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Title: Overexpression of yeast spermidine synthase impacts ripening, senescence and decay symptoms in tomato

Author
item NAMBEESAN, SAVITHRI - Purdue University
item DATSENKA, TATSIANA - Purdue University
item FERRUZZI, MARIO - Purdue University
item MALLADI, ANISH - University Of Georgia
item Mattoo, Autar
item HANDA, AVTAR - Purdue University

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2010
Publication Date: 7/20/2010
Citation: Nambeesan, S., Datsenka, T., Ferruzzi, M.G., Malladi, A., Mattoo, A.K., Handa, A.K. 2010. Overexpression of yeast spermidine synthase impacts ripening, senescence and decay symptoms in tomato. Plant Journal. 63:836-847.

Interpretive Summary: Postharvest shriveling of the fresh produce is a primary cause of their non-acceptance by consumers, contributing to significant food and economic losses worldwide. In developing countries, where refrigeration is not economical, this loss is more severe. Limited progress has been made in reducing these losses as the metabolic signals that impact shriveling of fruits and vegetable crops are not yet understood. Biogenic polyamines represent a major class of nitrogenous substances in plants which seem to play an important role in fruit development and ripening. However, specific polyamines regulating shelf life of harvested produce have not yet been identified. An ARS scientist and researchers at Purdue University and Georgia University have, in a collaborative work, embarked on a study to genetically test the role of the polyamine spermidine (Spd) in fruit physiology, by expressing a yeast spermidine synthase (ySpdSyn) gene under constitutive (CaMV35S) and fruit ripening-specific (E8) regulators in tomato. In this manuscript, these researchers report that ySpdSyn expression accumulates Spd and the homozygous tomato plants produce fruit that have greatly enhanced shelf life mainly due to delayed shriveling and microbial decay. Further, it is also shown that plants that constitutively expressed ySpdSyn lived longer and had delayed senescence of whole vegetative parts while their fruit were richer in the antioxidant lycopene. Collectively, these results for the first time identify the role of Spd as a metabolic signal that regulates plant organ shriveling without any negative effect on phenotype, including yield. These results are of particular importance to the horticulture industry, plant biologists and postharvest physiologists.

Technical Abstract: Postharvest shriveling of the fresh produce is a primary cause of their non-acceptance by consumers, contributing to significant food and economic losses worldwide. In developing countries, where refrigeration is not economical, this loss is more severe. Limited progress has been made in reducing these losses as the metabolic signals that impact shriveling of fruits and vegetable crops are not yet understood. Biogenic polyamines represent a major class of nitrogenous substances in plants which seem to play an important role in fruit development and ripening. However, specific polyamines regulating shelf life of harvested produce have not yet been identified. An ARS scientist and researchers at Purdue University and Georgia University have, in a collaborative work, embarked on a study to genetically test the role of the polyamine spermidine (Spd) in fruit physiology, by expressing a yeast spermidine synthase (ySpdSyn) gene under constitutive (CaMV35S) and fruit ripening-specific (E8) regulators in tomato. In this manuscript, these researchers report that ySpdSyn expression accumulates Spd and the homozygous tomato plants produce fruit that have greatly enhanced shelf life mainly due to delayed shriveling and microbial decay. Further, it is also shown that plants that constitutively expressed ySpdSyn lived longer and had delayed senescence of whole vegetative parts while their fruit were richer in the antioxidant lycopene. Collectively, these results for the first time identify the role of Spd as a metabolic signal that regulates plant organ shriveling without any negative effect on phenotype, including yield. These results are of particular importance to the horticulture industry, plant biologists and postharvest physiologists.