Pathogens are a reason for low yield in common wheat (Triticum aestivum L.). Stripe rust (or yellow rust), caused by the fungus Puccinia striiformis f. sp. tritici (Pst), is one of the most important foliar diseases of wheat. One of the most cost-effective and environmentally sound ways to control stripe rust is to use plant varieties that are resistant to this pathogen. It is an important task for wheat breeders and pathologists to identify new genes and pyramid them in order to achieve high-level, durable resistance to stripe rust. One spring wheat germplasm, HRMSN-81, with resistance to the most dominant races in China, is identified from the CIMMYT breeding lines. To elucidate the genetic basis of its resistance, HRMSN-81 was crossed with susceptible wheat genotype Taichung 29. Seedlings of the parents were tested with Chinese Pst isolates CYR31, CYR32, and CYR33 under controlled greenhouse conditions, and adult plants of the parents and F₁, F₂, and F_2:3 progeny were inoculated with the epidemic stripe rust mixed races, including CYR31, CYR32, and CYR33, in fields under natural infection.

Genetic analysis showed that HRMSN-81 has a single dominant gene conferring all-stage resistance, temporarily designated as YrHRMSN-81. Resistance gene analogue polymorphism (RGAP), simple sequence repeat (SSR), target region amplified polymorphism (TRAP), and sequence-related amplified polymorphism (SRAP) techniques in combination with bulked segregant analysis (BSA) were used to identify molecular markers linked to the resistance gene. A linkage map consisting of six RGAP, two SSR, one TRAP, and two SRAP markers was constructed for YrHRMSN-81 using 148 F₂ plants. The gene was mapped to chromosome arm 2DS by testing the complete set of nulli-tetrasomic lines and selected ditelosomic lines with two RGAP markers and was further confirmed by two chromosome-specific SSR markers. The results of gene characteristics and chromosome locations indicated that YrHRMSN-81 was probably a new stripe rust resistance gene. The two flanking markers Xwgp-180bp (93% polymorphism rate) and Xwmc453 (91% polymorphism rate) detected 100% polymorphism of the 56 tested wheat genotypes when they were used in combination. The identification of the gene YrHRMSN-81 and the determination of the flanking markers should be useful for rapidly transferring it in wheat breeding programs.

Current models of sorghum crop growth predict grain number using a calculated plant growth rate around flowering and a genotype-dependent parameter that describes the relationship between both traits. Few values for this parameter have been reported, being similar within triple-dwarf or single-dwarf sorghum genotypes. This approach narrows genotypic differences in grain number determination mostly to differences in traits affecting biomass production. Relevant traits such as biomass partitioning to reproductive structures and grain-set efficiency are not specifically considered, but both vary across genotypes and could improve grain number estimations. We first explored variation for these traits (CGR, crop growth rate around flowering; P_R, biomass partitioning to reproductive structures during this period; E_G, grain set per unit of accumulated reproductive biomass) for a set a sorghum commercial hybrids and inbred lines growing under different conditions. Later, we used a second set of experiments to test whether considering genotype-specific P_R and E_G improved estimates of grain number compared with the current approach used in crop simulation models.

Grain number variations (14–63 × 10³ grains m^–2) due to genotype and environment were a consequence of significant differences (P < 0.05) in all analysed traits (CGR, P_R, E_G). Biomass partitioning and grain set per unit of accumulated reproductive biomass showed consistent genotypic differences (P < 0.001); however, they also showed significant environment or genotype × environment effects. When these specific genotypic parameters dealing with biomass partitioning and grain-set efficiency were used for estimating grain number in other non-related experiments, the predicted accuracy improved (r² = 0.47, P < 0.05, RMSE = 7029 grains m^–2) relative to the general approach using a constant parameter for most genotypes (r² = 0.14, P < 0.28, RMSE = 12 630 grains m^–2) or a calculated parameter for each genotype (r² = 0.38, P < 0.10, RMSE = 8919 grains m^–2). We propose that these traits (P_R and E_G) need to be considered and included in sorghum crop growth models, as they help predict grain number performance of different genotypes in different growth environments.

