Malnoy M.,Research and Innovation Center |
Martens S.,Research and Innovation Center |
Norelli J.L.,Appalachian Fruit Research Station |
Barny M.-A.,French National Institute for Agricultural Research |
And 3 more authors.
Annual Review of Phytopathology | Year: 2012
The enterobacterial phytopathogen Erwinia amylovora causes fire blight, an invasive disease that threatens a wide range of commercial and ornamental Rosaceae host plants. The response elicited by E. amylovora in its host during disease development is similar to the hypersensitive reaction that typically leads to resistance in an incompatible host-pathogen interaction, yet no gene-for-gene resistance has been described for this host-pathogen system. Comparative genomic analysis has found an unprecedented degree of genetic uniformity among strains of E. amylovora, suggesting that the pathogen has undergone a recent genetic bottleneck. The genome of apple, an important host of E. amylovora, has been sequenced, creating new opportunities for the study of interactions between host and pathogen during fire blight development and for the identification of resistance genes. This review includes recent advances in the genomics of both host and pathogen. © 2012 by Annual Reviews. All rights reserved.
Brown M.W.,Appalachian Fruit Research Station |
Mathews C.R.,Shepherd University |
Krawczyk G.,Pennsylvania State University
Journal of Economic Entomology | Year: 2010
A common goal of conservation biological control is to enhance biodiversity and increase abundance and effectiveness of predators and parasitoids. Although many studies report an increase in abundance of natural enemies, it has been difficult to document increases in rates of biological control. To enhance parasitism of the tufted apple bud moth, Platynota idaeusalis (Walker) (Lepidoptera: Tortricidae), alternate food was provided by interplanting peaches bearing extrafloral nectaries into apple (Malus spp.) orchards. Laboratory studies showed that the presence of nectar increased longevity and parasitism rates by Goniozus floridanus (Bethylidae), the dominant parasitoid of tufted apple bud moth in West Virginia. In orchard studies, we found the total number of hymenopteran parasitoids was higher on peach (Prunus spp.) trees than on adjacent apple trees. Abundance of parasitic Hymenoptera also was significantly higher on the side of traps facing away from rather than toward peach trees, indicating attraction to peach trees. However, total parasitism rates of tufted apple bud moth were not affected by the presence of peach extrafloral nectar in any field studies. Insect injury to fruit at harvest showed that fruit from orchards with interplanted peach trees had less injury from San Jose scale, Quadraspidiotus perniciosus (Comstock) and stink bugs (Pentatomidae) than fruit from an apple monoculture. Although interplanting with peach trees did not produce the hypothesized result of increased biological control, the experiment did have beneficial results for pest management. These results demonstrate the importance of collecting data on variables beyond the targeted species when evaluating habitat manipulation experiments to fully assess the impact on the ecosystem. © 2010 Entomological Society of America.
Janisiewicz W.J.,Appalachian Fruit Research Station
Acta Horticulturae | Year: 2010
Biological control of postharvest decays (BCPD) has been used commercially on pome and citrus fruits since 1996 in the United States, and its use were later expanded to include cherries and seed potatoes. The spectrum of activity of these biocontrol products differs with respect to fruit type and maturity, stage of pathogen infection, and specific pathogen causing decay, and is not as broad as fungicides. Thus, commercial use of BCPD has been targeted for certain commodities and may even be limited to certain postharvest applications within a commodity. Unlike fungicides, currently registered biocontrol products are exempt from residue tolerance by the U.S. Environmental Protection Agency and can be used well into storage even to the point of packing fruit for shipment. Recent research has focused on improving biocontrol itself and/or combining BCPD with other alternative methods to synthetic fungicides. The efficacy of BCPD has been improved by developing antagonist mixtures, and manipulation of growth and formulations of antagonists. Manipulation of biocontrol mechanisms have not yet resulted in improved biocontrol. The potential of foreign antimicrobial genes introduced into antagonists is also being explored. Greater efficacy and broader spectrum of postharvest decay control on fruit was achieved by combining BCPD with heat treatment, GRAS substances, lytic enzymes, or the induction of resistance in fruit by physical or chemical means.
Interactions between extrafloral nectaries, ants (Hymenoptera: Formicidae), and other natural enemies affect biological control of grapholita molesta (Lepidoptera: Tortricidae) on peach (Rosales: Rosaceae)
Mathews C.R.,University of Maryland University College |
Mathews C.R.,Shepherd University |
Bottrell D.G.,University of Maryland University College |
Brown M.W.,Appalachian Fruit Research Station
Environmental Entomology | Year: 2011
Extrafloral nectaries (EFNs) are reported to benefit some plants when ants (Hymenoptera: Formicidae) use their secretions and fend off herbivores, but in some cases resulting competitive interactions may reduce biological control of specific herbivores. This research examined the interactions between ants and other natural enemies associated with the EFNs of peach [Prunus persica (L.) Batcsh] and the implications for biological control of a key pest, the oriental fruit moth [Grapholita molesta (Busck)]. Studies using sentinel G. molesta placed on peach trees ('â€̃Lovell'â€™ cultivar) with EFNs present and absent revealed that several natural enemy groups associated with the EFNs contribute to reductions in G. molesta eggs, larvae, and pupae in peach orchards. Ants on trees with EFNs antagonized the G. molesta egg parasitoid Trichogramma minutum (Riley), but the ants were crucial in reducing G. molesta in both the larval and pupal stages. Overall, individual trees with EFNs experienced higher ant and other (nonant) natural enemy densities and subsequent pest reductions, as compared with trees without EFNs. However, the implications of EFN-natural enemypest interactions to orchard-level biological control will likely depend on local G. molesta population dynamics. © 2011 Entomological Society of America.
Xia R.,Appalachian Fruit Research Station |
Xia R.,University of Delaware |
Ye S.,University of Maryland University College |
Liu Z.,Appalachian Fruit Research Station |
And 2 more authors.
Plant Physiology | Year: 2015
The wild strawberry (Fragaria vesca) has recently emerged as an excellent model for cultivated strawberry (Fragaria × ananassa) as well as other Rosaceae fruit crops due to its short seed-to-fruit cycle, diploidy, and sequenced genome. Deep sequencing and parallel analysis of RNA ends were used to identify F. vesca microRNAs (miRNAs) and their target genes, respectively. Thirtyeight novel and 31 known miRNAs were identified. Many known miRNAs targeted not only conserved mRNA targets but also developed new target genes in F. vesca. Significantly, two new clusters of miRNAs were found to collectively target 94 F-BOX (FBX) genes. One of the miRNAs in the new cluster is 22 nucleotides and triggers phased small interfering RNA production from six FBX genes, which amplifies the silencing to additional FBX genes. Comparative genomics revealed that the main novel miRNA cluster evolved from duplications of FBX genes. Finally, conserved trans-acting siRNA pathways were characterized and confirmed with distinct features. Our work identified novel miRNA-FBX networks in F. vesca and shed light on the evolution of miRNAs/phased small interfering RNA networks that regulate large gene families in higher plants. © 2015 American Society of Plant Biologists. All rights reserved.