|
Dr.
N. Richard Knowles
.jpg) 509-332-6807
rknowles@wsu.edu
Department
of Horticulture & Landscape Architecture. Professor/Horticulturist.
Ph.D. 1983, Washington
State University.
Research
Physiological and biochemical changes that mediate
loss of post harvest quality in fruit and vegetable crops are of
interest. We
currently have a major research focus on physiological aging of
potato seed-tubers. Potatoes are propagated vegetatively
from virus-free seed-tubers stored prior to planting. Storage
conditions can influence the rate of aging, which subsequently
affects plant growth and crop yield. Using potato as a model,
we are investigating metabolic changes associated with loss of
vigor and growth potential during aging. Ongoing studies
include: oxidative processes and associated defense mechanisms
in the aging process; age-induced changes in energy metabolism
during sprouting; mechanism of phospholipid and fatty acid catabolism
relative to deterioration in membrane function during aging; role
of NADPH oxidase in the age-induced loss of hypersensitive response
and wound-healing ability of tubers; and mechanisms by which proteins
become targeted for proteolysis during tuber aging.
Applied research
includes techniques to manipulate apical dominance of seed-tubers
to optimize tuber set and size development in relation to market
requirements, biochemical/molecular markers of apical dominance
and yield potential in seed-tubers, discovery and development of
sprout inhibitors, in-season stresses affecting storability and
postharvest quality, storage management techniques to preserve
processing quality, and potato variety development. My program
evaluates the storability, processing quality, and culinary attributes
of clones and cultivars in The Pacific Northwest Potato Variety
Development Program (WA, ID, OR). We thus have access to
potato genotypes with differential susceptibility/resistance to
major pathogens, insects, cold/heat tolerance, drought, etc. The
germplasm from this program offers a unique opportunity for fundamental
research on the metabolic bases of resistance/susceptibility to
various biotic and abiotic stresses in potato.
Selected
Publications
Kumar, G.N.M., Suresh Iyer and N.R. Knowles. 2007.
Extraction of RNA from fresh, frozen, and lyophilized tuber and
root tissues. J. Agric. Food Chem 55:1674-1678.
Knowles, N.R. and
E.S. Plissey. 2007. Maintaining tuber health during harvest storage,
and post-storage handling. In Potato Health Management, D. Johnson
ed., 2nd edition, APS Press (invited chapter) (in press).
Driskill,
E.P. Jr., L.O. Knowles, and N. R. Knowles. 2007. Temperature-induced
changes in potato processing quality during storage are modulated
by tuber maturity. Am. J. Pot. Res. (in press).
Grunenfelder, L.,
L.O. Knowles, L.K. Hiller and N.R. Knowles. 2006. Glycoalkaloid
development during greening of fresh market potatoes (Solanum
tuberosum L.). J. Agric. Food Chem 54:5847-5854.
Knowles, N.R. and L.O. Knowles.
2006. Manipulating stem number, tuber set, and yield relationships
for northern- and southern-grown potato seed lots. Crop Science
46:284-296.
Novy, R.G., S.L. Love, D.L. Corsini, J.J. Pavek,
J. Whitworth, A.R. Mosley, S.R. James, D.C. Hane, C.C. Shock, K.A.
Rykbost, C.R. Brown, R.E. Thornton, N.R. Knowles, M. Pavek, N.
Olsen, and D.A. Inglis. 2006. Defender: A high-yielding, processing
potato cultivar with foliar and tuber resistance to late blight.
Am. J. Pot. Res. 83:9-19.
Knowles N.R and L.O. Knowles. 2005. Use
of a, b unsaturated aldehydes and ketones to inhibit
potato tuber sprouting. U.S. patent no. 6,855,669.
Kumar, G.N.M.
and N.R. Knowles. 2003. Wound-induced superoxide production and
PAL activity decline with potato tuber age and wound healing ability.
Physiol. Plant. 117:108-117.
Zabrouskov,V., G.N.M. Kumar, J.P.
Spychalla and N.R. Knowles. 2002. Oxidative metabolism and the
physiological age of seed potatoes are affected by increased a-linolenate
content. Physiol. Plant. 116(2):172-185
Zabrouskov V. and N.R.
Knowles. 2002. Lipid metabolism during aging of high a-linolenate-phenotype
potato tubers. Arch. Biochem. Biophys. 402:136-148.
Zabrouskov
,V. and N.R. Knowles. 2002. Changes in lipid molecular species
and sterols of microsomal membranes during aging of potato (Solanum
tuberosum L.) seed-tubers. Lipids 37(3):309-315.
Kumar, G.N.M.,
R.L. Houtz and N.R. Knowles. 1999. Age-induced protein modifications
and increased proteolysis in potato seed-tubers. Plant Physiol.
119:89-100.
Rogiers, S.Y., G.N.M. Kumar and N.R. Knowles. 1998.
Regulation of ethylene production and ripening by saskatoon (Amelanchier
alnifolia Nutt.) fruit. Can. J. Bot. 76:1743-1754.
Rogiers, S.Y.,
G.N. Mohan Kumar and N.R. Knowles. 1998. Maturation and ripening
of fruit of Amelanchier alnifolia Nutt. are accompanied by increasing
oxidative stress. Ann. Bot. 81:203-211.
Kumar, G.N.M. and N.R.
Knowles. 1996. Oxidative stress results in increased sinks for
metabolic energy during aging and sprouting of potato seed-tubers.
Plant Physiol. 112:1301-1313.
Kumar, G.N.M. and N.R. Knowles. 1993.
Involvement of auxin in the loss of apical dominance and plant
growth potential accompanying aging of potato seed-tubers. Can.
J. Bot. 71:541-550.
Kumar, G.N.M. and N.R. Knowles. 1993. Changes
in lipid peroxidation and lipolytic and free-radical scavenging
enzyme activities during aging and sprouting of potato seed-tubers.
Plant Physiol. 102:115-124.
McArthur, D.A.J. and N.R. Knowles.
1992. Resistance responses of potato to VA mycorrhizal fungi under
varying abiotic phosphorus levels. Plant Physiol. 100:341-351.
|
