2009 Annual Report
1a.Objectives (from AD-416)
The objective of the Western Integrated Cropping Systems Research Unit is to develop new materials and methods for sustainable production of high quality cotton and other crops grown in the irrigated western United States. Specifically, research on integrated management of insects, identification and management of invasive plant pathogens and development of novel germplasm should enable efficient and profitable crop production with limited impact on the environment.
1b.Approach (from AD-416)
An interdisciplinary team consisting of an entomologist, geneticist, ecologist and plant pathologist will work together with Federal, State, and University collaborators to solve the major problems facing sustainable production of irrigated crops in the context of environmental stewardship. Efforts focus on discovering and developing new pest insect controls based on parasites and pathogens that impact only pest insects. Determination of overwintering locations and movement of pest insects will allow for more accurate prediction of future pest infestations and to identify release points of parasites. A process for rapid identification of race 4 Fusarium oxysporum vasinfectum (FOV), a disease new to the US will be developed and used to determine the extent of the infestation and to measure plant responses to remediation attempts. Conventional breeding techniques in combination with modern molecular techniques will lead to cotton germplasm with improved yield and fiber qualities and increased resistance to insects and diseases. “Replacing 5303-21220-002-00D (5/05)."
Ten cotton chromosomes were assayed for presence of molecular markers associated with resistance to Fusarium oxysporum f. sp. vasinfectum (FOV), the fungus causing Fusarium wilt. DNA sequences of thirty-one markers, associated with FOV or root-knot nematode resistance, or located close to other known markers, were obtained. In cooperation with the University of California-Riverside and UC-Davis, 460 cotton entries were evaluated for resistance levels to FOV races 1 and 4, and root-knot nematode in field and greenhouse studies. These studies revealed interactions in plant response to FOV between cotton entries, FOV races, and evaluation sites. Analyses of these data were initiated to investigate the inheritance and gene action of FOV-resistance. Isolates of FOV from Texas and the Ivory Coast of Africa were obtained and partially genotyped. The resulting sequences will be used as references to study genetic and pathogenic diversity of FOV in the U.S. Hot water treatments were evaluated for eliminating FOV infection in cottonseed to complement earlier studies of dry heat treatments. Fusarium infection of seed was reduced by exposure to 90 C for 90 sec or more. Field evaluations of treatments for reducing FOV inoculum in soil were repeated. Results were consistent with those from the previous year, in which three treatments (methyl bromide+chloropicrin, telone+chloropicrin, and solarization) reduced the incidence and severity of Fusarium wilt symptoms compared with untreated soil. Mark-release-recapture studies of sweep net collection efficiency for Lygus adults in cotton expanded to encompass among-sampler differences and the influence of release time on Lygus sampling. Results demonstrated the sweep net sampling technique can be standardized to eliminate among-sampler differences in population estimates. Higher recovery of Lygus adults sampled 2 hours after release, compared with recovery of Lygus released the previous day, indicated allowance of time for re-distribution of released Lygus within the plant canopy is important for accurate estimation of collection efficiency. Assays of the insect disease, Beauveria bassiana, against Lygus adults under low temperatures indicated a temperature-dependence of Lygus mortality but little difference among Beauveria isolates. Efforts to establish a Moroccan strain of a wasp parasite of Lygus, Peristenus relictus, were initiated in cooperation with the California Department of Food and Agriculture. The dynamics of development of morphological criteria for distinguishing diapause in Lygus adults was evaluated under controlled conditions. Key diagnostic characters were identified that suggest earlier reports of diapause response to photoperiod are inaccurate. Evaluations of the temperature-dependence of Lygus egg development were initiated to better understand the environmental ecology of this pest. Behavioral assays of Lygus feeding were conducted to gain insights into mechanisms of feeding injury in cotton. Observations suggest Lygus adults devote a higher proportion of time to feeding than was previously reported, and that feeding times are similar between genders.
Marker-assisted selection for root-knot nematode (RKN) resistance in cotton. The root-knot nematode is a small parasitic worm that injures roots of cotton plants. Attack by this nematode increases the severity of symptoms of Fusarium wilt in cotton. ARS scientists in Shafter, CA and collaborators at the University of California Riverside used crosses of Upland and Pima cottons expressing a range of RKN resistance to identify markers associated with two RKN resistance genes and demonstrate transgressive segregation (in which the progeny from a cross of a susceptible and a resistant parent exhibits a higher level of resistance than either parent) for the resistance trait. The markers identified can be used by breeders to identify resistant plants and thereby facilitate the incorporation of the resistant trait into elite cotton varieties.
|Number of the New/Active MTAs (providing only)||4|
Kantartzi, S.K., Ulloa, M., Sacks, E., Stewart, J.McD. 2009. Assessing genetic diversity in Gossypium arboreum L. cultivars using genomic and EST-derived microsatellites. Genetica 136: 141-147.
DeTar, W.R. 2009. Crop Coefficients and Water Use for Cowpea in the San Joaquin Valley of California. Agricultural Water Management. 96(1):53-66.
Suh, C.P., Armstrong, J.S., Spurgeon, D.W., Duke, S.E. 2009. Comparisons of boll weevil (Coleoptera: Curculionidae) pheromone traps with and without kill strips. Journal of Economic Entomology. 102:183-186.
Ulloa, M., Percy, R., Zhang, J., Hutmacher, R.B., Wright, S.D., Davis, R.M. 2009. Registration of four Pima cotton germplasm lines having good levels of Fusarium wilt race 4 resistance with moderate yields and good fibers. Journal of Plant Registrations. 3:198-202.
Wallace, T.P., Bowman, D., Campbell, B.T., Chee, P., Gutierrez, O.A., Kohel, R.J., McCarty, J., Myers, G., Percy, R., Robinson, F., Smith, W., Stelly, D.M., Stewart, J.M., Thaxton, P., Ulloa, M., Weaver, D.B. 2009. Status of the USA cotton germplasm collection and crop vulnerability. Genetic Resources and Crop Evolution 56:507-532.