Enhancement of fruit shelf life by suppressingN-glycan processing enzymes

Abstract

In a globalized economy, the control of fruit ripening is of strategic importance because excessive softening limits shelf life. Efforts have been made to reduce fruit softening in transgenic tomato through the suppression of genes encoding cell wall-degrading proteins. However, these have met with very limited success. N-glycans are reported to play an important role during fruit ripening, although the role of any particular enzyme is yet unknown. We have identified and targeted two ripening-specific N-glycoprotein modifying enzymes, α-mannosidase (α-Man) and β-D-N-acetylhexosaminidase (β-Hex). We show that their suppression enhances fruit shelf life, owing to the reduced rate of softening. Analysis of transgenic tomatoes revealed ≈2.5-and ≈2-fold firmer fruits in the α-Man and β-Hex RNAi lines, respectively, and ≈30 days of enhanced shelf life. Overexpression of α-Man or β-Hex resulted in excessive fruit softening. Expression of α-Man and β-Hex is induced by the ripening hormone ethylene and is modulated by a regulator of ripening, rin (ripening inhibitor). Furthermore, transcriptomic comparative studies demonstrate the downregulation of cell wall degradation-and ripening-related genes in RNAi fruits. It is evident from these results that N-glycan processing is involved in ripening-associated fruit softening. Genetic manipulation of N-glycan processing can be of strategic importance to enhance fruit shelf life, without any negative effect on phenotype, including yield.

Effect of Pre-harvest Application of Hexanal and Growth Regulators in Enhancing Shelf Life and Regulation of Membrane Associated Genes in Strawberry

“…Finally, phospholipase D causes membrane deterioration through catalyzing the hydrolysis of phospholipids, which maintain cell viability and homeostasis into phosphatidic acid (Dawidowicz 1987;Exton 1997). Suppressing such enzymes in fruit tissues considerably reduces softening rate, improve fruit quality, and extend shelf life (Brummell et al 1999;Sesmero et al 2007Sesmero et al , 2009Meli et al 2010).It was found that a primary alcohol such as hexanol, and an aldehyde such as hexanal were potent inhibitors of PLD activity (Paliyath et al 1999). Hexanal was proven to be a more potent inhibitor, apparently due F o r R e v i e w O n l y to the lack of hydroxyl group that may interrupt the complete hydrolysis of substrate-enzyme intermediate.…”

Phenotypic and molecular characterization of a tomato (Solanum lycopersicum L.) F2 population segregation for improving shelf life

“…Tomato is a climacteric fruit, and ethylene is required for normal ripening (Alexander and Grierson, 2002). The advanced RNA interference technique is an efficient method for downregulating the genes involved in ethylene biosynthesis as well as enzymes that degrade the cell wall (Carrari et al, 2007) to extend the shelf life of tomato (Kramer and Redenbaugh, 1994;Xiong et al, 2005;Batra et al, 2010;Meli et al, 2010). However, genetically modified crops are not marketable worldwide owing to environmental safety issues and social acceptance (Qaim, 2009).…”

Transient Expression of Homologous Hairpin RNA Interferes with Broad bean wilt virus 2 Infection in Nicotiana benthamiana

“…Numerous studies have indicated that IR constructs of transgenes can effectively induce RNA silencing to trigger knockout of specific gene expressions (Ali et al, 2010;Allen et al, 2004;Gavilano et al, 2006;Johansen and Carrington, 2001;Kusaba et al, 2003;Liu et al, 2002;Meli et al, 2010;Pandolfini et al, 2003;Segal et al, 2003;Smith et al, 2000;Xiong et al, 2005). In addition, a number of studies showed that IR constructs of transgenes containing virus-derived sequences transformed to plants can effectively protect plants from challenging viruses (Abhary et al 2006;Bucher et al 2006;Chen et al, 2004;Di Nicola-Negri et al 2005;Hammond et al 2006;Lennefors et al 2006;Pooggin et al 2003;Simón-Mateo and García, 2011;Tenllado et al 2003;Tenllado et al, 2004;Vanitharani et al, 2003;Wang et al, 2000).…”