Isolation and Expression analysis of OsPME1, encoding for a putative Pectin Methyl Esterase from Oryza sativa (subsp. indica).

Pectin Methyl Esterases (PMEs) play an essential role during plant development by affecting the mechanical properties of the plant cell walls. Recent studies indicated that PMEs play important role in pollen tube development. In this study, we isolated a 1.3 kb cDNA clone from rice panicle cDNA library. It contained a 1038 bp of open reading frame (ORF) encoding for a putative pectin methyl esterase of 345 aminoacids with a 20 aminoacid signal peptide and was hence designated as OsPME1 (Oryza sativaPectin Methyl Esterase 1). It contained the structural arrangement GXYXE and GXXDFIF, found in the active groups of all PMEs. OsPME1 gene product shared varying identities, ranging from 52 % to 33 % with PMEs from other plant species belonging to Brassicaceae, Fabaceae, Amaranthaceae and Funariaceae. Southern blot analysis indicated that PME1 exists as a single copy in the rice genome. Expression pattern analysis revealed that OsPME1 is expressed only in pollen grains, during the later stages of their development and was also regulated by various abiotic stress treatments and phytohormones. Functional characterization of this pollen specific PME from rice would enable us to understand its role in pollen development.