Search

Antimicrobial activity of chitosan has been previously demonstrated on some fungi species. In this work, the direct effect of a low molecular weight chitosan (121.6 kDa) on the morphology of Bipolaris oryzae was studied by light and scanning electron microscopy techniques. Changes in the hyphae and germ tubes were observed. Moreover, structural and morphological changes during the apical growth phase of the fungus were detected by scanning electron microscopy at 3 g/L chitosan. B. oryzae hyphae malformations were detected, with shortening and thickening of hyphae and spore germ tubes shortening and swelling, together with hyphae agglomerations, all these changes affecting the fungus' multiplication and spreading capacity. These results support the possible use of the assayed chitosan in pest control strategies against B. oryzae in rice crops. [ABSTRACT FROM AUTHOR]

To identify Nicotiana tabacum genes involved in resistance and susceptibility to the phytopathogenic fungus Rhizoctonia solani, transcripts were generated (by subtractive libraries), which were differentially expressed in each interaction. This enabled isolation of a gene coding for a protein kinase that becomes silent during the susceptibility interaction and is activated during resistance. The expression of this gene in tobacco plants significantly increased resistance against an aggressive isolate of R. solani. However, silencing the gene drastically reduced resistance to a nonaggressive isolate of R. solani. Besides, genes such as: superoxide dismutase, hsr203j, chitinases and phenylalanine ammonia lyase, related with resistance to tobacco plant diseases, in which the gene coding for the protein kinase is overexpressed or silenced, were evaluated. This gene can be used to design a strategy of resistance to R. solani in tobacco cultures or other plants of the Solanaceae family, susceptible to this phytopathogen. [ABSTRACT FROM AUTHOR]

To identify Nicotiana tabacum genes involved in resistance and susceptibility to the phytopathogenic fungus Rhizoctonia solani, transcripts were generated (by subtractive libraries), which were differentially expressed in each interaction. This enabled isolation of a gene coding for a protein kinase that becomes silent during the susceptibility interaction and is activated during resistance. The expression of this gene in tobacco plants significantly increased resistance against an aggressive isolate of R. solani. However, silencing the gene drastically reduced resistance to a non-aggressive isolate of R. solani. Besides, genes such as: superoxide dismutase, hsr203j, chitinases and phenylalanine ammonia lyase, related with resistance to tobacco plant diseases, in which the gene coding for the protein kinase is overexpressed or silenced, were evaluated. This gene can be used to design a strategy of resistance to R. solani in tobacco cultures or other plants of the Solanaceae family, susceptible to this phytopathogen.