Stephen L. Clement

Molecular Bases of Plant Resistance to Arthropods

Arthropod-resistant crops provide significant ecological and economic benefits to global agriculture. Incompatible interactions involving resistant plants and avirulent pest arthropods are mediated by constitutively produced and arthropod-induced plant proteins and defense allelochemicals synthesized by resistance gene products. Cloning and molecular mapping have identified the Mi-1.2 and Vat arthropod resistance genes as CC-NBS-LRR (coiled coil-nucleotide binding site-leucine rich repeat) subfamily NBS-LRR resistance proteins, as well as several resistance gene analogs. Genetic linkage mapping has identified more than 100 plant resistance gene loci and linked molecular markers used in cultivar development. Rice and sorghum arthropod-resistant cultivars and, to a lesser extent, raspberry and wheat cultivars are components of integrated pest management (IPM) programs in Asia, Australia, Europe, and North America. Nevertheless, arthropod resistance in most food and fiber crops has not been integrated due primarily to the application of synthetic insecticides. Plant and arthropod genomics provide many opportunities to more efficiently develop arthropod-resistant plants, but integration of resistant cultivars into IPM programs will succeed only through interdisciplinary collaboration.

Global plant genetic resources for insect-resistant crops

Foreword, Masa Iwanaga Cereal Crops Germplasm Evaluation and Utilization for Insect Resistance in Rice, Elvis A. Heinrichs and Sharron S. Quisenberry The Value of Conserved Wheat Germplasm Evaluated for Arthropod Resistance, C. Michael Smith, Sharron S. Quisenberry, and Francois du Toit Insect Resistance in Barley Germplasm, David R. Porter, Dolores W. Mornhinweg, and James A. Webster Genetic Diversity of Sorghum: A Source of Insect-Resistant Germplasm, George L. Teetes, Gary C. Peterson, Kanayo F. Nwanze, and Bonnie B. Pendleton Legume Crops Bean Germplasm Resources for Insect Resistance, Cesar Cardona and Julia Kornegay Assessment of Soybean Germplasm for Multiple Insect Resistance, David J. Boethel Germplasm Resources, Insect Resistance, and Grain Legume Improvement, Stephen L. Clement, Massimo Cristofaro, Susan E. Cowgill, and Susanne Weigand. Alfalfa Germplasm Resources and Insect Resistance, George R. Manglitz and Edgar L. Sorensen Vegetable Crops Vegetable Crops: Search for Arthropod Resistance in Genetic Resources, James D. Barbour Root and Tuber Crops Utilization of Sweetpotato Genetic Resources to Develop Insect Resistance, Wanda W. Collins , Edward E. Carey, Il-Gin Mok, Paul Thompson, and Zhang Da Peng The Potato: Genetic Resources and Insect Resistance, Kathy L. Flanders, Silvia Arnone, and Edward B. Radcliffe Basic Research and Biotechnology Plant Genetic Resources for the Study of Insect-Plant Interactions, Sanford D. Eigenbrode and Stephen L. Clement Biotechnological Applications of Plant Genes in the Production of Insect Resistant Crops, Angharad M.R. Gatehouse

Open-field Tests in Host-specificity Determination of Insects for Biological Control of Weeds

Open-field tests may be used for the host-specificity determination of insects used in the biological control of weeds. Such tests allow insects to exercise free choice of plants without constraints associated with the use of cages. Therefore, this testing method can generate host data on candidate biocontrol agents under more natural conditions than those obtained via cage tests. The literature contains 24 studies of open-field testing, involving 13 target weed species, more than 34 species of insects and one eriophyid mite. Field-test data were used to support the release of 20 of these candidate agents into new countries. Most field tests have been conducted in concert with laboratory host-specificity tests or in response to the results of laboratory tests. This review also provides information on experimental designs, locations, categories of test plants included and the constraints of open-field testing.

Isolation of resveratrol from Festuca versuta and evidence for the widespread occurrence of this stilbene in the poaceae

Abstract Resveratrol has been isolated from Festuca versuta seed and confirmed to be present in F. arundinacea (seed and forage), in several Lolium and Hordeum species, in Stipa robusta , and in Poa alsodes . Most of the plant materials examined were naturally infected with fungal endophytes of the genus Acremonium ; however, some endophyte-free samples from these same species also contained resveratrol, usually in reduced concentrations. These observations represent the first reports of the stilbene resveratrol in the Poaceae.

A PCR-Based Technique for Detection of Neotyphodium Endophytes in Diverse Accessions of Tall Fescue

A previously described polymerase chain reaction (PCR)-based method used for detection of Neotyphodium coenophialum in tall fescue detected Neotyphodium endophytes in some, but not all, infected plants from a geographically diverse sample. In the study reported here, a different set of primers, based on intervening sequences of the tubulin 2 gene, were prepared and used for PCR. PCR with these primers yielded the expected 444 base pair amplification product with DNA from 104 of the 106 infected accessions tested. In addition, one accession originally scored as endophyte-free on the basis of a tissue culture test was correctly rated as endophyte-infected using the PCR procedure. Results suggest that primers based on intervening sequences of the tubulin 2 gene can be used for PCR-based detection of Neotyphodium endophytes in tall fescue accessions of diverse origin.

Flies (Diptera: Muscidae: Calliphoridae) are efficient pollinators of Allium ampeloprasum L. (Alliaceae) in field cages.

