The Amino Acid Permease 5 (OsAAP5) Regulates Tiller Number and Grain Yield in Rice

Abstract

As fundamental nutrients, amino acids are important for rice (Oryza sativa) growth and development. Here, we identified the amino acid permease 5 (OsAAP5), that regulates tiller number and grain yield in rice. The OsAAP5 promoter sequence differed between indica and japonica rice varieties. Lower expression of OsAAP5 in the young leaf blade in indica varieties than in japonica varieties was associated with more tillers in indica than in japonica. Down-regulation of OsAAP5 expression in japonica using RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats led to increases in tiller number and grain yield, whereas OsAAP5 overexpression (OE) had the opposite effect. Both a protoplast amino acid uptake assay and HPLC analysis indicated that more basic (Lys, Arg) and neutral (Val, Ala) amino acids were transported and accumulated in the OE lines than in the wild type, but the opposite was observed in the RNAi lines. Furthermore, exogenous application of Lys, Arg, Val, and Ala in the OE lines substantially inhibited tiller bud elongation, but the effect was lost in the RNAi lines. Notably, concentrations of the cytokinins cis-zeatin and dihydrozeatin were much lower in the OE lines than in the wild type, whereas concentrations in the RNAi lines were higher. Thus, OsAAP5 could regulate tiller bud outgrowth by affecting cytokinin levels, and knockout of OsAAP5 could be valuable for japonica breeding programs seeking high yield and grain quality.

Transcriptomic and physiological analyses of rice seedlings under different nitrogen supplies provide insight into the regulation involved in axillary bud outgrowth

“…N is a crucial macronutrient for plant development. Although previous studies have elucidated the regulatory mechanisms of the axillary bud growth under N stress [22,26,27,29,35,54], many regulators and their regulatory mechanisms are still unclear. This work revealed that the axillary bud growth rate was altered by different N concentrations, and integrated transcriptomic data from the basal parts and axillary buds of rice plants grown under different N concentrations via RNA-seq.…”

Transcriptomic and physiological analyses of rice seedlings under different nitrogen supplies provide insight into the regulation involved in axillary bud outgrowth

“…N is a crucial macronutrient for plant development. Although previous studies have elucidated the regulatory mechanisms of the axillary bud growth under N stress [22,26,27,29,35,54], many regulators and their regulatory mechanisms are still unclear. This work revealed that the axillary bud growth rate was altered by different N concentrations, and integrated transcriptomic data from the basal parts and axillary buds of rice plants grown under different N concentrations via RNAseq.…”

Transcriptomic and physiological analyses of rice seedlings under different nitrogen supplies provide insight into the regulation involved in axillary bud outgrowth

“…N is a crucial macronutrient for plant development. Previous studies have elucidated the regulatory mechanisms of the axillary bud growth of plants grown under N stress [22,26,27,29,35,56]; however, many regulators and their regulatory mechanisms are still unclear. This work revealed that the growth rate of axillary buds was distinct in plants grown under different N concentrations, and integrated transcriptomic data from the basal parts and axillary buds of rice plants grown under six different N concentrations via RNA-sEq.…”

“…Amino acid permeases (AAPs) are responsible for amino acid transport, of which there are 19 members in rice [33]. Studies of OsAPP3 [34], OsAPP5 [35], and OsNADH-GOGAT1 [36] indicated that external N status has a profound influence on axillary bud outgrowth and tiller number in rice. A previous study revealed that the growth and yield of plants increase when nitrate and ammonium are supplied simultaneously [37], but the gene regulatory networks and signalling pathways involved in axillary bud formation and outgrowth in response to different external N supplies are still poorly understood, especially the link between N and hormones with respect to axillary bud outgrowth.…”