绿菇[Russula virescens(Schaeff.)Fr.]对灰霉菌(Bortrytis cinerea)的拮抗作用研究

本文首次研究了绿菇[Russula virescens(Schaeff.)Fr.]对5种灰霉菌的拮抗作用。结果表明,绿菇对灰霉菌的拮抗作用主要表现为菌丝体重寄生和代谢产物生长抑制作用,对峙生长抑制率介于46.9%～52.3%,重寄生现象明显;PDB培养基培养绿菇获得的发酵液生长抑制作用最强,对辣椒灰霉菌生长抑制率最高,为61.59%;发酵液热稳定性良好;绿菇菌丝提取液对供试灰霉菌无生长抑制作用。

Antagonistic Effect of Russula virescens(Schaeff.) Fr.against Bortrytis cinerea

[Objective] The paper was to study the antagonistic effect of Russula virescens （Schaeff.） Ft. against Bortrytis cinerea. [Method] Using the confrontation culture method, the antagonistic effect of mycelium, fermentation broth and mycelial extract of R. virescens against B. cinerea was studied. [Result] The antagonistic ef- fect of R. vivesscens against B. cinerea was mainly manifested as hyperparasitism of mycelium and inhibition effect of metabolites. The inhibition rate of confrontation growth was between 46.9% and 52.3%, and hyperparasitism phenomenon was obvi- ous. The fermentation broth of R. virescens cultured by PDB medium had the strongest growth inhibition effect, and the growth inhibition rate against B. cinerea was the highest of 61.59%. The thermal stability of fermentation broth was good, the mycelial extract of R. virescens had no inhibition effect against the growth of B. cinerea. [Conclusion] The study provided theoretical basis for subsequent differentiation and drug sensitivity of B. cinerea.

野生绿菇(Russula virescens)的生态学特性调查研究

实地调查结果表明:野生绿菇每年6￣9月份大量出菇,其间林间土壤温度为19￣24.5℃,含水量为54%￣68.5%,近地空气温度为20.5￣25.5℃,相对湿度61.5%￣94.5%。绿菇在8￣40年生的马尾松林中都可大量出菇并正常地生长发育,林分结构通常以马尾松为主,郁闭度50%￣80%,下层灌木为稀疏壳斗科植物,草本层为稀疏茅草或蕨类。土壤腐殖质及落叶层的厚度对子实体的发生影响不明显,但土壤pH值一般要求在4.5￣6.4之间。综合分析认为温度、湿度、光照、土壤pH是影响绿菇子实体生长的4大关键因素。其它生境因子,如坡向,坡度,坡位等是通过影响这些关键因素而间接地影响绿菇子实体的分布及生长发育。

Genome analysis of Heliothis virescens ascovirus 3h isolated from China

No ascovirus isolated from China has been sequenced so far. Therefore, in this study, we aimed to sequence the genome of Heliothis virescens ascovirus 3h （HvAV-3h） using the 454 pyrosequencing technology. The genome was found to be 190,519-bp long with a G＋C content of 45.5%. We also found that it encodes 185 hypothetical open reading frames （ORFs） along with at least 50 amino acids, including 181 ORFs found in other ascoviruses and 4 unique ORFs. Gene-parity plots and phylogenetic analysis revealed a close relationship between HvAV-3h and three other HvAV-3a strains and a distant relationship with Spodoptera frugiperda ascovirus la （SfAV-la）, Trichoplusia ni ascovirus 6a （TnAV-6a）, and Diadromus pulchellus ascovirus 4a （DpAV-4a）. Among the 185 potential genes encoded by the genome, 44 core genes were found in all the sequenced ascoviruses. In addition, 25 genes were found to be conserved in all ascoviruses except DpAV-4a. In the HvAV-3h genome, 24 baculovirus repeat ORFs （bros） were present, and the typical homologous repeat regions （hrs） were absent. This study supplies information important for understanding the conservation and functions of ascovirus genes as well as the variety of ascoviral genomes.

