This research investigated early transcriptional responses of the model legume, Medicago truncatula, to herbivory by caterpillars of the beet armyworm, Spodoptera exigua. Differentially expressed genes were identified by the differential display technique, cDNA-amplified fragment length polymorphism (cDNA-AFLP). To distinguish between caterpillar-specific responses and general wound responses, a subset of plants was mechanically damaged. Furthermore, to identify responses to salivary elicitors, plants were subject to herbivory by caterpillars with normal salivary secretions and those that had their spinneret, the appendage through which labial saliva is secreted, cauterized shut. Eighteen differentially expressed gene fragments, representing 16 genes, were identified. The expression pattern of 5 of these genes was analyzed by Northern analysis, confirming a caterpillar-specific reduction in transcripts encoding rubisco activase and glyceraldehyde-3-phosphate dehydrogenase. This research shows that plants are able to differentiate between caterpillar herbivory and mechanical damage and that transcriptional response are initiated within one hour after caterpillar infestation.

Death of flower parts near bloom due to inflorescence necrosis (IN) is associated with high ammonium (NH₄⁺) concentration in flower clusters, shade, cool wet weather preceding bloom, and excessive vigor. Faults in NH₄⁺ assimilation are suspected to cause a rise in NH₄⁺ concentration to toxic levels in flower cluster but not other tissues. In this study, shading whole vines of Pinot noir increased flower NH₄⁺ concentration if applied at budbreak (early) or 1 wk before bloom (late), but only late application of shade to individual shoots raised it. Late, complete shoot defoliation raised flower cluster NH₄⁺ in all three years of the experiment. Early or late removal of lower leaves on a shoot also increased flower cluster NH₄⁺. Lamina, petiole, and other shoot tissue NH₄⁺ levels responded differently to treatments than flower clusters. IN severity was not affected by treatments; however, on shoots whose primary clusters had been removed at bloom secondary clusters did show significant differences, with IN being more severe in the early defoliation and late, lower defoliation treatments. Ethephon, sprayed on whole vines, slowed shoot growth to zero and increased IN severity greatly, however, flower cluster NH₄⁺ concentration was increased only 20% over the controls. Methionine sulfoximine applied as a cluster dip, increased flower cluster NH₄⁺ by 100%, yet resulted in little necrosis. Rootstock and clone affected Pinot noir flower cluster NH₄⁺ and IN severity. Rootstocks 420A caused lower and 101-14 and 3309 higher NH₄⁺ concentrations than the average. IN severity and flower cluster NH₄⁺ varied between vineyard sites, possibly due to environment and management differences. Pinot noir clones UCD23 and 32 had lower and UCD4 higher than average flower cluster NH₄⁺. IN in clones UCD4 and DJN115 was the least and UCD23 the most severe. A single 73kDa protein from grape shoot tissues reacted with anti-rice Fd-GOGAT IgG. An extraction method and assay for Fd-GOGAT activity from grape tissues was developed and gel filtration was used to show that the native enzyme is a dimer or trimer of the 73kDa protein. Activity was found in lamina, petiole, flower, rachis, and tendril, but not pedicel tissue. / Graduation date: 1997

Graduation date: 1966

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 95-107). / Microfiche. / x, 107 leaves, bound ill. (some col.) 29 cm

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1975. / Bibliography: leaves [130]-141. / xi, 141 leaves ill. (some col.)

Typescript. Thesis (Ph. D.)--University of Hawaii, 1934. Bibliography: leaves 122-124.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 66-68). / x, 68 leaves, bound col. ill. 29 cm

Biological, serological, and molecular characteristics of the P4 pathotype of pea seedborne mosaic potyvirus (PSbMV) were investigated. The characterization allowed P4 to be differentiated from other pathotypes of the same virus. P4 was distinguished from P1 on the basis of host symptomatology. It induced varied, but often distinctive symptoms in systemically-infected pea (Pisum sativum) cultivars. P4 inoculation of indicator hosts, notably Chenopodium album, resulted in the formation of local lesions. Pathotype P4 was seed transmitted at low frequencies relative to P1. In ten selected pea cultivars, seed transmission of P4 never exceeded 0.7%, while P1 was transmitted at frequencies as high as 33%. In mixed infections with P1, pathotype P4 was seed transmitted at 0- 2% as determined by P4-specific indirect ELISA. However, limited polymerase chain reaction (PCR) data suggest that P4 may be transmitted with P1 at higher rates than indicated by ELISA data. P4 was also aphid transmitted at relatively low rates. Pea aphids (Acyrthosiphon pisum) allowed 3 or 5 min acquisition access periods (AAP's) transmitted P4 at a maximum rate of 16% (3 aphids/plant). P4 transmission required short (1-7 min) AAP's and exhibited no bimodal character within tested parameters. P4 could be serologically distinguished from the other pathotypes using monoclonal and polyclonal antibodies. Tests with cross-reactive P4 antiserum suggest that P4 is more closely related to P2 than P1. P4-specific antiserum was derived by cross-absorbing diluted antiserum with P1- infected pea sap to eliminate P1- reactive antibodies. P1 and P4 RNA was detected and differentiated using pathotype-specific oligonucleotide primers in conjunction with PCR. Viral RNA sequences were amplified in pure preparations as well as crude pea tissue (leaf, root, pollen, and seed) extracts. / Graduation date: 1993

No description available.

No description available.