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

Abstract

SUMMARYPolyamines (PAs) are ubiquitous, polycationic biogenic amines that are implicated in many biological processes, including plant growth and development, but their precise roles remain to be determined. Most of the previous studies have involved three biogenic amines: putrescine (Put), spermidine (Spd) and spermine (Spm), and their derivatives. We have expressed a yeast spermidine synthase (ySpdSyn) gene under constitutive (CaMV35S) and fruit-ripening specific (E8) promoters in Solanum lycopersicum (tomato), and determined alterations in tomato vegetative and fruit physiology in transformed lines compared with the control. Constitutive expression of ySpdSyn enhanced intracellular levels of Spd in the leaf, and transiently during fruit development, whereas E8-ySpdSyn expression led to Spd accumulation early and transiently during fruit ripening. The ySpdSyn transgenic fruits had a longer shelf life, reduced shriveling and delayed decay symptom development in comparison with the wild-type (WT) fruits. An increase in shelf life of ySpdSyn transgenic fruits was not facilitated by changes in the rate of water loss or ethylene evolution. Additionally, the expression of several cell wall and membrane degradation-related genes in ySpdSyn transgenic fruits was not correlated with an extension of shelf life, indicating that the Spd-mediated increase in fruit shelf life is independent of the above factors. Crop maturity, indicated by the percentage of ripening fruits on the vine, was delayed in a CaMV35S-ySpdSyn genotype, with fruits accumulating higher levels of the antioxidant lycopene. Notably, whole-plant senescence in the transgenic plants was also delayed compared with WT plants. Together, these results provide evidence for a role of PAs, particularly Spd, in increasing fruit shelf life, probably by reducing post-harvest senescence and decay.

Different ROS-Scavenging Properties of Flavonoids Determine Their Abilities to Extend Shelf Life of Tomato

“…The general antioxidant capacity of fleshy fruit can be enhanced by different breeding or bioengineering strategies (Rousseaux et al, 2005;Nambeesan et al, 2010;Minas et al, 2012;Zidenga et al, 2012;Zhang et al, 2013). Our results show that increasing the total antioxidant capacity of tomato is an efficient way to delay the overripening of fruit.…”

“…PAs have been found to decrease during fruit ripening, and increasing PA levels in fruit can enhance shelf life. This effect is associated with the high antioxidant capacity of PAs (Mehta et al, 2002;Nambeesan et al, 2010).…”

Target of Rapamycin Signaling Regulates Metabolism, Growth, and Life Span in Arabidopsis

“…C:N metabolism is intimately connected with plant growth and development (Nunes-Nesi et al, 2010). A polyamine connection with increased longevity has also been indicated in studies with yeast and animal models (Eisenberg et al, 2009) and delayed ripening and extended vegetative phase of growth in transgenic tomato (Solanum lycopersicum) plants expressing yeast spermidine synthase (Nambeesan et al, 2010). Thus, several other cellular signals may be in tune with TOR to integrate the nutrient and energy requirements with anabolism in plants.…”

Polyamines Attenuate Ethylene-Mediated Defense Responses to Abrogate Resistance to Botrytis cinerea in Tomato

“…A. tumefaciens strains harboring the chimeric constructs were used to transform cotyledons of tomato cv OH 8245 (Tieman et al, 1992). Fifteen independent transgenic plants expressing ySpdSyn under the CaMV35S promoter were generated (Nambeesan et al, 2010). Based on the transcript and protein expression analysis of T0 transgenic plants, two independent transgenic plants, C4 and C15, were selected and used for further studies.…”

“…We demonstrated a role of PAs in plant growth and development using high Spd-producing transgenic plants generated by expressing yeast SpdSyn in tomato (Nambeesan et al, 2010). Here, we investigated the response of these plants to the fungal pathogens B. cinerea and Alternaria solani, the bacterial pathogen Pseudomonas syringae, and the chewing insect tobacco hornworm Manduca sexta.…”