Utilization of VD toxin for rapid screening of cotton germplasm against Verticillium dahliae

摘要

The degree of virulence of different isolates of Verticillium dahliae (V08sn 1, Anyang and V07df2) was evaluatedusing pathogen and pathogen free approaches on upland cotton. Direct use of pathogen in the soil classified isolates intohighly virulent (V08sn 1), moderate virulent (Anyang) and less virulent (V07df2) with disease index of 65, 40 and 27 onthe basis of leaf necrosis and vascular browning. For pathogen free approach, toxins from these isolates were prepared andtheir protein contents were quantified. Results revealed highest level of soluble protein in V08sn 1 (78 mg/L) followed byAnyang (55 mg/L) and V07df2 (43 mg/L). Similarly, addition of toxin (10 μg/mL) on germinating cotton seeds inhibitedradical length in order of V08sn 1(62 %) Anyang (33%) V07df2 (17%). Besides, the addition of same quantity of toxinon detached cotton leaves produced marked symptoms of chlorosisecrosis which was more severe in V08sn 1 andfollowed by Anyang and V07df2. Moreover, dipping of leaf petiole in Vd toxin of Anyang isolate resulted in leaf wilting incontrast to the leaf dipped in equivalent amount of glucose solution (55 mg/L) which demonstrated that elicitor componentof Vd toxin is protein in nature. The results of Vd toxin experiment were consistent with the soil inoculation experimentusing V. dahliae but the onset of diseased symptoms was quicker in former than later. These findings suggest that utilizationof Vd toxin can be an environmental friendly and robust approach for plant breeders to accelerate the process of breedingnew resistant lines.