Genes Encoding Callose Synthase and Phytochrome A Are Adjacent to a MAP3Kα-Like Gene in Beta vulgaris US H20

Abstract

MAP3Kα, a gene that encodes a key conserved protein kinase, is responsible for initiating a rapid cascade of cellular events leading to localized cell death. Hypersensitive response, as it is termed, enables genetically resistant plants to limit microbial invasion under the right environmental conditions. Since knowledge of close physically linked genes is important for genome analysis and possibly for improving disease resistance, systematic DNA sequence analysis, gene annotation, and protein BLASTs were performed to identify and characterize genes in close physical proximity to a MAP3Kα-like gene in Beta vulgaris L. US H20. On the same 125 Kb BAC, callose synthase (BvCS) and phytochrome A (PhyA) genes were within 50 Kb of MAP3Kα. The close physical linkage of these genes may result from selection for coordinated responses to disease pressure. Bert, a new chromodomain-carrying gypsy-like LTR retrotransposon, resides within an intron of the BvCS gene, where it is transcribed from the opposing strand.

Highly diverse chromoviruses of Beta vulgaris are classified by chromodomains and chromosomal integration

“…A Bongo 3 copy was identified in the vicinity of a disease resistance-activating factor [30], and the recently described chromovirus Bert (in this paper assigned to Bingo elements) was found within an intron of the callose synthase gene [49]. It is possible that these plant retrotransposons have the ability to alter the expression of nearby genes, as the importance of TEs for the epigenetic regulation of plant genomes has been stated previously [50-52].…”