Open Collections

Studies on polyacetylene production in normal and transformed tissue cultures of Bidens alba

University of British Columbia

The organs of B idens alb a each have a different composition of polyacetylenes (PAs). Factors affecting production of these compounds in tissue and organ cultures, and characteristics of cultures showing sustained synthesis of PAs were - -investigated. Additional studies evaluated transmission of tumour markers and leaf PAs in sexually produced offspring. Polyacetylenes were separated and quantitated by high pressure liquid chromatography. Twenty-one compounds, representing six chromophores, were identified or indicated. The principal compounds were phenylheptatriyne (PHT), found in leaves and stems; phenyldiynene (PDE), found in stems; PDE-OAc, found in roots; and entetraynene acetate (ETE-OAc), found in roots. Production of PAs past the third passage could not be achieved in callus from normal plants, despite variations in medium formulations and environmental parameters. Calluses from crown galls induced on B_. alba and B_. p i lo sa by two strains of Agrobacterium tumefaciens, however, continued to produce PAs after three years in culture. Transformed callus lines showed wide fluctuations in levels and a declining proportion of PDE-OAc over time. Leaf and stem PAs were not found in tumour callus several months old. Callus contained PAs not found in the plant. Root cultures were used to determine the effect of environmental, hormonal, and nutritional parameters on growth, PA level and PA composition. Low temperatures, darkness, high kinetin levels, and increased sucrose/nitrate ratios increased production of PAs by roots. The proportion of PDE-OAc increased in light, high kinetin medium, and late log phase of growth. Leaf and stem PAs could not be induced in root cultures. Plants regenerated from nopaline galls rooted and set fertile seed. Selfs and crosses with normal plants demonstrated inheritance of tumour characteristics to the fourth generation. However, F₂ and succeeding generations had sharply reduced levels of nopaline, and showed differential loss of transformation markers. Transformed F₁ plants could form octopine galls and double transformant tissue was obtained. Transformed plants were morphologically different from normal plants. Crosses between 15. alba and B. pilosa, which did not contain PAs in leaves or stems, yielded F₂ which segregated for PHT synthesis, but not in Mendelian ratios. Synthesis of PHT was dominant but showed depressed levels in the F₂ which was incompatible with a gene dosage effect.

Text

2010-06-12

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

http://hdl.handle.net/2429/25610

Botany

University of British Columbia

Graduate