Abs.papers.html

Glimpses into Desiccation and Salt Tolerance
in Higher Plants

John C. Thomas
Department of Natural Sciences, University of Michigan-Dearborn , Dearborn, MI 48128-1491

AgBiotech News and Information 8(7): 127N-132N 1996

Future crops will be increasingly challenged by an arid global climate. Anticipating this desiccated environment, present-day studies are focused on understanding mechanisms of plant stress responses. In diverse plant species, responses to stress assist in conferring increased salt and desiccation tolerance. Free radical detoxification, the synthesis of methylated metabolic products, accumulation of "protective" molecules, ion transport and sequestration, structural and metabolic adjustments all play important roles in desiccation protection. A variety of biochemical and physiological pathways all appear to act, in the combinatorial sense, to create a "tolerant" phenotype. Ongoing gene isolation, modification, introduction and breeding programs will allow introduction of these tolerance traits into crops. To endorse the development of newly tolerant crop species, financial support from governmental and private sources is necessary today to abate future stress-induced yield depression and lowered crop quality.

Manduca sexta Encoded Protease Inhibitors Expressed in Nicotiana tabacum Provide Protection Against Insects.

John C. Thomas1, Deanna G. Adams1, Veronique D. Keppenne2, Catherine C. Wasmann3, Judith K. Brown2, Michael R. Kanost 4, and Hans J. Bohnert2,4 1 Department of Biochemistry, 2 Department of Plant Sciences, 3Department of Plant Pathology, University of Arizona, Tucson, AZ 85721, and 4Department of Biochemistry, Kansas State University, Manhatten KS 66506-0001, USA.

Reference: Plant Physiol. Biochem 33(5): 611-614 (1995)

Crop plants are damaged by a multitude of insect pests, lowering crop quality
and yield. Here we have expressed insect encoded anti-trypsin, anti-chymotrypsin
and anti-elastase protease inhibitor (PI) genes from Manduca sexta
L. in transgenic Nicotiana tabacum L. under the control of the 35S
promoter of cauliflower mosaic virus. PI levels accumulated in leaves to
0.05-0.1% of the total protein. When these plants were tested against the
new Bemisia tabaci (Genn.), sweetpotato whitefly type B, insect reproduction
was reduced by as much as 98 % compared to controls. This result suggests
that M. sexta derived protease inhibitors, together with other anti-insect
genes and plant-encoded responses to damage and attack, may be useful in
protecting crop plants against insects.

Key Words: transgenic tobacco, protease inhibitor, insect resistance

Abbreviations: Protease inhibitor, PI; polymerase chain reaction, PCR; small
subunit of RUBISCO, SSU; cauliflower mosaic virus, CaMV.

Protease Inhibitors of Manduca sexta Expressed in Transgenic Cotton.

John C. Thomas1, Deanna G. Adams1, Veronique D. Keppenne2, Catherine C.Wasmann3, Judith K. Brown2, Michael R. Kanost 4, and Hans J. Bohnert1,2 1 Department of Biochemistry, 2 Department of Plant Sciences, 3Department of Plant Pathology, University of Arizona, Tucson, AZ 85721, and 4Department of Biochemistry, Kansas State University, Manhatten KS 66506-0001, USA.

Key Words: Protease inhibitor - Plant transformation.
Reference: Plant Cell Reports 14: 758-762. (1995)

Summary
To explore the effectiveness of insect derived protease inhibitors in protecting
plants against insect feeding, anti-trypsin, anti-chymotrypsin and anti-elastase
protease inhibitor (PI) genes from Manduca sexta L. were expressed in transgenic
cotton (Gossypium hirsutum L.). From 198 independent transformants,
35 elite lines were further analyzed. Under the control of the 35S promoter
of CaMV, PI accumulated to approximately 0.1% of total protein, depending
on the tissue analyzed. Using cell-flow cytometry, DNA content/ nuclei of
transgenic and non-transformed cotton were identical. On cotton plants expressing
PIs, Bemisia tabaci (Genn.), the sweetpotato whitefly, fecundity
was reduced compared to controls. Expression of these protease inhibitors
may reduce the developmental rate of B. tabaci and other insects and
provide a strategy for cotton protection.

Tryptophan Decarboxylase, Tryptamine, and Reproduction of the Whitefly

John C. Thomas2, Deanna G. Adams, Craig L. Nessler, Judith K. Brown and Hans J. Bohnert, Department of Biochemistry (JCT, DGA, HJB) and Department of Plant Sciences (JKB, HJB), University of Arizona, Tucson, AZ 85721; and Department of Biology, Texas A&M University, College Station, TX 72843 (CLN).

Reference: Plant Physiology 109: 717-720 (1995)

Tryptophan decarboxylase (TDC) from Catharanthus roseus (periwinkle)
converts tryptophan to the indole-alkaloid tryptamine. When the TDC gene
was expressed in transgenic tobacco, the 55 kD enzyme and tryptamine were
accumulated. Bemisia tabaci (sweetpotato whitefly) reproduction on
transgenic plants decreased up to 97% relative to controls. Production of
tryptamine, its derivatives, or other products resulting from TDC activity
may discourage whitefly reproduction and provide a single-gene-based plant
protection strategy.