Amnon
Lers Ph.D Amnon
Lers Ph.D| Email: | alers@volcani.agri.gov.il |
| Tel: | +972-3-9683608 |
| Fax: | +972-3-9683622 |
Shaul
Burd, Ph.D. sburd@volcani.agri.gov.il
Lilian Sonego, M.Sc. lili@volcani.agri.gov.il
Worldwide, postharvest losses have been estimated to be as high as 24% in developed countries and even 50% in developing tropical countries. The susceptibility of fresh harvested produce to postharvest deterioration increases during extended storage, as a result of physiological and pathological changes occurring during storage and marketing. Losses caused by postharvest spoilage of fruits and vegetables have been controlled so far primarily by applying chemicals, which due to health and environmental hazards are steadily being banned from use. Alternatives should be developed and the use of biotechnology to develop new varieties with improved postharvest qualities has the potential to have large future impact in postharvest applied science. Identification and selection of key genes involved in postharvest-relevant responses of plants is a fundamental step in the development of biotechnology approach. Beside the use of identified genes in biotechnology-mediated improvement of agricultural important crop plants, these genes could be used in marker-assisted selection of improved varieties via classical genetic programs.
We are investigating different biological aspects of postharvest utilizing molecular,
biochemical and physiological research tools. The results of these studies should
improve our understanding of the biological processes involved and mode of action
of treatments known to improve postharvest quality. Furthermore, such research
should form the basis needed to enable us to use biotechnology for the development
of new varieties which will have improved postharvest qualities.
We are focusing on few main fields of research. In leaf senescence research
we identify and characterize enzymes related to the process of macromolecules
catabolism which is highly induced in advanced stage of senescence. We are mainly
investigating the function of senescence-associated nucleases and ribonucleases
and the molecular mechanism which governs the senescence-specific expression
of their encoding genes. Study of tomato and Arabidopsis mutant plants in which
expression of the ribonucleases/nuclease genes was altered should contribute
to our understanding of function of the encoded enzymes in senescence or other
developmental/stress-related processes. The molecular mechanism underlying senescence-specific
gene expression is investigated by detailed analysis of promoter sequences,
interacting protein factors and mutations affecting this senescence-specific
regulation.
Chilling sensitivity, in some fruits and vegetables, is a major limitation in
the use of low temperature for fresh produce storage, especially in tropical
or sub-tropical crops. Chilling injury is manifested in differently in different
plants such as membrane collapse and superficial browning in basil leaves or
texture changes such as wooliness in some peach varieties. The physiological,
biochemical and molecular basis for the acquirement of resistance toward chilling
by different postharvest treatments or due to genetic variation is investigated
mainly in basil leaves and peach fruits.
Senescence of harvested leafy vegetables is accelerated in many cases due to
their storage in the dark. Using Arabidopsis plant as a model system we carry
out a research aimed for identifying genes which have a role in dark-induced
senescence. Elevated concentration of CO2, in the range of 5-10%, is known to
be main factor in the delay of postharvest leaf senescence which plays a major
role in modified atmosphere packaging of fresh produce. Although its effect
is very significant in some commodities the mode of action by which CO2 exerts
its senescence retarding activity is not clear. Research is preformed to get
an insight into the mode of action of CO2 in delaying leaf senescence and improving
postharvest quality of leafy vegetables.
