Abstract:

The genome-wide analysis of the COL family in walnut（Juglans regia）was used to identify the COL（CONSTANS-Like）family members in walnut,and then to reveal molecular evolution and function of the COL family in walnut. Having ‘Xinxin 2'（Juglans regia cv. Xinxin No. 2）as research materials,the genome-wide identification and comprehensive analysis of the COL gene family in walnut were conducted,and their expressions in the female flower bud in different tissues and stages were analyzed. Totally,55 members of COL genes were identified from the whole genome of walnut,and they were unevenly distributed over 16 chromosomes and 1 Scaffold,designated as JrCOL1-JrCOL55,amino acids were 117-789,the molecular weight was between 12.99 to 86.08 kD,and the theoretical isoelectric point ranged from 4.00 to 8.94. The JrCOL proteins were classified into 3 subgroups by evolutionary tree analysis,and the conserved motifs and gene structure of each subgroup were similar. Cis-acting element analysis in the promoter region showed that JrCOLs contained a large number of functional domains related to light signal,plant hormone and stress. Spatial expression pattern analysis showed that JrCOL gene expression was tissue specific and the expression of JrCO1,JrCO7a-c,JrCO8,JrCOL23,JrCO31a-c,JrCO33,JrCOL35 and JrCOL50a-f was the highest in the leaves. And the RT-PCR analysis revealed that JrCOL1,JrCOL35,JrCOL50a-f and JrCOL52 showed consistent expression trend in female flower buds of ‘Xinxin 2',and JrCOL50a-f played an important role in the differential process of female flower buds of ‘Xinxin 2'. And 55 JrCOL members in 3 subgroups were identified in the walnut,and were unevenly distributed in 16 chromosomes and 1 Scaffold,with conserved motifs distributions and diverse expression patterns. It is suggested that JrCOL family gene plays key role in the development of walnut leaves.

Key words: Juglans regia cv. Xinxin No. 2, CONSTANS-Like, gene family in walnut, genome-wide identification, gene expression