Physio-biochemical and molecular response of rice (Oryza sativa L.) cultivars with different allelopathic potentials to potassium deficiency

In order to explore physio-biochemical and molecular response of rice cultivar with different allelopathic potentials to potassium deficiency, allelopathic rice “PI312777” and non-allelopathic rice “Lemont” were studied. Two rice accessions were cultured respectively in Hoagland solution at 5 mg(K)·L^-1 (low potassium) and 40 mg(K)·L^-1 (normal potassium). Morphological indexes (root length, shoot height, root-to-shoot ratio, and biomass) and physio-biochemical characteristics (SOD, POD, CAT, root activity, and N, P, K contents) were investigated at two potassium levels. Additional twelve rice genes of correlative key enzymes for N, P, K absorption and utilization were determined by Real-time Fluorescent Quantitative PCR (FQ-PCR) to evaluate expressed change under low potassium. The results show stimulation in root length, root-to-shoot ratio and allelopathic rice “PI312777” biomass, but with insignificant influence on shoot height; whereas all the indexes show inhibition in non-allelopathic rice “Lemont”. The SOD, POD, CAT and root activity of the two rice accessions exhibit inhibition, while N, P, K content decreases. However, the rate of inhibition of the physio-biochemical characteristics and the degree of decrease in N, P, K contents are significantly higher in non-allelopathic rice “Lemont” than in allelopathic rice “PI312777”. Through FQ-PCR detection, all the twelve genes of the key enzymes are up-regulated at a significantly higher order of magnitude in allelopathic rice “PI312777” than in non-allelopathic rice “Lemont”. The findings reveal that allelopathic rice “PI312777” has better adaptability and endurance to K deficiency than non-allelopathic rice “Lemont”.