Silicon Mediated Alleviation of Salinity Stress Regulated by Silicon Transporter Genes (Lsi1 and Lsi2) in Indica Rice

Abstract

Silicon accumulation is known to improve tolerance of plants under both biotic and abiotic stress. Salinity stress is an inevitable crisis causing wide spread damage to rice leading to food insecurity. The influence of Si (1mM) on two rice cultivars cv. Ghanteswari (high accumulator) and cv.Badami (low accumulator) which differs in Si uptake potential under saline (10ds/m EC) and non- saline conditions were studied in nutrient culture. The Si transporter genes were isolated and characterized to determine their function in salinity tolerance. Under stress, there was an increase in Si accumulation, Na⁺/K⁺ ratio, electrolyte leakage, lipid peroxidation and antioxidant activities. On addition of silicon, the K⁺ uptake increased, membrane damage reduced and osmolytes balance improve under salinity. But, the level of resurgence was varied in both cultivars, due to their differential Si-accumulation. Molecular characterizations of Lsi1 protein revealed its involvement in the movement of ion and water and therefore prevent osmotic stress. The Lsi2 is responsible for removal of Na⁺, reducing salt toxicity. Silicon accumulation is responsible for maintenance of cell water status, osmotic balance and Na⁺ ion exclusion during high salinity. The variable relative expression of Lsi2 provides a possible explanation for differential genotypic uptake of silicon.

Keywords:
differential Si-uptake; indicarice; Lsi1 and Lsi2 gene expression; Silicon; salt tolerance; qRT PCR