Abstract In conjunction with efforts to identify efficient insect pollinators for seed multiplication of cross-pollinated plant species stored and maintained by USDA–ARS Western Regional Plant Introduction Station (WRPIS), experiments were conducted to assess and compare the efficiency of the house fly, Musca domestica L. (Diptera: Muscidae), and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae), and different densities of each fly species, to pollinate leek, Allium ampeloprasum L., plant inventory (PI) accessions in field cages for seed yield maximization and high germination. Cages with flowering plants were exposed to 0 flies or stocked with 100, 250, and 500 M. domestica or C. vicina pupae per week for 6 (2002) and 7 (2004) wk. Seed yield (weight per cage) increased linearly as fly densities (C. vicina or M. domestica) increased from 0 to 500 pupae per week, with 500 fly cages averaging 340.7 g (C. vicina) and 70.5 g (M. domestica) of seed in 2002 (PI 368343) and 615.3 g (PI 168977) and 357.5 g (PI 368343) in 2004 when only the C. vicina was used. For 0, 100, and 250 fly cages, seed yields averaged between 2.3 and 175.3 g in 2002 and 10.7 and 273.1 g in 2004. Mean 100-seed weights between treatments ranged narrowly between 0.4 and 0.5 g in 2002 and 0.3 and 0.4 g in 2004, and germination rates of seed lots from “fly cages” were mostly ≥80% in both years. The C. vicina is an efficient and cost-effective pollinator (

Detrimental and Neutral Effects of a Wild Grass-Fungal Endophyte Symbiotum on Insect Preference and Performance

388.97 for pupae and shipping, compared with

Cereal Aphid and Natural Enemy Populations in Cereal Production Systems in Eastern Washington

2,400 for honey bee, Apis mellifera L. [Hymenoptera: Apidae], nuclei) for caged leek accessions, with 250 and 500 C. vicina pupae per week required to produce sufficient seed (130 g) to fill an accession storage bag in the WRPIS gene bank.

Bee associates of flowering Astragalus and Onobrychis germplasm accessions in eastern Washington

Abstract Seed-borne Epichloë/Neotyphodium Glenn, Bacon, Hanlin (Ascomycota: Hypocreales: Clavicipitaceae) fungal endophytes in temperate grasses can provide protection against insect attack with the degree of host resistance related to the grass—endophyte symbiotum and the insect species involved in an interaction. Few experimental studies with wild grass—endophyte symbiota, compared to endophyte-infected agricultural grasses, have tested for anti-insect benefits, let alone for resistance against more than one insect species. This study quantified the preference and performance of the bird cherry oat-aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) and the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), two important pests of forage and cereal grasses, on Neotyphodium-infected (E+) and uninfected (E-) plants of the wild grass Alpine timothy, Phleum alpinum L. (Poales: Poaceae). The experiments tested for both constitutive and wound-induced resistance in E+ plants to characterize possible plasticity of defense responses by a wild E+ grass. The aphid, R. padi preferred E- over E+ test plants in choice experiments and E+ undamaged test plants constitutively expressed antibiosis resistance to this aphid by suppressing population growth. Prior damage of E+ test plants did not induce higher levels of resistance to R. padi. By contrast, the beetle, O. melanopus showed no preference for E+ or E- test plants and endophyte infection did not adversely affect the survival and development of larvae. These results extend the phenomenon of variable effects of E+ wild grasses on the preference and performance of phytophagous insects. The wild grass— Neotyphodium symbiotum in this study broadens the number of wild E+ grasses available for expanded explorations into the effects of endophyte metabolites on insect herbivory.

Non-target plant use by a weed biocontrol agent in Idaho: host expansion or opportunistic behavior?

Abstract A 5 yr study in the semiarid wheat production region of eastern Washington documented the relative densities of pest aphids and their natural enemies in cereal production systems using on-farm replicated plots. The systems were reduced-tillage soft white winter wheat (SWW) (Triticum aestivum L.)—summer fallow rotation; no-till soft white spring wheat (SWS)—chemical fallow rotation; continuous no-till hard red spring wheat (HRS); and no-till HRS—no-till spring barley (SB) (Hordeum vulgare L.) rotation. The English grain aphid, Sitobion avenae (F.), was the dominant species, followed in abundance by the Russian wheat aphid, Diuraphis noxia (Mordvilko). The bird cherry-oat aphid, Rhopalosiphum padi (L.), and rose grass aphid, Metopolophium dirhodum (Walter), were infrequently encountered. Overall, aphid densities were low, with aphids rare or absent in SWW and SB plots. The data revealed no clear and consistent effects of cereal production systems on aphid densities, but it did reveal, based on analysis of data from continuous HRS plots, high among-year variability in S. avenae and D. noxia densities. Only in 1996 and only in continuous HRS was it necessary to chemically control damaging populations of D. noxia. English grain aphid densities never approached threshold levels. S. avenae parasitism averaged >16% in some spring wheat systems in 1998 and 2000, while only two mummified D. noxia were observed. Coccinellid beetle counts in all plots totaled 143 in 1998 and 163 in 2000, with 90.2% and 94.5% in the genus Hippodamia, respectively. The ladybird beetle Coccinella septempunctata L. comprised 9.8% (1998) and 5.5% (2000) of the populations. The results suggest that damaging aphid populations are unlikely to develop in winter wheat, but populations in spring cereals warrant monitoring because they fluctuate from year-to-year and can be damaging.