TEXAS
TEXAS A&M UNIVERSITY
Amarillo.
M.D. Lazar, G.J. Michels Jr., C.D. Salisbury, W.C. Wang, K.B. Porter, and
G.L. Peterson.
High Plains crop year. Most of the 1996-97 crop year was dry, with a total of 2.39 inches of precipitation falling at Bushland from October through March. In addition, for the third year in the past 4, severe freeze damage occurred in the spring. The temperature at Bushland reached a low of 15°F on April 13. Most primary tillers but few crowns appeared severely damaged, so that April rainfall totalling 5.60" at Bushland resulted in excellent dryland yields but relatively little irrigation advantage. In dryland variety tests, no varieties yielded less than 30 bu/A, but greatest yields of 45-50 bu/A were observed for Hickok, 2137 and TAM 200. Irrigated nurseries were provided about 11.5" of water in May, and the greatest yields under irrigation were those of Ogallala, TAM 200, and TAM 105, at over 80 bu/A.
Wheat genetics. Closely related wheat lines (BC3 sister lines)
differing in response to irrigation and NILs differing for resistance to
biotype E greenbug have been characterized previously for physiological
and agronomic performance. Recent efforts have focused on development of
methods for tagging genes for these traits. We have developed an amplified
fragment length polymorphism (AFLP) method for wheat that distinguishes
among the above sets of lines. Using two restriction enzymes and eight combinations
of primers, we identified 42 polymorphisms between two NILs and 60 among
three of the backcross sister lines. Field and laboratory analysis of population
growth of biotype E greenbugs confined to resistant or susceptible NILs
have continued to indicate that although resistance is largely antibiosis
based, resistant wheat in combination with greenbug predation by Coccinellids
may be more effective than either control method alone. In the past year,
we also have successfully produced the first stable hard red winter wheat
transformants via particle bombardment. Stable transformation was demonstrated
by GUS and BAR expression in multiple tissues of T2 generation plants, as
well as by amplification of a region of the GUS gene using primers specific
to that region.
Publications.
Lazar MD, Worrall WD, Peterson GL, Porter KB, Rooney LW, Tuleen NA, Marshall DS, McDaniel ME, and Nelson LR. 1997. Registration of 'TAM 110' wheat. Crop Sci 37:1978-1979.
Lazar MD, Piccinni G, Xue Q, Wang WC, Salisbury CD, and Saulescu NN. 1997. Yield variation among closely related wheat lines under water stress is related to root length and osmotic adjustment. Plant Physiol 114:107.
Michels GJ Jr, Lazar MD, Fritts DA, and Booker JD. 1997. Biotype E greenbug
reproduction and development through three generations on resistant and
susceptible winter wheat genotypes. Southwest Ent (in press).
College Station / Vernon.
A. Fritz, W.D. Worrall, S. Caldwell, N. Tuleen, and R. Herrington.
1997 crop year. A cooler than average spring resulted in a late harvest in south Texas. The highest yielding commercial cultivars at Uvalde were Ogallala (64.5 bu/A), Jagger (64.4), and TAM 201 (61.8). Leaf rust infection was moderate to severe at all South Texas locations.
Russian wheat aphid. An F2 population between PI 386156, a resistant Russian triticale and NE88T222, a susceptible triticale, was used to examine the inheritance of resistance to the RWA. Five distinct classes of reaction to the RWA were observed, indicating that this trait is not controlled by a single dominant gene in this population. Bulked segregant analysis was performed, using DNA from plants representing the most resistant and most susceptible classes. A codominant marker amplified by primer OP-M09 explains more than 60 % of the variation observed for resistance. Sequencing results revealed a deletion in the 'S' parent relative to the 'R' parent. Using a set of wheat-rye addition lines, the target fragment was mapped to chromosome 4R, which has been identified previously as the critical chromosome for RWA resistance from PI 386156 and other Russian triticales.
Greenbug. KS81H1640GB was used as the source of Gb4 and crossed with the D-genome Chinese Spring monsomics. Monosomic analysis placed this gene on chromosome 7D. In addition, KS89WGRC04, which carries a previously unmapped Ae. tauschii-derived gene for resistance to greenbug also was crossed with the D genome monosomics. The gene in KS89WGRC04 also was found to reside on chromosome 7D.
David Marshall was on sabbatical leave during 6 months of 1997 at AgResearch
in Palmerston North, New Zealand, studying wheat:fungal endophyte interactions.
Overton.
L.R. Nelson, S. Ward, and J. Crowder.
Wheat grain yields in 1997 were near normal with the mean yield in the
uniform variety test at Overton at 50 bu/A. In the variety test at Overton,
the highest yielding cultivars were Coker 9134 (61 bu), Jaypee (59), Pioneer
2684 (57), Pioneer 2580 (56), and Clemens (55 bu/A). The highest yield experimental
lines were TX87-57 and TX86-6 with 57 and 56 bu/A, respectively. At Mt.
Pleasant, Pioneer 2571 produced a yield of 96 bu/A in the variety trials
. Leaf rust and powdery mildew disease levels were sufficient to obtain
good disease ratings on all nurseries. Research on Stagonospora nodorum
(Septoria glume blotch) on wheat continues. Results indicate that two good
sources of resistance in our soft red winter wheats are TX18NT (PI 602363)
and TX82-11. A hard wheat that also has excellent resistance is SWM14240
a germplasm from CIMMYT. Crosses are being made to pyramid several sources
of resistance into new lines with superior resistance to glume blotch disease.
Publications.
Lazar MD, Worrall WD, Peterson GL, Porter KB, Rooney LW, Tuleen NA, Marshall DS, McDaniel ME, and Nelson LR. 1997. Registration of 'TAM 110' wheat. Crop Sci 37:1978-1979.
Nelson LR, Ward SL, Crowder J, and Du CG. 1997. Forage variety tests for small grains at Overton in 199495 and 3-year means. In: Forage Research in Texas, 1996. TAES CPR-5258 p. 1-6.