جستجوی مقالات مرتبط با کلیدواژه « Rhizoctonia solani » در نشریات گروه « زیست شناسی »

MicroRNAs, as small non-coding RNAs, are recently reported to be involved in plant defense system against pathogens including fungi.

In this research, it was intended to investigate candidate susceptible rice (Oryza Sativa) Osa-miRNA expression alteration following the infection by Rhizoctonia solani.

To this aim, literature review suggested eight conserved plant miRNAs that are involved in other plant-pathogen interactions. Then, sixty days old rice plants (Hashemi, susceptible cultivar) were inoculated with R. solani and candidate miRNA expression alterations were investigated 2 hpi (hours post inoculation), 2 dpi (days post inoculation) and 6 dpi.

RT-qPCR analysis suggested four subgroups of candidate miRNAs based on the time of their responses to the pathogenesis of R. solani. While Osa-miR-156 was early-responsive, Osa-miR159 was the last-responsive and Osa-miR167, Osa-miR171, Osa-miR408, and Osa-miR444 were late responsive to R. solani infection. Osa-miR166 and Osa-miR393 were non-responsive to this infection, compared to the mock-inoculated control group. Consistently, Os-SPL3 and Os-MADS known target genes were expressed in reverse correlation to Osa-miR156 and Osa-miR444, respectively.

From these data, it is suggested that both early (Osa-miR-156) and late (Osa-miR167, Osa-miR171, OsamiR408, Osa-miR444) responsive miRNAs might be involved in R. solani infection in rice plants.

High antagonistic ability of different Trichoderma species against a diverse range of plant pathogenic fungi has led them to be used as a biological fungicide in agriculture. They can also promote plant growth, fertility, resistance to stress, and absorption of nutrients. They are also opportunistic and symbiotic pathogens, which can lead to the activation of plant defense mechanisms.

The aim of this present study was to investigate possible enhancement of lytic enzymes production and biocontrol activity of T. virens against Rhizoctonia solani through gamma radiation and to find the relationship between changes in lytic enzyme production and antagonistic activity of T. virens.

Dual culture conditions were used to evaluate the antagonistic effect of T. virens and its gamma mutants against R. solani. Then, their chitinase and cellulase activities were measured. For more detailed investigation of enzymes, densitometry pattern of the proteins was extracted from the T. virens wild-type and its mutants were obtained viaSDS-polyacrylamide gel electrophoresis.

The mutant T.vi M8, T. virens wild-type and mutant T.vi M20 strains showed the maximum antagonistic effects against the pathogen, respectively. Data showed that the mutant T. vi M8 reduced the growth of R. solani by 58 %. The mutants revealed significantly different (p <0.05) protein contents, chitinase and cellulase production (mg.mL-1) and activity (U.mL-1) compared to the wild-type strain. The highest extracellular protein production in the supernatant of chitinase and cellulase TFM was observed for the T.vi M11 and T.vi M17 strains, respectively. The T.vi M12 and wild-type strains secretedchitinase and cellulase significantly more than other strains did. Densitometry of SDS-PAGE gel bands indicated that both the amount and diversity of chitinase related proteins in the selected mutant (T. vi M8) were far higher than those of the wild-type. The diversity of molecular weight of proteins extracted from the T. virens M8 (20 proteins or bands) was very high compared to the wild-type (10 proteins) and mutant T.vi M15 (2 proteins).

Overall, there was a strong link between the diversity of various chitinase proteins and the antagonistic properties of the mutant M8.

The bacteria which are members of the genus Bacillus are known to produce a wide variety of antimicrobial substances and bacteriocins. The main objective of this study was to investigate the effect of these bacteriocins on eukaryotic cells such as fungi, yeast and plant seeds. Several strains were screened for antifungal activities and identified by the means of polymerase chain reaction (PCR) of the 16s rRNA gene and sequencing. Our experiments showed that the Bacillus pumilus ZED17 and DFAR8 strains, had antifungal activities against Rhizoctonia solani and selected for further investigations. Extracellular peptides produced by these strains were purified by ammonium sulfate precipitation and dialysis. Addition of these peptides to Potato Dextrose Agar (PDA) medium inoculated with R. solani indicated significant inhibition of the fungal growth. The antifungal peptides were thermo-stable and remained active after boiling at 100˚C for 15 min. The molecular weight of the peptide with antifungal activity was estimated by electrophoresis on the Sodium Dodecyl Sulfate Poly Acrylamide Gel (SDS-PAGE) as about 5 KDa. Structural nature of this peptide was determined after gel extraction by Fourier-transform infrared spectroscopy (FTIR). Moreover, this peptide showed inhibiting effect on seeds germination of some herbs. This peptide could be applied to control herbal fungal disease induced by R. solani which is a broad host range plant pathogen fungus and its inhibition is very important. The peptide also prevents seed germination. Hence, it can be appropriate for inhibiting weeds growth. No significant effect against Saccharomyces cerevisiae and Candida albicans was observed.

There is a growing demand for mass production of shikalkin (a natural pigment consisted of shikonin and alkannin) due to its increasing applications in cosmetics, pharmaceutical and nutrition industries. The root of Iranian Arnebia euchroma produces shikalkin. The promising capability of this plant for shikalkin production has already been demonstrated in cell culture studies. Elicitation effect of Rhizoctonia solani (R. solani) in comparison with the effects of Cu2+, methyl jasmonate (MJ), and salicylic acid (SA) on the shikalkin production was investigated in A. euchroma callus. The calli from different origins (leaf, collar and root) were proliferated on a modified Linsmaier-Skoog (mLS) medium and were subsequently transferred onto the pigment production medium containing various amounts of the desirable elicitor. Observations were quantified and the pigment production was precisely measured spectrophotometrically. Pigment biosynthesis was induced on White medium containing IAA (1 mM) and kinetin (10 mM) in dark at 25°C. Use of R. solani increased the pigment production by 7 fold greater than normal White medium. Cu2+ only doubled the shikalkin production. MJ and SA showed enhancing effects comparable to that of Cu2+. It is assumed that upon binding of the polysaccharides of the fungal cells to the plant cell surface, a cascade of signaling is initiated that led to expression of genes involving in the biosynthesis of shikalkin.