Course Introduction

Rev.  01/01/20

Nematology 100 - General Plant Nematology

Course alias: Biology, Ecology and Management of Plant and Soil Nematodes

Introduction to the Department

Two in U.C. - elsewhere in Plant Pathology and Entomology

Supporting and subsequent courses

Nematology Teaching program arranged in 2-unit modules at the graduate level, generally offered in alternate years:

Supporting resources:

Current issues

• Cell lineages, programmed cell death (apoptosis),
• Nematodes as biological model systems.
• Aging (age1 and clk1)
• Association of gene structures with biochemical events and cellular/whole organism expression.
  • The complete genome of Caenorhabditis elegans has been sequenced, it consists of a 100,278,047 nucleotide sequence (100*10⁷ base pairs in the double strand) that constitute about 19,500 genes (Bird et al., 2005).
  • By comparison, the human genome is 3.3*10⁹ base pairs, approximately 34 times larger, but constitutes only about 25,000 genes.
  • The lineage of the approximately 970 cell divisions of C. elegans has been traced. About 2/3 of the cell divisions take place in the egg and most of the remainder in the J4 and young adult stages, associated with maturation of the reproductive system.
  • At least 50% of C. elegans genes are similar to those found in humans.
  • There is a complete map of its nervous system, including its 302 neurons and 7,000 connections.
• Host-plant resistance, transgenics, rhizosphere biology, signaling.
• Pesticides, environmental protection, indicators, decomposition, waste disposal, nutrient cycling.
• The Montreal Protocol and phase-out of methyl bromide; ozone depletion.
• Farming without fumigants. 

Cobb, 1914 ( Transactions of the American Microscopical Society):

"They occur in arid deserts and at the bottoms of lakes and rivers, in the waters of hot springs and in polar seas where the temperature is constantly below the freezing point of pure water.  They were thawed out alive from Antarctic ice in the far south by members of the Shackelton expedition. They occur at enormous depths in alpine lakes and in the ocean."

Also in 1914, Cobb wrote:

".....if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we would find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species would be determined by an examination of their erstwhile nematode parasites."

Addendum:

At the millennium we can provide detail to Cobb's pictorial prose by adding that, with present and emerging knowledge, fields in which the soils have been managed in a sustainable manner would be apparent, likewise those in which the soils are damaged by misuse of pesticides or irreversibly polluted with heavy metals. Areas in which the soils have increased in salinity, acidity and eutrophication would be evident as would those with undisturbed and pristine habitats which warrant the highest priority for protection. Our synthesis of the ecological function of nematodes in soil ecosystems has progressed to the extent that we can assess nematode faunal assemblages to measure the impact of stressors which threaten the functioning of soils, we can predict crop losses and can provide advice on cropping sequences and soil management practices so that sustainable optimal yields can be attained.

References

Bird, D.M., M.L. Blaxter, J.P. McCarter, M. Mitreva, P.W. Sternberg and W.K. Thomas. 2005. A white paper on nematode comparative genomics. Journal of Nematology 37:408-416.

Bongers, T. and H. Ferris (1999). Nematode community structure as a bioindicator in environmental monitoring. Trends in Evolution and Ecology 14:224-228.

Cobb, N. A. (1914). Nematodes and their relationships, USDA Yearbook. Agric. 1914, 457-490.