LESLIE RESEARCH CENTRE
(formerly Queensland Wheat Research Institute)PO Box 2282, Toowoomba, QLD, 4350, Australia.
Yellow spot epidemic.
Paul Brennan, Phillip Banks, and John Sheppard.
Wheat production in northeast Australia was greatly reduced in 1998 through an epidemic of P. tritici-repentis and other factors arising from the large amount of rain experienced between August and September. A carryover of yellow spot-infected stubble from a small epidemic in 1996 may have provided the innoculum for the 1998 epidemic.
The yellow spot epidemic also had a pronounced negative effect on quality of the crop through the production of small but not pinched grain.
Other factors that may have contributed to crop loss included water logging and the melanism associated with the stem rust resistance gene Sr2, which was prominently expressed even by varieties considered to have high levels of supression of this attribute.
The total loss to wheat growers in northeast Australia has been estimated to be AUS$ 400,000,000.
Breeding activities.
Paul Brennan, Phillip Banks, and John Sheppard.
Data from most of the yield trials conducted in 1998 reflected yellow spot resistance and consequently will be of limited value for selection for yield. A surprise from the season was the number of parential lines used for attributes other than yellow spot that exhibited useful levels of yellow spot resistance.
Unfortunately, the level of yellow spot in seed production and selection nurseries was low, which was caused by escape due to purposefully late planting. Good evaluation for yellow spot resistance in this material was not possible.
The Queensland grain growers have determined that they wish to have varietal (genetic) solutions for yellow spot and other diseases and pests that can cause considerable crop loss. They are requesting that funding be made available to have at least one variety for each maturity group that, in addition to yield, quality, and rust resistance, has resistance to yellow spot, crown rot, the root lesion nematode, blackpoint, and sprouting by the year 2010.
Research. Three students are nearing the submission of their theses, Ma Wujun, Steve Kammholz, and Rachelle Grams. Their work has focussed on the relevance of doubled haploids and their use in identifying molecular and protein markers for quality attributes. A number of markers have been identified and their implementation in the breeding program will now be considered.
Varieties released.
Paul Brennan, Phillip Banks, and John Sheppard.
Baxter. Baxter is an intermediate variety that is seen as a replacement for Cunningham. The advantages of Baxter over Cunningham include yield, quality, crown-rot resistance, and root lesion nematode tolerance.
Kennedy. This variety is derived from the cross 'Hartog / Veery #5' and is seen as an alternative to Hartog, because of its superior baking quality and moderate yellow spot resistance.
Foliar diseases.
P.M. Williamson, M. Michalowitz, and P. Horne.
The winter cereal crop in southern Queensland endured one of the wettest seasons on record, which provided ideal conditions for foliar diseases. Yellow spot was the most conspicuous disease on wheat crops, particularly where recommended stubble management practices were not adhered to. Wheat varieties with partial resistance to yellow spot performed much better than susceptible varieties, even where these resistance levels are quite low. Although grown only in small areas, the newly released variety Leichhardt performed relatively well, as did Hybrid Mercury, Sunlin, Kennedy, and the durum Yallaroi.
Saturated soils produced high humidity during grain filling and ripening and provided optimum conditions for black point levels to increase in susceptible varieties. Grain from varieties that were badly damaged by yellow spot did not show high levels of black point, but other varieties, particularly Sunlin, frequently showed levels of over 40 % discoloration.
Biotechnology.
S. Weining and M. Osborne.
The biotechnology laboratory at the LRC was substantially upgraded in 1998. This lab has now been equipped to handle a range of molecular biology projects that involve recombinant DNA and radioisotopes. The major task of this lab is to provide assistance to the wheat and oat breeding programs at the LRC with the development and application of various molecular markers. In addition to a number of markers obtained from other labs in Australia and overseas, we are focusing our attention on the development of microsatellite and AFLP markers. We also are participating in the Wheat Microsatellite Consortium organised by Agrogene. Other marker-related projects include rust resistance in oat, cereal variety identification, and nematode DNA fingerprinting. As part of the tradition of this lab, research in preharvest sprouting in wheat used the barley alpha-amylase inhibitor gene. Furthermore, the genetic basis of preharvest sprouting will be addressed through gene regulation by a newly funded project.
Wheat x maize-derived doubled haploids for genetic studies of dough properties.
S.J. Kammholz, P.M. Banks, and M.W. Sutherland.
Improved flour quality is a major objective of the Northern Wheat Improvement Program. Pliable doughs with short mixing requirements are necessary for modern high-speed bakeries. The initial aim of this study was to develop a doubled haploid wheat population, suitable for a genetic study, from an F1 between parents with a wide range of quality characteristics. Grain produced from this population was harvested from several trials sites in 1997 and 1998, and quality assessments were made. Detailed evaluation of these lines should give a better understanding of the genetic mechanisms of wheat quality characters.
