RESEARCH PROJECTS
Expression
and Activity of Sorbitol Dehydrogenase in Apple
Sorbitol dehydrogenase (SDH, EC 1.1.1.14) has been identified as the
primary enzyme that metabolizes sorbitol, the major phloem-transported
carbohydrate in apple. Thus SDH may play a critical role in defining
apple fruit set, development, and postharvest quality. We have
developed the biochemical and molecular tools to assess patterns of SDH
transcript and protein accumulation along with SDH enzyme activity. In
recent work we have found 1) nine distinct isoforms of SDH in
apple, 2) expression and activity of SDH during the fruit set
period the first 5 weeks after bloom, and 3) little correlation between
SDH protein quantity and activity patterns suggesting posttranslational
control of activity. We are currently examining SDH expression in fruit
flesh versus seed, developing techniques to determine at what
developmental times and in which tissues the isoforms might be
expressed, and assessing how sorbitol availability may influence SDH
expression and activity during fruit set.
Pawpaw
Fruit Ripening and Postharvest Storage
The pawpaw [Asimina triloba (L.) Dunal] is a promising tree
fruit crop for
Kentucky and the United
States. Pawpaw
grows wild in the mesic hardwood forests of 26 states in the eastern
United States and is the largest edible fruit native to North America. This
project is a collaboration with Dr.
Kirk Pomper at Kentucky
State University, who directs a comprehenisve program towards
developing pawpaw as a new
commercial tree fruit crop. The goals of our collaborative project are
to fully characterize pawpaw fruit
ripening, and to develop recommendations for maximizing postharvest
storage life while maintaining high fruit quality. For further
information on pawpaw, visit the Pawpaw
Information Website.
Plant Volatile Compounds
and Microbial
Development on Strawberry
Strawberry fruit produce a
diverse group of wound volatile compounds,
including aldehydes, alcohols, and esters, derived from the
lipoxygenase-hydroperoxide lyase pathway. The volatile (E)-2-hexenal, a 6-carbon aldehyde,
is a major volatile product produced in response to bruising. We have
determined that this volatile can influence the development of the
major fungal mold on strawberry fruit, Botrytis cinerea L. or gray mold.
Our current goals are to determine how bruising alters biosynthesis of
the volatile compound and how the volatile interacts with the
fungus.