Normal root elongation requires arginine produced by argininosuccinate lyase in rice

Abstract

SUMMARYPlant roots play an important role in the uptake of water and nutrients, structural support and environmental sensing, but the molecular mechanisms involved in root development are poorly understood in rice (Oryza sativa), which is characterized by a dense fibrous root system. Here we report a rice mutant (red1 for root elongation defect 1) with short roots. Morphological and physiological analyses showed that the mutant had a shorter length from the quiescent center (QC) to the starting point of the elongation zone but a similar cell size and number of lateral and crown roots compared with the wild type. Furthermore, the mutant had similar radial structure and nutrient uptake patterns to the wild type. Map-based cloning revealed that the mutant phenotype was caused by a point mutation of a gene encoding an argininosuccinate lyase (ASL), catalyzing the last step of arginine biosynthesis. The OsASL1 gene has two distinct transcripts, OsASL1.1 and OsASL1.2, which result from different transcription start sites, but only OsASL1.1 was able to complement the mutant phenotype. OsASL1.1 was expressed in both the roots and shoots. The protein encoded by OsASL1.1 showed ASL activity in yeast. OsALS1.1 was localized to the plastid. The short root of the mutant was rescued by exogenous addition of arginine, but not by other amino acids. These results indicate that arginine produced by ASL is required for normal root elongation in rice.

Comprehensive Transcriptome Profiling Reveals Long Noncoding RNA Expression and Alternative Splicing Regulation during Fruit Development and Ripening in Kiwifruit (Actinidia chinensis)

“…In addition, the ASL gene ( Achn041381 ) was highly expressed in mature fruit and postharvest stage (Table S10). In rice, normal root elongation requires arginine produced by OsASS and OsASL (Xia et al, 2014). Aspartate transaminase (AspAT) is an important enzyme in amino acid metabolism which catalyzes the interconversion of aspartate and α-ketoglutarate to oxaloacetate and glutamate (Brauc et al, 2011).…”

An appropriate concentration of arginine is required for normal root growth in rice

“…Recently, we isolated a mutant with short root. 3 Genetic and molecular analysis showed that the gene (OsASL1) responsible for the short root encodes argininosuccinate lyase cleaving argininosuccinate to arginine and fumarate reversibly at the last enzymatic reaction of arginine (Arg) biosynthesis. These findings indicate that Arg is essential for normal root growth in rice.…”

“…3 OsASL1 gene has 2 distinct transcripts produced from different transcription start sites of OsASL1, OsASL1.1 and OsASL1.2, respectively. However, yeast assay revealed that only OsASL1.1 has an argininosuccinate lyase activity, 3 indicating that the N-terminal region of OsASL1 is important for the enzyme activity or substrate specificity. The OsASL1.1 transcript was detected in both the roots and shoots at the vegetative stage.…”

A Cation-Chloride Cotransporter Gene Is Required for Cell Elongation and Osmoregulation in Rice

“…A number of genes involved in root development in rice have been identified by different approaches. These genes are involved in various biological processes controlling the development of primary root (Zhuang et al, 2006;Qi et al, 2012;Qin et al, 2013;Xia et al, 2014), crown root (Wang et al, 2011;Woo et al, 2007;Inukai et al, 2005), lateral root (Nakamura et al, 2006;Zhu et al, 2012;Kitomi et al, 2012), and root hair (Yuo et al, 2009;Kim et al, 2007;Won et al, 2010).…”