis, but also affected plant growth and increased risk of contamination during leakage and drainage. This phenomenon was similar to that found by Cisse et al (2020). It might due to the fact that there was no significant difference in Rubisco activity and nonphotochemical quenching (NPQ) between the N4-N5 and the N3 level; thus, excessive energy could not be dissipated by NPQ, leading to oxidative stress, resulting in a decrease in Pn when excessive nitrogen was applied.…”

Promising physiological traits associated with nitrogen use efficiency in rice under reduced N application

“…A significantly higher Pn of 29.52 µmol (CO 2 ) m −2 s −1 at 150% of RDN was noted compared with a Pn of 17.41 µmol (CO 2 ) m −2 s −1 at 0% of RDN ( Devika et al., 2018 ). Flag leaf N content increased significantly with increased N application and is in accordance with the earlier findings ( Swarna et al., 2017 ; Cisse et al., 2020 ; Hou et al., 2020 ). Leaf N plays a crucial role in photosynthesis, which ultimately affects biomass production ( Ladha et al., 1998 ).…”

Responses of Linear and Cyclic Electron Flow to Nitrogen Stress in an N-Sensitive Species Panax notoginseng

“…However, plants exposed to long-term N deficiency would suffer an imbalance between the capability for absorbing light energy and consuming this excess light energy, resulting in the generation of reactive oxygen species (ROS) ( Yamori et al, 2016 ; Che et al, 2020 ; Mu and Chen, 2021 ). Photosystem II (PSII) is susceptible to HN and low N (LN) ( Cisse et al, 2020 ; Zhang Z. et al, 2021 ). HN and LN can inhibit either on the acceptor side or on the donor side of PSII, resulting in damaging PSII functions.…”

“…The donor side of PSII in Porphyridium cruentum , O. sativa , and Vitis labrusca were seriously impacted by N deficiency, leading to the inactivation of the oxygen-evolving complex (OEC) and the reduced photochemical efficiency ( Chen and Cheng, 2003 ; Zhao et al, 2017 ; Tantray et al, 2020 ). HN supply increases the PSII photoinhibition in O. sativa and Chenopodium quinoa because it does not sustain the balance of light absorption and utilization and consequently accumulates large amounts of H 2 O 2 at PSII ( Bascuñán-Godoy et al, 2018 ; Cisse et al, 2020 ). Diverse environmental stress can also result in the impairment of photosystem I (PSI) ( Ivanov et al, 2015 ; Lima-Melo et al, 2019 ).…”