Identification of the gene coding for seed cotyledon albumin SCA in the pea (Pisum L.) genome

Abstract

Albumins SCA and SAA are short, highly hydrohylic proteins accumulated in large quantity in the cotyledons and seed axes, respectively, of a dry pea (Pisum sativum L.) seed. SCA was earlier shown to have two allelic variants differing in mobility in polyacrylamide gel electrophoresis in acid medium. Using them the corresponding gene SCA was mapped on Linkage Group V. This gene was used as a useful genetic and phylogeographical marker that still required electrophoretic analysis of the protein while the DNA sequence of the corresponding SCA gene remained unknown. Based the length, the positive charge in acid conditions and the number of lysine residues of SCA and SAA albumins, estimated earlier electrophoretically, the high throughput sequencing data available in public databases were searched for the respective candidates for the corresponding genes SCA and SAA genes among coding sequences residing in the region of the pea genome corresponding to the map position of SCA. Then we sequenced them in a number of pea accessions. Concordance of the earlier electrophoretic data and sequence variation indicated the sequence Psat0s797g0160 of the reference pea genome to be the SCA gene. The sequence Psat0s797g0240 could encode a minor related albumin SA-a2, while a candidate gene for albumin SAA is still missing (as well as electrophoretic variation of both latter albumins). DNA amplification using original primers SCA1_3f and SCA1_3r from genomic DNA and restriction by endonuclease Hind II made SCA a convenient CAPS marker in peas. Thus, the gene encoding the highly hydrophilic albumin SCA accumulated in pea seeds, with its alleles useful classification of pea wild relatives, is now identified in the pea genome and a convenient CAPS marker is worked out on its base.