Cellulase in Anoplophora glabripennis adults emerging from different host tree species

In order to investigate different kinds of cellulase in insect pests, we selected male and female adults of Anoplophora glabripennis （Motschulsky） emerging from four different host species （Populus alba var. pyramidalis, P. nigra var. thevestina （Dode） Bean., P. simonii × P. pyramidliscr cv. Opera 8277 Hsu. and Salix matsudana f. lobato-glandulosa） as our research material. The enzyme activitives of three kinds of cellulase in the intestines of the adult insects were measured. The Cx-cellulase isozymes were detected with a CMC-incorporated polyacrylamide gel. The results show that： there are no statistically significant differences between the enzyme activities of males and females emerging from the different host species. The order of magnitude in activity is： Cx-cellulase 〉 β-glycosidase 〉 C1-cellulase. When the adults emerge from the same host species, there are no statistically significant differences between male and female enzyme activities of β-glycosidase and C1-cellulase, but the enzyme activity of Cx-cellulase of males is clearly higher than that of females. The patterns and migration of Cx-cellulase isozymes of males and females emerging from differ-ent hosts trees are clearly not different, and neither are they different when emerging from the same hosts.

Cellulase in Anoplophora glabripennis adults fed on original host tree species and non-original host trees

Cellulase activities of Anoplophora glabripennis （Motsch.） adults from two host plants （Populus simonii x p pyramidliscr cv. Opera Hsu. and Salix matsudana Koidz） fed on three different host tree species （Acer negundo Linn., S. matsudana Koidz and P simonii x P pyramidliscr cv. Opera Hsu.） were investigated. Enzyme activities of endoglucanase and β-glucosidase in the intestines of the insects were measured. The results show that there are no statistically significant differences in the enzyme activities of endoglucanase between male and female insects from the two host plants fed on three host trees, neither inβ-glucosidase. No statistically significant differences in the enzyme activities of endoglucanase and β-glucosidase were found between males and females from the two plants fed on three host tree species, except that the endoglucanase activity in males from the opera poplar fed on Hankow willow is lower than that fed on ash-leaf maple and opera poplar.

Primary Host Tree Species of the Gypsy Moth Lymantria dispar （Lepidoptera： Lymantriidae）in Hyrcanian Forests

Invasions by exotic insects and diseases are one of the most important threats to the stability and productivity of forest ecosystems around the world. Lymantria dispar （Lepidoptera： Lymantriidae） in Iran was observed for the first time in 1937 by Jalal Afshar in oak forests of the Guilan state region. Since its introduction, gypsy moth has spread to the northern, western and south-western regions of Iran. The largest outbreaks of gypsy moth occurred in the Talesh Oak forests of the Hyrcanian zone in 1975. The gypsy moth is a highly polyphagous folivore species that feeds on over 300 species of woody plants. Among its most preferred hosts are oaks and aspens. Some trees are resistant to the gypsy moth including honey locust, black locust, silver maple, green ash, dogwood, sycamore, horse chestnut, firs, and tulip trees. Defoliation during severe outbreaks alters the appearance of forest habitats and leads to tree mortality and changes in stand composition. This study was conducted during 2008 and 2009 in an effort to determine the primary host tree species that the gypsy moth infests in the Hyrcanian forests of lran. For that purpose all egg masses in the area were counted and conclusively significant differences in defoliation levels among tree species were found. The primary host tree species of gypsy moth in Iran was Persian ironweed, Parrotia persica.

Analysis of the Abnormal Segregation of Pathogenicity in Magnaporthe grisea by Using a Genetic Cross of Oryza and Eleusine Isolates

A genetic cross between Oryza isolate Y93-164a-1 and Eleusine isolate SA98-4 was established, and the pathogenicity of 151 F1 progeny isolates was investigated on both host plants rice and finger millet. Results showed that the segregation of pathogenicity in this genetic cross was abnormal, i.e., most of the progeny isolates were nonpathogenic on both host plants. However, no abnormal segregation was observed when middle repetitive sequence MGR586 and 31 single-copy RFLP markers from all of the chromosomes were genetically analyzed. At the same time, comparison of the chromosomal organization among two pairs of parental isolates did not find any genomic abnormity. These results suggested that the ＂abnormal＂ inheritance of pathogenicity in this cross was most likely due to the reassortment of numerous host species specificity genes but not the biased segregation of the host species specificity genes. The host species specificities in M. grisea were likely to be multigenically controlled, at least in the genetic cross involving rice pathogen and the grasses pathogen other than rice.

Rhizosphere fungal community assembly varied across functional guilds in a temperate forest

Background Rhizosphere fungi play an important role in plant community dynamics and biogeochemical cycling.While the drivers of fungal community assembly have been studied in varied ecosystems,it is still unclear how these processes function for rhizosphere soil fungi in temperate forests.Furthermore,it is unknown whether the relative contributions of important determinants remain consistent or vary across fungal ecological guilds.This study used high-throughput next-generation sequencing to characterize the fungal communities of 247 rhizosphere soil samples from 19 tree species in a temperate forest within Northeast China.We aimed to investigate how three important determinants in temperate forests(host tree species,neighbouring plant communities,and edaphic properties)influence the community assembly of fungal functional guilds in the rhizosphere soil of trees.Results We found that host tree species contributed more to plant pathogens’community composition than ectomycorrhizal fungi,and plant pathogens consistently showed higher host specialization than ectomycorrhizal fungi.Saprotrophs also showed high host specialization,which was mediated by the tree species’effect on rhizosphere soil pH.Although neighboring plant communities contributed remarkably to richness of all fungal guilds,this effect on fungal composition varied across functional guilds,with stronger effect for biotrophic guilds(plant pathogens and ectomycorrhizal fungi)than for non-biotrophic guild(saprotrophs).Neighboring plant communities shaped the ectomycorrhizal community composition strongly in all samples regardless of host trees’mycorrhizal type,whereas edaphic properties were the most important drivers for this guild in samples from only ectomycorrhizal-associated trees.Edaphic properties played an important role in shaping ectomycorrhizal and saprotrophic fungal compositions,indicating the importance of edaphic properties on the fungal functional guilds associated with the absorption and decomposition of nutrients.Conclusions These results demonstrated that rhizosphere soil fungal community assembly determinants varied across fungal guilds,reflecting their different ecological functions in temperate forest ecosystems.