Authors:R. Radhajeyalakshmi, K. Yamunarani, K. Seetharaman and R. Velazhahan
Seed extracts of pearl millet, sorghum, Japanese barnyard millet, foxtail millet, samai and proso millet were evaluated in vitro for their ability to inhibit the growth of Rhizoctonia solani, Macrophomina phaseolina and Fusarium oxysporum. Among them, seed extracts of pearl millet and sorghum were highly effective in inhibiting the growth of all three examined phytopathogenic fungi. The seed extracts were tested for the presence of thaumatin-like proteins (TLPs) by Western blot analysis using bean TLP antiserum. Results of Western blot analysis indicated the presence of a 23-kDa TLP in seeds of pearl millet, sorghum and Japanese barnyard millet. The 23-kDa TLP was more abundant in the seeds of pearl millet. The distribution of TLP in various parts of pearl millet was analyzed by Western blotting. The results indicated that the 23 kDa TLP was predominantly expressed in seeds and inflorescence of pearl millet.
Authors:K. Yamunarani, R. Jaganathan, R. Bhaskaran, P. Govindaraju and R. Velazhahan
The antifungal activity of 30 medicinal plants belonging to different families was tested in vitro on the phytopathogenic fungus Rhizoctonia solani. The results revealed that protein extract from the galls of Quercus infectoria belonging to Fagaceae family was highly effective in inhibiting the mycelial growth of R. solani. The gall extract of Q. infectoria also inhibited the growth of other agronomically important fungal pathogens viz. Fusarium oxysporum, Cochliobolus miyabeanus, Macrophomina phaseolina, Colletotrichum gloeosporioides, Magnaporthe salvinii, Cochliobolus lunatus, Alternaria solani, Pythium aphanidermatum and Colletotrichum falcatum. A 29-kDa glycoprotein was purified from the galls of Q. infectoria by ammonium sulphate fractionation followed by gel filtration on Sephadex G-50 column. The purified protein showed the absorption maxima at 640 nm and 308 nm. The purified protein was stable even after heating at 100 °C for 10 min or autoclaving at 121 °C for 20 min. When the 29-kDa protein was treated with NaIO4 and pronase the antifungal activity was drastically reduced. The 29-kDa protein inhibited the mycelial growth of R. solani and C. miyabeanus at 2 µg level.