Characterization of Aluminum Stress Tolerance in Mung Bean for Crop Improvement

Abstract

Under acidic soil and aluminum stress conditions, the crop plants are facing several growth defects. Particularly significant decrease in root growth, nutrient uptake and low yield are the very common problems. Besides, several organic acid transporters are involved in Al sensing, transport and detoxification mechanisms. In this study, Al stress tolerance of mungbean plants was studied under different Al stress conditions. The results showed that the mungbean plants are severely affected by Al stress and released significant amount of malate in hydroponics media when compared with control plants. Based on this study and expression analysis of Al stress responsive genes, further, we developed ALMT1 overexpressors and ALMT1-RNAi transgenic plants of mungbean to analyze the acid soil tolerance. Later, these transgenic mungbean plants were challenged with different Al concentrations to check their stress responses. The ALMT1-RNAi lines showed almost no root growth variations in hydroponics media when compared to WT plants under normal growth conditions but displayed significant decrease in root length on exposure to Aluminum. Further, when AtALMT1 was overexpressed, even in absence of Aluminum stress, there was approximately 12% increase in length of primary roots when compared with WT. Malate efflux was almost doubled in the AtALMT1 overexpressed plant lines whereas KD lines showed around 36% drop in malate efflux under Al stress conditions. Therefore, based on these observations, we concluded that VrALMT1 has a significant role on Aluminum stress tolerance responses in mungbean plants.