A doubled-haploid population derived from a 'Neeepawa / Hartog' F1 was used for this study. A wide variation in quality was evident within this population despite both parents containing 5 + 10 at the Glu-1d locus, the glutenin locus reported as having a major influence on properties such as dough strength. Other characters are currently being screened in the hope of finding associations with quality traits. Only 1 of 2 years of quality analysis is completed. The results todate highlight the environmental influences on certain wheat quality characters, particularly in longer season wheats. The level of variation for all quality characters indicated to the possibility for genetic improvement in these traits. Once the quality analysis has been completed for the second year, a better understanding of other influences (e.g., G x E) can be established.
Synthetic-derived lines yield well despite conditions.
I. Haak.
The weather conditions of last season were ideal for the development of a yellow spot epidemic. Many varieties performed very poorly, although this was not the case with lines derived from a number of synthetics. In a trial at Condamine on the Darling Downs, several of these lines yielded in excess of 5 t/ha, with the top yield being over 5.7 t/ha. The site was chosen as a root-lesion nematode tolerance trial because of the high numbers of nematodes present in the soil. Yields of commercial lines in the trial were much lower than expected, with the best of them being Kennedy at 2.3 t/ha. Sunvale, which normally yields near the top of the root-lestion nematode tolerance trials, produced only 1.6 t/ha. Without yellow spot, it would have yielded an estimated 4.8 to 4.9 t/ha. The high yields of the synthetic derived lines were due to a combination of good nematode tolerance and good yellow spot resistance. Many of these lines were already known to have levels of yellow spot resistance as high or higher than that of Kennedy.
Resistance to root-lesion nematodes.
N. Seymour, J. Thompson, and T. Clewett.
Our aim is to develop methods that screen single wheat plants in order to rapidly breed wheat varieties with superior resistance to root-lesion nematodes. These nematodes cause major yield losses to wheat crops in southern Queensland and Northern New South Wales. Damage is likely to be severe when wheat is grown after wheat. Farmers growing intolerant wheat varieties can expect yield losses of more than 50 % where soils are infested with RLNs. Crop rotation and variety selection holds the key to managing RLN when numbers are high. Currently, only RLN-tolerant varieties are available commercially. These varieties grow and yield well in the presence of RLN, but the nematodes continue to multiply. Resistant varieties prevent the nematode from multiplying, but there are no commercial wheat varieties resistant to P. thornei. The work on this project is vital for the rapid development of RLN-resistant lines.
Under this project, we have identified several valuable sources of resistance among wheat varieties from the Middle East that could be used in Australian wheat breeding programs. Results todate have helped develop a single plant test that is efficient, reliable, and reproducible. Methods that reduce the time taken for nematode extraction and quantification have been developed, making our resistance tests more applicable to large-scale breeding programs. Progress has been good in determining a method whereby in one generation, plants can be assessed and backcrossed if they show resistance, and seed collected at maturity.
Soilborne diseases in Queensland.
G.B. Wildermuth, R.B. Mcnamara, and T. Sparks.
Because of the extremely wet season in 1998, crown rot was not as serious as it had been in previous years in southern Queensland. However, numerous reports were received from central Queensland. Previously, crown rot had been found only in isolated areas in this district. Few dead heads occurred in field experiments, and discrimination between genotypes will not be as good as in previous years.
In early October, symptoms of head blight were found in a number of wheat crops throughout all wheat areas of Queensland. These symptoms were accompanied by rapid senescence of the head. Isolation from glumes indicated that F. graminearum group1 was present in 23 % of samples. This group of the fungus is responsible for crown rot. Causes of the blighting in the remainder of the heads is unknown but probably could be ascribed to the extreme wet conditions of the season. Subsequent testing of grain could not detect any toxins. Fungal isolations from grain from throughout the state showed that F. graminearum was present in all areas, with an overall incidence in samples of 25 %. Levels of infection in samples were mostly less than 1 %, although a few samples had levels of up to 5 %.
Microscopic holes also were detected in the testa of some grains. Known as fractured grain, this symptom was found throughout southern Queensland at levels of 15 %. Emergence tests with fractured and unfractured grain treated and untreated with Vitavax showed that emergence was not affected by this condition.
THE UNIVERSITY OF SYDNEY
PBI Cobbitty and Department of Crop Sciences, Private Bag 11, Camden, NSW, 2570; and Sydney, 2006, Australia.
F. Afshari, H.S. Bariana, J. Bell, L.W. Burgess, G.N. Brown, K.S. Gosal, M. Hayden, D.R. Marshall, R.A. Mcintosh, J.D. Oates, R.F. Park, P.J. Sharp, F.L. Stoddard, C.R. Wellings, A. Zakeri, and C. Zhao.
