Treatment of pea pods with Bruchin B results in up-regulation of a gene similar to MtN19

Differential display was used to examine changes in gene expression that resulted from treatment of pea (Pisum sativum L.) with Bruchin B. This lipid-derived regulator, one of several closely related compounds collectively referred to as bruchins, is an insect elicitor that causes localized cell division and callus formation when applied to pods of pea and certain other legumes. A DNA fragment that was prominently displayed after bruchin treatment was cloned and sequenced, and a full-length cDNA was obtained. This cDNA exhibited a high degree of sequence similarity to a gene, MtN19, expressed in root nodules of Medicago truncatula Gaertn. MtN19 codes for a putative protein of unknown function that is similar in sequence to predicted proteins from a number of other plant species, both leguminous and non-leguminous. Quantitative real-time PCR showed that the expression of this MtN19-like gene was significantly up-regulated within 1.5 h of bruchin treatment, and increased more than 100-fold within 6 h of treatment. Given the rapid and strong up-regulation after exposure of pods to a bruchin, it is likely that this gene plays an important role in the response of pea to these insect elicitors.