Study On Exogenous Methyl Jasmonate Regulating Carotenoid Synthesis In Germinated Maize Kernels

Carotenoid is a kind of nutrient with various physiological functions,and it is also an important variety of natural pigments.Lutein is the main carotenoid in maize.It is mainly synthesized in the cytoplasm through the isoprenoid pathway.The synthesis process is affected and regulated by a variety of external factors.Among them,plant hormones play a significant role in regulating the expression of enzymes.In.this paper,the effects of exogenous methyl jasmonate(MeJA)on the physiological metabolism,mainly carotenoids of germinated maize kernels and their antioxidant capacity were studied.The optimal treatment concentration of exogenous MeJA was obtained.The mechanism of lutein enrichment in germinated maize kernels under the treatment of exogenous MeJA was revealed based on the expression level of gene.The effects of exogenous MeJA treatment on physiological and biochemical changes and carotenoid accumulation in germinated maize kernels under NaCl stress were also studied.The main contents are as follows:(1)The effects of different concentrations of exogenous MeJA treatment on physiological and biochemical indexes in germinated maize kernels were investigated.The results showed that application of 0.1-5.0 ?M exogenous MeJA can significantly increase the germination percentage and sprout length of maize kernels at 72 h of germination.Among them,0.5 ?M MeJA has the most significant effect.The germination percentage and sprout length were increased compared with the control group.The reducing sugar content reached a maximum of 71.77 mg/g DW at a MeJA concentration of 0.5 ?M,and the soluble protein content and free amino acid content reached a maximum at a MeJA concentration of 5.0 ?M,which were 689.50 mg/100g DW and 8.19 mg/g DW,respectively.(2)Different concentrations of exogenous MeJA treatment significantly affected the growth and development of germinated maize kernels.Under the treatment of 0.5 ?M MeJA,the lutein content in germinated maize kernels reached a high level of 11.82 ?g/g DW,which was 42.5%higher than that of the control group.Zeaxanthin,?-cryptoxanthin,?-cryptoxanthin and ?-carotene content also reached peak values of 7.28 ?g/g DW,1.07 ?g/g DW,0.29?g/g DW,and 0.63 ?g/g DW,respectively.Compared with the control group,it increased by 19.5%,45%,32%and 70%,and its enrichment effect was extremely significant.(3)Exogenous MeJA treatment led to different expression patterns of key genes in the carotenoid synthesis pathway.The transcriptional expression of PSY increased by 1.8 and 1.2 times in 0.5 ?M and 1.0 ?M MeJA treatment,respectively,but decreased by 0.8 times in the 5.0?M group.In 0.5?M MeJA treatment,the expression levels of PDS and ZDS were 1.4 times that of the control group,and the expression levels of LCYB,LCYE,CYP97C,and BCH1 were significantly increased,which were 3.8 times,3.3 times,3.9 times,and 1.8 times of the control group.Times.The highest expression level of CYP97C is much higher than that of BCH1,which is the main reason that the increase of lutein in the synthetic pathway is far more than that of zeaxanthin.However,the expression of all key carotenoid genes was significantly reduced in the MeJA synthesis inhibitor SHAM treatment group.(4)The application of exogenous MeJA can effectively alleviate the adverse effects of 300 mM NaCl stress on germinated maize kernels and increase the carotenoid accumulation.Among them,1 ?M MeJA had the best effect,in which the lutein content was increased by 12.1%compared with the 300 mM NaCl treatment group,and 58.0%compared with the control group.Among them,1 ?M MeJA had the best effect,and the lutein content was increased by 12.1%compared with the 300 mM NaCl treatment group,and 58.0%compared with the blank control group.Considering the growth and development of maize kernels,the application of 1 ?M MeJA can not only effectively alleviate the adverse effects of salt stress on growth and development,but also further increase the accumulation of secondary metabolites carotenoids(mainly lutein).This not only provides a new idea for alleviating plant salt resistance,but also provides a new method for enriching lutein in maize kernels.