Studies on the interspecies competition between the azuki bean weevil and the southern cowpea weevil IV. Competition between strains

This study analyzes results of interspecies competition between the azuki bean weevil, Callosobruchus chinensis and the southern cowpea weevil, C. maculatus using the four geographical strains of each species.

1. Fifteen combinations of one strain from each species were set up to compete. The strains of C. chinensis, rather than of C. maculatus, characteristically determine the eventual outcomes of competition. Some strains of C. chinensis (jC and kC) invariably won every encounter with C. maculatus. Another strain (nC) always lost its encounters, while one other strain (iC) won some encounters (:cQ and :cQ) and lost others (:tQ and :bQ). For any combination the competition results were deterministic and no reversal in outcome was observed among the replicates.
2. The weakness of strain nC in competition is explained by its characteristics in single species populations, different greatly from other strains of C. chinensis, although it had the similar primary (individual) characteristics as other strains of C. chinensis. Strain iC had the shortest adult longevity in the four strains of C. chinensis although it behaved similar to strain jC at the single species population level. Especially under the food supply schedule of the present experiment the shortness of adult longevity might be the important factor determining the outcome.
3. The relationship of the eight strains based on the individual and single species population characteristics, and that based on the competition results were very similar. Even when the competition results could not be explained by any one or two of these characteristics alone, the outcome would be largely decided by the overall biotic profile made by several characteristics.

     

影响菜豆普通花叶病毒种子传毒的因素

研究了影响菜豆普通花叶病毒(BCMV)种子传毒的一些因素,不同品种,不同感染时期种子的传毒率有显著差异,苗期感病的植株,不同荚位的种子传毒率是:下部>中部>上部,花期感病者则是:中部>上部>下部,感病植株的斑驳荚种子传毒率,依品种的不同,比无斑驳荚者高3.2～9.3倍。     

Effects of anti-microtubule drugs onin vitro polymerization of tubulin from mung bean

Effects of anti-microbule drugs on tubulin polymerizationin vitro were investigated using purified mung bean (Vigna radiata) tubuli. Colchicine induced the formation of macrotubules at the relatively low concentration of 10 μM. and the appearance of corkscrew-like filaments from the ends of the macrotubules at concentrations of more than 100 μM. Vinblastine substantially inhibited polymerization at 1 μM and caused the formation of paracrystals at concentrations greater than 10 μM. Oryzalin inhibited polymerization at 1 μM partially and at 10 μM completely. Paracrystal formation was also induced by cremart at 10 μM, but these paracrystals appeared to be more rigid than those induced by vinblastine. Amiprophos methyl (APM), with a chemical configuration similar to cremart, substantially inhibited polymerization at 1 μM, but the formation of paracrystals was weak. Griseofulvin at 10 μMalso inhibited the polymerization of tubulin while at higher concentrations aggregates of helices were formed. Inhibition of polymerization by phenylcarbamate herbicides was more effective than that caused by benzimidazoylcarbamate fungicides. The effects of drugs onin vitro preformed (MTs) were also investigated. Colchicine and vinblastine showed identical effects to those on the polymerization process. Griseofulvin, cremart and APM induced only macrotubule formation while the other drugs tested had no major effects     

Isolation and characterization of a novel mung bean protease inhibitor with antipathogenic and anti-proliferative activities

A novel protease inhibitor, designated mungoin, with both antifungal and antibacterial activities, and exhibiting a molecular mass of 10 kDa in SDS-polyacrylamide gel electrophoresis, was isolated from mung bean (Phaseolus mungo) seeds. The isolation procedure involved a combination of extraction, ammonium sulfate precipitation, ion exchange chromatography on CM-Sephadex, and high-performance liquid chromatography (HPLC) on SP-Toyopearl. Its isoelectric point was estimated to be 9.8 by isoelectric focusing. Its N-terminal amino acid sequence was determined to be EMPGKPACLDTDDFCYKP, demonstrating some resemblance to the C-terminal sequences of other protease inhibitors and inhibitor precursors from leguminous plants. It exerted a potent inhibitory action toward a variety of fungal species including Physalospora piricola, Mycosphaerella arachidicola, Botrytis cinerea, Pythium aphanidermatum, Sclerotium rolfsii and Fusarium oxysporum, as well as an antibacterial action against Staphylococcus aureus. In addition, this novel plant protease inhibitor displayed anti-proliferative activity toward tumor cells.     

