Investigating the Role of the RAMOSA3 Gene in Brachypodium distachyon
Date
2023-06-02
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Understanding the genes that regulate floral organs in the Poaceae, the
grass family, could increase grain production, contributing to food
security. Species in Poaceae have diverse floral morphologies. Floral organ
suppression contributes to this diversity. Zea mays (maize) has unisexual,
staminate flowers containing pollen grains and unisexual pistillate flowers
containing ovules. RAMOSA3 (RA3) and GRASSY TILLERS1 (GT1) are
two genes that regulate carpel suppression to create staminate flowers. ra3
mutants have partially enlarged carpels and increased axillary branching.
gt1;ra3 double mutants also have enhanced branching and enlarged pistils
with silks emerging from the tassel. Enhanced branching suggests that
RA3 regulates axillary meristem suppression in addition to carpel
development.
Another grass model system, Brachypodium distachyon (brachypodium),
has bisexual flowers with stamens and pistils. Brachypodium and maize
have orthologs of the RAMOSA3 gene, but why do they have different
floral sexualities? My project aims to discover if RA3 has a conserved role
in controlling floral organ suppression and inflorescence branching in
grasses. I investigated the role of the RA3 homolog in brachypodium
using CRISPR/Cas9 and the sodium azide mutant line NaN372. The
transformed brachypodium did not have any CRISPR edits. However,
NaN372 has an amino acid substitution in the RA3 gene. The mutant
phenotype suggests that Bdra3 mutants do not have more flowers than the
wild-type, contrary to what I predicted if RA3 function is conserved.
Description
Keywords
Brachypodium, RAMOSA3, inflorescence branching