Effect of CAX1a TILLING mutations and calcium concentration on some primary metabolism processes in Brassica rapa plants

Abstract

Cation/H+ exchanger transporters (CAXs) are crucial in Ca homeostasis and in the generation of Ca profiles involved in signalling processes. Given the crucial role of CAX1 in Ca homeostasis, CAX1 modifications could have effects on plant metabolism. Three Brassica rapa mutants for CAX1 were obtained through TILLING. The aim of this work is to assess the effect of the different mutations and different Ca doses on plant metabolism. For this, the mutants and the parental line were grown under low, control and high Ca doses and parameters related to nitrogen (N) and tricarboxylic acid (TCA) metabolisms, and amino acid (AAs) and phytohormone profiles were measured. The results show that BraA.cax1a mutations affect to metabolism especially under high Ca dose. Thus, BraA.cax1a-7 inhibited some N metabolism enzymes and activated photorespiration activity. On the opposite side, BraA.cax1a-12 mutation provides a better tolerance to high Ca dose. This tolerance could be provided by an improved N and TCA metabolisms enzymes, and by a higher glutamate, malate, indole-3-acetic acid and abscisic acid concentrations. Therefore, BraA.cax1a-12 mutation could be useful in B. rapa improving and the metabolomics changes observed in this mutant could be key for a greater tolerance to high Ca doses.