Transcriptomic analysis showed differential modulation of taproots and fibrous roots attending to carbohydrate metabolism in Medicago truncatula under water deficit stress
Medicago truncatula is a model legume widely cultivated in Australia and relatively drought-tolerant. Mt plants were subjected to moderate and severe water deficit stress. Physiological and transcriptomic analysis of the leaves, taproots and fibrous roots were analysed in response to water deficit stress. Overall metabolism was modulated during water deficit stress, and tissue-specific differential response to water stress was reported. Leaves and fibrous roots were the more affected organs under stress conditions while taproots were the more resilient organ to water deficit. Carbohydrate, growth, signalling, TF, oxidative protection and stress-related metabolism were highly modulated. Regarding carbohydrate metabolism, sucrose-degrading and synthesis enzymes, glycolysis and starch metabolism were up-regulated in the taproots and fibrous roots, while raffinose and myo-inositol related genes were reported as leaves-specific, under WD conditions. Relative to carbohydrate transporters encoding genes, a differential modulation depending on the transported molecule was reported during stress conditions. Under drought conditions, sucrose metabolism is regulated by different isoforms of sucrose synthase (SUS), invertase (INV) and sucrose phosphate synthase (SPS). These SUS, INV, SPS isoforms and the different sucrose transporters were defined as tissue specific and involved in a continuous recycling and transport of sucrose in Mt.