Molecular Evolution and Functional Divergence of Chitinase Gene Family in Hevea brasiliensis Genome
|Scooped by Biswapriya Biswavas Misra|
Hevea brasiliensis, the largest commercial source of natural rubber, is known to be invaded by multiple fungal pathogens, affecting the global rubber production resulting in severe economic losses. Usually, chitinases form the very first line of defense against fungal pathogens in plants. However, the chitinase gene family structure remains elusive in the rubber tree genome. A complete overview of this gene family in rubber tree is presented, underscoring the gene structures, phylogeny, and conserved features of encoded proteins. Using homology-based bioinformatic approaches, it is reported that the chitinase gene family in rubber comprise of 39 members belonging to glycoside hydrolase (GH) classes. They are represented as 7 Class I [GH 19], 1 Class II [GH 19], 16 Class III [GH18], 5 Class IV [GH19] and 10 Class V [GH18] sequences as inferred from their sequence and structural features. Moreover, Class I chitinases share sequence similarity to plant lectins. Notably, the lysozyme-like domains in Class III chitinases, also known as hevamines, provide specialized machinery for resistance against pathogens. EST and transcriptome analyses indicate the exclusive expression of Class IV and V chitinases in leaves, while others are expressed in both leaves and latex. Phylogenetic and comparative genomic analyses of the sequences reveal the constant and selective evolutionary divergence of specific classes of chitinases in rubber tree, probably, to enable the tree against the fungal attacks and as adaptive mechanism for endophytic fungi. These molecular tools would provide enormous applications in management of phytopatho-interactions in rubber tree in future.