Effects Of Cold Stress On Adaptability Of Oat

Oat(A.nuda L.)is an annual herb of the genus(Avena L.)in the Gramineae family.It is an important food and feed crop.Although oat has excellent cold resistance characteristics,cold reversal in spring is still an important abiotic factor affecting the production and quality of oat.Cold injury at seedling stage can lead to leaf wilt,curling and even plant death.In this study,the experiment was carried out in the three leaves one heart period,which is easy to meet with the cold period of spring.Cold injury at seedling stage can lead to leaf wilt,curling and even plant death.In order to further study the adaptability difference of different varieties of oat seedlings after cold stress,two local varieties of Oat R85(Xiao Yanmai)and R109(Wu Du)in southwest China and two local varieties of Oat R95(Yu Mai L30)and R126(Gu Yuan Youmai)in northwest China were used as experimental materials,and the oat seedlings of three leaves and one heart stage were subjected to cold stress treatment at4℃ for 48 h.The phenotypic differences of the tested oat seedlings were detected,according to phenotypic data,oat seedling leaves of R85(Xiao Yanmai),which was more sensitive to cold,and R95(Yu Mai L30),which was less sensitive to cold,were selected for transcriptomic analysis.The specific results were as follows:(1)Cold stress affected the seedling phenotypes of four Oat varieties.After cold stress at 4℃ and 48 h,the chlorophyll content of plant height,root length and fresh and dry weight of stem and leaf of R85(Xiao Yanmai)were significantly decreased compared with the control group.Leaf stomata were mostly closed,root structure was partially destroyed,cortical parenchyma cells were damaged,and cell space became smaller.The root length,plant height,stem and leaf dry weight of R95(Yu Mai L30)showed no significant changes in shape,and the root structure only showed cell shrinkage,but did not show damage to cortical parenchyma cells.After 3 d of cold stress recovery,the survival rate of R109(Wu Du)and R126(Gu Yuan Youmai)seedlings was lower than that of R85(Xiao Yanmai)and R95(Yu Mai L30).R85(Xiao Yanmai)and R95(Yu Mai L30)had stronger cold resistance.(2)PE150 mode sequencing was performed by Illumina Nova Seq6000 sequencing platform.Eukaryotic reference transcriptome(RNA-seq)analysis of 12 samples in control and stress groups of R85(Xiao Yanmai)and R95(Yu Mai L30)was completed,and the number of differential expression genes of the two Oat cultivars increased significantly before and after cold stress.The number of differentially expressed genes in R85(Xiao Yanmai)(20,942)was much higher than that in(Yu Mai L30)(16,660).The gene expression of the two oat varieties was verified by RT-qPCR and was consistent with the transcriptome results.GO enrichment analysis showed that after cold stress,DEGs of R85(Xiao Yanmai)and R95(Yu Mai L30)were significantly enriched in photocooperation,light collection,chloroplast thylakoid membrane,Oxidoreductase activity,UDP-glycosyltransferase activity and other items.KEGG enrichment analysis showed that 60 metabolic pathways were significantly enriched in R85(Xiao Yanmai)and 55 in R95(Yu Mai L30)after cold stress treatment,and the major significant pathways were photosynthesis-antenna protein,amino acid biosynthesis,plant hormone signal transduction,etc.According to the classification and annotation of COG,DEGs of R95(Yu Mai L30)and R85(Xiao Yanmai)mainly focus on carbohydrate transport and metabolism,post-translational modification,protein turnover,molecular chaperone,signal transduction mechanism,and general function prediction.In this study,the cold stress response genes of different cultivars from different regional sources were excavated,and the environmental adaptation mechanism of oat was explored.This will lay a foundation for further research on cold tolerance regulation network and breeding new cold tolerance varieties.