In Vitro Infectious Risk Assessment of Heliothis virescens ascovirus 3j(HvAV-3j) toward Non-target Vertebrate Cells

As specific pathogens of noctuid pests,including Spodoptera exigua,S.litura,Helicoverpa armigera,and Mythimna separata,ascoviruses are suitable for the development of bioinsecticides.In this study,the infectivity of Heliothis virescens ascovirus 3j(HvAV-3j)on insect and mammalian cells was evaluated.HvAV-3j infection induced drastic morphological changes in Sf9,HzAMl,SeFB,and HaFB cells,including swelling and detachmen Notably,the latter phenomena did not occur in HvAV-3j-inoculated mammalian cells(HEK293,7402,HePG2,PK15,ST,and TM3).MTT assays indicated that HvAV-3j inhibited the growth of host insect cells from the 6th hpi,but no effects were detected in the HvAV-3j-inoculated mammalian cells.Furthermore,viral DNA replication,gene transcription,and protein expression were investigated,and the results consistently suggested that HvAV-3j viruses were not able to replicate their genomic DNA,transcribe,or express their proteins in the non-target vertebrate cells.The HvAV-3j genes were only transcribed and expressed in the four insect cell lines.These results indicated that HvAV-3j was infectious to cells derived from S.frugiperda,S.exigua,H.armigera,and H.zea but not to cells derived from human,pig,and mouse,suggesting that ascoviruses are safe to nontarget vertebrate cells.

3H-31, A Non-structural Protein of Heliothis virescens ascovirus 3h,Inhibits the Host Larval Cathepsin and Chitinase Activities

3h-31 of Heliothis virescens ascovirus 3h(Hv AV-3h)is a highly conserved gene of ascoviruses.As an early gene of Hv AV-3h,3h-31 codes for a non-structural protein(3H-31)of Hv AV-3h.In the study,3h-31 was initially transcribed and expressed at 3 h post-infection(hpi)in the infected Spodoptera exigua fat body cells(Se FB).3h-31 was further inserted into the bacmid of Autographa californica nucleopolyhedrovirus(Ac MNPV)to generate an infectious baculovirus(Ac MNPV-31).In vivo experiments showed that budded virus production and viral DNA replication decreased with the expression of 3H-31,and lucent tubular structures were found around the virogenic stroma in the Ac MNPV-31-infected Se FB cells.In vivo,both LD50and LD90values of Ac MNPV-31 were significantly higher than those of the wild-type Ac MNPV(Ac MNPV-wt)in third instar S.exigua larvae.An interesting finding was that the liquefaction of the larvae killed by the infection of Ac MNPV-31 was delayed.Chitinase and cathepsin activities of Ac MNPV-31-infected larvae were significantly lower than those of Ac MNPV-wt-infected larvae.The possible regulatory function of the chitinase and cathepsin for 3H-31 was further confirmed by RNAi,which showed that larval cathepsin activity was significantly upregulated,but chitinase activity was not significantly changed due to the RNAi of 3h-31.Based on the obtained results,we assumed that the function of 3H-31 was associated with the inhibition of host larval chitinase and cathepsin activities,so as to restrain the hosts in their larval stages.

Melanization induced by Heliothis virescens ascovirus 3h promotes viral replication

Melanization is an important innate immune defense mechanism of insects,which can kill invading pathogens.Most pathogens,for their survival and reproduction,inhibit the melanization of the host.Interestingly,our results suggested that after infection with Heliothis virescens ascovirus 3h(HvAV-3h),the speed of melanization in infected Spodoptera exigiia larval hemolymph was accelerated and that the phenoloxidase(PO)activity of hemolymph in larvae infected with HvAV-3h increased significantly(1.20-fold at 96 hpi,1.52-fold at 120 hpi,1.23-fold at 144 hpi,1.12-fold at 168 hpi).The transcription level of the gene encoding S.exigua prophenoloxidase-1(SePPO-1 gene)was upregulated dramatically in the fat body during the middle stage of infection.In addition,when melanization was inhibited or promoted,the replication of HvAV-3h was inhibited or promoted,respectively.In conclusion,infection with HvAV-3h can markedly induce melanization in the middle stage of infection,and melanization is helpful for HvAV-3h viral replication.