Cobbitty: national cereal rust control program.
Despite relatively wet conditions, stem rust occurred at extremely low levels throughout most of eastern Australia. However, the December survey of long-season wheats in Victoria and South Australia (SA) found a wide distribution of stem rust throughout the region; rust levels within individual crops were generally low, and no crop losses were anticipated. The variety Paterson was as susceptible as Lawson, Declic, and More, indicating that pathotype 98 1,2,3,5,6 was involved. No rust was found in Gordon. In the March 1998 survey, stem-rusted wheat and barley were found at Langhorns Creek, near Murray Bridge, SA. These crops consisted of a summer increase of wheat for the University of Adelaide and summer-sown barley growing under irrigation.
Early infections of stem rust were reported in West Australia (WA), but epidemic conditions did not eventuate. Pathotypes identified from Victorian and SA samples included 98-1,2,3,5,6, 343-1,2,3,5,6 and 21-2,7 (1 sample), whereas those in WA samples were 34-2,7 and 34-2,7,10.
Leaf rust was widespread throughout southeastern Australia and WA during the 1998 season, reaching damaging levels in irrigated crops of Triller in the Murrumbidgee Irrigation Area and in some parts of SA. Rust also was detected in long-season wheats in mid December. Of the samples processed to date, all were either 104 1,2,3,(6),(7),11 (all mainland states); the Triller pathotype 104-1,2,3,(6),(7),9,11 (mainly in southern NSW, but also SA and Victoria), 53-1,(6),(7),10,11,12 (on long season wheat in Tasmania); or 76-1,3,5,10,12 (on long-season wheat in NSW and Victoria). The suffix '12' indicates virulence on seedlings of Harrier, which has Lr17b.
Leaf rust was observed on Paterson winter wheat in Victoria and on the northern NSW tablelands. Declic and More also may be affected by the same pathotype.
Stripe rust was found on wheat at very low levels in 1998. A notable exception was heavy stripe rust on Warden wheat grown near Ballarat in a mixture with a tall oat for use for chaff. However, barley grass, both in cereal crops and pastures, showed a significant increase in the incidence of stripe rust. Many of the stripe rust samples from barley grass proved virulent on the wheat differential Chinese 166 but were either avirulent or significantly less aggressive on virtually all other wheats. Overseas, barley stripe rust has been noted to have these characteristics, and tests on certain barleys indicated greater aggressiveness than wheat stripe rust controls.
Initially, we concluded that we had barley stripe rust in Australia, but more recent tests indicate that the new rust is not particularly aggressive on barley, and the responses of selected Australian barleys were not as we would expect from tests on such barleys in Mexico. These results are consistent with the fact that despite the widespread occurrence of the new rust, barley crops were not affected. One sample came from Skiff barley, but in the past, occasional samples of wheat stripe rust also came from barleys. We now believe this is an introduced grass rust probably adapted to wild barleys.
Virulence for Yr17 has been detected in New Zealand. Several Australian wheats, including Sunbri, Sunstate, Sunvale, and Trident, have this gene.
Host genetics: seedling resistances. The separate identity of a gene for resistance isolated from an Israeli line with Yr15 has not been confirmed. The putatively new resistance gene was recognized by slight changes in symptoms of the resistance response. F2 populations are available for tests of linkage involving Yr15, Yr24, and Yr10, all of which occur on chromosome 1BS. This work is currently being undertaken by a Ph.D. student, Mr. A. Zakeri.
A gene for stripe rust resistance isolated from the European wheat Carstens V was located in chromosome 2A. Crosses were made to determine genetic linkage with other genes known to be on this chromosome. This work is being continued by a Ph.D. student, Mr. F. Afshari.
A gene for stripe rust resistance derived from the European wheat Spaldings Prolific was located in chromosome 2B. Linkage studies are being continued by a Ph.D. student, Mr. K. Gossal.
Leaf rust resistance gene, Lr11, was located on chromosome 2d. Crosses were made to study linkage with other genes in this chromosome, Lr2, Lr15, and Lr22. The NIL 'Tc / Lr11' has a dominant gene for grass clump dwarfism, and D4 may be present.
Stripe rust resistance gene Yr27 showed a close repulsion linkage with Lr13. Larger segregating populations are being tested.
Adult plant resistances: stripe rust. A major disappointment in 1998 was the failure to obtain a satisfactory epidemic for stripe rust screening at the PBIC testing sites. Despite apparently suitable conditions and several attempts to produce infections, stripe rust developed only sporadically. All trials aimed at obtaining adult plant response in the field were unsatisfactory. By contrast, infections of leaf rust and stem rust were excellent.
