MrCreC, a carbon catabolite repression gene, is required for the growth, conidiation, stress tolerance and virulence of Metarhizium robertsii.

As a key component of carbon source metabolism in fungi, CreC WD40 repeat protein is regulated by carbon catabolite repression (CCR). However, the understanding of the functions of CreC in entomopathogenic fungi is currently limited. Here, CreC in Metarhizium robertsii (MrCreC) was identified, and its roles in fungal development, conidiation, environmental stress response, and insecticidal virulence were explored. MrCreC is localized to cytoplasm, and MrCreC deletion affects fungal growth on various nutrients. Compared to the wild type, the sporulation of ΔMrCreC strain was significantly decreased by 60.3%. Further qPCR analysis found that deletion of MrCreC resulted in repression of sporulation-related genes such as AbaA, FlbA, Flbc, MedA, FlbD, FluG, and wetA. In addition, MrCreC loss did not alter heat stress tolerance but resulted in enhanced tolerance to UV-B. Interestingly, bioassays showed that the virulence following exposures to topical applications or injection of conidial suspensions of both infection and injection was impaired compared with that of the wild type. Further analysis showed that the adhesion and cuticle penetration genes in ΔMrCreC was down-regulated during infection, and the appressorial formation rate was significantly reduced. A deletion of MrCreC significantly also reduced immune escape and nutrient utilization genes in insect hemocoel. In conclusion, MrCreC is involved in the growth, development and virulence of M. robertsii. These findings advance our understanding of the function of CCR pathway-related genes.

Three new Pyrenula species with 3-septate ascospores with red or orange oil when over-mature (Ascomycota, Pyrenulales, Pyrenulaceae) from China.

The lichenised fungal genus Pyrenula is a very common crustose lichen element in tropical to subtropical forests, but little research has been done on this genus in China. During our study on Pyrenula in China, based on morphological characteristics, chemical traits and molecular phylogenetic analysis (ITS and nuLSU), three new 3-septate species with red or orange oil in over-mature ascospores were found: Pyrenulainspersasp. nov., P.thailandicoidessp. nov. and P.apiculatasp. nov. Compared to the known 3-septate species of Pyrenula with red or orange oil, P.inspersa is characterised by the inspersed hamathecium; P.thailandicoides is characterised by the IKI+ red hamathecium and the existence of an unknown lichen substance; and P.apiculata is characterised by the absence of endospore layers in the spore tips and the absence of pseudocyphellae. It is reported for the first time that the presence of a gelatinous halo around the ascospores of Pyrenula is common. A word key for the Pyrenula species with red or orange oil in over-mature ascospores is provided.

New species and records of Chapsa (Graphidaceae) in China.

We studied the genus Chapsa in China based on morphological characteristics, chemical traits and molecular phylogenetic analysis. One species new to science (C.murioelongata M.Z. Dou & M. Li) and two records new to China were found (C.wolseleyana Weerakoon, Lumbsch & Lücking and C.niveocarpa Mangold). Chapsamurioelongata sp. nov. is characterised by its lobed thalline margin, orange discs with white pruina, clear hymenium, and submuriform and long ascospores. Chapsawolseleyana was recombined into Astrochapsa based on phenotypic traits. Sequences of this species are for the first time reported here and phylogenetic analyses of three loci (mtSSU, ITS and nuLSU) supported the position of this species within Chapsa. A key for the Chapsa species known in China is provided.

Constitutive expression of CaHSP22.5 enhances chilling tolerance in transgenic tobacco by promoting the activity of antioxidative enzymes.

Chilling stress limits the productivity and geographical distribution of many organisms throughout the world. In plants, the small heat shock proteins (sHSPs) belong to a group of proteins known as chaperones. The sweet pepper (Capsicum annuum L.) cDNA clone CaHSP22.5, which encodes an endoplasmic reticulum-located sHSP (ER-sHSP), was isolated and introduced into tobacco (Nicotiana tabacum L.) plants and Escherichia coli. The performance index and the maximal efficiency of PSII photochemistry (Fv/Fm) were higher and the accumulation of H2O2 and superoxide radicals (O2-) was lower in the transgenic lines than in the untransformed plants under chilling stress, which suggested that CaHSP22.5 accumulation enhanced photochemical activity and oxidation resistance. However, purified CaHSP22.5 could not directly reduce the contents of H2O2 and O2- in vitro. Additionally, heterologously expressed recombinant CaHSP22.5 enhanced E. coli viability under oxidative stress, helping to elucidate the cellular antioxidant function of CaHSP22.5 in vivo. At the same time, antioxidant enzyme activity was higher, which was consistent with the lower relative electrolyte conductivity and malondialdehyde contents of the transgenic lines compared with the wild-type. Furthermore, constitutive expression of CaHSP22.5 decreased the expression of other endoplasmic reticulum molecular chaperones, which indicated that the constitutive expression of ER-sHSP alleviated endoplasmic reticulum stress caused by chilling stress in plants. We hypothesise that CaHSP22.5 stabilises unfolded proteins as a chaperone and increases the activity of reactive oxygen species-scavenging enzymes to avoid oxidation damage under chilling stress, thereby suggesting that CaHSP22.5 could be useful for improving the tolerance of chilling-sensitive plant types.