HT-SuperSAGE of the gut tissue of a Vip3Aa-resistant Heliothis virescens (Lepidoptera: Noctuidae) strain provides insights into the basis of resistance

Multitoxin Bt-crops expressing insecticidal toxins with different modes of action, for example, Cry and Vip, are expected to improve resistance management in target pests. While Cry1A resistance has been relatively well characterized in some insect species, this is not the case for Vip3A, for which no mechanism of resistance has yet been identified. Here we applied HT-SuperSAGE to analyze the transcriptome of the gut tissue of tobacco budworm Heliothis virescens (F.) laboratory-selected for Vip3Aa resistance. From a total of 1 324 252 sequence reads, 5 895 126-bp tags were obtained representing 17 751 nonsingleton unique transcripts (UniTags) from genetically similar Vip3Aa-resistant (Vip- Sel) and susceptible control (Vip-Unsel) strains. Differential expression was significant (≥2.5 fold or ≤0.4;P < 0.05) for 1989 sequences (11.2% of total UniTags), where 420 represented overexpressed (OE) and 1569 underexpressed (UE) genes in Vip-Sel. BLASTN searches mapped 419 UniTags to H. virescens sequence contigs, of which, 416 (106 OE and 310 UE) were unambiguously annotated to proteins in NCBI nonredundant protein databases. Gene Ontology distributed 345 of annotated UniTags in 14 functional categories with metabolism (including serine-type hydrolases) and translation/ribosome biogenesis being the most prevalent. A UniTag homologous to a particular member of the REsponse to PAThogen (REPAT) family was found among most overexpressed, while UniTags related to the putative Vip3Aa-binding ribosomal protein S2 (RpS2) were underexpressed. qRT-PCR of a subset of UniTags validated the HT-SuperSAGE data. This study is the first providing lepidopteran gut transcriptome associated with Vip3Aa resistance and a foundation for future attempts to elucidate the resistance mechanism.

An insert in the Hpy region of hscp in Hefiothis virescens （Lepidoptera： Noctuidae） reveals a possible CORE-SINE of insects

A new putative transposon was identified in the tobacco budworm, Helio- this virescens. This transposon was characterized as a full length CORE-SINE （65 bp of ＂CORE＂ core specific nucleotide short interspersed elements） that resembled sequences from three other lepidopterans and humans. In particular, the A-box and B-box regions of this sequence most closely conformed to the signature of CORE-SINEs from widely divergent species. This CORE-SINE was present as a polymorphism in a hypervariable region of the gene hscp, which is the target of pyrethroid insecticides and other xenobiotics in the nerve axon. We described this new putative transposon as Noct-1 due to its presence in a noctuid moth. This is the first description of a full-length CORE-SINE with the A-box, B-box, target site duplication, and candidate core domain from an insect.

Green Rice Leafhopper Resistance Gene Transferring Through Backcrossing and CAPS Marker Assisted Selection

Grh2, a green rice leafhopper resistant gene from an indica cultivar DV85, was located on chromosome 11, and two RFLP markers C189 and G1465 were found to be linked to this gene. In order to transfer Grh2 into Taichung65, a japonica cultivar with elite characters, backcross method with Taichung65 as the recurrent parent was used and the two RFLP markers were converted into CAPS markers for marker assisted selection (MAS). In the BC6F3 population, both phenotypic evaluation and MAS were conducted to screen the resistant plants with Taichung65 background. The linkage distance between CAPS markers and Grh2 was calculated and the efficiency of MAS was analyzed.

青头菌研究进展

对青头菌形态特征、营养成分、生物活性物质及人工培养等研究进展进行总结,为其进一步开发应用研究提供一定的理论依据。

A Chromosome-level Reference Genome of African Oil Palm Provides Insights into Its Divergence and Stress Adaptation

