In this study, we report the cloning of the SsCut gene encoding cutinase from Sclerotinia sclerotiorum. We isolated a 609-bp cDNA encoding a polypeptide of 202 amino acids with a molecular weight of 20.4 kDa. Heterologous expression of SsCut in Escherichia coli (His-SsCut) caused the formation of lesions in tobacco that closely resembled hypersensitive response lesions. Mutational analysis identified the C-terminal-half peptide and the same amino acids indispensable for both enzyme and elicitor activity. His-SsCut was caused cell death in Arabidopsis, soybean (Glycine max), oilseed rape (Brassica napus), rice (Oryza sativa), maize (Zea mays), and wheat (Triticum aestivum), indicating that both dicot and monocot species are responsive to the elicitor. Furthermore, the elicitation of tobacco was effective in the induction of the activities of hydrogen peroxide, phenylalanine ammonia-lyase, peroxides, and polyphenol oxidase. His-SsCut-treated plants exhibited enhanced resistance as indicated by a significant reduction in the number and size of S. sclerotiorum, Phytophthora sojae, and P. nicotianae lesions on leaves relative to controls. Real-time PCR results indicated that the expression of defense-related genes and genes involved in signal transduction were induced by His-SsCut. Our results demonstrate that SsCut is an elicitor that triggers defense responses in plants and will help to clarify its relationship to downstream signaling pathways that induce defense responses.
With the improper application of fungicides, Phytophthora sojae begins to develop resistance to fungicides, and biological control is one of the potential ways to control it. We screened two strains of Bacillus; Bacillus amyloliquefaciens JDF3 and Bacillus subtilis RSS-1, which had an efficient inhibitory effect on P. sojae. They could inhibit mycelial growth, the germination of the cysts, and the swimming of the motile zoospores. To elucidate the response of P. sojae under the stress of B. amyloliquefaciens and B. subtilis, and the molecular mechanism of biological control, comparative transcriptome analysis was applied. Transcriptome analysis revealed that the expression gene of P. sojae showed significant changes, and a total of 1616 differentially expressed genes (DEGs) were detected. They participated in two major types of regulation, namely “specificity” regulation and “common” regulation. They might inhibit the growth of P. sojae mainly by inhibiting the activity of ribosome. A pot experiment indicated that B. amyloliquefaciens and B. subtilis enhanced the resistance of soybean to P. sojae, and their control effects of them were 70.7% and 65.5%, respectively. In addition, B. amyloliquefaciens fermentation broth could induce an active oxygen burst, NO production, callose deposition, and lignification. B. subtilis could also stimulate the systemic to develop the resistance of soybean by lignification, and phytoalexin.
The production of asexual spores plays a critical role in rice blast disease. However, the mechanisms of the genes involved in the conidiogenesis pathway are not well understood. F-box proteins are specific adaptors to E3 ubiquitin ligases that determine the fate of different substrates in ubiquitin-mediated protein degradation and play diverse roles in fungal growth regulation. Here, we identify a Saccharomyces cerevisiae Grr1 homolog, MoGrr1, in Magnaporthe oryzae. Targeted disruption of Mogrr1 resulted in defects in vegetative growth, melanin pigmentation, conidial production, and resistance to oxidative stress, and these mutants consequently exhibited attenuated virulence to host plants. Microscopy studies revealed that the inability to form conidiophores is responsible for the defect in conidiation. Although the Mogrr1 mutants could develop melanized appressoria from hyphal tips, the appressoria were unable to penetrate into plant tissues due to insufficient turgor pressure within the appressorium, thereby attenuating the virulence of the mutants. Quantitative RT-PCR results revealed significantly decreased expression of chitin synthase-encoding genes, which are involved in fungal cell wall integrity, in the Mogrr1 mutants. The Mogrr1 mutants also displayed reduced expression of central components of the MAP kinase and cAMP signaling pathways, which are required for appressorium differentiation. Furthermore, domain complementation analysis indicated that two putative protein-interacting domains in MoGrr1 play essential roles during fungal development and pathogenicity. Taken together, our results suggest that MoGrr1 plays essential roles in fungal development and is required for the full virulence of M. oryzae.
growth ehamber at 25°C (day) and 20°C (night) with a 14-h photoperiod. The isolates were eultured on PDA at 25°C for 7 days. Stems were wounded at 10 em height with a drill. Eaeh isolate was inoeulated to 25 replieates per eultivar by plaeing a myeelia agar plug (4 to 5 mm diameter) in the hole and wrapping the stem with Parafilm. Plants treated identieally with sterile agar plugs were used as eontrols. Plants were then maintained at 100% relative humidity for 2 h. Both isolates indueed diseases symptoms and death of seedlings of both cultivars at a mean time of 37.5 days after inoeulation. No signifieant differenees between isolates or between cultivars were deteeted. Twenty eontrol plants similarly treated with sterile PDA dises did not display symptoms. C. parasítica was re-isolated from lesions, eonfirming Koeh's postulates. Andalusia has 14,000 ha of chestnut crops with high eommereial value due to their preeoeity. Dispersion of ehestnut blight in this zone ean reduee crop produetivity. To our knowledge, this is the first report of C. parasítica eausing chestnut blight in Andalusia (southern Spain), one of the few areas left in southwestern Europe free of ehestnut blight. . Plant Dis. 98:284, 2014; published online as http://dx.
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