Auxin Synthesized by the YUCCA Flavin Monooxygenases Is Essential for Embryogenesis and Leaf Formation inArabidopsis

Abstract

Auxin plays a key role in embryogenesis and seedling development, but the auxin sources for the two processes are not defined. Here, we demonstrate that auxin synthesized by the YUCCA (YUC) flavin monooxygenases is essential for the establishment of the basal body region during embryogenesis and the formation of embryonic and postembryonic organs. Both YUC1 and YUC4 are expressed in discrete groups of cells throughout embryogenesis, and their expression patterns overlap with those of YUC10 and YUC11 during embryogenesis. The quadruple mutants of yuc1 yuc4 yuc10 yuc11 fail to develop a hypocotyl and a root meristem, a phenotype similar to those of mp and tir1 afb1 afb2 afb3 auxin signaling mutants. We further show that YUC genes play an essential role in the formation of rosette leaves by analyzing combinations of yuc mutants and the polar auxin transport mutants pin1 and aux1. Disruption of YUC1, YUC4, or PIN1 alone does not abolish leaf formation, but the triple mutant yuc1 yuc4 pin1 fails to form leaves and flowers. Furthermore, disruption of auxin influx carrier AUX1 in the quadruple mutant yuc1 yuc2 yuc4 yuc6, but not in wild-type background, phenocopies yuc1 yuc4 pin1, demonstrating that auxin influx is required for plant leaf and flower development. Our data demonstrate that auxin synthesized by the YUC flavin monooxygenases is an essential auxin source for Arabidopsis thaliana embryogenesis and postembryonic organ formation.

Genomic DNA methylation analyses reveal the distinct profiles in castor bean seeds with persistent endosperms

“…For example, gene 28629.m000565 encoding a b-fructofuranosidase involved in carbohydrate metabolic processes was strongly expressed in endosperm. Gene 30093. m000370, homologous to AtYUCCA10 (AT1G48910) involved in regulating seed development in Arabidopsis (Cheng et al, 2007), was expressed strongly in endosperm. The two genes exhibited substantially lower DNA methylation extents and higher expression levels in endosperm than in embryo.…”

Biochemical analyses of indole-3-acetaldoxime-dependent auxin biosynthesis in Arabidopsis

“…The YUC genes have been shown to be essential for embryogenesis, seedling growth, vascular patterning, and flower development (16,17). The IPA pathway also plays a key role in embryogenesis and shade avoidance (34,35).…”

“…Because the production of IAN from IG occurs in response to tissue damage, it is not clear whether IG metabolism contributes to IAA biosynthesis under normal growth conditions. IAA biosynthesis via the YUC pathway is essential for many developmental processes including embryogenesis, seedling growth, vascular patterning, and flower development (16,17). Overexpression of YUC genes leads to elongated hypocotyls and epinastic cotyledons, and inactivation of YUC genes causes severe developmental phenotypes that can be rescued by in situ production of IAA (17).…”

Auxin Control of Embryo Patterning

“…The other branch of the Trpdependent IAA biosynthesis pathway is represented by the YUCCA (YUC) family of flavin monooxygenases. Arabidopsis has 11 YUC genes of which YUC1, 4, 10, and 11 have been shown to be expressed in the embryo in overlapping patterns (Cheng et al 2007). TAR1 and the YUC1, 4, 10, and 11 genes are all expressed from the globular stage on in the apical embryo region.…”