Differential expressions of genes modulating the mechanism of resistance to A. alternata in naturally infected mango fruits. (A) Effect of HWB on alternaria black spot (ABS) symptom development on mango cvs. Palmer, Kent, Tommy Atkins, Keitt, Lily and Shelly. (B) ABS symptom development on naturally infected fruits cv. Keitt following HWB treatment. (C) qRT-PCR differential expression profiling of genes Syn121, glutardoxin, IT1K2 and AOS of cv. Shelly. Fruit peel tissues were sampled at four different time points after HWB treatment. RNA was extracted and served as a template for cDNA followed by qRT-PCR analysis of the genes of interest. Proportional increases in relative expression values were normalized against the samples of untreated mango fruits at 0 h. Expression data are means of two replicates. ABS-covered area was evaluated after 4 weeks of storage at 12°C. Average values followed by different letters differ significantly at P <0.05 according to the Tukey-Kramer HSD test.