PHYSIOLOGICAL RESPONSE OF COTTON LEAF CURL BUREWALA VIRUSINFECTED PLANTS OF TOLERANT AND SUSCEPTIBLE GENOTYPES OF DIFFERENT GOSSYPIUM SPECIES
Z. Siddique, K.P. Akhtar, A. Hameed, I. Ul-Haq, M.Y. Ashraf, N. Sarwar, M.K.R. Khan
The effect of Cotton leaf curl Burewala virus (CLCuBuV) on cotton growth, yield, photosynthetic gas exchange, chlorophyll fluorescence and chlorophyll contents was studied in susceptible (CIM-496 and NIAB-111 from Gossypium hirsutum) and tolerant (Ravi from G. arboreum and Co Tiep Khac from G. herbaceum) cotton genotypes under glasshouse condition through artificial inoculation. Compared to the non-inoculated plants, the inoculated plants of susceptible genotypes showed stunted growth, reflected as significant decrease in plant height, internode length, number of leaves per plant, leaf area, number of bolls per plant, boll weight and yield per plant. Upon virus inoculation, transpiration rate decreased significantly in both susceptible genotypes while water use efficiency (WUE) was enhanced in CIM-496 compared to the non- inoculated plants. However, overall plant growth, net photosynthetic rate, leaf transpiration, stomatal conductance and WUE remained unaffected by CLCuBuV-infection in tolerant genotypes. Moreover, chlorophyll b and total chlorophyll content increased in one of the tolerant genotypes (Ravi) in response to CLCuBuV-infection while remaining unaffected in all other genotypes. Level of chlorophyll a and chlorophyll fluorescence (Fv/Fm) was not affected by CLCuBuV-infection in all genotypes. In conclusion, CLCuBuV infection adversely affected the overall plant growth and yield in susceptible genotypes while tolerant genotypes were able to maintain the growth and yield in the presence of infection. Reduced transpiration rate and increased WUE in susceptible genotypes and increased chlorophyll b and total chlorophyll content in tolerant genotypes on virus inoculation provided evidence for their significant involvement in CLCuBuV-tolerance mechanism in cotton.