Synergistic disruptions in seuss cyp85A2 double mutants reveal a role for brassinolide synthesis during gynoecium and ovule development

Abstract

BackgroundThe Arabidopsis SEUSS (SEU) gene encodes a transcriptional adaptor protein that is required for a diverse set of developmental events, including floral organ identity specification, as well as gynoecium, ovule and embryo development. In order to better understand the molecular mechanisms of SEUSS action we undertook a genetic modifier screen to identify seuss-modifier (sum) mutations.ResultsScreening of M2 lines representing approximately 5,000 M1 individuals identified mutations that enhance the seuss mutant phenotypic disruptions in ovules and gynoecia; here we describe the phenotype of the sum63 mutant and enhanced disruptions of ovule and gynoecial development in the seu sum63 double mutant. Mapping and genetic complementation tests indicate that sum63 is allelic to CYP85A2 (AT3G30180) a cytochrome p450 enzyme that catalyzes the final steps in the synthesis of the phytohormone brassinolide.ConclusionsOur identification of mutations in CYP85A2 as enhancers of the seuss mutant phenotype suggests a previously unrecognized role for brassinolide synthesis in gynoecial and ovule outer integument development. The work also suggests that seuss mutants may be more sensitive to the loss or reduction of brassinolide synthesis than are wild type plants.

Boosting Crop Yields with Plant Steroids

“…Mutation in the BR biosynthetic enzyme CYP85A2 enhances the phenotype of the Arabidopsis mutant seuss, which is defective in ovule and gynoecial development (Nole-Wilson et al, 2010). In addition, the CYP85A1 gene is expressed in the developing female gametophyte and cyp85a1 mutants exhibit a semisterile phenotype (Pé rez-Españ a et al, 2011).…”

Brassinosteroid Signal Transduction: From Receptor Kinase Activation to Transcriptional Networks Regulating Plant Development

“…Moreover, the same study showed by ChIP analysis that BES1 directly binds to the promoters of many of these genes, indicating there is a direct BR response on the expression of genes essential for anther and pollen development (Ye et al, 2010). A novel role for BRs in gynoecium and ovule development has also been uncovered recently through genetic screens that identified a BR biosynthetic enzyme as a suppressor of mutations in the Arabidopsis SEUSS gene, encoding a transcriptional adaptor protein involved in floral organ identity and the development of the carpel margin meristem (Nole-Wilson et al, 2010).…”

SEUSS Integrates Gibberellin Signaling with Transcriptional Inputs from the SHR-SCR-SCL3 Module to Regulate Middle Cortex Formation in the Arabidopsis Root

“…Bars with different letters are significantly different at P , 0.05, ANOVA. Bao et al, 2010;Nole-Wilson et al, 2010;Lee et al, 2014), we initiated studies to determine the potential role of SEU in root development. Two seu mutants, seu-3 and seu-4, which were previously identified in searches for floral organ patterning mutants (Pfluger and Zambryski, 2004), were utilized for these studies.…”

“…nA, No antibody; Ab, GFP antibody. Azhakanandam et al, 2008;Bao et al, 2010;Nole-Wilson et al, 2010;Lee et al, 2014). Interestingly, although SEU does not appear to possess a recognizable DNA-binding motif, it was shown by chromatin immunoprecipitation (ChIP) to associate with cis-regulatory elements located in the second intron of the floral homeotic gene AGAMOUS (AG; Sridhar et al, 2006) and with cisregulatory elements of miR172 genes (Grigorova et al, 2011).…”