Cyanide produced with ethylene by ACS and its incomplete detoxification by β-CAS in mango inflorescence leads to malformation

Abstract

Malformation of mango inflorescences (MMI) disease causes severe economic losses worldwide. Present research investigates the underlying causes of MMI. Results revealed significantly higher levels of cyanide, a by-product of ethylene biosynthesis, in malformed inflorescences (MI) of mango cultivars. There was a significant rise in ACS transcripts, ACS enzyme activity and cyanide and ethylene levels in MI as compared to healthy inflorescences (HI). Significant differences 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 field trials, increased malformed-necrotic-inflorescence (MNI) by spraying ethrel and decreased MNI by treating with ethylene inhibitors (silver and cobalt ions) further confirmed 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 inflorescence malformation, and also help manipulate mango varieties genetically for resistance to malformation.

Thiol-based Oxidative Posttranslational Modifications (OxiPTMs) of Plant Proteins

“…2018 , Cressey and Reeve 2019 , Gotor et al. 2019 ) and is also released as a co-product of ethylene biosynthesis ( Ansari et al. 2019 ).…”

Ethylene mediated physiological response for in vitro development of salinity tolerant tomato

“…ACC (1-aminocyclo propnae 1-carbooxylic acid) synthase (ACS) is a key enzype of ethylene biosynthesis pathway as it catalyzes the rate-limiting step in the pathway, and also plays a crucial role in ethylene signaling and salinity stress response (Win et al 2018). Therefore, increased endogenous ethylene is associated with enhanced ACS expression and increased cellular ACS enzyme activity (Ansari et al 2019). Sato and Theologis (1989) reported cloning the first ACS gene from Cucurbita pepo.…”