http://hdl.handle.net/1957/1934 2013-06-20T06:05:05Z 2013-06-20T06:05:05Z Govindarajulu, Rajanikanth Liston, Aaron Ashman, Tia-Lynn http://hdl.handle.net/1957/39431 2013-06-17T19:22:19Z 2013-05-01T00:00:00Z

Sex-determining chromosomes and sexual dimorphism: insights from genetic mapping of sex expression in a natural hybrid Fragaria ×ananassa subsp. cuneifolia Govindarajulu, Rajanikanth; Liston, Aaron; Ashman, Tia-Lynn We studied the natural hybrid (Fragaria ×ananassa subsp. cuneifolia) between two sexually dimorphic octoploid strawberry species (F. virginiana and F. chiloensis) to gain insight into the dynamics of sex chromosomes and the genesis of sexual dimorphism. Male sterility is dominant in both the parental species and thus will be inherited maternally, but the chromosome that houses the sex-determining region differs. Thus, we asked whether 1) the cytotypic composition of hybrid populations represents one or both maternal species, 2) the sex-determining chromosome of the hybrid reflects the location of male sterility within the maternal donor species, and 3) crosses from the hybrid species show less sexual dimorphism than the parental species. We found that F. ×ananassa subsp. cuneifolia populations consisted of both parental cytotypes but one predominated within each population. Genetic linkage mapping of two crosses showed dominance of male sterility similar to the parental species, however, the map location of male sterility reflected the maternal donor in one cross, but not the other. Moreover, female function mapped to a single region in the first cross, but to two regions in the second cross. Aside from components of female function (fruit set and seed set), other traits that have been found to be significantly sexually dimorphic in the pure species were either not dimorphic or were dimorphic in the opposite direction to the parental species. These results suggest that hybrids experience some disruption of dimorphism in secondary sexual traits, as well as novel location and number of QTL affecting sex function. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Nature Publishing Group and can be found at: http://www.nature.com/hdy/index.html.

2013-05-01T00:00:00Z Salamone, Isabella Govindarajulu, Rajanikanth Falk, Stacey Parks, Matthew Liston, Aaron Ashnam, Tia-Lynn http://hdl.handle.net/1957/39422 2013-06-17T18:15:46Z 2013-05-01T00:00:00Z

Bioclimatic, ecological, and phenotypic intermediacy and high genetic admixture in a natural hybrid of octoploid strawberries Salamone, Isabella; Govindarajulu, Rajanikanth; Falk, Stacey; Parks, Matthew; Liston, Aaron; Ashnam, Tia-Lynn Premise of the Study: Hybrid zones provide "natural laboratories" for understanding the processes of selection, reinforcement, and speciation. We sought to gain insight into the degree of introgression and the extent of ecological-phenotypic intermediacy in the natural hybrid strawberry, Fragaria x ananassa subsp. cuneifolia. Methods: We used whole-plastome sequencing to identify parental species-specific (Fragaria chiloensis and F. virginiana) chloroplast single-nucleotide polymorphisms and combined the use of these with nuclear microsatellite markers to genetically characterize the hybrid zone. We assessed the potential role of selection in the observed geographic patterns by bioclimatically characterizing the niche of the hybrid populations and phenotypically characterizing hybrid individuals of known genomic constitution. Key Results: Significant admixture and little overall maternal bias in chloroplast or nuclear genomes suggest a high degree of interfertility among the parental and hybrid species and point to a long history of backcrossing and genetic mixing in the hybrid zone. Even though hybrids were phenotypically intermediate to the parental species, there was a discernible fingerprint of the parental genotype within hybrid individuals. Thus, although the pattern of introgression observed suggests geographic limitations to gene flow, it may be reinforced by selection for specific parental traits in the bioclimatically intermediate habitat occupied by the hybrid. Conclusions: This work uncovered the genetic complexity underlying the hybrid zone of the wild relatives of the cultivated strawberry. It lays the foundation for experimental dissection of the causes of genomic introgression and nuclear-cytoplasmic disassociation, and for understanding other parts of Fragaria evolutionary history. This is the publisher’s final pdf. The published article is copyrighted by Botanical Society of America and can be found at: http://www.botany.org/.

2013-05-01T00:00:00Z Kropf, S. M. Putnam, M. L. Serdani, M. Twomey, M. C. Woods, J. L. Gent, D. H. http://hdl.handle.net/1957/39369 2013-06-12T22:08:18Z 2012-04-01T00:00:00Z

Sclerotinia Wilt of Hop (Humulus lupulus) Caused by Sclerotinia sclerotiorum in the Pacific Northwest United States Kropf, S. M.; Putnam, M. L.; Serdani, M.; Twomey, M. C.; Woods, J. L.; Gent, D. H. This is the publisher’s final pdf. The published article is copyrighted by The American Phytopathological Society and can be found at: http://apsjournals.apsnet.org/loi/pdis. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.

2012-04-01T00:00:00Z Stockwell, V. O. Duffy, B. http://hdl.handle.net/1957/39357 2013-06-12T21:00:50Z 2012-04-01T00:00:00Z

Use of antibiotics in plant agriculture Stockwell, V. O.; Duffy, B. Antibiotics are essential for control of bacterial diseases of plants, especially fire blight of pear and apple and bacterial spot of peach. Streptomycin is used in several countries; the use of oxytetracycline, oxolinic acid and gentamicin is limited to only a few countries. Springtime antibiotic sprays suppress pathogen growth on flowers and leaf surfaces before infection; after infection, antibiotics are ineffective. Antibiotics are applied when disease risk is high, and consequently the majority of orchards are not treated annually. In 2009 in the United States, 16,465 kg (active ingredient) was applied to orchards, which is 0.12% of the total antibiotics used in animal agriculture. Antibiotics are active on plants for less than a week, and significant residues have not been found on harvested fruit. Antibiotics have been indispensable for crop protection in the United States for more than 50 years without reports of adverse effects on human health or persistent impacts on the environment. This is the publisher’s final pdf. The published article is copyrighted by World Organisation for Animal Health (OIE) and can be found at: http://www.oie.int/fr/publications-et-documentation/revue-scientifique-et-technique-acces-libre/liste-des-numeros/. "With the kind authorisation of the World Organisation for Animal Health (OIE) (www.oie.int), OIE Scientific and Technical Review Stockwell V.O. & Duffy B. (2012). Use of antibiotics in plant agriculture. In Antibiotic resistance in animal and public health (G. Moulin & J.F. Acar, eds). Rev. sci. tech. Off. int. Epiz., 31 (1), 199-210."

2012-04-01T00:00:00Z