Effect of foliar application of Pseudomonas fluoresencens on activities of phenylalanine ammonia-lyase, chitinase and β-1,3–glucanase and accumulation of phenolics in rice

Changes in activities of phenylalanine ammonia-lyase,chitinase,ß-1,3-glucanase and phenolic content in rice leaves were measured at different times after treatment of leaves with Pseudomonas fluorescens strain Pf1.When rice leaves were sprayed with P.fluorescens,substantial increase in the phenylalanine ammonia-lyase activity was observed 1 day after treatment.Following increase of the first enzyme of the phenylpropanoid pathway,phenolic content of rice leaves also increased to a maximum at 4 days after P.fluorescens treatment.Chitinase activity increased in rice leaves in response to application of P.fluorescens and the maximum enzyme activity was observed 3 days after treatment.ß-1,3-Glucanase activity also increased significantly from 1 day after P.fluorescens treatment and continued to increase through 7 days.A five-fold increase in glucanase activity was observed 7 days after P.fluorescens treatment

Evidence of salicylic acid regulatory mechanisms of disease resistance against banana vascular wilt Fusarium oxysporium f.sp. cubense in Arabidopsis thaliana

Symptomatological studies on Arabidopsis- Fusarium oxysporium f.sp. cubense (Foc) interaction has led to the identification of signaling pathways required for plant resistance to Foc, as well as key regulators of innate immunity against this type of vascular wilt pathogens. From the in planta symptom expressions of Foc on Arabidopsis, there is a clear indication of involvement of salicylic acid (SA) and jasmonic acid (JA) for disease resistance. Mutations occur in synthesis of salicylic acid and Jasmonic acid, which modulate disease resistance with the evident of severe veinal necrosis on leaves and petiole. The typical symptom of leaf rosetting was the clear indication of the active participation of SA biosynthesis for Foc resistance in nahG, npr-1 plants. This analysis revealed that salicylic acid, ethylene (ET) and jasmonic acid (JA) pathways influence the Foc disease outcome in Arabidopsis. All the three signaling pathways interact in a positive way in the activation of Arabidopsis resistance to Foc. Hence, there must be co-ordinate regulation of both SA and JA for Foc resistance in Arabidopsis. Constitutive expressions of some transcriptional regulators of these pathways are sufficient to confer enhanced resistance to Foc and it might be an oligogenic trait.Keywords: Fusarium oxysporium f.sp.cubense, Arabidopsis thaliana, disease resistance.African Journal of Biotechnology, Vol 13(30) 3030-302

Existence of Thaumatin-like Proteins (TLPs) in Seeds of Cereals

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

Analyzing the Variability in Maize (Zea mays L.) Genotypes Using Principal Component Analysis under Varied Ecosystems

Maize is a cereal cross-pollinated crop which belongs to the family poaceae. It is grown over a wider range of environment than any other cereal crop. The present study was conducted to study genetic variability using principal component analysis. Twenty maize genotypes were used in the study. Ten characters viz., plant height, ear height, days to 50 % tasselling, days to 50 % silking, ASI, cob length, number of rows per cob, hundred seed weight, shelling percentage and yield were recorded for the study. In the PCA, four principal components exhibited eigen value more than 1.0 exhibiting 84.54 percent of the variability for the characters under irrigated conditions. The PC1 negative loadings for the flowering traits, viz., days to 50 % silking (-0.3886), ASI (-0.3233) and days to 50 % tasselling (-0.2972) and positive loadings with higher contribution from cob length (0.4033), no of rows per cob (0.3480) followed by shelling percentage were observed. Positive loadings were exhibited by days to tasselling (0.4780), plant height (0.4670) and hundred seed weight (0.4518) in PC2. In PC3 positive loadings for the characters viz., number of rows per cob (0.5338), ASI (0.5226) and cob length (0.3299) and negative loadings for the traits grain yield (-0.3815), ear height (-0.2658) and plant height (-0.2437) and in PC4 positive loadings for plant height (0.4953), ear height (0.2546) and negative loadings were shown by days to grain yield (-0.6632), shelling percentage (-0.3751), ASI (-0.2369) and 50 % silking (-0.0648) were observed. In rainfed conditions, the two principal components had eigen value of more than 1. Under normal irrigated condition,  PC1 and PC2  had eigen value of 5.689 and 1.6439. Plant height (0.3866), cob length (0.3726), number of rows per cob (0.3551), shelling % (0.3196), grain yield (0.2941), and hundred seed weight (0.2847) contributed positively to PC1. PC 2 had highest positive contributions from days to 50 % tasselling (0.5676), days to 50 % silking (0.5249), shelling % (0.3885), hundred seed weight (0.3763) and grain yield (0.2007). Negative loadings were shown by ear height (-0.1356) and plant height (-0.0093). Positive loadings were contributed by days to 50 % tasselling (0.5676), Days to 50 % silking, shelling percentage (0.3885) and hundred grain weight (0.3763)