Thiourea mediated regulation in the expression profile of aquaporins and its impact on water homeostasis under salinity stress in Brassica juncea roots

Bioregulatory molecules such as thiourea (TU) play an important role in imparting stress tolerance to crops. However, the molecular mechanism involved in the TU-mediated tolerance has not been elucidated. Towards this endeavour, the expression profile of various PIPs (plasma membrane intrinsic proteins) was studied under salt stress (NaCl; 700 mM) with/without thiourea (TU; 6.5 mM) at different time periods in roots of Brassica juncea. Various aquaporin isoforms demonstrated an upregulation upon salinity stress imposition, whereas they were downregulated upon TU supplementation. TU treatment also led to a decrease in the accumulation of reactive oxygen species and delimited the need for an enhanced accumulation of osmolytes. The vacuolar pH was also maintained in NaCl + TU treatment as demonstrated by in vivo31P NMR of roots. In conclusion, TU supplementation to salt stressed seedlings was found to maintain the water homeostasis of roots through coordinated regulation of different PIP isoforms.