SAPK2 contributes to rice yield by modulating nitrogen metabolic processes under reproductive stage drought stress

Dengji Lou,Diqiu Yu,Zhen Chen,Xiaoyan Yang

doi:10.1186/s12284-020-00395-3

Abstract

BackgroundThe sucrose non-fermenting 1-related kinases 2 (SnRK2s) play important roles in osmotic stress responses in A. thaliana and rice (Oryza sativa L.). Osmotic stress/ABA–activated protein kinase 2 (SAPK2) is a member of SnRK2s subclass II in rice, but its function in rice yield under drought stress is unclear.ResultsCompared with wild-type (Oryza.Sativa L.spp.japonica, WT) plants, the sapk2 rice mutant lines were shorter and produced fewer grains per panicle, smaller grains and lower grain yield under reproductive stage drought stress (RDS). Subsequent analysis suggested that SAPK2 considerably influences the nitrogen, phosphorus, and potassium contents of rice grains. The examination of rice seedling growth and development under nutrient-deprived conditions (−N, −K, and − P) proved that SAPK2 can significantly affect rice seedling growth and root development in hydroponic cultures lacking N and K. Moreover, the NO3− influx rate and nitrate concentration analysis indicated that SAPK2 promotes nitrate uptake and assimilation by regulating nitrate-related transporters.ConclusionThese results suggest that SAPK2 could enhance grain production by regulating nitrogen utilization efficiency under RDS. Our work provided insights to breeding drought tolerant rice with high nutrient uptake.

Highlights

The sucrose non-fermenting 1-related kinases 2 (SnRK2s) play important roles in osmotic stress responses in A. thaliana and rice (Oryza sativa L.)
We found that the sapk2 mutant showed lower grains yield and lower nitrogen, phosphorus, and potassium contents of rice grains than the Wild type (WT) reproductive stage drought stress (RDS)
The NO3− influx rate and nitrate concentration analysis indicated that stress/Abscisic acid (ABA)–activated protein kinase 2 (SAPK2) promotes nitrate uptake and assimilation by regulating nitrate-related transporters

Summary

Introduction

The sucrose non-fermenting 1-related kinases 2 (SnRK2s) play important roles in osmotic stress responses in A. thaliana and rice (Oryza sativa L.). Drought stress, which is important abiotic factor limiting crop productivity worldwide, is responsible for extensive crop losses and will likely worsen in the near future. Enhancing the drought tolerance of rice is Drought stress can affect plants at all growth stages, and the extent of the changes to productivity depend on the plant species and its genotype, age, and size as well as the duration and severity of the stress (Gall et al 2015). Water-stressed plants are shorter than normal and have a smaller leaf area, which decreases the amount of photo synthetically active radiation absorbed by leaves, the photosynthetic rate, and yield. Water deficit induces stomata closure, which leads to limited CO2 uptake by leaves and decreased net photosynthesis

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