Identification and characterization of oxalyl-CoA synthetase gene (LsAAE3) in grasspea (Lathyrus sativus L.)

Grasspea is a pulse crop popular due to its hardiness and low cost of production. Presence of the anti-nutritional factor ‘P-ODAP’ in seeds and other plant parts hinders widespread cultivation and usage of grasspea. Oxalyl-CoA synthetase is one of the key enzymes of the CoA-dependent pathway of oxalate degradation and the P-ODAP biosynthesis pathway in grasspea. ACYL ACTIVATING ENZYME 3 (AAE3) gene has been characterised to encode an oxalyl-CoA synthetase enzyme in many plant species. We report here the identification and isolation of full-length AAE3 homolog in grasspea. The AAE3 homolog in grasspea was identified by PCR using degenerate primers. The partial gene sequence was then used for identification and cloning of full-length gene by the RT-PCR method. Determination of LsAAE3 gene and protein structure and phylogenetic relationship analysis strongly suggests that LsAAE3 is a true homolog of AAE3 gene that encodes an oxalyl-CoA synthetase. Subcellular localization and expression pattern of grasspea AAE3 was similar to AAE3 orthologs specifically involved in CoA-dependent pathway oxalate degradation, thus indicating the existence of CoA-dependent pathway of oxalate degradation in grasspea. The existence of this catabolic pathway in grasspea was further confirmed by the identification of other components of the CoA-dependent pathway of oxalate degradation in the transcriptome datasets of grasspea. These findings suggest that LsAAE3 encoded oxalyl-CoA synthetase most likely functions in CoA-dependent pathway of oxalate degradation. As grasspea also uses oxalate and oxalyl-CoA synthetase for the biosynthesis of P-ODAP, therefore, this study paves way for functional characterization of LsAAE3 gene to understand how the CoA-dependent pathway of oxalate degradation and p-ODAP biosynthesis pathway in grasspea are regulated.