Establishing Fragaria vesca (diploid strawberry) as a model

F. vesca (yellow wonder 5AF7) flower

Fragaria vesca is a diploid strawberry that offers many advantages over the commercial strawberry, which is octoploid. In collaboration with Drs. Janet Slovin and Nadim Alkharouf, we have initiated a project to investigate molecular events underlying the cross-talk between phytohormone auxin and flower and early fruit development in F. vesca. This effort and project details are described at following website GEPR: Flower and Fruit Development in Diploid Strawberry. In addition, in collaboration with Chinese scientists, we are initiating efforts in F. vesca mutant screen and generation of genetic resources.

Regulation of floral homeotic gene in Arabidopsis thaliana

ag mutant flower

The floral homeotic gene AGAMOUS is a key regulatory gene for flower development. It specifies carpel and stamen identity, represses sepal and petal identity, and controls floral meristem determinacy (see photo to the left). AG transcription is only turned on at stage 3 floral meristen and is only located in the inner two whorls of a flower. We have identified three genes, LEUNG (LUG), SEUSS (SEU) and LARSON/BELLRINGER (BRL), whose activities are required to prevent ectopic AG expression in floral and shoot meristems (see figure below).

AG mRNA expression in wild type (left) and in lug seu double mutant (right).

Using Chromatin Immunoprecipitation (ChIP), transient gene expression assay, reporter gene expression, yeast two hybrid, BiFC, qRT-PCR, in situ hybridization, we have begun to reveal the molecular mechanisms underlying how the transcriptional co-repressors, we identified and their DNA-binding partners such as APETALA1 work together to control stage- and domain-specific expression of class C genes.

Wild-type flower (left) and additional flower mutants (middle and right)

Arabidopsis TSO genes in regulating floral organ morphogenesis

tso1-1 mutant inflorescence

We have identified two Arabidopsis mutants, tso1 and tso2 (TSO means ugly in Chinese). Genetic analyses and molecular isolation of both genes revealed other aspects of floral organ regulation, namely the control of proper cell division, organ growth, and morphogenesis. Current efforts have been on dissecting the role of TSO1 in coordinating the cell division regulation with cell differentiation.