proline content alterative 17 (pca17) is involved in glucose response through sulfate metabolism-mediated pathway

Abstract

Sulfate metabolism and glucose (Glc) signaling are important processes required for plant growth, development, and environmental responses. However, whether sulfate metabolism is involved in Arabidopsis response to Glc stress remains largely unclear. Recently, we have found that proline content alterative 17 (pca17) is a double-mutant line in which both AtRZF1 (for Arabidopsis thaliana Ring Zinc Finger 1) and AHL (for Arabidopsis Halotolerance 2-like) genes are mutated. It was found that insensitive response of atrzf1 mutant to abiotic stresses was suppressed in pca17 mutant by regulating proline metabolism. Here, pca17 appeared to have sensitive response to Glc treatment by reducing cysteine (Cys) and adenosine monophosphate (AMP) contents in sulfate metabolism. Under Glc treatment, transcript levels of sulfate metabolism-related genes were significantly lower in pca17 than those in wild-type (WT) and atrzf1. Furthermore, AHL-overexpressing transgenic lines displayed more insensitive phenotypes than WT during Glc condition while ahl RNAi lines exhibited sensitive responses based on several parameters, including seed germination rate, cotyledon greening percentage, root elongation, and fresh weight. Interestingly, the pca17 phenotype in applied AMP with Glc treatment was similar to atrzf1 phenotype. Taken together, our results indicate that AHL is involved in Glc response by modulating sulfate metabolism in Arabidopsis.