Thus, green peach aphids must have broadly effective mechanisms to avoid or inactivate plant toxins and other defenses.Īnalysis of salivary proteins, which are injected into the plant phloem when aphids are feeding, has demonstrated that some act as effectors that suppress plant defenses, whereas others are recognized by plants as signals to initiate defense responses. As broad generalist herbivores, green peach aphids are exposed to a wide variety of toxic metabolites in the plants from which they are feeding. The green peach aphid ( Myzus persicae) feeds readily on hundreds of plant species, including the genetic model plants Arabidopsis thaliana (Arabidopsis) and Nicotiana benthamiana (an Australian tobacco species). By reducing aphid gene expression in a targeted manner, it is possible to study the function of specific genes in plant-aphid interactions.Ī fourth-instar green peach aphid ( Myzus persicae) on an Arabidopsis leaf To investigate the insect side of the interaction, Sugarcane mosaic virus, which infects maize and is transmitted by aphids, has been engineered for virus-induced silencing of aphid transcription. Specific genes that mediate aphid resistance have been identified by quantitative trait locus (QTL) mapping of aphid progeny production on different maize inbred lines. Cultivated maize varieties show wide variation in their resistance to aphid feeding. A current research focus is the regulation of other maize defenses by benzoxazinoids and their breakdown products.Īmong insects that feed on maize, Rhopalosiphum maidis (corn leaf aphids) have been a longer-term research interest in the lab. Research in the Jander lab has included the discovery of previously unknown genes involved in maize benzoxazinoid biosynthesis, isolation of mutations that affect defense-induced benzoxazinoid production, and investigation of defensive trade-offs in the production of different types of benzoxazinoids. Thirteen corn leaf aphids ( Rhopalosiphum maidis) and one green peach aphid ( Myzus persicae) on the stem of a maize plant.īenzoxazinoids, a group indole-derived metabolites, have a prominent role in the herbivore defenses of maize, wheat, rye, and other grasses. On the insect side of the interaction, a major research focus is the investigation of strategies that herbivores use to avoid plant defenses or suppress them in a targeted manner.Įxamples of current research projects in the Jander lab are: Genetic mapping of natural variation in insect resistance, mass spectrometry-based screens to identify previously unknown plant defensive metabolites, and characterization of biosynthetic enzymes through knockout mutations and in vitro enzyme assays have led to the discovery of novel plant defense mechanisms. Plant species that are currently being investigated include Zea mays (maize), Arabidopsis thaliana (mouse-ear cress), Asclepias syriaca (common milkweed), Asclepias syriaca (tropical milkweed), Erysimum cheiranthoides (wormseed wallflower), and Nicotiana benthamiana (an Australian tobacco species). This includes not only the identification of novel defense-related plant metabolites, but also characterization of the genes and enzymes that are involved in their biosynthesis. The Jander lab studies the genetic and biochemical mechanisms that mediate plant interactions with insect herbivores. Many, perhaps most of these completely unknown plant metabolites function in defense against herbivores and/or pathogens. A typical leaf contains a few thousand different small molecules that can be detected by mass spectrometry, but only a few hundred of these have identified structures. However, the great majority of plant defensive metabolites remain completely unknown. nicotine in tobacco and glucosinolates in cruciferous vegetables, have been studied extensively. Some economically important plant toxins, e.g. Between- and within-species variation in the production of defensive chemicals often determines which plants a particular insect species is able to consume. To a large extent, resistance to herbivory is mediated by a wide array of toxic and deterrent plant metabolites. Nevertheless, the world is still green, and any given plant species is resistant to attack by most insects.
Plants in nature are faced with attack by potentially several hundred thousand species of herbivorous insects. High School Workforce Advantage Program.High School Research Projects & Faculty.Undergraduate Research Projects & Faculty.Center for Plant Biotechnology Research.
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