Functional Analysis Of Rice Lectin Gene OsJRL In Response To Cadmium Stress

Rice is an important food crop in China,but with the strongest potential to accumulate cadmium among the major cereal crops.In recent years,rice lectin has been found to be related to the stress resistance in rice.Through genome-wide association analysis of cadmium content in 300 rice materials,several SNPs were associated with lectin gene OsJRL.Transcriptome analysis also showed that the OsJRL gene in cadmium tolerant rice was induced by cadmium stress.Studies have shown that the OsJRL gene responding to abiotic stress,but few studies were reported on the response to cadmium stress.In this study,the bioinformatics of the OsJRL gene was analyzed,and OsJRL was transformed into yeast cadmium sensitive strain ?ycf1 to study the its' response to cadmium stress.At the same time,we editted the OsJRL gene in Nipponbare by CRISPR/cas9 technology.The agronomic traits,cadmium accumulation and physiological characteristics of the obtained homozygous mutants under cadmium stress were investigated.That might promote further studies on the mechanism of OsJRL gene responding to cadmium stress in rice,and enrich the germplasm resources of low cadmium rice and provide reference for safe producing of rice.The main results are as follows:1)OsJRL gene was able to respond to cadmium stress and expressed mainly in rice roots.The ?ycf1 strain overexpressing OsJRL gene showed high tolerance to cadmium stress.OsJRL gene was supposed to be responded to cadmium stress and functioned majorly in root;2)CRISPR/Cas gene knock-out vector was constructed successfully,and positive transgenic rice lines were obtained.The mutated OsJRL gene were predicted to encode uncomplete protein due to early termination or amino acids deleted.The obtained homozygous mutants could inherite stably;3)Three stably inherited homozygous lines: osjrl-1,osjrl-3,osjrl-4 with different OsJRL mutation types were selected for hydroponic experiments with cadmium stress.The results showed that the content of cadmium in roots,stems and leaves of OsJRL mutants was higher than that in wild type.The cadmium absorption capacity among different varieties was: osjrl-3>osjrl-1>osjrl-4>wild type.Under cadmium treatment,the cadmium content in the roots,stems,and leaves of the mutants were increased 4.64,2.47,and 2.27 times to that of the wild type,respectively.And the cadmium content in plant at maturity between the mutant and the wild type were different significantly.Mutation of OsJRL gene does not affect plant growth,but affects biomass accumulation and yield traits,while the influence is dependent on growth stages and mutation types.Under cadmium treatment,the MDA content,SOD,POD and CAT enzyme activities in osjrl-1 were 42.11%,23.91%,50.01% and 14.24% higher than that of the wild type,respectively.The soluble protein content in osjrl-1 was decreased to 77.92% of the wild type.The mutation of OsJRL enhanced the sensitivity of rice to cadmium.OsJRL may be involved in cadmium metabolism in rice,acted as a cadmium ion efflux transporter and mainly involved in the absorption of cadmium in the root and transpotation from root to stem at the late growth stage.