Study On The Function And Expression Patterns Of Oxidized MRNA Associated With Artificial Aging In Maize Embryo

Seed aging is a complex biological process resulting in the decrease of seed vigor.It is a great significance to study and elucidate the mechanism of seed aging for seed storage and preservation of germplasm resources.In this study,maize seeds(zhengdan 958)were selected as experimental material to study the effect of artificial aging treatment(temperature: 45?,relative humidity: 100%)on the seed vigor,the content of H2O2,CAT activity,MDA content and m RNA oxidation in embryo.In situ hybridization and fluorescence quantitative PCR technology were used to analyze the expression patterns of some highly oxidized protein synthesis and energy metabolism related m RNAs.The results were as follows:1.The color of the seed coat gradually fades and tarnish during the artificial aging treatment.The seed germination rate,vigor index and germination index all showed a decreasing trend.2.The activity of catalase in seed embryo decreased during the aging treatment.The content of hydrogen peroxide in the embryo reaches its maximum on the third day and then decreased.Reactive oxygen species produced and accumulated in the radicle first in the process of seed aging.The content of malonaldehyde increased,which indicated that the damage to the membrane system increased.3.Twenty-seven highly oxidized storage m RNAs were selected,which mainly focused on protein synthesis and energy metabolism.Highly oxidized protein synthesis m RNA mainly included mature enzyme and ribosomal proteins m RNAs.The main function of mature enzyme is to bind the intron RNA to promote the splicing of RNA.The ribosomal proteins play an important role in protein synthesis and were involved in DNA replication,transcription,translation and other processes.The high oxidation of mature enzyme and ribosomal proteins m RNAs may hinder protein synthesis and was adverse to the development of seeds.The highly oxidized m RNA related to energy metabolism are mainly cytochrome c oxidase,NADH dehydrogenase and ATP synthase.Cytochrome c oxidase and NADH dehydrogenase are the main components of cell electron transport chain.ATP synthase is involved in oxidative phosphorylation and photophosphorylation.The oxidation of cytochrome c oxidase,NADH dehydrogenase and ATP synthase m RNAs have direct influence on the normal energy supply of cells.4.In situ hybridization results showed that these protein synthesis m RNAs(GRM ZM5G851769?GRMZM5G881135)and energy metabolism m RNAs(GRMZM5G872710?GRMZM2G156536)expressed in the whole embryo and expressed more strongly in the radicle and germ then mbryo axis.The expression patterns of protein synthesis and energy metabolism m RNAs in radicle,embryo axis and germ of maize were quantified respectively.The results showed that the relative expression value of protein synthesis and energy metabolism m RNA in the radicle and germ of maize was significantly higher than that in the embryo axis,which were similar to the results of in situ hybridization.5.The expression patterns of m RNAs related to protein synthesis and energy metabolism were validated by q RT-PCR.The resultes illustrated that the expression of protein synthesis and energy metabolism m RNAs decreased gradually in the process of artificial aging treatment.6.According to the previous research of our laboratory,the possible mechanism of seed aging was proposed by combining the results of this experiment: in the process of aging treatment,the activity of antioxidant enzymes decreased,which lead to the accumulation of ROS.These would further lead to the oxidative damage to the embryo storage m RNAs,which hinder the synthesis of protein and cause the insufficient of energy in the seed germination process,ultimately lead to the decline of seed vigor.