Research paper Field application of safe chemical elicitors induced the expression of some resistance genes against grey mold and cottony rot diseases during snap bean pods storage Hoda A.S. El-Garhy a, ⁎, Ismail A.S. Rashid b , Rania M. Abou-Ali c , Mahmoud M.A. Moustafa a a Genetics and Genetic Engineering Department, Faculty of Agriculture, Benha University, Moshtohor 13736, Qalyubia, Egypt b Post-harvest Diseases Department, Plant Pathology Research Institute, Agricultural Research Center (ARC), Giza, Egypt c Nucleic Acid and Protein Structure Department, Agricultural Genetic Engineering Research Institute (AGERI), Agricultural Research Center (ARC), Giza, Egypt abstract article info Article history: Received 5 May 2015 Received in revised form 17 September 2015 Accepted 19 October 2015 Available online 23 October 2015 Keywords: Snap bean Sustainable agriculture Grey mold Cottony rot qRT-PCR Defense genes Phaseolus vulgaris is subjected to serious post-harvest diseases such as grey mold and cottony rot diseases caused by Botrytis cinerea and Pythium aphanidermatum, respectively. In current study, potassium silicate (KSi), potassi- um thiosulfate (KTS) and potassium sulfate (KS) suppressed moderately the growth of B. cinerea and P. aphanidermatum in vitro. The applied treatments significantly suppressed grey mold and cottony rot of Xera and Valentino snap beans varieties' pods stored at 7 ± 1 °C and 90–95% RH for 20 days. Ethylene responsive factor (ERF), polygalacturonase inhibitor protein (PGIP), phosphatase associated to defense (PA) and pathogenesis- related protein (PR1) defense genes were over-expressed in leaves tissue of both bean varieties responding pos- itively to potassium salts field application. The expression of these genes was influenced by plant genotype and environment as it varied by snap bean varieties. Accumulation of ERF, GIP, PA and PR1 genes transcript under KTS at 4000 ppm treatment were the highest in Xera tissues (3.5-, 4.8-, 4- and 4.8-fold, respectively). In conclusion, pre-harvest potassium salt in vivo application could be used as effective safe alternatives to fungicides against grey mold and cottony rot diseases of snap beans during storage for up to 20 days at 7 ± 1 °C. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Snap bean (Phaseolus vulgaris) is one of the most world's impor- tant economic vegetable crops for direct human consumption. It comprises about 50% of the vegetable legumes consumed worldwide (Broughton et al., 2003; Graham et al., 2003). In Egypt, snap bean production for local consumption and export increased considerably in recent years and reached about 251,000 Mg (mega grams) produced from about 24,300 ha with average production of 10.33 Mg ha -1 (Min., Agric., ARE., 2012). All over the world, post-harvest losses of fruits and vegetables have been estimated to range from 5% to 50% from har- vested amounts (Statistics, FAO., 2012). Snap bean pods of Xera and Valentino varieties are attacked by many fungi causing several diseases during growth in the field, harvest, storage and marketing. Under the Egyptian environmental conditions, economic post-harvest losses in snap beans occurred due to development of grey mold and cottony rot post-harvest diseases caused by Botrytis cinerea and Pythium aphanidermatum, respectively, affecting snap bean productivity as well as its exportation competitiveness (Snowdon, 1992; Suslow and Cantwell, 1998). They cause serious problems to the harvested snap bean pods during transportation, exportation and storage. Al- though the use of chemical fungicides gave satisfactory control against fungal infections, the pre-harvest interval and fungicide resi- dues have harmful effects on human health and the environment resulting frequently in rejection of fungicides treated pods for human consumption (Eckert and Ogawa, 1988; Farouk and Osman, 2011). Fungicides are becoming increasingly used but are less acceptable in the national and international markets. Therefore development of envi- ronment friendly methods for disease control is an important goal to be achieved. Treatment of plants with a variety of abiotic and biotic resis- tance elicitor's agents, including cell wall fragments, plant extracts and synthetic chemicals can be induced to develop enhanced resistance to subsequent pathogen attack both locally and systemically as systemic acquired resistance (SAR) (Walters and Fountaine, 2009). Systemic ac- quired resistance (SAR) is the readiness of plant to repel subsequent pathogen attacks spread throughout the whole plant (Vallad and Goodman, 2004). Introduction of safe chemical elicitors for resistance gene expression into agricultural practices could manage post-harvest Gene 576 (2016) 358–365 Abbreviations: cDNA, DNA complementary to RNA; dNTP, deoxyribonucleoside triphosphate; Ksi, potassium silicate; KTs, potassium thiosulfate; KS, potassium sulfate; ERF gene, ethylene responsive factor; PGIP gene, polygalacturonase inhibitor protein; PA gene, phosphatase associated to defense; PR1 gene, pathogenesis-related protein; EF-1α gene, elongation factor; qRT-PCR, quantitative real time polymerase chain reaction; PDA, potato dextrose agar; mRNA, messenger RNA; gDNA, genomic DNA; NTC, non-template control. ⁎ Corresponding author at: Genetics Department, Faculty of Agriculture, Benha University, Moshtohor 13736, Qalyubia, Egypt. E-mail address: hoda.algarhy@fagr.bu.edu.eg (H.A.S. El-Garhy). http://dx.doi.org/10.1016/j.gene.2015.10.048 0378-1119/© 2015 Elsevier B.V. All rights reserved. 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