Influence of hypergravity – a novel stimulus on root growth phenotype and physio-biochemical parameters in sorghum (Sorghum bicolor L.)

Abstract

Plants on Earth are evolutionarily subjected to constant mechanical stimulation of the gravitational field. Earth’s gravity (1g) significantly influences the growth and morphogenesis of crop plants. Hypergravity, an evolutionarily novel environment has been exploited to comprehend the response of plants in the context of terrestrial and extra-terrestrial applications. Recently, researchers have shown that hypergravity induces desired phenotypic variability that can be utilized for improving terrestrial agriculture. In the present study, we tested the hypothesis that hypergravity can be used as a novel tool for inducing reliable phenotypes that can be further exploited for crop improvement programs. In the present investigation, screening is done with varied hypergravity regimen in sorghum, The acute hypergravity (1000g for 1 hr) regimen induced a significant increase in seedling vigor and plant growth parameters in both laboratory and greenhouse conditions. Among nine genotypes screened, three best-responding were chosen for further study. Additionally, we quantified associated biochemical, and hormonal changes. Resultant data revealed a significant increase in total dehydrogenase enzyme activity in seed; catalase, superoxide dismutase enzymes in seedlings, and elevated total chlorophyll content in response to hypergravity. Further, hypergravity elicits robust phytohormones dynamics in the root seedlings, and endogenous levels of 3-Indole Acetic Acid and indole-3-butyric acid are shown to have a direct correlation with the regulation of root phenotypes. Collectively, this work describes the utility of hypergravity as a novel tool for inducing phenotype/s that could be potentially exploited for improving crop plants in the future.