We investigated variability in the response of oil fatty acid composition to temperature among high stearic and high stearic-high oleic sunflower (Helianthus annuus L.) genotypes. Two experiments were conducted with high stearic (including the CAS-3 mutation) and high stearic-high oleic inbred lines (including both the CAS-3 and the high oleic Soldatov mutations). Plants were cultivated in pots with soil, irrigated, and fertilised. Plants were exposed to different day/night temperatures during grain filling: 16/16°C, 26/16°C, 26/26°C, and 32/26°C. Oil fatty acid composition was determined by gas–liquid chromatography in seeds harvested after physiological maturity. Higher temperature during grain filling increased palmitic and oleic acid percentages and reduced stearic and linoleic acid percentages, suggesting some modifications on enzymatic activities. When the high oleic mutation was included, the variation in stearic and oleic acid percentages in response to temperature was reduced but not the variation in palmitic acid concentration. Variations in fatty acid composition in high stearic genotypes were mainly associated with night temperature as reported previously for traditional and high oleic hybrids. Knowing the effect of temperature on oil fatty acid composition in traditional and mutated genotypes is useful for selecting the environment in which to produce grains with the desired oil quality.

White clover is an important pasture legume of temperate regions, generally through co-cultivation with a pasture grass in a mixed-sward setting. White clover provides herbage with high nutritional quality to grazing animals, along with the environmental benefit of biological nitrogen fixation. Several key agronomic traits are amenable to modification in white clover through use of transgenic technology. Efficient methods for Agrobacterium-mediated transformation of white clover have been developed. The current status of transgenic research is reviewed for the following traits: resistance to viruses and insect pests; aluminium tolerance and phosphorus acquisition efficiency; control of leaf senescence and seed yield; biosynthesis of flavonoids and rumen bypass proteins for bloat safety and enhanced ruminant nutrition; cyanogenesis; and drought tolerance. Future prospects for transgenic technology in molecular breeding in white clover are also discussed.

The temperate pasture grass Lolium perenne L. is commonly found in association with the fungal endophyte Neotyphodium lolii. Viability of both seed and endophyte was evaluated by inoculation of individual genotypes from the host cultivar Bronsyn with six distinct endophyte strains. The resulting populations were subjected to either long-term storage under various temperature conditions, or accelerated ageing (AA) treatments. High temperature storage was detrimental to endophyte viability. The AA variables (relative humidity [RH] and time) and subsequent temperature and duration of storage significantly (P < 0.05) affected both seed germination and endophyte viability. Significant interaction effects between the AA treatment and storage conditions were also observed. Endophyte viability following AA treatment was inversely correlated with both increasing RH and duration of treatment. Differential responses between different endophytes within the Bronsyn host were also apparent. The standard endophyte (SE) strain and the novel endophytes AR1 and AR37 exhibited higher viability than NEA2, NEA3, and NEA6 during seed storage, suggesting the importance of identification and selection for compatible symbiotic associations in agronomic varieties. The observed similarity between assessments of endophyte viability after AA treatments and following long-term storage confirmed the capacity of moderate conditions (e.g. 80% RH for 7 days or 100% RH for 4 days) to predict variation in viability between different endophyte strains.

Increasing the supply of sulfur (S) to forage plants can change their nitrogen (N) metabolism, causing changes in the N : S ratio that can potentially affect forage production and quality. The present study was focussed on revealing how supply (low, intermediate, high) of S affects amino acid composition and concentrations of total S, total N, sulfate-S, nitrate-N, and soluble protein in the leaves of tropical pasture species.

Greenhouse experiments were conducted in ground quartz (inert solid substrate) culture to examine the effect of S supply in two tropical species: Panicum maximum cv. Tanzania (Guinea grass) and Stylosanthes guianensis cv. Mineirão (stylo). Because legumes have greater S requirement than do grass species, application levels of S varied according to the species. Guinea grass was grown with 0.10, 0.55, 1.00, 1.45, and 1.90 mmol L⁻¹ of S, and stylo with 0.10, 0.70, 1.30, 1.90 and 2.50 mmol L⁻¹ of S. Plants of both species were harvested on two occasions.

Low S availability (0.10 mmol L⁻¹) caused a nutritional imbalance with N in Guinea grass and stylo plants, as shown by a high N : S ratio (>60 : 1), and high concentrations of nitrate-N and free amino acids in plant tissues. Increased S supply regulated the N : S ratio at values close to 20 : 1, which provided N and S concentrations more suitable for protein synthesis and optimum forage production for both forage species. Asparagine was the predominant amino acid present in S-limited Guinea grass, whereas arginine was more abundant in S-limited stylo. This result indicates that a limitation of S increases nitrate-N and free amino acids while decreasing plant growth rates and soluble protein concentrations in these forage species.

