STY1 regulates auxin homeostasis and affects apical–basal patterning of the Arabidopsis gynoecium

Abstract

SummaryGynoecia of the Arabidopsis mutant sty1-1 display abnormal style morphology and altered vascular patterning. These phenotypes, which are enhanced in the sty1-1 sty2-1 double mutant, suggest that auxin homeostasis or signalling might be affected by mutations in STY1 and STY2, both members of the SHI gene family. Chemical inhibition of polar auxin transport (PAT) severely affects the apical-basal patterning of the gynoecium, as do mutations in the auxin transport/signalling genes PIN1, PID and ETT. Here we show that the apical-basal patterning of sty1-1 and sty1-1 sty2-1 gynoecia is hypersensitive to reductions in PAT, and that sty1-1 enhances the PAT inhibition-like phenotypes of pin1-5, pid-8 and ett-1 gynoecia. Furthermore, we show that STY1 activates transcription of the flavin monooxygenase-encoding gene THREAD/YUCCA4, involved in auxin biosynthesis, and that changes in expression of STY1 and related genes lead to altered auxin homeostasis. Our results suggest that STY1 and related genes promote normal development of the style and affect apical-basal patterning of the gynoecium through regulation of auxin homeostasis.

EARLY BUD-BREAK 1 (EBB1) is a regulator of release from seasonal dormancy in poplar trees

“…These were dominated by genes involved in auxin signaling and brassinosteroid biosynthesis. In addition, two of the putative EBB1 gene targets encode SHORT INTERNODE RELATED SEQUEN-CES (SRS), which are transcription factors that have been implicated in regulation of auxin biosynthesis in Arabidopsis through activation of the YUCCA gene (41,42). In support of our findings, recent evidence suggests that auxin is important for reinitiating growth after dormancy (43).…”

Shedding light on flower development

“…2,[26][27][28][29] Meanwhile, numerous recent studies have investigated the relationship between phyB and phytohormones, with a large focus on auxin pathways. Indeed, phytochrome signaling has been shown to influence auxin pathways at different levels: auxin production, auxin distribution and sensitivity to auxin signals (reviewed in ref.…”

Do Trees Grow on Money? Auxin as the Currency of the Cellular Economy

“…1). Current models propose that auxin levels are manipulated through coordinated regulation of SHORT INTERNODE (SHI)/STYLISH (STY) transcription factor family-induced local auxin biosynthesis and the relative efficiency of auxin transport away from sites of synthesis (Sohlberg et al 2006;Alvarez et al 2009;Trigueros et al 2009). The balance of production and transport determines the timing and location of style and stigmatic tissue development.…”

“…Expression of STY1 and STY2 become restricted to the apical end of the gynoecium 1-2 days before stigmatic papillae become visible. An inducible STY1 causes rapid induction of the gene encoding the auxin biosynthetic enzyme YUCCA4 and a concomitant increase in free auxin levels (Sohlberg et al 2006). This auxin maximum in the ring of cells near the apex of gynoecium primordia triggers activation of the NGATHA (NGA) genes (Alvarez et al 2009;Trigueros et al 2009).…”