Nodule-expressed Cyp15a cysteine protease genes map to syntenic genome regions in Pisum and Medicago spp.

PsCyp15a is a gene that encodes a vacuolar cysteine protease expressed in w ilt-induced shoots of Pisum sativum (pea) and in root nodules, To further t he understanding of nodular PsCyp15a expression, a region 5' to the coding sequence of the gene was cloned. Varying lengths of 5' untranslated sequenc e were fused with the uidA coding region and introduced from Agrobacterium rhizogenes into "hairy roots" of Vicia hirsuta. ln this transgenic root nod ulation assay, a promoter sequence of 900 bp was sufficient to give an expr ession pattern indistinguishable from that obtained in pea nodules by in si tu hybridization, An orthologue of PsCyp15a was cloned from nodule mRNA of Medicago sativa and a corresponding gene identified in M. truncatula was al so shown to express strongly in nodules, With molecular mapping techniques, it was demonstrated that these genes map to a syntenic genome location in pea and Medicago spp,, but the map positions of the Cyp15a genes cannot be correlated with existing nodulation mutants.