Soybeans are an important crop because of the quantity and quality of
protein and oil in the seeds. Seed storage protein and fatty acids accumulate
during seed development, and this process depends upon precise orchestration
of gene transcription – both genetic and environmental factors influence
the eventual composition of seeds. To understand these factors we study
soybean seed development. The goal of this work is to make soybean plants
with a more nutritious balance of proteins in the seed, and oils that are
either healthier or better suited for industrial applications, and to understand
how events that occur during seed development impact yield.
Current Projects in the laboratory include:
Gene expression during soybean seed development
In order to understand how the expression of genes relevant to seed composition
and yield is controlled, the laboratory studies networks of gene regulation
in developing soybean seeds. Recent work has focused on the control of
seed gene expression by diurnal cycles or the plant circadian clock. Many
of the biological and physiological processes involved in protein biosynthesis,
plant secondary metabolism, and carbohydrate metabolism are known to be
controlled by the circadian clock or influenced by diurnal cycles. However,
it was not known to what extent these factors influence gene expression
during seed development. We used microarray expression profiling to identify
genes that are regulated by the circadian clock in developing soybean seeds.
Over 400 genes in developing seeds show evidence of circadian regulation,
and these genes encode proteins that are predicted to be involved in many
different metabolic processes in the seeds. Interesting differences in
gene expression were observed between leaves and seeds of the same plants
in circadian clock controlled gene expression and diurnal cycles. A number
of transcriptional regulators that are controlled by the circadian clock
in soybean seeds were identified, and are currently being characterized.
In addition, promoter motifs were found to be common to subsets of co-regulated
genes, which represent potential targets of transcription factor binding.
We are also using several parallel approaches to characterize the expression
and function of candidate genes in soybean that are believed to be important
for seed development and composition based on their roles in seed development
in other plant species.
Soybean TILLInG population
The soybean TILLInG (Targeting Induced Local Lesions In Genomes) population
is a resource of induced mutant soybean plants that are being screened
for genetic variation in useful traits. Forward genetic screening of this
population has identified genetic loci involved in determining seed responsiveness
to the plant hormone abscisic acid, and loci required for the normal fatty
acid composition of soybeans. In addition, we are testing ways to use the
population for reverse genetic screening to identify mutations in genes
that may be of interest to other soybean researchers.