Molecular Mechanism Of Maize Annong 876 Parents In Response To Salt Stress

Maize(Zea mays L.)is an important food crop,feed crop,and industrial material in China,but soil salinization severely affects maize growth,resulting in lower yield and quality.Mining salt tolerance related genes and studying their functions to breed new varieties is an effective way to cope with salinity soils and improve the quality and yield of maize.In this study,two maize inbred lines,Annong 876 male parent cmh15 and Annong 876 female parent CM37,were used as experimental materials to identify the changes in phenotypic,physiological and biochemical indexes in response to salt stress at the seedling stage.At the same time,transcriptome sequencing was further used to screen the differentially expressed genes in response to salt and identify the key differentially expressed genes and related hormonal signaling pathways in response to salt stress.The findings provide an important theoretical basis and application for further mining new functional genes and breeding new cultivars of maize with salt tolerance.The main research results are as follows:1.The three-leaf stage seedlings of Annong 876 male and female parents were treated with 300 m M Na Cl stress.Based on plant phenotypes such as plant height,root length and leaf colour,we found that the male parent cmh15 had a milder salt stress phenotype than the female parent CM37 after treatment.2.Relative water content,relative electrical conductivity,malondialdehyde content,and peroxidase profiles of the three leaf stage seedlings of Annong 876 parents were measured,and it was further clarified that the male parent cmh15 was more tolerant to salt stress than the female parent CM37.3.Sequencing analysis of the 2 parents before and after treatment by RNA-Seq identified6836,9000,4329,and 5391 differentially expressed genes in the 4 comparison groups CKMVS-CKF,UVM-VS-UVF,CKM-VS-UVM and CKF-VS-UVF,respectively.4.GO and KEGG enrichment analyses were performed on the identified differentially expressed genes,and to understand the mechanism of salt resistance in the two inbred lines cmh15 and CM37,we found that the differentially expressed genes in the two groups CKFVS-UVF and CKM-VS-UVM were enriched in several GO terms and KEGG pathways related to plant stress resistance,for example,GO terms such as response to salt stress,response to stress and response to oxidative stress,KEGG pathways such as tyrosine metabolism,flavonoid biosynthesis and fatty acid metabolism.5.Based on the KEGG enrichment results of both CKF-VS-UVF and CKM-VS-UVM groups,four major hormonal signaling pathways were found,namely abscisic acid signaling pathway,auxin signaling pathway,cytokinin signaling pathway and ethylene signaling pathway,and different numbers and types of related differentially expressed genes in each signaling pathway were involved in the regulation.6.A total of 132 shared differentially expressed transcription factors were identified from the two groups,CKF-VS-UVF and CKM-VS-UVM,from which 12 transcription factor genes were selected as candidates for quantitative real-time PCR analysis to determine their salt-induced expression patterns in the maize inbred line B73.