Jie Wu, Zi-Sheng Zhang, Jin-Qiu Xia, Alamin Alfatih, Ying Song, Yi-Jie Huang, Guang-Yu Wan, Liang-Qi Sun, Hui Tang, Yang Liu, Shi-Mei Wang, Qi-Sheng Zhu, Peng Qin, Yu-Ping Wang, Shi-Gui Li, Chuan-Zao Mao, Gui-Quan Zhang, Chengcai Chu, Lin-Hui Yu, Cheng-Bin Xiang

Plant Biotechnol J. 2021 Mar;19(3):448-461.  doi: 10.1111/pbi.13475. Epub 2020 Sep 17.

Abstract

Nitrogen (N) is one of the key essential macronutrients that affects rice growth and yield. Inorganic N fertilizers are excessively used to boost yield and generate serious collateral environmental pollution. Therefore, improving crop N use efficiency (NUE) is highly desirable and has been a major endeavour in crop improvement. However, only a few regulators have been identified that can be used to improve NUE in rice to date. Here we show that the rice NIN-like protein 4 (OsNLP4) significantly improves the rice NUE and yield. Field trials consistently showed that loss-of-OsNLP4 dramatically reduced yield and NUE compared with wild type under different N regimes. In contrast, the OsNLP4 overexpression lines remarkably increased yield by 30% and NUE by 47% under moderate N level compared with wild type. Transcriptomic analyses revealed that OsNLP4 orchestrates the expression of a majority of known N uptake, assimilation and signalling genes by directly binding to the nitrate-responsive cis-element in their promoters to regulate their expression. Moreover, overexpression of OsNLP4 can recover the phenotype of Arabidopsis nlp7 mutant and enhance its biomass. Our results demonstrate that OsNLP4 plays a pivotal role in rice NUE and sheds light on crop NUE improvement.

See https://pubmed.ncbi.nlm.nih.gov/32876985/

Figure 1:

OsNLP4 influences plant growth under different nitrate conditions. (A) Phenotypes of wild‐type (WT), nlp4 mutants (nlp4‐1/nlp4‐2) and OsNLP4‐OE lines (OE‐1/OE‐9) grown in hydroponic medium with different nitrate concentrations for 25 days. Bar = 4.0 cm. (B‐H) Seedling biomass. Total fresh weight (B), shoot fresh weight (C), root fresh weight (D), shoot fresh weight/root fresh weight ratio (E), root numbers (F), root length (G), shoot length (H) of seedlings were measured. Values are the mean ± SD of four independent replications each containing 10 plants per genotype. P values are from the one‐way ANOVA (The letters a, b, c and others indicate significant differences. P < 0.05). FW, fresh weight.