Malformation of mango inforescences (MMI) disease causes severe economic losses worldwide. Present research investigates the underlying causes of MMI. Results revealed signifcantly higher levels of cyanide, a by-product of ethylene biosynthesis, in malformed inforescences (MI) of mango cultivars. There was a signifcant rise in ACS transcripts, ACS enzyme activity and cyanide and ethylene levels in MI as compared to healthy inforescences (HI). Signifcant diferences in levels of methionine, phosphate, S-adenosyl-L-methionine, S-adenosyl-L-homocysteine, ascorbate and glutathione, and activities of dehydroascorbate reductase and glutathione reductase were seen in MI over HI. Further, a lower expression of β-cyanoalanine synthase (β-CAS) transcript was associated with decreased cellular β-CAS activity in MI, indicating accumulation of unmetabolized cyanide. TEM studies showed increased gum-resinosis and necrotic cell organelles, which might be attributed to unmetabolized cyanide. In feld trials, increased malformed-necrotic-inforescence (MNI) by spraying ethrel and decreased MNI by treating with ethylene inhibitors (silver and cobalt ions) further confrmed the involvement of cyanide in MMI. Implying a role for cyanide in MMI at the physiological and molecular level, this study will contribute to better understanding of the etiology of mango inforescence malformation, and also help manipulate mango varieties genetically for resistance to malformation.

Malformation of mango inforescences (MMI) disease causes severe economic losses worldwide. Present research investigates the underlying causes of MMI. Results revealed signifcantly higher levels of cyanide, a by-product of ethylene biosynthesis, in malformed inforescences (MI) of mango cultivars. Th...