Biochemical responses in cotton as diagnostic parameter for resistance against cotton leaf curl virus (CLCuV)

Abstract Cotton (Gossypium hirsutum L) is one of the most important staple fibrous crops cultivated in India and globally. Its production and quality are greatly hampered by cotton leaf curl disease (CLCuD) caused by cotton leaf curl virus (CLCuV). Therefore, the aim of present study was to investigate biochemical resistance responses in different cotton varieties against CLCuV. Four commercial cotton varieties with susceptible (HS 6 and RCH-134 BG-II) and resistant (HS 1236 and Bunty) response were used to analyse the role of primary (sugar, protein and chlorophyll) and secondary (gossypol, phenol and tannin) biochemical compounds produced by the plants against infection of CLCuV. The resistant cultivars with increased activity of protein, phenol and tannin exhibited as biochemical barriers against CLCuV infection imparting the resistance in cotton cultivars. Whereas, other biochemical compounds including chlorophyll, sugar and gossypol did not show significant role in resistance against CLCuV. Nevertheless, these compounds virtually associated with basic physiological and metabolic mechanisms of cotton plants. Among the primary biochemical compounds, only protein activity proposed as first line of defence in cotton against CLCuV. The secondary level of defence line in resistance exhibited the activity of secondary biochemical compounds phenol and tannins which exhibited significant increase in their level while imparting resistance against CLCuV in cotton.