, a HOG-type mitogen-activated protein kinase (MAPK) encoding gene of
was constitutively expressed in all types of fungal cells. Δ
mutants grew normally on artificial media; sporulation and spore germination were also normal. The mating capability of M24, a representative strain of the Δ
mutants, showed no detectable decline, indicating that this HOG-type MAPK gene is dispensable for growth and reproduction under optimal culture conditions. Strain M24 had increased tolerance to vinclozoline and fludioxonil fungicides. Invasive growth of the wild type and three Δ
gene replacement mutants (M21, M24, M36) were assessed on tomato fruits. All strains behaved similarly, i.e. they produced visible symptoms on the second day after infection, and produced ∼3 cm lesion, overgrown by fungal mycelium after six days of incubation. These data suggest that the HOG-type MAPK pathway is not required for the invasive growth of this fungus.
Based on multiple sequence alignment of mitogen activated protein kinase (MAPK) genes from 28 fungal species, we could identify twelve new hallmark sequences, specific to YSAPK (yeast and fungal stress activated protein kinases) MAPK subgroup within fungal MAPKs. Six of the motifs (I-a, I-b, IV-b, V-b, X-b1 and X-b2) showed especially high degree of specificity. Two of these six motifs, I-b (SA[RK]DQLT) and IV-b (F[IL]SPLED[IV]) were specific within eukaryotic proteins, too. The other type of motifs contained not only YSAPK specific residues but residue(s) conserved on fungal MAPK and all MAPK levels. From the viewpoint of functional role, YSAPK motif VII-a (IL[VI]NENCDL) coincided with a loop spanning 7b-8b sheets in human p38a and ERK2 MAPK proteins (consensus indicated by bold face letters). This motif was shown to be involved in interaction with L-x-L type docking motifs of activators (MAPK kinases) and transcription factors. A fungal MAPK specific signal sequence in protein kinase subdomain IX-b (AE[ML][LVI]xG[KR]PxFxG[KR]D) was also described. A subgroup specific nested PCR-based cloning approach was developed to amplify YSAPK sequences in different filamentous fungal species based on motifs I, I-b, VIII and X-b3 as primers. Putative YSAPK MAPK amplicons obtained by this approach were identified by (i) the presence of newly characterized YSAPK specific motifs and (ii) alignments to known YSAPK MAPK genes. A neighbor-joining phylogenetic tree constructed by comparing 50 fungal MAPK sequences clearly demonstrated a dichotomic origin of fungal MAPKs and separated YSAPK MAPKs from the other two fungal MAPK subgroups. Comparing the number and distribution of known MAPK genes in Fusarium and other species it is tempting to speculate that this triple structural diversity of MAPKs, at least in filamentous species is a general phenomenon. Phylogenetic analysis revealed no separation of phytopathogenic species. Blumeria graminis, Alternaria brassicicola and Aspergillus species, however were separated from the majority of filamentous Ascomycetes in all of the three MAPK subgroups.
Fvwc1 and Fvwc2, orthologues of the wc-1 and wc-2 genes encoding for proteins of the white collar complex (WCC) in Neurospora crassa were cloned from Fusarium verticillioides and lack-of-function wc mutants were obtained by targeted gene disruption. Photo-conidiation was found to be absent in F. verticillioides, on the contrary, the wild type strain produced less conidia under continuous illumination than in the dark. Inactivation of any of the wc genes led to total female sterility, without affecting male fertility or asexual conidiation. No loss in colonization capability/invasive growth of the wc mutants was observed, when assessed on tomato fruits. Both Fvwc1 and Fvwc2 showed constitutive expression in the wild type cultures incubated in the dark and exposure to light caused only negligible increases in their transcription. Both Fvwc1 and Fvwc2 were down-regulated in a ΔFvmat1-2-1 gene disruption mutant, lacking a functional mating type (mat1-2-1) gene, suggesting that the MAT1-2-1 product has a positive regulatory effect on the white collar genes.
Species richness and composition of Staphylinidae communities were investigated at ground level when differently treated with pesticides and in abandoned apple and pear orchards in Hungary. Altogether 6099 individuals were collected belonging to 241 staphylinid species. 233 have been identified to species level and 8 staphylinid taxa were determined up to generic level. More than 20% of the Hungarian staphylinid fauna was represented in the orchards. The similarity (Jaccard index) between apple and pear orchards at ground level were 54%. The species richness in each orchard varied between 23 and 100 species. The most widely occurring species in orchard ground level were: Dinaraea angustula, Palporus nitidulus, Tachyporus hypnorum, Sphenoma abdominale, Omalium caesum, Philonthus carbonarius, Drusilla canaliculata, Sepedophilus marshami, Mocyta orbata, Coprochara bipustulata, Mocyta fungi, Hyponygrus angustatus, Purrolinus laeticeps, Paraphallus linearis, Omalium cursor, Heterothops dissimilis and Atheta crassicornis.
Dry oak forests have one of the richest understory vegetation in Europe, but the environmental drivers of this community have been scarcely revealed. In this study, we assessed whether the amount of light, soil pH or stand heterogeneity affect primarily the species composition of this community. We investigaed 332 sampling plots in 40-165 year old managed and abandoned Quercus cerris and Q. petraea dominated forests in North Hungary. Presence-absence data of herbaceous species and seedlings of woody species were recorded in 28 subplots within each sampling plot. Stand structure, canopy openness and soil pH were also measured in each plot. The relationships between stand characteristics and the species assemblage were explored by redundancy analysis, while the individual responses of species and species groups were studied by generalized linear mixed models. Multivariate methods and individual species response analyses provided similar results, the amount of light and soil pH were equally important variables (both of them explained 2.8% of species variance), while stand heterogeneity had a bit lower, albeit still significant role in determining understory species composition (1.9% of species variance explained). Seedlings of woody species preferred shaded (half-shaded) conditions, while many herbaceous species were positively related to light. The effect of the three explanatory variables was hard to separate, since they influenced each other as well. Sessile oak seedlings and herbs typical of dry forests, forest edges, grasslands and acidic soil habitats preferred light rich habitats with homogeneous stand structure and low soil pH. Mesic forest herbs and seedlings of other woody species were related to relatively high soil pH, heterogeneous stand structure and closed canopy. These two understory types were clearly separated regarding composition. This study emphasizes the importance of heterogenous light conditions and mosaic, diverse forest structure (presence of homogeneous and heterogeneous forest patches) during forest management for the maintenance of understory biodiversity.
The effect of four rhizobacterial strains on the severity of spot blotch disease
caused by cochliobolus sativus was evaluated for two growing
seasons under rainfed conditions. Three barley genotypes were used as host
plant. All strains reduced C. sativus severity, with effect
more pronounced when Pseudomonas putida BTP1 and
Bacillus subtilis Bs2508 were used. The disease reduction
was up to 56% in Arabi Abiad / P. putida BTP1. The grain yield
was not obviously affected by the presence of the rhizobacteria, except some
signifitive increase in season 2. Raising the resistance by soaking seed with
rhizobacterial strains might be of ultimate value in agriculture.