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.
Lers, A., Khalchitski, A., Lomaniec, E., Burd, S. and Green, P. J. (1998) Senescence-induced RNases in tomato. Plant Mol. Biol. 36: 439-449.
Pérez-Amador, M. A., Abler, M. L., De Rocher, E. J, Thompson, D. M., van Hoof, A., LeBrasseur, N., Lers, A. and Green, P. J. (1999) Identification of BFN1, a bifunctional nuclease induced during leaf and stem senescence in Arabidopsis thaliana. Plant Physiol. 122: 169-179.
Lers, A. Lomaniec, E. Burd, S. and Khalchitski, A. (2001) The characterization of LeNUC1, a nuclease associated with leaf senescence of tomato. Physiol. Plant. 112: 176-182.
Canetti, L., Lomaniec, E., Elkind, Y. and Lers, A. (2002) Nuclease activities associated with dark-induced and natural leaf senescence in parsley. Plant Science 163: 873 - 880
Lomaniec, E., Aharon, Z., Aharoni, N. and Lers, A. (2003) Effect of the ethylene action inhibitor 1-methylcyclopropene on parsley leaf senescence and ethylene biosynthesis. Postharvest Biol. Technol. 30: 67-74.
Lers, A., Sonego, S., Green P.J. and Burd, S. (2006) Suppression of LX Ribonuclease in Tomato Results in a Delay of Leaf Senescence and Abscission. Plant Physiol. 142: 710-721.
Lers, A., (2007) Physiological and molecular aspects of postharvest leaf senescence. Stewart Postharvest Review. 3: 1-6.
Lers, A., (2007) Environmental regulation of leaf senescence. In the Annual Plant Reviews series, volume on: Senescence Processes in Plants (Gan S. ed), Blackwell Publishing, Oxford. pp 108-144.
Abebie, B., Lers, A., Philosoph-Hadas, S., Goren, R., Riov, J. and Meir, S. (2008) Differential Effects of NAA and 2,4-D in Reducing Floret Abscission in Cestrum (Cestrum elegans) Cut Flowers are Associated with their Differential Activation of Aux/IAA Homologous Genes. Ann. Bot. 101: 249-259.
Farage-Barhom, S., Burd, S., Sonego, L., Perl-Treves, R., Lers, A. (2008) Expression analysis of theBFN1 nuclease gene promoter during senescence, abscission, and programmed cell death-related processes. J. Exp. Bot. 59: 3247-3258.
Lers, A. (2011) Potential application of biotechnology to maintain fresh produce postharvest quality and reduce losses during storage. Plant Biotechnology and Agriculture, (Altman, A. and Hasegawa, P. M., eds.), Elsevier.
Farage-Barhom, S., Burd, S., Sonego, L., Mett, A., Belausov, E., Gidoni, D. and Lers, A. (2011) Localization of the Arabidopsis senescence- and cell death-associated BFN1 nuclease: from the ER to fragmented nuclei. Molecular Plant 4: 1062-1073.
Bar-Dror, T., Dermastia, M., Kladnik, A., Tusek Znidaric, M., Pompe Novak, M., Meir, S., Burd, S.,Philosoph-Hadas, S., Ori, N., Sonego, L., Dickman, M. B. and Lers, A. (2011) Programmed Cell Death Occurs Asymmetrically during Abscission in Tomato. The Plant Cell 23: 4146-4163.
Matallana-Ramirez, L.P., Rauf, M., Farage-Barhom, S., Dortay, H., Xue, G.P., Droge-Laser, W., Lers, A., Balazadeh, S., and Mueller-Roeber, B. (2013) NAC Transcription Factor ORE1 and Senescence-Induced BIFUNCTIONAL NUCLEASE1 (BFN1) Constitute a Regulatory Cascade in Arabidopsis.Molecular Plant 6: 1438-1452
Thatcher, S.R., Burd, S., Wright, C., Lers, A. and Green, P.J. (2014) Differential expression of miRNAs and their target genes in senescing leaves and siliques: insights from deep sequencing of small RNAs and cleaved target RNAs. Plant, Cell and Environment 38: 188–200
Ma, C., Burd, S. and Lers, A. (2015) MiR408 is involve in abiotic stress responses in Arabidopsis. Plant J. 84: 169-187