Abstract
Until now, there are few studies and reports on the use of endogenous promoters of obligate biotrophic fungi. The WY195 promoter in the genome of Oidium heveae, the rubber powdery mildew pathogen, was predicted using PromoterScan and its promoter function was verified by the transient expression of the β-glucuronidase (GUS) gene. WY195 drove high levels of GUS expression in dicotyledons and monocotyledons. qRT-PCR indicated that GUS expression regulated by the WY195 promoter was 17.54-fold greater than that obtained using the CaMV 35S promoter in dicotyledons (Nicotiana tabacum), and 5.09-fold greater than that obtained using the ACT1 promoter in monocotyledons (Oryza sativa). Furthermore, WY195-regulated GUS gene expression was induced under high-temperature and drought conditions. Soluble proteins extracted from WY195-hpaXm transgenic tobacco was bioactive. Defensive micro-HR induced by the transgene expression of hpaXm was observed on transgenic tobacco leaves. Disease resistance bioassays showed that WY195-hpaXm transgenic tobacco enhanced the resistance to tobacco mosaic virus (TMV). WY195 has great potential for development as a new tool for genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms and the pathogenic mechanisms of O. heveae.
Highlights
No promoter with the same sequence of WY195 searched in the eukaryotic promoter database (EPD)
The results showed that the expression of hpaXm which was regulated by WY195 promoter produced defensive responses with partial hypersensitive cell death in transgenic tobacco leaves, and it is more severe than that in pBI121-hpaXm transgenic tobacco
Most of the filamentous fungal endogenous promoters that have been applied or developed are used to express endogenous genes or to express exogenous genes in their own, but rarely used to express exogenous genes in plants or animals. It has greatly developed the endogenous genes of filamentous fungi, the application of these excellent promoters is relatively
Summary
Filamentous fungi can express surprisingly high levels of endogenous genes, which indicates that endogenous genes are regulated by powerful promoters. This implies that filamentous fungi may be a good source of potential promoters that can be developed for biotechnological applications. There are few studies and reports on the use of endogenous promoters of filamentous fungi to express exogenous genes in filamentous fungi. Examples of inducible promoters that have been used to express exogenous genes of filamentous fungi include the Trichoderma reesei cbh promoter (Cherry and Fidantsef, 2003), the Aspergillus glaA promoter (Brunt, 1986), and the Aspergillus nidulans alcA promoter (Hintz et al, 1995); examples of constitutive promoters include the Aspergillus nidulans gpdA promoter (Punt et al, 1990) and the Trichoderma pki promoter (Mach et al, 1994)
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