A project on the development and global testing of a set of NILs based on Avocet 'S' for field studies of variability in P. striiformis is being supported by the Australian Centre of International Agricultural Research. We obtained data from 15 sites in 1998. The project will continue for another 3 years.
Germ plasm screening and enhancement. Stem rust and leaf rust infections in field plots were excellent. A stripe rust epidemic did not develop, despite repeated inoculations of spreaders and experimental plots.
Routine tests. Each breeding organization submitted average numbers of entries for screening. A total of 36,504 lines was screened as routine single seedling tests for stem rust and leaf rust response and at field test sites with two stem rust pathotypes [98-1,2,3,5,6 (Sr9g-virulent) and 343-1,2,3,5,6,8,9 (Sr30-virulent)]; two leaf rust pathotype groups [104-2,3,6,(7) + 53-1,5,(6),(7),11 (Lr13-virulent) and 104-1,2,3,(6),(7),11]; and one stripe rust pathotype (110 E143A+).
Detailed tests. We tested 395 entries with seven stem rust pathotypes, five leaf rust pathotypes, and four stripe rust pathotypes in the greenhouse. These entries were field tested in the routine manner.
THE UNIVERSITY OF SYDNEY
IA Watson Wheat Research Centre, Narrabri, 2390, NSW Australia.
L. O'Brien, F.W. Ellison, and S.G. Moore.
In October 1998, the Centre held a field day to celebrate 40 years of service to the grains industry. Established by the grain growers of the region in 1958, the Centre is unique in that the property is still owned by the growers and leased to the university for grains research. The first soft-grained wheat variety to be developed by the university was released for commercial production at the field day.
The new variety Sunsoft 98 is based on the popular southern NSW-grown soft wheat Rosella, but has superior resistance to stem rust. Sunsoft 98 is a bearded, semidwarf, winter wheat that has a similar yield and flowers and matures at the same time as Rosella. At low protein levels, the flour of Sunsoft 98 has dough properties that make it suitable for sweet biscuits and cakes. At intermediate protein content, its high starch paste viscosity results in the desired textural properties required by Asian markets for the production of white salted noodles. At high protein content, the high starch paste viscosity again contributes to it being good for starch and gluten separation. Consequently, the quality attributes provide for a wide range of soft wheat applications across the range of protein contents experienced by growers in northern NSW.
The 1998 season saw above-average annual rainfall, with Narrabri receiving 597 mm between April and October (the growing season). This is almost the annual average for the area (603 mm). Extended periods of leaf wetness during winter and early spring promoted development of yellow spot. Susceptible varieties were defoliated shortly after flowering, and light-weight grain was common in commercial crops. The best performing entries in regional trials were almost without exception those lines with some yellow spot resistance.
Late maturity alpha-amylase (LMA) in wheat.
K. Mrva.
LMA, a genetic defect that results in unacceptably high levels of grain a-amylase at maturity in the absence of sprouting, is widespread in Australian breeding programs. Cultivars containing the LMA gene respond to cool temperatures during mid-grain filling by producing high PI (germination-type) alpha-amylase isozymes coded by the a-Amy-1 genes located on the long arms of the group 6 chromosomes, seemingly from the entire aleurone.
A new screening procedure, utilizing detached tillers (ear, flag leaf, and stem with 2 or 3 nodes) from field or greenhouse-grown plants approximately 20 days after anthesis, was developed. The new system has proved as effective as intact plants and greatly reduces the amount of greenhouse or controlled-environment space required.
Recent screening for breeders has highlighted the severity of this defect in some Veery lines (1, 5, and 7) and a high proportion of released cultivars and high-yielding breeding lines derived from Veery 5.
Preharvest sprouting tolerance.
D.J. Mares.
Several advanced breeding lines with sprouting tolerance derived from the dormant white-grained wheat AUS1408 were compared with sprouting-susceptible Australian prime hard wheats, Janz and Hartog, and with a sprouting tolerant cultivar, Sunlin, developed by Dr. Frank Ellison. The original cross involved the moderately tolerant varieties Sunelg and Suneca. Samples were compared at 0, 10, and 20 days-after-harvest ripeness (12 % moisture) using germination of isolated grains and the effect of a standard wetting treatment on falling number. The performance of some of the AUS1408 derivatives was similar to that of the tolerant parent, whereas others showed a variable but generally intermediate tolerance. Tolerance in the latter group appeared to be much more sensitive to changes in environmental conditions or agronomic changes. These genotypes possibly do not contain all of the tolerance genes present in AUS1408. The cultivar Sunlin appeared to be more tolerant than either of its parents and in some trials also was similar to AUS1408.