Identification Of F-box Gene Family In Brassica Oleracea And Expression Analysis In Response To Low Temperature Stress

Brassica oleracea is one of the important vegetable crops that are widely grown everywhere.Low temperature is the main limiting factor for overwintering cultivation of cabbage in the open field,which cause a decrease in yield and quality.The F-box protein family is characterized by the inclusion of at least one F-box motif that has been shown to play an important role in regulating various developmental processes and stress responses.At present,studies on the F-box gene family of Brassica oleracea have not been reported.In this study,303 F-box genes in the cabbage genome were identified based on the Linux system by using the hidden Markov model for two searches.These genes were subdivided into different groups according to their functional domains.Basic information,chromosomal localization,tissue expression pattern,low temperature stress response et al.were further analysed.The main results are as follow:(1)303 F-box genes were identified in the cabbage genome,of which 224 F-box genes were unevenly distributed on 9 chromosomes of cabbage.The cabbage F-box family is divided into 9 groups according to the functional domains involved.There are 229 pairs of tandem repeat genes in cabbage,of which 51 pairs are positively selected.It is speculated that gene duplication events in or between chromosome arms may promote the expansion of the gene family in cabbage.(2)Studies have shown that most F-box proteins are tissue-organ specific and have different functions in different organs.In the analysis of the tissue-specific expression of the cabbage F-box gene family,it was found that the six F-box genes except the BoFBX156 gene had the highest expression in rosette leaves,followed by roots and stems.(3)Under low temperature stress,the expression of BoFBX156 gene was decreased,and the expression of the other five F-box genes was increased.The expression level in the processing below zero is significantly higher than the processing above zero,and the transcription level was highest at 0℃.The expression of F-box gene in the cold-tolerant variety "ZG" was greater than that of the cold sensitive material "YC".With the prolongation of stress time,the expression activity of each gene in "ZG" was higher than that of"YC" at 24h,and it was more resistant to low temperature.These results indicate that different F-box genes exhibit different expression patterns under cold stress conditions.