Physiological Effects Of Strigolactone On Rice Seedlings Under Low Phosphorus Stress

Major element phosphorus(P)is a necessary nutrient element for plant growth and development.Lack of phosphorus in production will seriously affect plant growth and crop yield.Under low phosphorus stress,plants will improve their ability to resist adversity through their own stress system,remove adverse growth factors,and reduce damage to themselves.At the same time,plants can also improve their ability to absorb phosphorus in the environment by changing root configuration.Therefore,good root morphology is the basis for plants to absorb nutrient elements when facing low phosphorus stress.Strigolactone and its derivatives are a new plant hormone discovered in recent years.Related studies show that Strigolactone(SL)is also involved in the regulation of plant growth and development under different stresses.Under low phosphorus stress,the synthesis and secretion of strigolactone in plants increased significantly.However,it is not clear whether strigolactone is involved in low phosphorus regulation of plant growth and development and related molecular mechanisms.This is the main content of this study.In this experiment,the morphological indexes,antioxidant enzyme activities and chlorophyll fluorescence parameters of rice leaves and roots under low phosphorus stress were measured to study the short-term regulation mechanism of rice seedling growth under low phosphorus stress and exogenous GR24 on rice seedling under low phosphorus stress,and to clarify the correlation between strigolactone and rice growth under low phosphorus stress.This study will provide reference for further study on the interaction between different elements and strigolactone on the growth of rice seedlings.The main results of the experiment are as follows:1?Compared with the normal phosphorus treatment group,the plant height of rice seedlings increased under low phosphorus condition;the accumulation of dry matter decreased significantly,and low phosphorus mainly inhibited the accumulation of dry matter in the aboveground part,while the accumulation of dry matter in roots increased,resulting in root-shoot ratio.Increase and decrease the seedling index.However,strigolactone mediates the adverse effects of low phosphorus on the morphological indexes of rice seedlings,and further alleviated the growth and development of rice seedlings under low phosphorus conditions.2.The change of root morphology of rice seedlings under low phosphorus condition is the result of strigolactone: exogenous gr24 increased the root length and lateral root length of rice seedlings under low phosphorus condition;this is the reversal of monopoione lactone.Phosphorus inhibits the main root and reduces the number of lateral roots.The strigolactone causes the rice seedlings under low phosphorus to exhibit the root configuration under normal phosphorus treatment.The chlorophyll content in rice leaves decreased with low phosphorus,and the Fv/Fm,Fv/Fo and qP values decreased in chlorophyll fluorescence parameters,while qN values showed an upward trend.However,the chlorophyll content and chlorophyll fluorescence parameters of rice leaves under low phosphorus condition were mediated by strigolactone,which alleviated the effect of low phosphorus stress on photosynthesis of rice seedlings.4.Under low phosphorus,the content of malondialdehyde(MDA)increased,while the activity of antioxidant enzyme system decreased,while the osmotic adjustment substance(soluble sugar,soluble protein content)decreased,and the accumulation of active oxygen increased.0.1?mol/L GR24 reduced the accumulation of active oxygen in plants under low phosphorus treatment,and increased the activities of protective enzymes(SOD,POD,CAT,APX and NR),thus alleviating the effects of low phosphorus stress on the growth of rice seedlings.After 0.1?mol/L GR24 treatment for 10 days,the gene expression in rice roots changed significantly.After genomic enrichment and KEGG analysis,it was found that GR24 treatment had significant effects on the metabolic pathways in rice roots,especially phenylacetone(Phenylpropanoid biosynthesis)biosynthetic pathway(ko00940).Further analysis of the expression of related genes revealed that GR24 promoted the expression of homologous genes of key enzymes in the biosynthesis of lignin and secondary metabolites,and down-regulated the expression of differential genes in the pathway.In summary,the results showed that low phosphorus induced changes in the growth and development of rice seedlings,and strigolactone mediates the changes of root morphology and protective enzyme activities of rice seedlings under low phosphorus.