Polar auxin transport together with AINTEGUMENTA and REVOLUTA coordinate early Arabidopsis gynoecium development

Abstract

In flowering plants the gynoecium is the female reproductive structure and the site of oogenesis, fertilization, and maturation of the embryo and the seed. Proper development of the gynoecium requires that the early gynoecial primordium be partitioned into distinct spatial domains with divergent fates. Regulated transport of the phytohormone auxin previously has been shown to play a role in the patterning of spatial domains along the apical-basal axis of the gynoecium. Here we establish a role for auxin transport in patterning along the medio-lateral axis of the gynoecial ovary. We demonstrate that auxin transport is required for the development of the medial ovary domain that contains the carpel margin meristem, a vital female reproductive structure. Disruptions in auxin transport enhance the medial domain defects observed in aintegumenta and revoluta mutant genotypes. Aintegumenta and revoluta are likely to function in parallel and partially overlapping pathways required for medial domain development. Our data indicate that different ovary domains are differentially sensitive to the reduction of polar auxin transport and the loss of aintegumenta and revoluta activity. We suggest that an auxin-mediated positional cue is important for the differential specification of the medial and lateral ovary domains.

Cross talk between the sporophyte and the megagametophyte during ovule development

“…Auxin regulates also ovule development, as a transient application of N-1-naphthylphthalamic acid (NPA, an auxin efflux inhibitor) causes significant loss of ovules (Nemhauser et al 2000). These data have been recently confirmed by Nole-Wilson et al (2010), which associate ovule loss with severe reduction in local auxin biosynthesis. Arabidopsis inflorescences treated with NPA show a great inhibition of TAA1 (TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1) (Stepanova et al 2008;Tao et al 2008;Nole-Wilson et al 2010), a gene that encodes for a tryptophan aminotransferase and is critical for the synthesis of auxin via the indole-3-pyruvic acid (IPA) pathway (Stepanova et al 2008;Tao et al 2008).…”

Cytokinin response factors integrate auxin and cytokinin pathways for female reproductive organ development

“…Placenta formation and ovule growth require auxins. Reduced local auxin biosynthesis or transport causes severe defects in pistil development with a consequent loss of placental tissue and ovules (Nemhauser et al, 2000;Nole-Wilson et al, 2010). The auxin efflux carrier PIN-FORMED 1 (PIN1) is one of the main elements modulating auxin accumulation during all phases of ovule development (Benková et al, 2003;Ceccato et al, 2013).…”

Polar Auxin Transport Is Essential for Medial versus Lateral Tissue Specification and Vascular-Mediated Valve Outgrowth in Arabidopsis Gynoecia

“…It is commonly accepted that the plant hormone auxin is important for gynoecium development, and several models have been put forward to explain this on a mechanistic level (Nemhauser et al, 2000;Østergaard, 2009;Sundberg and Østergaard, 2009;Nole-Wilson et al, 2010;Marsch-Martínez et al, 2012;Hawkins and Liu, 2014). However, we still lack a clear picture of the auxin dynamics and response sites during the earliest developmental stages when the major patterning decisions are made.…”