title: Auxin and Cell Wall Invertase Related Signaling during Rice Grain Development.
abstract: Indole-3-acetic acid (IAA) synthesis is required for grain-fill in maize and appears to be regulated by cell-wall invertase (CWIN) activity. OsYUC12 is one of three IAA biosynthesis genes we previously reported as expressed during early rice grain development, correlating with a large increase in IAA content of the grain. This work aimed to investigate further the role of OsYUC12 and its relationship to CWIN activity and invertase inhibitors (INVINH). The analysis shows a brief peak of OsYUC12 expression early in endosperm development. Meta-analysis of microarray data, confirmed by quantitative expression analysis, revealed that OsYUC12 is coexpressed with OsIAA29, which encodes an unusual AUX/IAA transcription factor previously reported as poorly expressed. Maximum expression of OsYUC12 and OsIAA29 coincided with maximum CWIN activity, but also with a peak in INVINH expression. Unlike ZmYUC1, OsYUC12 expression is not reduced in the rice CWIN mutant, gif1. Several reports have investigated CWIN expression in rice grains but none has reported on expression of INVINH in this species. We show that rice has 54 genes encoding putative invertase/pectin methylesterase inhibitors, seven of which are expressed exclusively during grain development. Our results suggest a more complex relationship between IAA, CWIN, and INVINH than previously proposed.
authors.affiliation: Molecular and Cellular Biology, University of New England, Armidale, New South Wales 2351, Australia. SKRussellFrench@dow.com.
authors.forename: Sarah Russell
authors.initials: SR
authors.lastname: French
authors.affiliation: Department of Biology, Faculty of Science, Islamic University, Madinah 170, Saudi Arabia. yousefaz@yahoo.com.
authors.forename: Yousef
authors.initials: Y
authors.lastname: Abu-Zaitoon
authors.affiliation: Department of Microbiology, University of Chittagong, Chittagong 4331, Bangladesh. mynuddincu@gmail.com.
authors.forename: Md Myn
authors.initials: MM
authors.lastname: Uddin
authors.affiliation: Molecular and Cellular Biology, University of New England, Armidale, New South Wales 2351, Australia. kbennett@peracto.com.
authors.forename: Karina
authors.initials: K
authors.lastname: Bennett
authors.affiliation: Molecular and Cellular Biology, University of New England, Armidale, New South Wales 2351, Australia. hnonheb2@une.edu.au.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Nonhebel
keywords: OsHAP3D; OsIAA29; ZmEBE-like; cell wall invertase; defensin-like; grain-fill; indole-3-acetic acid; invertase inhibitor; lipid transfer protein; rice