J. L. Starr

Root-knot nematodes

Plant-parasitic nematodes devastate crops worldwide, in turn impacting international trade, social and economic development. Effective control of nematodes is essential for crop protection, and requires an understanding of nematode biology, taxonomy, population dynamics and sampling methods. Providing a broad introduction to nematodes as plant parasites, this book begins by describing nematodes by genera, and builds on this foundation to detail nematode biology and pest management, including biological and chemical control. Chapters are authored by international experts and enhanced by extensive illustrations and focus boxes. Fully updated throughout, this new edition is an essential resource for postgraduate students, extension officers, researchers and crop protection scientists

Meloidogyne species: a diverse group of novel and important plant parasites

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Plant Resistance to Parasitic Nematodes

Starr, J. L., Bridge, J., Cook, R. (2002). Plant Resistance to Parasitic Nematodes. CABI Publishing, Wallingford, ISBN: 0851994660, 288 pp. Table of Contents Contributors Preface 1. Resistance to Plant-parasitic Nematodes: History, Current Use and Future Potential , J.L. Starr, J. Bridge and R. Cook 2. Concepts and Consequences of Resistance , P.A. Roberts 3. Root-knot Nematodes: Meloidogyne Species , R.S. Hussey and G.J.W. Janssen 4. Cyst Nematodes: Globodera and Heterodera Species , R. Cook and G.R. Noel 5. Ditylenchus Species , R.A. Plowright, G. Caubel and K.A. Mizen 6. Foliar Nematodes: Aphelenchoides Species , D. De Waele 7. Reniform Nematodes: Rotylenchulus Species , A.F. Robinson 8. Migratory Endoparasites: Pratylenchus and Radopholus Species , D. De Waele and A. Elsen 9. The Citrus Nematode: Tylenchulus semipenetrans , S. Verdejo-Lucas and D.T. Kaplan 10. The Yam Nematode: Scutellonema bradys , C. Kwoseh, R.A. Plowright and J. Bridge 11. Ectoparasitic Nematodes , J.L. Starr and I.F. Bendezu 12. Marker-assisted Selection for Soybean Cyst Nematode Resistance , N.D. Young and J. Mudge Index Contributors Preface 1. Resistance to Plant-parasitic Nematodes: History, Current Use and Future Potential , J.L. Starr, J. Bridge and R. Cook 2. Concepts and Consequences of Resistance , P.A. Roberts 3. Root-knot Nematodes: Meloidogyne Species , R.S. Hussey and G.J.W. Janssen 4. Cyst Nematodes: Globodera and Heterodera Species , R. Cook and G.R. Noel 5. Ditylenchus Species , R.A. Plowright, G. Caubel and K.A. Mizen 6. Foliar Nematodes: Aphelenchoides Species , D. De Waele 7. Reniform Nematodes: Rotylenchulus Species , A.F. Robinson 8. Migratory Endoparasites: Pratylenchus and Radopholus Species , D. De Waele and A. Elsen 9. The Citrus Nematode: Tylenchulus semipenetrans , S. Verdejo-Lucas and D.T. Kaplan 10. The Yam Nematode: Scutellonema bradys , C. Kwoseh, R.A. Plowright and J. Bridge 11. Ectoparasitic Nematodes , J.L. Starr and I.F. Bendezu 12. Marker-assisted Selection for Soybean Cyst Nematode Resistance , N.D. Young and J. Mudge Index

Maize 9-Lipoxygenase ZmLOX3 Controls Development, Root-Specific Expression of Defense Genes, and Resistance to Root-Knot Nematodes

Root-knot nematodes (RKN) are severe pests of maize. Although lipoxygenase (LOX) pathways and their oxylipin products have been implicated in plant-nematode interactions, prior to this report there was no conclusive genetic evidence for the function of any plant LOX gene in such interactions. We showed that expression of a maize 9-LOX gene, ZmLOX3, increased steadily and peaked at 7 days after inoculation with Meloidogyne incognita RKN. Mu-insertional lox3-4 mutants displayed increased attractiveness to RKN and an increased number of juveniles and eggs. A set of jasmonic acid (JA)- and ethylene (ET)-responsive and biosynthetic genes as well as salicylic acid (SA)-dependent genes were overexpressed specifically in the roots of lox3-4 mutants. Consistent with this, levels of JA, SA, and ET were elevated in lox3-4 mutant roots, but not in leaves. Unlike wild types, in lox3-4 mutant roots, a phenylalanine ammonia lyase (PAL) gene was not RKN-inducible, suggesting a role for PAL-mediated metabolism in nematode resistance. In addition to these alterations in the defense status of roots, lox3-4 knockout mutants displayed precocious senescence and reduced root length and plant height compared with the wild type, suggesting that ZmLOX3 is required for normal plant development. Taken together, our data indicate that the ZmLOX3-mediated pathway may act as a root-specific suppressor of all three major defense signaling pathways to channel plant energy into growth processes, but is required for normal levels of resistance against nematodes.