The palm family(Arecaceae),consisting of2600 species,is the third most economically important family of plants.The African oil palm(Elaeis guineensis)is one of the most important palms.However,the genome sequences of palms that are currently available are still limited and fragmented.Here,we report a high-quality chromosome-level reference genome of an oil palm,Dura,assembled by integrating long reads with150 genome coverage.The assembled genome was 1.7 Gb in size,covering 94.5%of the estimated genome,of which 91.6%was assigned into 16 pseudochromosomes and 73.7%was repetitive sequences.Relying on the conserved synteny with oil palm,the existing draft genome sequences of both date palm and coconut were further assembled into chromosomal level.Transposon burst,particularly long terminal repeat retrotransposons,following the last whole-genome duplication,likely explains the genome size variation across palms.Sequence analysis of the VIRESCENS gene in palms suggests that DNA variations in this gene are related to fruit colors.Recent duplications of highly tandemly repeated pathogenesis-related proteins from the same tandem arrays play an important role in defense responses to Ganoderma.Whole-genome resequencing of both ancestral African and introduced oil palms in Southeast Asia reveals that genes under putative selection are notably associated with stress responses,suggesting adaptation to stresses in the new habitat.The genomic resources and insights gained in this study could be exploited for accelerating genetic improvement and understanding the evolution of palms.

Novel strategies for the biocontrol of noctuid pests(Lepidoptera)based on improving ascovirus infectivity using Bacillus thuringiensis

ldentifying novel biocontrol agents and developing new strategies are urgent goals in insect pest biocontrol.Ascoviruses are potential competent insect viruses that may be developed into bioinsecticides,but this aim is impeded by their poor oral infectivity.To improve the per os infectivity of ascovirus,Bacillus thuringiensis kurstaki(Btk)was employed as a helper to damage the midgut of lepidopteran larvae(Helicoverpa armigera,Mythimna separata,Spodoptera frugiperda,and S.litura)in formulations with Heliothis virescens ascovirus isolates(HvAV-3h and HvAV-3j).Btk and ascovirus mixtures(Btk/HvAV-3h and B1k/HvAV-3j)were fed to insect larvae(3rd instar).With the exception of S.frugiperda larvae,which exhibited low mortality after ingesting Btk,the larvae of the other tested species showed three types of response to feeding on the formulas:type I,the tested larvae(H.armigera)were killed by Btk infection so quickly that insufficient time and resources remained for ascoviral invasion;type II,both Btk and the ascovirus were depleted by their competition,such that neither was successfully released or colonized the tissue;type II,Btk was eliminated by the ascovirus,and the ascovirus achieved systemic infection in the tested larvae.The feeding of Btk/ascovirus formulas led to a great reduction in larval diet consumption and resulted in a significant decrease in the emergence rate of H.armigera,M.separata,and S.litura larvae,which suggested that the formulas exerted marked oral control effects on both the contemporary individuals and the next generation of these tested pest species.

The role of herbivore- and plant-related experiences in intraspecific host preference of a relatively specialized parasitoid

Parasitoids use odor cues from infested plants and herbivore hosts to locate their hosts. Specialist parasitoids of generalist herbivores are predicted to rely more on herbivorederived cues than plant-derived cues. Microplitis croceipes (Cresson)(Hymenoptera: Braconidae) is a relatively specialized larval endoparasitoid of Heliothis virescens (F.)(Lepidoptera: Noctuidae), which is a generalist herbivore on several crops including cotton and soybean. Using M. croceipes/H. virescens as a model system, we tested the following predictions about specialist parasitoids of generalist herbivores:(i) naive parasitoids will show innate responses to herbivore-emitted kairomones, regardless of host plant identity and (ii) herbivore-related experience will have a greater influence on intraspecific oviposition preference than plant-related experience. Inexperienced (naive) female M. croceipes did not discriminate between cotton-fed and soybean-fed H. virescens in oviposition choice tests, supporting our first prediction. Oviposition experience alone with either host group influenced subsequent oviposition preference while experience with infested plants alone did not elicit preference in M. croceipes, supporting our second prediction. Furthermore, associative learning of oviposition with host-damaged plants facilitated host location. I terestingly, naive parasitoids attacked more soybeathan cotton-fed host larvae in two-choice tests when a background of host-infested cotton odor was supplied, and vice versa. This suggests that plant volatiles may have created an olfactory contrast effect. We discussed ecological significance of the results and concluded that both plant- and herbivore-related experiences play important role in parasitoid host foraging.