Molecular distinction in genetic regulation of nonphotochemical quenching in rice

Abstract

Nonphotochemical quenching (NPQ) regulates energy conversion in photosystem II and protects plants from photoinhibition. Here we analyze NPQ capacity in a number of rice cultivars. NPQ was strongly induced under medium and high light intensities in rice leaves. Japonica cultivars generally showed higher NPQ capacities than Indica cultivars when we measured a rice core collection. We mapped NPQ regulator and identified a locus (qNPQ1-2) that seems to be responsible for the difference in NPQ capacity between Indica and Japonica. One of the two rice PsbS homologues (OsPsbS1) was found within the qNPQ1-2 region. PsbS protein was not accumulated in the leaf blade of the mutant harboring transferred DNA insertion in OsPsbS1. NPQ capacity increased as OsPsbS1 expression increased in a series of transgenic lines ectopically expressing OsPsbS1 in an Indica cultivar. Indica cultivars lack a 2.7-kb region at the point 0.4 kb upstream of the OsPsbS1 gene, suggesting evolutionary discrimination of this gene.chlorophyll fluorescence | pulse amplitude modulation | quantitative trait loci analysis | rice subclass P lants have the potential to transform absorbed light energy to chemical energy at relatively high efficiency. However, the actual efficiency is dependent on the inherent capacities of photochemistry and carbon assimilation, and environmental factors including light intensity. The sites at which light energy is absorbed are photosystem I and II (PSI and PSII), which drive photochemistry and production of chemical energy (ATP and NADPH). For PSII, energy transformation processes of chlorophyll excitation energy can be measured by the pulse amplitude modulation technique of chlorophyll fluorescence measurement (1-3).Chlorophyll deexcitation processes are divided into three groups: photochemistry (photosynthetic electron transport), basal dissipation/ non-light induced quenching (NO), and thermal dissipation, which results in nonphotochemical quenching (NPQ) of chlorophyll fluorescence. Basal dissipation consists of chlorophyll fluorescence, internal conversion, and intersystem crossing. With increasing light intensity, there is a decrease in efficiency of use of excitons in photochemistry and an increase in NPQ. More than half of absorbed energy can be lost through NPQ under high illumination (4, 5). NPQ consists of several components. These can be distinguished by the rate of induction of NPQ in the light and by the rate of its relaxation in the dark (6). The NPQ component that is rapidly induced by illumination and relaxes rapidly in the dark is called qE. qE is the energy-dependent quenching linked to the proton motive force.Photoinhibition indicates light stress and, under high illumination, excessive energy results in photodamage with inactivation of the PSII machinery. This leads to a decrease in the photochemical rate constant and thermal loss of energy caused by photoinhibition. Photoinhibition results in inactivation of a part of the PSII reaction centers. The degree of photoinhibition and the intrinsic loss of...

High-Resolution Three-Dimensional Structural Data Quantify the Impact of Photoinhibition on Long-Term Carbon Gain in Wheat Canopies in the Field

“…This will be true for many irrigated rice and yield environments. In the case of tropical rice, there is known genotypic diversity in susceptibility (Murchie et al, 1999;Demao and Xia, 2001) that may be the result of genetically determined nonphotochemical quenching levels (Kasajima et al, 2011). It is highly probable that we can improve biomass and yield by optimizing photoinhibition, and this requires understanding of the existing canopy architecture.…”

“…We considered that this approach is not appropriate for comparisons between species and lineages where there may be variation in the quantum requirements for photoinhibition. There are known genotype-dependent differences in cereal species (Kasajima et al, 2011); therefore, we derived a scaling factor (SF) directly from F v /F m data taken in the field measured at different canopy levels.…”

Collective Calculation of Actual Values of Non-Photochemical Quenching from Their Apparent Values after Chloroplast Movement and Photoinhibition

“…Wild-type Oryza sativa (cultivar Hwayoung) and a homozygous line of psbS1 mutant (1C-032-61) developed by Gynheung An and obtained from the Pohang University of Science and Technology were selected in a previous report [8]. After germination in a growth chamber, the seeds were grown in nutrient-rich soil (Son-sol no.…”

“…1, Sumitomo Chemical, Tokyo, Japan) for 41 d in a partly sun-lit greenhouse. The characteristics of psbS1 were described by [8].…”

“…Agricultural applications of fluorescence parameters have also been developed, including the detection of pathogen infection, estimation of stress tolerance in different cultivars, and detection of non-visible symptom of manganese deficiency [4]- [7]. We previously compared the fluorescence parameters of rice cultivars and detected differences in the size of non-photochemical quenching (NPQ: measured by the parameter NPQ) between two subclasses of Indica and Japonica [8]. Although the agricultural significance of the difference in NPQ size is not clear, it may explain the cold tolerance of Japonica cultivars.…”