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.

A wheat 1‐FEH w3 variant underlies enzyme activity for stem WSC remobilization to grain under drought

“…Recently, a complex relationship has been reported between AUX signaling, cw INV activity and cw INV inhibitors in developing rice kernels (French et al ., ). This fits well with the emerging view that sugars and sugar signaling control auxin levels in plants (LeClere et al ., ; Sairanen et al ., ; Wang & Ruan, ).…”

MADS78 and MADS79 Are Essential Regulators of Early Seed Development in Rice

“…8A; Supplemental Table S5). Previous work has shown that ABCB4/11/14/22, DAO, GH3s, and IAAs are up-regulated in developing rice seeds at 24 HAF (Jain and Khurana, 2009;Uchiumi and Okamoto, 2010;French et al, 2014;Basunia and Nonhebel, 2019). TRYPTOPHAN AMINOTRANSFER-ASE-RELATED PROTEIN2 (TAR2), the auxin biosynthesis gene that is preferentially expressed prior to cellularization (Abu-Zaitoon et al, 2012), exhibited lower transcript levels in MADS78 and MADS79 mutants, while YUCCA7 was unaltered in the MADS78 mutant and showed higher transcript abundance in the MADS79 mutant (Fig.…”

Critical Roles of Vacuolar Invertase in Floral Organ Development and Male and Female Fertilities Are Revealed through Characterization of GhVIN1-RNAi Cotton Plants

“…For example, VIN-derived hexose signaling likely plays an indispensable role in cotton (Gossypium hirsutum) fiber (seed trichome) initiation by regulating the expression of some MYB transcription factors and auxin signaling genes (Wang et al, 2014). Furthermore, interactions between CWINs and hormone signaling pathways have been implicated in the development of wheat pollen (abscisic acid; Ji et al, 2011), maize seed (cytokinins [Rijavec et al, 2009] and auxin [LeClere et al, 2010]), rice grain (auxin; French et al, 2014), tomato fruit (ethylene; Zanor et al, 2009), and Arabidopsis (Arabidopsis thaliana) seed extrafloral nectar secretion (jasmonic acid [JA]; Millán-Cañongo et al, 2014).…”