Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Suppression of fruit softening and extension of shelf life of pear by putrescine application Veerpartap Singh ⁎ , S.K. Jawandha, P.P.S. Gill, M.S. Gill Department of Fruit Science, Punjab Agricultural University Ludhiana, 141 004, Punjab, India ARTICLE INFO Keywords: Cellulase Fruit quality Pear PME Putrescine Softening ABSTRACT Softening during storage limits the shelf life of pear fruit (Pyrus spp.) which lead to remarkable losses. To develop an effective technique to reduce softening and maintain quality of pear fruit, the effect of postharvest dip treatment of putrescine (PUT) @ 1 mM, 2 mM and 3 mM was investigated on pear fruit cv. Punjab Beauty. The 2 mM and 3 mM PUT treatment effectively reduced the weight loss (WL), retained higher firmness, suppressed the degradation of starch and titratable acidity (TA) and maintained the higher quality of fruit. Moreover, these treatments suppress the activity of cell wall degrading enzymes pectin methyl esterase (PME) and cellulase concomitant with reduction in fruit softening than in control. The 2 mM and 3 mM PUT exhibited the lower spoilage of fruit. These results suggest that, 2 mM and 3 mM PUT suppressed the activity of cell wall degrading enzymes and maintained higher sensory quality (SQ) with prolongation of shelf life of 12 days under ambient conditions. 1. Introduction Pears (Pyrus spp.) are important fruit crop due to its high anti- oxidant, nutritional value and unique phyto-constituents made nu- merous medicinal properties. Pears maintain body pH and also have properties like anti-oxidants, anti-inflammatory, uro-disinfectant, anti- bacterial, anti-diabetic, sedative and antipyretic etc (Parle and Arzoo, 2016). However, pear fruit matured in the mid-summer; the rapid changes in postharvest physiology account for a short postharvest life (Nath et al., 2012). Other softening changes like reduction in firmness, cell turgor pressure and cell wall degradation are the most important indications for the deterioration of quality as well as storage life. On the other hand, high temperature instantly after harvest and unsuitable storage conditions advance the physiological disorders, en- hancing the respiration and cell membrane disrupter (Lim et al., 2007). The degradation of the cell wall composition and structure have been ascribed to the activity of cell wall degrading enzymes like PME and cellulase on the polysaccharide content such as pectin, hemicelluloses and cellulose in the cell wall (Cheng et al., 2009) while, loss of cell wall adhesion due to the above polysaccharide decomposition is a major cause for softening during storage (Johnston et al., 2002). Pears are climacteric fruit ripened in association with a rise in ethylene production and burst in respiration rate during storage (Hansen, 1943). The peak production of ethylene is accompanied by volatiles burst, pulp softening by cell wall decomposition and finally lead to a increase in softening and reduction in storage life of fruit (Hong et al., 2015), while polyamines (PAs) are highly effective to re- duce or control these incidences and appear to retain natural properties of pear, as they are antagonist to ripening after harvest (Valero et al., 2002). PAs are positively charged aliphatic amines have low molecular weight are organic metabolites available in all organisms. The PAs PUT 2+ , cadaverine 2+ , spermidine 2+ and spermine 3+ have been pos- tulated in the process of cell division, fruit development, ripening, softening and senescence (Khan et al., 2007). PAs application has been proved to reduce the softening progression by inhibition of the activity of cell wall modifying enzymes (Kramer et al., 1991). In general; PUT is a predominant PA that closely asso- ciated with fruit softening (Dibble et al., 1988). In literature, the effi- cacy of PUT application in delaying softening and improving the sto- rage life of fruit is well documented. To the best of our knowledge, no information is accessible on the role of PUT in modulating the cell wall degrading enzyme activity and fruit softening in sub-tropical pear during ambient storage and this warrants further investigation. There- fore, the role of PUT in regulating the cell wall degrading enzymes activity including PME and cellulase and other physico-chemical changes of pear fruit during ambient storage was investigated. https://doi.org/10.1016/j.scienta.2019.108623 Received 27 May 2019; Received in revised form 26 June 2019; Accepted 27 June 2019 ⁎ Corresponding author. E-mail address: veerpartapsingh91@gmail.com (V. Singh). Scientia Horticulturae 256 (2019) 108623 0304-4238/ © 2019 Elsevier B.V. All rights reserved. T