Identification of peanut (Arachis hypogaea L.) RAPD markers diagnostic of root-knot nematode (Meloidogyne arenaria (Neal) Chitwood) resistance

DNA markers linked to a root-knot nematode resistance gene derived from wild peanut species have been identified. The wild diploid peanut accessions K9484 (Arachis batizocoi Krapov. & W. C. Gregory), GKP10017, (A. cardenasii Krapov & W. C. Gregory), and GKP10602 (A. diogoi Hoehne) possess genes for ressitance to Meloidogyne arenaria. These three accessions and A. hypogaea cv. Florunner were crossed to generate the hybrid resistant breeding line TxAg-7. This line was used as donor parent to develop a BC4F2 population segregating for resistance. Three RAPD markers associated with nematode resistance were identified in this population by bulked segregant analysis. Linkage was confirmed by screening 21 segregatingh BC4F2 and 63 BC5F2 single plants. Recombination between marker RKN410 and resistance, and between marker RKN440 and resistance, was estimated to be 5.4±1.9% and 5.8±2.1%, respectively, on a per-generation basis. These two markers identified a resistance gene derived from either A. cardenasii or A. diogoi, and were closely linked to each other. Recombination between a third marker, RKN229, inherited from A. cardenasii or A. diogoi, and resistance was 9.0±3.2% per generation. Markers RKN410 and RKN229 appeared to be linked genetically and flank the same resistance gene. All markers were confirmed by hybridization of cloned or gel-purified marker DNA to blots of PCR-amplified DNA. Pooled data on the segregation of BC5F2 plants was consistent with the presence of one resistance gene in the advanced breeding lines. Different distributions of resistance in the BC5F2 progeny and TxAG-7 suggest the presence of additional resistance genes in TxAG-7.

Plant-Parasitic Nematodes Attacking Cotton in the United States Old and Emerging Production Challenges

Cotton is the most important fiber crop in the world, and current U.S. lint production accounts for nearly one quarter of the world supply. The unique role of cotton in world and American history is profound. Primitive cottons have been used in Africa, Asia, and the Americas for millennia. Domestic and international demand for cotton fiber contributed greatly to the westward expansion of the United States, the American Civil War, and the industrial revolution (81). The land area devoted to cotton production in the United States peaked in 1926 with approximately 18 million hectares (Fig. 1). The advent of mechanized farming equipment and the availability of effective, relatively low-cost fertilizers, pesticides, and improved cotton cultivars after World War II allowed the production of significantly greater yields per unit of land area, and hectarage declined. U.S. production of cotton lint in the past 5 years has varied from 3.0 × 10 to 4.4 × 10 kg produced on about 5 million hectares (147). Additionally, cotton seed is a valuable source of vegetable oil and protein used in animal feed, with production of 4.9 × 10 to 5.9 × 10 kg of cotton seed annually. Since World War II, cotton cultivation was increasingly dependent on inputs of chemical pesticides for weed and insect control. Historically, the cotton boll weevil, Anthonomus grandis Boheman, was the most costly pest of cotton in the United States. The combination of crop loss due to this insect directly and the expense for insecticides that was incurred by cotton growers attempting to control it amounted to several billion dollars annually until recently (130). The successful establishment of the Boll Weevil Eradication Program coordinated by the U.S. Department of Agriculture in many states in the eastern half of the country has resulted in a reduction in insecticide usage, improved profitability for growers, and has led to a resurgence of cotton production in the Southeast (37). In addition, the current widespread use of transgenic cotton cultivars with resistance to herbicides and/or insects also has greatly reduced the need for inputs of pesticides. Currently, 71% of cotton grown in the United States is herbicide resistant, resistant to lepidopteran insects, or has resistance to both (3). Reductions in pest pressure from weeds and insects as a result of the deployment of transgenic resistance and the boll weevil eradication program have

The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton

Mutualistic plant-endophyte symbioses can benefit plants by increasing host fitness through reductions in herbivory. The fungus, Chaetomium globosum strain TAMU 520, was previously isolated as an endophyte from cotton (Gossypium hirsutum) and can be re-inoculated to systemically colonize cotton plants via seed treatment. We evaluated the potential impacts of the endophyte in cotton on plant parasitic nematodes belowground, along with piercing-sucking and chewing insects aboveground. Endophytic C. globosum inhibited root-knot nematode (Meloidogyne incognita) infection and reduced female reproduction belowground. To confirm the endophytic effect of C. globosum on root-knot nematode, a contact fungicide was applied to remove soil-borne and epiphytic C. globosum Consistent inhibition of nematode activity was observed post-fungicide treatment, with positive C. globosum colonization confirmed within plant tissues. Aboveground, endophytic C. globosum also negatively affected the fecundity of both cotton aphids (Aphis gossypii) and beet armyworms (Spodoptera exigua). Faster development rates and smaller head capsule of beet armyworm larvae were observed when fed Chaetomium-colonized plants. However, no larval weight difference was found between Chaetomium-colonized and control plants. No consistent effect on plant performance was found across experiments. Our findings illustrate how a single facultative fungal endophyte can increase plant systemic resistance against a range of invertebrate herbivores in a major crop.