Zinc finger transcription factor ZFP1 is associated with growth, conidiation, osmoregulation, and virulence in the Polygonatum kingianum pathogen Fusarium oxysporum.

Rhizome rot is a destructive soil-borne disease of Polygonatum kingianum and adversely affects the yield and sustenance of the plant. Understanding how the causal fungus Fusarium oxysporum infects P. kingianum may suggest effective control measures against rhizome rot. In germinating conidia of infectious F. oxysporum, expression of the zinc finger transcription factor gene Zfp1, consisting of two C2H2 motifs, was up-regulated. To characterize the critical role of ZFP1, we generated independent deletion mutants (zfp1) and complemented one mutant with a transgenic copy of ZFP1 (zfp1 tZFP1). Mycelial growth and conidial production of zfp1 were slower than those of wild type (ZFP1) and zfp1 tZFP1. Additionally, a reduced inhibition of growth suggested zfp1 was less sensitive to conditions promoting cell wall and osmotic stresses than ZFP1 and zfp1 tZFP1. Furthermore pathogenicity tests suggested a critical role for growth of zfp1 in infected leaves and rhizomes of P. kingianum. Thus ZFP1 is important for mycelial growth, conidiation, osmoregulation, and pathogenicity in P. kingianum.

[Isolation and identification of an endophytic fungus of Polygonatum cyrtonema and its antifungal metabolites].

OBJECTIVE: Endophytic fungi in medicinal plants produce a variety of bioactivity compounds. In this study, an endophytic fungus zjqy610 with antifungal activity was isolated from Polygonatum cyrtonema in Zhejiang Qingyuan Baishanzu Mountain nature reserve. METHODS: Strain zjqy610 was identified as Penicillium canescens based on the morphology and its rDNA sequence analysis. Three antifungal compounds were isolated from the fermentation broth of zjqy610 through normal-phase silica gel column chromatography and gel (Sephadex LH-20) column chromatography, traced by ultraviolet light or iodine vapor with bioassay-guided fractionation. RESULTS: These three compounds were elucidated as o-acetylbenzeneamidinocarboxylic acid (zjqy610B-g-3), griseofulvin (zjqy610D-4) and naphtho [1,2-b] furan-3-carboxylic acid, 4-hydroxy-5-methoxy-2-methyl-(zjqy610F-2) based on mass spectrometry and nuclear magnetic resonance spectroscopy. The antifungal activity assays showed that the three compounds had inhibitory to variety of plant pathogenic fungi. Compound zjqy610D-4 had strong antifungal activity against Botrytis cinerea, Colletotrichum orbiculare, Didymella bryoniae and Sclerotinia sclerotiorum. EC50 was 0.68, 0.38, 0.91 and 0.61 mg/L, respectively. CONCLUSION: Zjqy610D-4 is deserved to develop an agricultural antibiotics.

Community structure of arbuscular mycorrhizal fungi in a primary successional volcanic desert on the southeast slope of Mount Fuji.

Community structure of arbuscular mycorrhizal fungi (AMF), evaluated as spore samples and mycorrhizal roots of four herbaceous plant species, was investigated at different altitudes in a primary successional volcanic desert on Mount Fuji using molecular methods (fragment and sequence analysis of the large ribosomal subunit RNA gene). In total, 17 different AMF clades were identified, and most were members of the Glomaceae, Acaulosporaceae, and Gigasporaceae. The AMF community structures detected by spore sampling were inconsistent with those from plant roots. Of all AMF clades, six (35.3%) were detected only on the basis of spores, six (35.3%) only in roots, and five corresponded to both spores and roots (29.4%). Although an Acaulospora species was the most dominant among spores (67.1%), it accounted for only 6.8% in root samples. A species analysis of AMF communities at different altitudes demonstrated that AMF species diversity increased as altitude decreased and that the species enrichment at lower altitudes resulted from the addition of new species rather than species replacement. The inconsistencies in the species composition of spore communities with those in roots and the change in species diversity with altitude are discussed.

Arbuscular mycorrhizal colonization of the dominant plant species in primary successional volcanic deserts on the Southeast slope of Mount Fuji.

Arbuscular mycorrhizal (AM) colonization was observed on four plant species in primary successional volcanic deserts on the Southeast slope of Mount Fuji. The AM colonization of the dominant species, Polygonum cuspidatum, contradicts the conclusion that Polygonaceae are often regarded as being non-mycorrhizal species. The secondary dominant species, Polygonum weyrichii var. alpinum, formed no mycorrhizas. The roots of Cirsium purpuratum, Clematis stans and Campanula punctata ssp. hondoensis, showed a higher percentage of AM colonization than P. cuspidatum. AM colonization and spore density in the rhizosphere soil of P. cuspidatum significantly decreased as elevation increased. AM colonization in roots of Cirsium purpuratum and Clematis stans also tended to decrease with increased altitudes. Cirsium purpuratum and Campanula punctata ssp. hondoensis formed single structural types of Arum- and Paris-type, respectively, whereas P. cuspidatum and Clematis stans formed both Arum- and Paris-type morphologies.