Comparative biochemical, histochemical and expression analysis of SOD gene in a few traditional rice varieties under aluminium toxicity and phosphorous deficiency in Assam, India

Abstract

Assam soil is mostly acidic where rice is extensively cultivated that causes serious problems of aluminium (Al) toxicity and phosphorus (P) deficiency. Al is one of the major constraints that limit nutrient uptake and consequently growth and yield in rice. Identifying promising rice varieties having genetic ability that can cope up with Al toxicity and P deficiency is essential. In this study, five rice varieties with contrasting characters viz., Holpuna (tolerant), Soria sali, Beto (moderately tolerant), Baismuthi and Moti (susceptible) were selected to evaluate a comparative antioxidant protection mechanism under Al toxicity and P deficiency through standard biochemical, enzymatic and non-enzymatic analyses. Holpuna was seen to have enhanced capabilities of antioxidant protection in all the enzymatic and non-enzymatic analyses. Moreover, increasing tendency in malone dialdehyde (MDA), superoxide dismutase (SOD), ascorbate peroxidase (APX) and hydrogen peroxide on exposure to stress suggests the activation of internal detoxification of plant to cope with the surrounding stress. Histochemical assay also elucidate the level of reactive oxygen species (ROS) accumulation in the seedlings, showing higher accumulation of singlet oxygen in the susceptible varieties that forms dark complexes with the stain. Gene expression patterns further strengthen the expression of superoxide radicals in the tolerant and susceptible varieties. The susceptible varieties on exposure to 100 µM concentration of stress showed relatively higher fold change and vice versa in case of Holpuna. Findings of the work would be useful to identify potential rice variety for further recommendation for rice breeding programme.