OKLAHOMA
OKLAHOMA STATE UNIVERSITY
Department of Plant and Soil Sciences, 368 Ag Hall, Stillwater, OK 74078-6028, USA.
B.F. Carver, E.G. Krenzer, A.K. Klatt, and A.C. Guenzi.
E.G. Krenzer.
In 2002, 98 x 106 bushels of hard winter wheat were harvested from 3.5 x 10^6^ acres for an average yield of 28 bu/acre. Both acres harvested and average yield decreased from last year's numbers of 4.2 x 10^6^ acres harvested and 34 bu/acre.
The 2001-02 wheat crop started slowly for the second consecutive year. Soils remained exceedingly dry through early September, when the first significant rainfall occurred around 10 September 2001. September temperatures were not exceptionally high, so early-planted wheat resulted in very good stands. By 1 October 2001, 60 % of the wheat acreage had been planted compared to a 5-year average of 31 %. Little rainfall occurred from October 2001 through January 2002, with the National Weather Service reporting between 25 and 50 % of the normal precipitation for Oklahoma during that period. Wheat in most areas continued to suffer drought stress, limiting forage production. Spring rains were barely adequate in many areas and were too little, too late, or nonexistent in the panhandle where the dryland wheat was almost 100 % abandoned. Grain-filling conditions were quite good except where limited moisture hastened maturity and reduced test weight.
The leading cultivars planted in Oklahoma for the 2002 crop
were Jagger, 2174, 2137, 2180, and Custer at 45,13, 5, 4, and
4 % of the acres, respectively.
B.F. Carver.
Seven HRWW breeding lines were placed under final breeder seed increase in 2002-03.
OK94P549-21 HBY756A/Siouxland//2180 OK94P549-11 HBY756A/Siouxland//2180 OK95616-56 TXGH13622/2180 OK96705-38 2180//OK88803/Abilene OK95548-54 OK86216/Cimarron sib//2180 OK98699 TAM 200/HBB313E//2158 seln OK98690 OK91724(=Chisholm*2/Yantar)/Karl
OK98690 and OK98699 have above-average milling and baking quality, whereas OK96705-38 and OK95548-54 (the latter has the T1BL·1RS wheat-rye translocation from Aurora) possess below-average quality and will likely not be released for that reason. All seven show a high level of resistance to WSBMV and, with the exception of OK96705-38 and OK98699, a moderately high level of APR to leaf rust. Extremely high priority has been given to improving resistance to these diseases in the cultivar-development program in the past 5 years. Other agronomic priorities have included improving field tolerance to acidic soils and adaptation to a dual-purpose management system. A key component to the latter objective is the combination of early heading date with a nonprecocious dormancy release in the late winter, which is quantified by date of first hollow-stem stage. Though changes are not yet confirmed, this type of selection pressure could elicit upward shifts in vernalization requirement and photoperiod sensitivity or a downward shift in heat sensitivity. All lines listed above show timely dormancy release patterns except OK95616-56, which is similar to Jagger.
The Wheat Improvement Team at OSU is also attempting to incorporate
the awnletted character into a grain-type cultivar to allow producers
in the southern Great Plains the added flexibility to defer their
decision to use a standing crop either for grain production or
for hay or late-season grazing. Though the vast majority of HRWW
cultivars are awned, we tested the hypothesis that an awnletted
type would produce equivalent grain yield and quality if flag
leaf senescence was delayed by protection against leaf rust.
NILs were developed by Dr. Stan Cox (formerly with USDA-ARS, Manhattan,
KS) in a Century background featuring all combinations of leaf
rust resistance (from either Lr41 or Lr42) and awn
type. For most attributes, genes controlling awns and rust resistance
acted additively but with unequal effects. The average effect
of leaf rust resistance genes was more than twofold greater than
the average effect of awns for grain yield, test weight, and kernel
weight. Awnletted genotypes with leaf rust resistance were equivalent
in yield and quality to the conventional awned types. We are
aggressively pursuing the development of leaf rust-resistant,
awnletted cultivars with moderate-to-high forage production and
desirable external and internal quality characteristics. OK98690
fits that description.
The variability enhancement/germ plasm development program at OSU has two primary objectives: 1) incorporate new genetic diversity into the winter wheat improvement program that will serve as the basis for future increases in productivity and 2) transfer improved resistance to leaf rust into adapted winter wheat materials for Oklahoma. Spring and winter wheat materials from CIMMYT serve as the primary sources of genetic diversity. More than 3,000 lines from CIMMYT and numerous materials from other sources have been introduced in the past 4 years. All introductions are screened for multiple disease resistance and agronomic type, and the best materials were incorporated into the crossing program.
Long-term, stable leaf rust resistance has not been achieved
in the southern and central Great Plains. A new cultivar typically
maintains leaf rust resistance for a short period of time (2-4
years). As a result, breeders in the region must devote extensive
resources to breeding for leaf rust resistance. Efforts are underway
to transfer durable leaf rust resistance from CIMMYT spring wheat
germ plasm into adapted winter wheats. This resistance is characterized
by low levels of infection and generally is based on one or more
major genes plus several minor genes. Additionally, an extensive
crossing program to synthetic wheats and synthetic derivatives
developed by CIMMYT is underway and this effort has multiple objectives,
including new sources of leaf rust resistance, improved kernel
size, enhanced stay green characteristics, and improved biomass
and yield potential. For information regarding this program,
contact Dr. Art Klatt, Department of Plant and Soil Sciences,
274 Ag Hall, Stillwater, OK 74078 or via E-mail at aklatt@okstate.edu.
A.C. Guenzi.
We continue to evaluate the use of osmoprotectants to improve drought tolerance and the quality of refrigerated and frozen-dough products. Osmoprotectants are small molecules (e.g., glycine betaine, proline, trehalose, and mannitol) that raise the osmotic potential of the cell's cytoplasm to drive water uptake or that act as osmolytes to counteract imbalances caused by dehydration. Alternatively, these substances have a protective role during dehydration by stabilizing macromolecules and scavenging free radical oxygen species. During the past year, hybrids containing a transgene for mannitol biosynthesis were backcrossed to elite lines in the wheat breeding program. Physiological characterization of one transformation event is in press (Abebe et al. 2003; Plant Physiol 131:1-8).
Now that transformation has become a tool for the genetic manipulation of wheat, it is becoming apparent that the bottleneck for directing the use of this technology is having genes to transform and understanding the biology of traits we wish to manipulate. With this in mind, we have initiated a functional genomics project to understand the responses of wheat roots to soilborne fungal pathogens. A systematic characterization is being initiated to define transcription profiles between the interactions of wheat roots and 1) Gaeumanomyces graminis var. tritici 2) Rhizoctonia solani, and 3) Pythium arrhenomanes. Light and confocal microscopy was utilized to identify key stages of infection (root surface colonization, epidermis penetration, and cortex colonization) and DNA libraries for each stage were established. To date, approximately 7,000 clones have been recovered for DNA sequencing and expression analysis.