Abstract BBX (B-box) protein is a subfamily of zinc finger transcription factor protein family, which is widely involved in plant growth and development. And, they also play an important role in abiotic stress response. Eucalyptus is an economic tree species in southern China. However, most cultivated Eucalyptus species are sensitive to abiotic stresses, which made the extension of Eucalyptus cultivation range and the improvement of cultivation benefit limited. In order to enrich gene resources of abiotic stress resistance and provide the basis for molecular assisted breeding for Eucalyptus, total of 21 EgrBBX gene family members were identified from the Eucalyptus grandis genome. Chromosomes distribution, protein sequence structure, and the classes and distribution of cis-elements in promoters were characterized with software of mg2c, Protparam, MEGA and PlantCARE. And, tissue specific expression of EgrBBX family genes and their expression profiling under low temperature, drought and salinity were also analyzed with qRT-PCR. The results showed that EgrBBX genes, named EgrBBX1~21, were distributed at 9 chromosomes. The encoded protein sequences contained classic B1, B2 and CCT domains and could be classified into 5 classes: B1+B2+CCT type ⅠandⅡ, B1+B2, B1+CCT and B1. The results of promoter element analysis indicated that a large number of light-responsive elements and abiotic stress response elements such as ABRE (ABA-responsive element), MBS (MYB binding site), LTR (low-temperature responsiveness), and HSE (heat-stress responsive element) existed in promoter sequences of EgrBBX family gene. qRT-PCR results showed that EgrBBX1, EgrBBX7, EgrBBX9, EgrBBX13 and EgrBBX18 were mainly expressed in leaves, and EgrBBX3, EgrBBX6 and EgrBBX15 had relatively high expression levels in stems. Under the treatments of different time at 4 °C, drought and high- salinity (200 mmol/L NaCl), most EgrBBX gene expression were changed. During the time of low temperature treatment, expression of EgrBBX4, EgrBBX7, EgrBBX8, EgrBBX14, EgrBBX16 and EgrBBX17 showed strong inhibition. EgrBBX8, EgrBBX11, EgrBBX12 and EgrBBX18 showed significant up-regulated expression at 1 d after drought treatment, and the induction effect weakened or disappeared after 2 d. Under high salinity treatment, 13 of 21 EgrBBX genes reached expression peak after 12 h treatment and then gradually decreased. The results in this study provided a basis for further revealing the functions of EgrBBX family in abiotic stress response, and could facilitate the screening of EgrBBX genes which are stress-resistant in Eucalyptus.
YANG Ning,CONG Qing,WANG Xiao-Rong, et al. Identification of EgrBBX Gene Family and Its Expression Analysis Under Abiotic Stress in Eucalyptus grandis[J]. 农业生物技术学报, 2020, 28(4): 658-671.
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