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Abstract Background Puccinia striiformis f. sp. tritici is an obligate biotrophic pathogen that causes leaf stripe rust on wheat. Although it is critical to understand molecular mechanisms of pathogenesis in the wheat stripe rust fungus for developing novel disease management strategies, little is known about its genome and gene functions due to difficulties in molecular studies with this important pathogen. To identify genes expressed during early infection stages, in this study we constructed a cDNA library with RNA isolated from urediniospores of P. striiformis f. sp. tritici germinated for 10 h. Results A total of 4798 ESTs were sequenced from the germinated urediniospore library and assembled into 315 contigs and 803 singletons. About 23.9% and 13.3% of the resulting 1118 unisequences were homologous to functionally characterized proteins and hypothetical proteins, respectively. The rest 62.8% unisequences had no significant homologs in GenBank. Several of these ESTs shared significant homology with known fungal pathogenicity or virulence factors, such as HESP767 of the flax rust and PMK1, GAS1, and GAS2 of the rice blast fungus. We selected six ESTs (Ps28, Ps85, Ps87, Ps259, Ps261, and Ps159) for assaying their expression patterns during urediniospore germination and wheat infection by quantitative real-time PCR. All of them had the highest transcript level in germinated urediniospores and a much less transcript level in un-germinated urediniospores and infected wheat tissues (1–7 dpi). The transcript level of Ps159 increased at later infection stages (6–7 dpi). Our data indicated that these genes were highly expressed in germinated urediniospores and may play important roles in fungal-plant interactions during early infection stages in the wheat stripe rust fungus. Conclusion Genes expressed in germinated urediniospores of P. striiformis f. sp. tritici were identified by EST analysis. Six of them were confirmed by quantitative real-time PCR assays to be highly expressed in germinated urediniospores.

Summary: Velvet protein family members are important fungal‐specific regulators which are involved in conidial development, secondary metabolism and virulence. To gain a broader insight into the physiological functions of the velvet protein family of Valsa mali, which causes a highly destructive canker disease on apple, we conducted a functional analysis of two velvet protein family members (VmVeA and VmVelB) via a gene replacement strategy. Deletion mutants of VmVeA and VmVelB showed increased melanin production, conidiation and sensitivity to abiotic stresses, but exhibited reduced virulence on detached apple leaves and twigs. Further studies demonstrated that the regulation of conidiation by VmVeA and VmVelB was positively correlated with the melanin synthesis transcription factor VmCmr1. More importantly, transcript levels of pectinase genes were shown to be decreased in deletion mutants compared with those of the wild‐type during infection. However, the expression of other cell wall‐degrading enzyme genes, including cellulase, hemi‐cellulase and ligninase genes, was not affected in the deletion mutants. Furthermore, the determination of pectinase activity and immunogold labelling of pectin demonstrated that the capacity for pectin degradation was attenuated as a result of deletions of VmVeA and VmVelB. Finally, the interaction of VmVeA with VmVelB was identified through co‐immunoprecipitation assays. VmVeA and VmVelB play critical roles in conidiation and virulence, probably via the regulation of the melanin synthesis transcription factor VmCmr1 and their effect on pectinase gene expression in V. mali, respectively. [ABSTRACT FROM AUTHOR]

Summary Pathogenic fungi such as Valsa mali secrete effector proteins to manipulate host defenses and facilitate infection. Subtilases are identified as potential virulence factors, yet their specific roles in fruit tree pathogens, such as those affecting apple trees, are poorly understood. Our research shows VmSpm1 as a virulence factor in V. mali. Knocking it out decreased virulence, whereas its heterologous expression in apple led to reduced disease resistance. Using Y2H, BiFC, SLC, and Co‐IP techniques, we demonstrated an interaction between VmSpm1 and MdPYL4. MdPYL4 levels increased during V. mali infection. The stable transgenic apple lines inoculation experiment showed that MdPYL4 correlates with enhanced resistance to Apple Valsa canker when overexpressed in apples. Furthermore, through in vitro and in vivo assays, we showed the degradative role of VmSpm1 on MdPYL4. MdPYL4 promotes the synthesis of jasmonic acid (JA) in apples in an abscisic acid‐dependent manner. The degradation of MdPYL4 leads to a reduction in JA content in apples during V. mali infection, thereby impairing JA signal transduction and decreasing disease resistance in apple plants. In summary, this study reveals how V. mali utilizes VmSpm1 to subvert JA signaling, shedding light on fungal manipulation of plant hormones to disrupt immunity. [ABSTRACT FROM AUTHOR]

Single-component catalysts with integrated multiple reactive centers could work in concert to achieve enhanced activity tailored for specific catalytic reactions, but they remain underdeveloped. Herein, we report the construction of heterogeneous bimetallic porous coordination polymers (PCPs) containing both porphyrin and N -heterocyclic carbene (NHC) metal sites via the coordinative assembly of the NHC functionalities. Three heterobimetallic PCPs ( TIPP-Zn-Pd , TIPP-Cu-Pd and TIPP-Ni-Pd ) have been prepared to verify this facile synthetic strategy for the first time. In order to establish a cooperative action toward the catalytic CO 2 cycloaddition with epoxides, an additional tetraalkylammonium bromide functionality has also been incorporated into these polymeric structures through the N -substituent of the NHC moieties. The resulting heterogeneous bimetallic catalyst TIPP-Zn-Pd exhibits the best catalytic performance in CO 2 cycloaddition with styrene oxide (SO) under solvent-free conditions at atmospheric pressure and is applicable to a wide range of epoxides. More importantly, TIPP-Zn-Pd works smoothly and is recyclable in the absence of a cocatalyst under 1.0 MPa of CO 2 at 60 °C. This indicates that TIPP-Zn-Pd is quite competitive with the reported heterogeneous catalysts, which typically require a high reaction temperature above 100 °C under cocatalyst-free conditions. Thus, this work provides a new approach to design heterogeneous bimetallic PCP catalysts for high-performance CO 2 fixation under mild reaction conditions.