Isolation, analysis and expression of homologues of the soybean early nodulin gene GmENOD93 (GmN93) from rice

Rice (Oryza sativa var. Nipponbare) possesses two different homologues of t he soybean early nodulin gene GmENOD93 (GmN93). Analysis of the cDNA clones of rice homologues showed that OsENOD93a has an open reading frame (ORF) w ith a coding sequence homology of 58.2% to GmENOD93, whereas the ORF of OsE NOD93b has displayed a homology of 42.3%. OsENOD93a and OsENOD93b genes are differentially expressed in different parts of the rice plant, as well as in cultured cells induced or non-induced with chitin oligomer. In intact ri ce tissues, OsENOD93b, was most abundantly expressed in roots and at much l ower levels in etiolated and green leaves, whereas the expression of OsENOD 93a was very low in roots and etiolated leaves, and was not detected in gre en leaves. The level of OsENOD93a expression was enhanced markedly in suspe nsion-cultured cells, whereas that of OsENOD93b did not increase. The appli cation of chitin oligomer, an elicitor which induces a defence response in plants, did not significantly alter the expression of both these homologues in suspension cultures. (C) 1998 Elsevier Science B.V. All rights reserved .