Metabolic Conversion of Castasterone and Brassinolide into Their Glucosides in Higher Plants

Castasterone (CS) and brassinolide (BL) were administered to mung bean (Vigna radiata) explants, Arabidopsis thaliana seedlings, and cultured Catharanthus roseus cells, and the glucosylated metabolites were analyzed using LC/MS/MS. In mung bean and C. roseus, CS-2-O-glucoside (CS-2G), -3-O-glucoside (CS-3G), -22-O-glucoside (CS-22G), and -23-O-glucoside (CS-23G) were identified as metabolites of CS, whereas BL-2G, BL-3G, and BL-23G were identified as metabolites of BL. In A. thaliana, CS and BL were converted into their respective 2-O- and 23-O-glucosides. Of the metabolites identified with BL and CS administration, BL-23G was the predominant metabolite in mung bean and A. thaliana, whereas the 3-O-glucoside of BL was abundant in C. roseus. This is the first report of the metabolic conversion of CS into CS-2G, CS-3G, CS-22G, and CS-23G, and of BL into BL-2G and BL-3G. Our results indicate that the glucosylation profiles of BL and CS vary with plant species, and that the glucosylation of CS is rather limited quantitatively, compared with that of BL.     

Combination of the antifeedant bean flour and the predator Cheyletus malaccensis suppresses storage mites under laboratory conditions

Stored product mites are pests of serious economic and medical importance. Recently, it has been shown that the biological control of these pests based on the use of natural compounds and predators had a high potential for success. In this study, we investigated the suppression of three pest mites by combination of the predator Cheyletus malaccensis Oudemans, 1913 and bean flour (Phaseolus vulgaris), which is an antifeedant. Wheat grain (100 g) was contaminated with 100 individuals (Acarus siro (Linnaeus, 1758), Aleuroglyphus ovatus (Troupeau, 1878) or Tyrophagus putrescentiae (Schrank, 1781)). We added bean flour in concentrations of 0, 1, 5 and 10 g kg⁻¹ (wt/wt) and/or the predator with initial predator/prey ratios 0, 1/50, 1/25 and 1/10. The experiment was carried out under abiotic conditions that are optimal for pest development. After 21 days, pest and predators numbers were recorded. Application of flour significantly reduced populations of A. siro, slightly reduced populations of T. putrescentiae, the efficiency increased with increasing concentration. A. ovatus was not affect by bean flour. Populations of all mite species were successfully reduced by the sole addition of C. malaccensis, with a higher efficiency at higher Cheyletus ratios. The additive effect of the predator and flour was mainly apparent in the reduction of T. putrescientae. The population of C. malaccensis was not affected by the presence of bean flour. It is therefore recommended to use bean flour for the reduction of A. siro, a combination of bean flour and Cheyletus for the reduction of T. putrescientae, and only Cheyletus for the reduction of A. ovatus. Handling Editor: Arne Janssen.     

Control of the bean rust fungus <Emphasis Type="Italic">Uromyces appendiculatus</Emphasis> by means of <Emphasis Type="Italic">Trichoderma harzianum</Emphasis>: leaf disc assays on the antibiotic effect of spore suspensions and culture filtrates

Several species of the fungal genus Trichoderma act as antagonists of other fungi. A number of strains from the Trichoderma species T. harzianum Rifai are used as biological control agents for the control of soilborne as well as foliar plant pathogens. Six T. harzianum strains, five of them isolated from commercial preparations, were evaluated for their capability to control the bean rust fungus Uromyces appendiculatus (Pers. ex Pers.) Unger. Different kinds of leaf disc assays were performed with conidial spore suspensions and sterile culture filtrates of the T. harzianum strains. Great differences were observed concerning the efficacy of the Trichoderma strains to reduce the number of the uredial pustules developing after rust inoculation which followed the application of the particular Trichoderma strains. Efficacy values ranged from 1 to over 50%. Increasing spore or culture filtrate concentrations of the two most effective isolates T12 and T_U led to decreases in the number of developing uredial pustules. Culture filtrate applications had a protective but no curative effect. T12 spore suspensions maintained their disease reducing activity even when autoclaved. This and some other evidence for an antibiotic interaction between T. harzianum and U. appendiculatus are discussed. Handling Editor: Reijo Karjalainen.     

