MOLECULAR APPROACHES TO ENHANCE PLANT NUTRIENT CONTENT, SHELF-LIFE AND STRESS TOLERANCE
Title: Differential and functional interactions emphasize the multiple roles of polyamines in plants
Submitted to: Plant Physiology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 16, 2010
Publication Date: February 21, 2010
Citation: Handa, A.K., Mattoo, A.K. 2010. Differential and functional interactions emphasize the multiple roles of polyamines in plants. Plant Physiology and Biochemistry. 48:540-546.
Interpretive Summary: A class of chemicals present in nature called polyamines consisting of putrescine (Put), spermidine(Spd) and spermine (Spm) have been grouped together in relation to their being essential for growth and cell proliferation. In plants these chemicals have been shown to delay fruit ripening, enhance nutritional quality, protect against drought and salinity, and delay leaf senescence. The mechanisms involved are not as yet known. Also, no distinction has been made in delineating the role of the individual components of this group, Put vs. Spd vs. Spm, in biology. Previously, we have genetically manipulated the contents of Spd and Spm, at the cost of Put, in tomato fruit using a transgenic approach. These fruit were then analyzed to obtain reproducible datasets on the number and type of genes, proteins and nutritional molecules compared to the wild type fruit. Using these datasets, the USDA-ARS scientist, in collaboration with a scientist at Purdue Unversity, has now determined the linear correlation coefficients between the endogenous levels of Put, Spd and Spm with a number of parameters including the fruit phenotype. Results of this analysis clearly show that the effects of Put generally contrast those with Spd and Spm, and point out that each individual polyamine should be considered to have a defined action in plant biology, the differential effects being on several molecular levels that define plant growth and development. A plurality model of polyamine action is discussed to explain the role of polyamines in most organisms, in general, and ripening fruit, in particular. These findings are of particular significance to plant biologists, biochemists and molecular biologists.
Biogenic amines putrescine, spermidine and spermine are ubiquitous in nature and have interested researchers because they are essential for cell division and viability, and due to a large body of their pharmacological effects on growth and development in most living cells. The genes and enzymes involved in their biosynthetic pathways are now established and characterized. In recent years, molecular aspects of polyamine action have also begun to emerge. Our model is the ripening tomato fruit in which processes of cell division, cell expansion and cell growth have ceased, and yet the cells are responsive at biochemical and molecular levels to genetically manipulated concentrations of putrescine (Put), spermidine (Spd) and spermine (Spm). Thus, transcriptome, limited protein profiling, and metabolome studies of transgenic tomato fruit have yielded significant new information on cellular processes impacted by polyamine manipulation. We have used these datasets to determine the linear correlation coefficients between the endogenous levels of Put, Spd and Spm with several parameters. Results of our analysis presented here show that effects of the diamine Put generally contrast those with polyamines Spd and Spm, emphasizing that individual biogenic amines should be considered to have defined action in plant biology and that they differentially affect growth and development. A plurality model of polyamine action is discussed to explain the role of polyamines in most organisms, in general, and ripening fruit, in particular.