优质甜玉米骨干系在低温下种子萌发及幼苗抗性研究OA北大核心CSTPCD

Sweet maize generally suffers from low seed germination and sensitivity to low temperature.In order to explore cold tolerance of sweet maize during germination and seedlings,12 sweet maize backbone inbred lines were used for testing the germination-related physiological indexes at 25℃(optimum temperature),18℃(normal growth temperature)and 12℃(low temperature),and then advantageous materials under low-temperature conditions were screened by combining with correlation and clustering analyses.5 advantageous materials were selected to treat with 4℃low-temperature treatment at seedling stage,and then the cold tolerance physiological indexes and genes expression were investigated.The results showed that the seed germination rate,germination potential,germination index and vigor index were decreased with temperature decreased,among these,the variation in germination rate was 82.5%,75.8%,and 62.5%,respectively.The analysis of variance(ANOVA)showed that there were highly significant differences in germination rate and germination energy indexes among different temperature,variety and temperature-variety interactions.At 18 and 12℃,8 individual indicators of low temperature tolerance showed there were significant correlations between germination rate,germination potential,germination index and vigor index.The 12 varieties were classified into three categories,which were cold-tolerant,general and sensitive,and 7 advantageous materials,the Min sweet line T146(1-46),the Min sweet line L18(L18),the 12hi307(307),the Min sweet line JR8609(JR86),the Min sweet line AS67(AS67),the Min sweet line X9034(X90),and the Min sweet line AG87(AG87)with better low temperature germination tolerance were screened out.Seedlings of 1-46,L18,307,JR86 and AS67 were subjected to low temperature treatment,among which malondialdehyde(MDA)of L18 seedlings was significantly lower than those of the remaining four materials,while proline(Pro),superoxide dismutase(SOD)and peroxidase(POD)enzyme activities showed opposite performance.The cold-resistant gene expression analysis revealed that ZmCesA2,ZmCesA10 and ZmDREB1.7 were highly expressed in AS67 and L18,while ZmMPK2 was expressed the lowest in L18.Comprehensive analysis indicated L18 and AS67 have strong cold resistance.These results enriched the researches on cold resistance in sweet maize,and provided advantageous material resources for breeding new cold resistant varieties.