Overexpression of OsMYB305 in Rice Enhances the Nitrogen Uptake Under Low-Nitrogen Condition

Abstract

Excessive nitrogen fertilizer application causes severe environmental degradation and drives up agricultural production costs. Thus, improving crop nitrogen use efficiency (NUE) is essential for the development of sustainable agriculture. Here, we characterized the roles of the MYB transcription factor OsMYB305 in nitrogen uptake and assimilation in rice. OsMYB305 encoded a transcriptional activator and its expression was induced by N deficiency in rice root. Under low-N condition, OsMYB305 overexpression significantly increased the tiller number, shoot dry weight and total N concentration. In the roots of OsMYB305-OE rice lines, the expression of OsNRT2.1, OsNRT2.2, OsNAR2.1, and OsNiR2 was up-regulated and 15 NO 3 − influx was significantly increased. In contrast, the expression of lignocellulose biosynthesis-related genes was repressed so that cellulose content decreased, and soluble sugar concentration increased. Certain intermediates in the glycolytic pathway and the tricarboxylic acid cycle were significantly altered and NADH-GOGAT, Pyr-K, and G6PDH were markedly elevated in the roots of OsMYB305-OE rice lines grown under low-N condition. Our results revealed that OsMYB305 overexpression suppressed cellulose biosynthesis under low-nitrogen condition, thereby freeing up carbohydrate for nitrate uptake and assimilation and enhancing rice growth. OsMYB305 is a potential molecular target for increasing NUE in rice.

Deciphering the Genetic Basis of Root and Biomass Traits in Rapeseed (Brassica napus L.) through the Integration of GWAS and RNA-Seq under Nitrogen Stress

“…We identified 12 and 4 candidate genes related to root growth and nitrogen stress by integrating GWAS, WGCNA, and DEGs. For example, BnaA09g04260D, a major hub gene in the MEsalmon module and located in the region of the QTL cluster qcA09-1, encodes a major facilitator superfamily protein, whose homologous AtSTP13 had a potential role in root growth responses and nitrogen uptake under nitrogen-starved conditions [ 56 , 57 , 58 ]. Another hub gene in the MEsalmon module and the qcA09-1 region, BnaA09g05270D, has been reported to have a crucial role in regulating root gravitropism and elongation against various environmental stresses [ 59 , 60 ].…”

Transcriptome Analysis of Two Near-Isogenic Lines with Different NUE under Normal Nitrogen Conditions in Wheat

“…Studies have found that overexpression of TaNAC2-5A TF significantly promoted the genes encoding NRT and GS under low N conditions in wheat [ 59 ]. Similarly, overexpression of OsMYB305 positively regulates OsNRT2.1 , OsNRT2.2 , and OsNiR2 expression, thereby promoting N uptake and assimilation in rice [ 60 ]. The expression levels of WRKY TF genes were upregulated in wheat under low-N conditions [ 22 ], WRKY proteins may contribute to the formation of complex signaling networks and thus improve plant tolerance to low-N stress [ 23 ].…”

Recent Advances on Nitrogen Use Efficiency in Rice

“…OsMYB305 encodes a transcriptional activator; its expression is enhanced in N deficient roots [100]. The overexpression of OsMYB305 enhances N uptake and assimilation, and improved growth under low N, increased tiller number, shoot dry weight, and total N concentration [100]. GROWTH-REGULATING FACTOR 4 (OsGRF4) is a transcriptional regulator of multiple N metabolism genes [101].…”