Role Of Abscisic Acid In Aluminum Tolerance In Rice Bean (Vigna Umbellata) And Its Underlying Molecular And Physiological Mechanism

Aluminum toxicity is one of the main factors affecting food production in acid soil area. Some plants evolve aluminum tolerance mechanisms against Al toxicity. Understanding of the adaptation mechanisms of crop to aluminum toxicity is important for improving the tolerance of crop to aluminum and ensuring food safety production in acid soil by biological engineering or molecular breeding. Abscisic acid (ABA) is an important plant hormone, it plays a vital role in various biotic and abiotic stresses. However, whether ABA is a signal for regulating the plant aluminum tolerance mechanisms is still controversial, the molecular basis of ABA regulating aluminum resistance is also not clear. In this study, the rice bean we used is an Al-tolerance leguminous species and grows well in acidic soils. Then we studied the effects of exogenous ABA on aluminum tolerance of rice bean, and through transcriptome analysis in order to define the molecular mechanism of ABA in regulating rice bean aluminum tolerance. Main research results as follow:(1)A1 stress resulted in the rapid accumulation of ABA in root apex of rice bean,and decreasing leaf stomatal conductance, indicating that ABA can be transported from root to leaf rapidly; Exogenous ABA can effectively alleviate the aluminum induced inhibition of root elongation, while the improvement of ABA-mediated Al tolerance is not related to VuMATE1-dependent citrate secretion; we analyzed both cell wall and cell sap Al content in the root apices, the results showed that reduction of aluminum toxicity by ABA is not involve in aluminum resistance mechanism.(2) We obtained 48751 annotated Unigene of rice bean apex by Genome-wide transcriptomic analysis. Gene expression difference analysis revealed that nearly one-third of transcripts expression is common to both Al stress and ABA treatment., therefore, ABA signal transfer has important relationship with aluminum tolerance of rice bean.In addition, lots of genes related to cell wall modificaiton and osmotic adjustment are specific up-regulated under Al+ABA treatment, indicating that cell wall modificaiton and osmotic adjustment have an important role in enhancement of rice bean resistant aluminum is related to Al tolerance.