Salt stress affects mRNA editing in soybean chloroplasts

Abstract

Soybean, a crop known by its economic and nutritional importance, has been the subject of several studies that assess the impact and the effective plant responses to abiotic stresses. Salt stress is one of the main environmental stresses and negatively impacts crop growth and yield. In this work, the RNA editing process in the chloroplast of soybean plants was evaluated in response to a salt stress. Bioinformatics approach using sRNA and mRNA libraries were employed to detect specific sites showing differences in editing efficiency. RT-qPCR was used to measure editing efficiency at selected sites. We observed that transcripts of NDHA, NDHB, RPS14 and RPS16 genes presented differences in coverage and editing rates between control and salt-treated libraries. RT-qPCR assays demonstrated an increase in editing efficiency of selected genes. The salt stress enhanced the RNA editing process in transcripts, indicating responses to components of the electron transfer chain, photosystem and translation complexes. These increases can be a response to keep the homeostasis of chloroplast protein functions in response to salt stress.

Figure 1. Schematic illustration of qPCR analysis of RNA editing frequency showing relative locations of (A) specific-reverse and (B) specific-forward qPCR primers. Arrows depict the annealing sites of qPCR primers.

Figure 2. Boxplot indicating the editing of (a) NDHB-149, (b) PSBF-77, (c) RPS14-80, and (d) RPS16-212 sites of control and salt stress plants, in 4h and 24 hours treatment. Box area represents the lower and the upper percentiles. The upper whisker of the boxplot indicates the highest editing value observed; the lower whisker, the lowest editing value; and the middle line, the median editing value. Asterisk indicate significantly different values at P < 0.05.