Physiological And Molecular Mechanisms Of Response To Cold Stress In Maize Seedling Stage

Maize(Zea mays.L)is a staple food crop in the world.Low temperature limited the growth,development and yield of maize has been widely studied.A large number of physiological and biochemical indicators have been used to study the growth of maize seedlings under low temperature stress,but there are few studies on maize proteomics under low temperature stress,and most of them are combined with transcriptomics,so they are limited to early responses.In order to understand the related mechanism of maize to cold tolerance,the cold-resistant genotype maize(MT)and the cold-sensitive genotype maize(MS)were used in the present study.The three visible leaves maize seedlings were shift to 4°C for4 days.The differences of morphology,physiology and biochemistry were compared study between the two genotypes maize.As well as the compared proteomics were conducted between the two genotypes maize with the relative and absolute quantification(isobaric tags for relative and absolute quantification,i TRAQ)method.The research results are as follows.(1)The continuous low temperature will cause the maize leaves to curl or even wilt both in cold-tolerant and cold-sensitive maize,and the plant height and root length are significantly reduced.However,a small decrease in MT was observed as comparing to MS.The paraffin section showed that the cells were low temperature both in cold-sensitive and cold-tolerant maize,but the damage degree of cold-sensitive maize cells is much higher than that of cold-tolerant maize.The leaf wilting may cause by the damage of plant cells.(2)In this study,the relative electrical conductivity(REC),malondialdehyde(MDA),and reactive oxygen species(ROS),which are indicators of plant damage,were significantly increased in MS and MT after exposure to low temperature,but MT did not The values of MDA,REC and ROS in leaves and roots were lower than those in MS.The analysis of the antioxidant enzyme system and osmotic regulator substances,which can improve plant stress resistance,showed that under low temperature stress,the antioxidant enzyme system(SOD,POD,CAT and APX)and osmotic regulator substances(proline,soluble sugar and soluble protein)were increased,but the amount of change in MT was significantly higher than in MS compared to control.Physiological and biochemical results showed that low temperature stress caused damage to maize seedlings,and MT had higher cold tolerance than MS.(3)The GO analysis,KEGG pathway enrichment and protein interaction analysis of differential proteins(DAPs)showed that the following metabolic changes may cause the MT has stronger cold tolerance than MS.(1)Carbohydrate and energy metabolism;(2)Transportation and metabolism of amino acids;(3)The scavenging ability of reactive oxygen species;(4)Post-transcriptional regulation and post-transcriptional modification.A batch of candidate proteins related to maize cold resistance were obtained and verified at the transcriptional level.This study can provide reference value for further analysis and verification of the role of these proteins in maize cold resistance.