Grazed pastures in south-eastern Australia are typically based on temperate (C₃) species, such as perennial ryegrass (Lolium perenne). With predictions of warming to occur in this region, there has been growing interest in the performance of more heat-tolerant and deep-rooted subtropical (C₄) pasture grasses, such as kikuyu (Pennisetum clandestinum). This study used an existing pasture model to estimate the production of kikuyu compared with the commonly used perennial ryegrass at seven sites in south-eastern Australia, using an historical baseline climate scenario between 1971 and 2010, and the daily temperature of the baseline scenario adjusted by 1, 2, and 3°C to represent potential warming in the future. The seven sites were chosen to represent the range of climatic zones and soil types in the region. First, the model predictions of monthly kikuyu dry matter (DM) production were validated with measured data at Taree, Camden, and Bega, with results showing good agreement. Second, pasture production (t DM/ha), metabolisable energy (ME, MJ/kg DM) content, and ME yield (GJ/ha) were predicted using the baseline and warmer climate scenarios. The study was based on 56 simulations of the factorial arrangement of seven sites × four temperature scenarios × two pastures. The month and annual ME yield of a kikuyu–subterranean clover (Trifolium subterraneum) pasture and a perennial ryegrass–subterranean clover pasture were compared. This study showed that in summer-dominant rainfall locations, where the average maximum temperature is >23°C, kikuyu was a more productive pasture species than perennial ryegrass. In winter-dominant rainfall locations during the warmer months of December–March, kikuyu can provide a useful source of ME when perennial ryegrass is less productive. With warming of up to 3°C at the winter-dominant rainfall sites, the average ME yield per year of kikuyu was predicted to surpass that of perennial ryegrass, but inter-annual variation in kikuyu production was higher. The nutritive value, seasonal distribution of growth, total annual production, and its variability are all important considerations for producers when selecting pasture species.

Herbaceous perennial legumes that can provide forage in the summer–autumn dry period are urgently required in Mediterranean climates to complement annual pastures and the perennial legume lucerne (Medicago sativa). This study evaluated the establishment, survival, and herbage production of tedera (Bituminaria bituminosa var. albomarginata) and Cullen spp. native to Australia. Two experiments were replicated at Buntine (warmer site) and Newdegate (cooler site) in the low-rainfall cropping zone (<350 mm average annual rainfall) of Western Australia from June 2008 to September 2010. In the first experiment, established by transplanting seedlings, survival and herbage production of two accessions each of B. bituminosa and C. australasicum were studied under densities of 1, 2, 4, 8, and 16 plants/m² with 0, 1, 2, or 3 cuts in summer–autumn in addition to a winter–spring cut. In the second experiment, established from seed, emergence and survival of several accessions of B. bituminosa, C. australasicum, and M. sativa were studied, along with C. pallidum and C. cinereum.

In the first experiment, B. bituminosa survived better than C. australasicum (70–80% v. 18–45%), especially at Buntine, but there was little impact of density or cutting frequency on survival. Plant death was highest during summer. Shoot dry weight (DW) accumulation varied greatly with site, year, and plant density. When rainfall was close to average, shoot DW was greater at Newdegate (B. bituminosa ≤7.4 t/ha, C. australasicum ≤4.5 t/ha) than at Buntine (≤2.3 t/ha), and both species produced much of their shoot DW in summer–autumn (e.g. 6 t/ha for B. bituminosa and 3 t/ha for C. australasicum at Newdegate). An early-summer cut reduced the DW that could be harvested later in summer–autumn. In the second experiment, emergence of B. bituminosa was either similar to, or higher than, emergence of the other species, being 43% at Buntine and 44% at Newdegate. Survival of B. bituminosa, compared with M. sativa, was similar at Buntine (13%) and slightly lower at Newdegate (14%). Emergence and survival of Cullen spp. varied among species and accessions, with survival of the best performing accession of C. australasicum (SA4966) similar to that of B. bituminosa and M. sativa at both sites. We conclude that B. bituminosa shows promise as a perennial summer forage for low-rainfall zones, with a density of 8–16 plants/m² and cutting frequency of 3 cuts/year (i.e. cut twice in summer–autumn), while C. australasicum and C. pallidum warrant further study.