EXPRESSION OF THE 4-COUMARATE:COA LIGASE GENE FAMILY IN COMPATIBLE AND INCOMPATIBLE PRUNUS GRAFTS

Abstract

Graft incompatibility is a significant problem for development of new Prunus rootstocks. Recently, several authors have reported that phenylpropanoid metabolism is related with this phenomenon. The aim of the present work was to analyze the gene expression patterns of the 4-Coumarate:CoA ligase genes in compatible and incompatible graft combinations two years after grafting. The relationship of Prunus 4CLs with other plants was also studied. To perform this study different graft combinations were evaluated: the peach cultivar ‘Chimarrita’ (P. persica L. Batsch.) grafted onto three different rootstocks ‘Capdeboscq’ (P. persica L. Batsch.), ‘Tsukuba 1’ (P. persica L. Batsch.) and ‘Umezeiro’ (P. mume Sieb. et Zucc.). Transcript abundance was analyzed by real-time PCR using genespecific primers designed to amplify the three 4CL genes identified in the assembled peach genome. The results showed that the three 4CL transcripts are expressed in all combinations examined, although the quantitative levels of 4CL mRNA were higher in ‘Umezeiro’, the incompatible combination. The 4CL3 gene was the most highly expressed in the incompatible combination and the most divergent isoform in the phylogenetic analysis.