Identification And Sterility Mechanism Research Of Photo-thermo-sensitive Male Sterile Line CB1208-82 In Maize

The utilization of photo-thermo-sensitive genic male sterile line in hybrid seed production is an important way to achieve heterosis.Maize inbred line "CB1208-82”is a newly discovered male sterile line in Zhejiang University.Under sterile condition,the male sterile line aborted completely,and the tassel had only branches,no spikelets and florets.In this experiment,the sensitive period and critical condition of fertility transformation were identified by combining stage sowing in Sanya,Hainan and Hangzhou,Zhejiang with growth chamber treatment.The fertility of F1 and F2 generations was analyzed statistically,so as to identify their genetic characteristics.The activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)and ascorbic acid peroxidase(APX),the production rate of O2-and the contents of malondialdehyde(MDA),hydrogen peroxide(H2O2),chlorophyll,soluble sugar and free proline in the leaves of sterile and fertile plants at different developmental stages of tassels were measured.In order to explain the abortion mechanism from the perspective of physiology,biochemistry and proteomics,the content of protein in the leaves of fertile and sterile plants at different stages and the content of amino acid(AA)in the sensitive period of fertility transformation were determined,and the proteomics study was carried out using the leaves and young spikes in the sensitive period of fertility transformation.The results were as follows.1.The male sterile line 'CB1208-82' is a photo-thermo-sensitive genic male sterile line.Its fertility is controlled by a pair of recessive genes.The sensitive period of fertility transformation was spikelet differentiation stage.The male sterile line was completely abortive under low temperature and light intensity,and its sterility was stable.It was fertile under high temperature and light intensity.The critical daily average temperature was 23.0 ?and the critical illumination intensity was 13000 Lux.There was a complementary effect between temperature and illumination intensity.2.On the whole,antioxidant enzyme activity in leaves of male sterile plants are always lower than that of fertile plants in the same period,and the contents of MDA,H2O2 and the production rate of O2-in leaves of male sterile plants were higher than those of male sterile plants in the same period.It suggested that low activity of antioxidant enzymes and high accumulation of reactive oxygen species(ROS)in leaves might be one of the causes of male sterility.The contents of chlorophyll,soluble protein,AA and soluble sugar in leaves of sterile plants were lower than those of fertile plants in the same period,and in particular,during the early stage of tassel development,the soluble sugar content in leaves of sterile plants was significantly lower than that of fertile plants.,which indicated that low photosynthetic efficiency and lack of nutrients might lead to abnormal tassel development.3.Proteomics studies showed that compared with fertile plants,the proteins involved in sugar metabolism,protein folding,hydroxyllipid biosynthesis,photosynthesis,starch biosynthesis,chloroplast tissue and other biological processes in the leaves of sterile plants were significantly down-regulated.Compared with fertile plants,the proteins involved in translation,protein folding,intracellular transport,cell protein decomposition,protein refolding,thermal reaction,cell redox balance,GTP biosynthesis.UTP biosynthesis,acetyl pyruvate coenzyme A synthesis,transcriptional initiation of RNA polymerase ? promoter,hypoxia reaction,nucleosome assembly,the metabolic process of phosphorus-containing compounds and CTP biosynthesis were significantly down-regulated.These differential proteins in leaves and young panicles and metabolic changes associated with them may be related to sterility of sterile plants.