High level protein expression in plants through the use of a novel autonomously replicating geminivirus shuttle vector

We constructed a novel autonomously replicating gene expression shuttle vector, with the aim of developing a system for transiently expressing proteins at levels useful for commercial production of vaccines and other proteins in plants. The vector, pRIC, is based on the mild strain of the geminivirus Bean yellow dwarf virus (BeYDV-m) and is replicationally released into plant cells from a recombinant Agrobacterium tumefaciens Ti plasmid. pRIC differs from most other geminivirus-based vectors in that the BeYDV replication-associated elements were included in cis rather than from a co-transfected plasmid, while the BeYDV capsid protein (CP) and movement protein (MP) genes were replaced by an antigen encoding transgene expression cassette derived from the non-replicating A. tumefaciens vector, pTRAc. We tested vector efficacy in Nicotiana benthamiana by comparing transient cytoplasmic expression between pRIC and pTRAc constructs encoding either enhanced green fluorescent protein (EGFP) or the subunit vaccine antigens, human papillomavirus subtype 16 (HPV-16) major CP L1 and human immunodeficiency virus subtype C p24 antigen. The pRIC constructs were amplified in planta by up to two orders of magnitude by replication, while 50% more HPV-16 L1 and three- to seven-fold more EGFP and HIV-1 p24 were expressed from pRIC than from pTRAc. Vector replication was shown to be correlated with increased protein expression. We anticipate that this new high-yielding plant expression vector will contribute towards the development of a viable plant production platform for vaccine candidates and other pharmaceuticals.     

Costs of mating and egg production in female Callosobruchus chinensis

Costs of reproduction include the costs of mating and egg production. Specific techniques such as irradiation or genetic mutation have been used to divide the expense into costs of mating and egg production in previous studies. We tried to divide the costs in the adzuki bean beetle, Callosobruchus chinensis (Coleoptera: Bruchidae), which needs some kinds of bean as an oviposition substrate. Mated females that were not allowed to lay eggs had a shorter life span than virgin females, but they had a longer life span than mated females that were allowed to lay eggs. The results showed two independent significant costs, mating and egg production, on the life span in C. chinensis. Costs of mating, however, include the costs of sexual harassment by males and copulation itself, and we need further studies to divide the costs. The present method for dividing the cost of reproduction into costs of mating and egg production can be applied to a broad taxonomic range of insect species, and thus it will be a useful model system for inter-specific comparisons of costs of mating and egg production.     

Heterogeneous inbred populations are useful as sources of near-isogenic lines for RAPD marker localization

The development and use of RAPD markers for applications in crop improvement has recently generated considerable interest within the plant breeding community. One potential application of RAPDs is their use for tagging simply-inherited (monogenic) pest-resistance genes and enabling more efficient identification and selection of genotypes carrying specific combinations of resistance genes. In this report, we propose and describe the use of heterogeneous inbred populations as sources of near-isogenic lines (NILs) for targeting RAPD markers linked to major pest resistance genes. The development of these NILs for RAPD marker analyses involved a sequence of line and mass selection during successive generations of inbreeding. DNA bulks derived from the NILs were used to identify a RAPD marker (designated OK14₆₂₀, generated by 5-CCCGCTACAC-3 decamer) that was tightly linked (2.23±1.33 centiMorgans) to an important rust [Uromyces appendiculatus (Pers.) Unger var. appendiculatus] resistance gene (Ur-3) in common bean (Phaseolus vulgaris L.). The efficiency of this approach was demonstrated by a low rate of false-positives identified, the tightness of the linkage identified, and the ability to detect polymorphism between genomic regions that are representative of the same gene pool of common bean. This method of deriving NILs should find application by researchers interested in utilizing marker-assisted selection for one or more major pest resistance genes. The identification of OK14₆₂₀ should help to facilitate continued use of the Ur-3 resistance source and will now enable marker-assisted pyramiding of three different bean rust resistance sources (two previously tagged) to provide effective and stable resistance to this important pathogen.Research supported in part by the grant DAN 1310-G-SS-6008-00 from the USAID Bean/Cowpea Collaborative Research Support Program, the Michigan Agricultural Experiment Station, and the USDA-ARS. Mention of a trademark or a proprietary product does not constitute a guarantee or warranty of the product by the USDA and does not imply its approval to the exclusion of other products that may also be suitable