Molecular cloning, sequence characterization and tissue-specific expression of six NAC-like genes in soybean (Glycine max (L.) Merr.)

NAC proteins have been considered as one of the novel classes of plant-specific transcription factors functioning in diverse and vital physiotogical processes during plant development. In this study, six NAC-like genes from soybean, designated as GmNAC1-GmNAC6, were cloned and characterized. They each contained two introns and three exons and shared conservative structure of genomic organization. The predicted proteins, GmNAC1-GmNAC6, were similar in sequences, especially in NAC domain regions. However, RT-PCR analysis indicated that each GmNAC gene exhibited a specific expression pattern in tissues examined. GmNAC2, 3, 4, and 6 were expressed in most tested tissues while GmNAC1 and GmNAC5 were limited to a few tissues. In addition, expression patterns of GmNAC genes were characterized during seed filling and coordinated expression was observed between GmNAC genes. Finally, based on phylogenetic analysis, six GmNAC proteins were classed into five subgroups with different putative functions. To our knowledge, this is the first report on molecular cloning and initial characterization of NAC-like genes in soybean. Our results may provide the basis for future investigations of NAC-like genes' roles in seed development and other physiological processes in this important crop. (C) 2006 Elsevier GmbH. All rights reserved.