Reference-Aided Full-length Transcript Assembly, cDNA Cloning, and Molecular Characterization of 1 Coronatine-insensitive 1b (COI1b) Gene in Coconut (Cocos nucifera L.)

In the Philippines, 26% of the total agricultural land is devoted to coconut production making coconut one of the most valuable industrial crop in the country. However, the countrys multimillion-dollar coconut industry is threatened by the outbreak of coconut-scale insect (CSI) and other re-emerging insect pests promoting national research institutes to work jointly on developing new tolerant coconut varieties. Here, we report the cloning and characterization of coronatine-insensitive 1 (COI1) gene, one of the candidate insect defense genes, using Catigan Green Dwarf (CATD) genome sequence assembly as reference. Two (2) splicing variants were identified and annotated - CnCOI1b-1 and CnCOI1b-2. The full-length cDNA of CnCOI1b-1 was 7,919 bp with an ORF of 1,176 bp encoding for a deduced protein of 391 amino acids while CnCOI1b-2 has 2,360 bp full-length cDNA with an ORF of 1,743 bp encoding a deduced protein of 580 amino acids. The 3D structural model for the two (2) isoforms were generated through homology modelling. Functional analysis revealed that both isoforms are involved in various physiological and developmental plant processes including defense response of plants to insects and pathogens. Phylogenetic analysis confirms high degree of COI1 protein conservation during evolution, especially among monocot species. Key MessageThis paper reports the molecular cloning and characterization of corononatine-insensitive I (COI1) gene in coconut using reference-guided transcript assembly approach. As a well-known insect defense-response gene in other crops, the results of this study are expected to assist in the development of new resistant coconut varieties as one of the strategies to address threats in coconut production.