Bill Newcomb - Associate Professor

Research: While I have rather wide interests in developmental botany, my current research endeavours make extensive use of correlated light and transmission electron microscopy to study the developmental and structural aspects of interactions between roots and soil micro-organisms occurring in the morphogenesis of nitrogen-fixing root nodules, as well as embryo development in higher plants.

Nitrogen is the chemical element occurring most commonly in rate-limiting amounts in agricultural and forestry situations. The problems of augmenting crop production to meet the needs of an increasing world population is responsible in part for the high levels of interest in understanding the processes associated with biological nitrogen fixation and possibly developing methods for improving the efficiency of the process. Two groups, of angiosperms, legumes and actinorhizal plants, possess the capability to bear root nodules. Gram-negative bacteria belonging to the genera Rhizobium and Bradyrhizobium initiate nodules on the roots of certain leguminous plants. Actinomycetes, gram-positive bacteria which have hyphae during some part of their life cycle, belonging to the genus Frankia, form nodules on certain perennial non-leguminous angiosperms. These host plants, which are termed actinorhizal, include alder (Alnus), sweet fern (Comptonia), sweet gale (Myrica), buffaloberry (Shepherdia), Russian olive (Elaeagnus), mountain avens (Dryas), Australian pine or sheoak (Casuarina) and several other genera. While the actinorhizal plants are not valuable as food plants, they are used as trees for forestry, horticulture and land reclamation.

Current projects involve ultrastructual studies of the cytoskeleton in infected nitrogen-fixing cells in pea nodules.  Studies are also being carried out on transgenic tobacco plants which produce low frequencies of viable seed.  With angiosperm embryos, current projects involve ultrastructural studies of embryo formation from developing pollen of canola.  Heat treatments switch development from the pollen pathway to that of embryos which being haploid are useful for breeding studies.

»» No Lab Website »« email: newcombw@queensu.ca »« telephone: 613-533-6131 ««

Some Recent Publications:

• Davidson, A. L. and W. Newcomb. 2001. Organization of microtubules in developing pea root nodule cells. Canadian Journal of Botany 79: 777-786.
• Zhao, J.P., D.H. Simmonds and W. Newcomb. 1996. High frequency production of doubled haploid plants of Brassica napus cv. Topas derived from colchicine-induced microspore embryogenesis without heat shock. Plant Cell Reports 15:668-671.
• Telmer, C.A., W. Newcomb and D.H. Simmonds. 1993. Microspore development in Brassica napus and the effect of high temperature on division in vivo and In vitro. Protoplasma 172:154-165.