Identification and Characterization of the COBRA-Like Gene Family in the Spinacia oleracea L. Genome

Abstract

COBL genes play an important role in the biosynthesis of cellulose, the main component of the cell wall. This study aimed to identify and characterize members of the COBL gene family that have not been characterized in the spinach genome. Eleven COBL members carrying the COBRA and/or COBL domains were found in the spinach genome. Among the So-COBL proteins, So-COBL1 and So-COBL2 are unstable. All So-COBL proteins are hydrophilic and, with aliphatic indices below 100, are not heat-stable. Both tandem and segmental duplications have occurred during the evolution of So-COBL genes. Because the Ka/Ks ratio is less than one, they have been subjected to purifying selection throughout evolution, eliminating deleterious variants. So-COBL genes contain cis elements in their promoter region that respond to many environmental stimuli, particularly hormone and light responses. Phylogeny analysis of spinach, Arabidopsis, and quinoa COBL genes revealed two groups, COBRA and COBL7-like. The intron-exon organization, motif, and domain structure of the genes grouped in the same group are similar. Synteny analysis revealed further orthology between quinoa and spinach. This study highlights the importance of COBL genes for future studies.

COBL genes play an important role in the biosynthesis of cellulose, the main component of the cell wall. This study aimed to identify and characterize members of the COBL gene family that have not been characterized in the spinach genome. Eleven COBL members carrying the COBRA and/or COBL domains were found in the spinach genome. Among the So-COBL proteins, So-COBL1 and So-COBL2 are unstable. All So-COBL proteins are hydrophilic and, with aliphatic indices below 100, are not heat-stable. Both tandem and segmental duplications have occurred during the evolution of So-COBL genes. Because the Ka/Ks ratio is less than one, they have been subjected to purifying selection throughout evolution, eliminating deleterious variants. So-COBL genes contain cis elements in their promoter region that respond to many environmental stimuli, particularly hormone and light responses. Phylogeny analysis of spinach, Arabidopsis, and quinoa COBL genes revealed two groups, COBRA and COBL7-like. The intron-exon organization, motif, and domain structure of the genes grouped in the same group are similar. Synteny analysis revealed further orthology between quinoa and spinach. This study highlights the importance of COBL genes for future studies.