Analysis of genetic diversity among Chinese Pleurotus citrinopileatus Singer cultivars using two molecular marker systems (ISSRs and SRAPs) and morphological traits.

To evaluate the genetic diversity of Pleurotus citrinopileatus Singer cultivars in China, 20 P. citrinopileatus strains were analyzed using morphological traits, inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) molecular markers. Eleven ISSR primers amplified a total of 116 DNA fragments of which 96 (82.91%) were polymorphic, whereas 8 SRAP primer pairs amplified 69 fragments of which 65 (93.47%) were polymorphic. Phylogenetic trees constructed on the basis of ISSR, SRAP, and combined ISSR/SRAP analyses using the Unweighted Pair-group Method with Arithmetic Averages method distributed the 20 strains into three or six major groups. The grouping exhibited great similarity and was generally consistent with their morphological characters and antagonism test, which indicated a high level of genetic diversity among P. citrinopileatus Singer and relationship between each other. Based on the genetic analysis, the primary mini-core strains were constructed with progressive sampling method of the smallest genetic distance. The mini-core germplasm collection included 4 strains (strain 2, 5, 7 and 11). Our findings will provide a scientific fundament for facilitating parent selection for broadening genetic base, accelerating the genetic breeding, identification of cultivated strains and the development of bioactive products from this commercially important medicinal mushroom.

[Optimization of submerged culture condition for production of mycelial biomass by Armillaria mellea].

OBJECTIVE: To optimize the submerged culture conditions for the production of mycelial biomass by Amillaria mellea. METHODS: Using the statistically based experimental design in a shake flask culture, optimum concentration of each medium component was determined using the statistical method. RESULTS: Dextrin was the suitable carbon source, bean cake extract was the suitable nitrogen source. Both corn steep liquor and thiamin favored the mycelial growth. Ethanol also favored the mycelial growth. (NH4 )2SO4 and NaNO3 inhibited mycelial growth whereas KH2PO4 favored the mycelial growth. CONCLUSION: The optimal combination of the media concentrations for mycelial growth was as follows: bean cake extract 25%, corn steep liquor 2%, dextrin 2.5%, thiamin 0.06%, ethanol 1.0%, KH2PO4 0.3%, pH 6.0. Under the optimal culture condition, the production of mycelial biomass achieved 1.9g/100ml.

Increased pollinator service and reduced pollen limitation in the fixed dune populations of a desert shrub.

Evaluations of restoration success usually focus on the structural aspects of ecosystems. Pollination, as an important functional aspect, is often overlooked. Here, the shifts in pollinator assemblage and pollen limitation in the desert shrub Caragana microphylla were examined along a restoration gradient in Horqin Sand Land, northern China. We identified seven species of bees; however, only four bee species were found to be effective pollinators, with Xanthosaurus remota dominating in the fixed dunes, and with no bee species or only a single species, X. remota, being observed in the semi-fixed and mobile dunes. Flower visitation rate was nearly ten times higher in the fixed dunes than in the mobile and semi-fixed dunes. Experimental floral manipulations revealed that the fixed dune populations experienced less pollen limitation, along with the increase in pollinator availability. Between the mobile and semi-fixed dune populations, pollen limitation was severe and at similar levels. The intensity of pollen limitation was negatively related to pollinator abundance and richness. Overall, the dependence on pollinators for reproduction may be an important constraint that limits persistence in this system. Increased pollinator service during the restoration process may ameliorate pollen limitation, benefiting the restoration of vegetation in this semiarid sandy area.

Earlier flowering did not alter pollen limitation in an early flowering shrub under short-term experimental warming.

In animal pollinated plants, phenological shifts caused by climate change may have important ecological consequences. However, no empirical evidence exists at present on the consequences that flowering phenology shifts have on the strength of pollen limitation under experimental warming. Here, we investigated the effects of experimental warming on flowering phenology, flower density, reproductive success, and pollen limitation intensity in Caragana microphylla and evaluated whether earlier flowering phenology affected plant reproduction and the level of pollen limitation using warmed and unwarmed open top chambers in the Horqin Sandy Land of Inner Mongolia, northern China. The results of this study indicated that artificial warming markedly advanced flower phenology rather than extending the duration of the flowering. Additionally, warming was found to significantly reduce flower density which led to seed production reduction, since there were insignificant effects observed on fruit set and seed number per fruit. Experimental floral manipulations showed that warming did not affect pollen limitation. These results revealed the negative effects of advanced phenology induced by warming on flower density and reproductive output, as well as the neutral effects on reproductive success and pollen limitation intensity of long surviving plants.