Transcriptional profiling of OsHin1 in rice plants:: a potential role in defense/stress and development

OsHin1, a single copy gene in the rice (Oryza saliva L.) genome, encodes a protein of 205 amino acids (aa) with a predicted molecular mass of 22232.99 and pI of 9.14. Its transcriptional profiling in 2-week-old seedlings (cv. Nipponbare) revealed weak constitutive expression in healthy leaves and no induction in leaf segments treated with a fungal elicitor chitosan (CT). In planta infection with Magnaporthe grisea in a compatible host-pathogen interaction did not induce the OsHin I expression. On the other hand, wounding (by cut) strongly up-regulated its expression in leaf segments, which was further enhanced by treatment with protein phosphatase inhibitors such as cantharidin, endothall (EN), and okadaic acid. Interestingly, signaling molecules including jasmonic acid (JA) and salicylic acid (SA) and a heavy metal (copper) failed to induce the OsHin1 expression over wounding. Furthermore, cycloheximide (CHX) treatment along with wounding, JA, SA, EN, and CT, suggested possible involvement of de novo synthesized negative protein factor(s) in its regulation. Intriguingly, OsHin1 mRNA expression manifested a clear rhythmicity under a light/dark cycle, and was developmentally regulated. These results provide insight into the importance of OsHin1 in rice defense and development. (C) 2004 Elsevier Ireland Ltd. All rights reserved.