Proteomics Analysis Reveals Non-Controlled Activation of Photosynthesis and Protein Synthesis in a Rice npp1 Mutant under High Temperature and Elevated CO2 Conditions

Abstract

Rice nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) catalyzes the hydrolytic breakdown of the pyrophosphate and phosphodiester bonds of a number of nucleotides including ADP-glucose and ATP. Under high temperature and elevated CO2 conditions (HT + ECO2), the npp1 knockout rice mutant displayed rapid growth and high starch content phenotypes, indicating that NPP1 exerts a negative effect on starch accumulation and growth. To gain further insight into the mechanisms involved in the NPP1 downregulation induced starch overaccumulation, in this study we conducted photosynthesis, leaf proteomic, and chloroplast phosphoproteomic analyses of wild-type (WT) and npp1 plants cultured under HT + ECO2. Photosynthesis in npp1 leaves was significantly higher than in WT. Additionally, npp1 leaves accumulated higher levels of sucrose than WT. The proteomic analyses revealed upregulation of proteins related to carbohydrate metabolism and the protein synthesis system in npp1 plants. Further, our data indicate the induction of 14-3-3 proteins in npp1 plants. Our finding demonstrates a higher level of protein phosphorylation in npp1 chloroplasts, which may play an important role in carbohydrate accumulation. Together, these results offer novel targets and provide additional insights into carbohydrate metabolism regulation under ambient and adverse conditions.

Photosynthesis in a Changing Global Climate: Scaling Up and Scaling Down in Crops

“…Similar effects are observed under nutrient starvation, including Mg 2+ and Fe 2+ , which are essential co-factors for several redox-active proteins in the photosynthetic ETC. More recently, Inomata et al (2018) reported the chloroplast phosphoproteome profile of a rice nucleotide pyrophosphatase / phosphodiesterase 1 (NPP1) mutant. This study highlighted that the loss-of-function of NPP1 in rice leaves increased stomatal conductance, photosynthesis, starch, and sucrose storage while also impacting proteins involved in carbohydrate metabolism and protein synthesis system under high temperature and CO 2 conditions.…”

Functional Analysis of Rice Long-Chain Acyl-CoA Synthetase 9 (OsLACS9) in the Chloroplast Envelope Membrane

“…Intact chloroplasts were purified from seedlings grown in a light condition using the Percoll (GE Healthcare) density-gradient centrifugation method, as described earlier [45,46] and analyzed by SDS-PAGE and immunoblotting. Proteins were extracted from brown rice seed (harvested in the field), calli (cultured in a dedifferentiation medium for four weeks), shoot (germinated at 30 • C for seven days in the dark and moved to a growth chamber (28:23 • C, 12:12 h, light:dark; 20,000 lux) for three days), and mature leaves (germinated at 30 • C for seven days in the dark and moved to a growth chamber (28:23 • C, 12:12 h, light:dark; 20,000 lux) for eight days).…”

Strategies of Plant Biotechnology to Meet the Increasing Demand of Food and Nutrition in India

“…Interestingly, non-controlled activation of protein translation and photosynthesis has been revealed by proteomic investigations in a rice npp1 mutant under conditions of elevated temperature and carbon dioxide [35]. In the npp1 mutants, increased expression of several 14-3-3 proteins was noted, indicating that the NPP1 gene disruption can alter protein phosphorylation status.…”