Anthony O. Anyia

Gene discovery in cereals through quantitative trait loci and expression analysis in water-use efficiency measured by carbon isotope discrimination.

Drought continues to be a major constraint on cereal production in many areas, and the frequency of drought is likely to increase in most arid and semi-arid regions under future climate change scenarios. Considerable research and breeding efforts have been devoted to investigating crop responses to drought at various levels and producing drought-resistant genotypes. Plant physiology has provided new insights to yield improvement in drought-prone environments. Crop performance could be improved through increases in water use, water-use efficiency (WUE) and harvest index. Greater WUE can be achieved by coordination between photosynthesis and transpiration. Carbon isotope discrimination (Δ(13) C) has been demonstrated to be a simple but reliable measure of WUE, and negative correlation between them has been used to indirectly estimate WUE under selected environments. New tools, such as quantitative trait loci (QTL) mapping and gene expression profiling, are playing vital roles in dissecting drought resistance-related traits. The combination of gene expression and association mapping could help identify candidate genes underlying the QTL of interest and complement map-based cloning and marker-assisted selection. Eventually, improved cultivars can be produced through genetic engineering. Future efficient and effective breeding progress in cereals under targeted drought environments will come from the integrated knowledge of physiology and genomics.

Quantitative trait loci for water-use efficiency in barley (Hordeum vulgare L.) measured by carbon isotope discrimination under rain-fed conditions on the Canadian Prairies

Barley (Hordeum vulgare L.) yield is commonly limited by low rainfall and high temperature during the growing season on the Canadian Prairies. Empirical knowledge suggests that carbon isotope discrimination (Δ13C), through its negative relationship with water-use efficiency (WUE), is a good index for selecting stable yielding crops in some rain-fed environments. Identification of quantitative trait loci (QTL) and linked markers for Δ13C will enhance its use efficiency in breeding programs. In the present study, two barley populations (W89001002003xa0×xa0I60049 or Wxa0×xa0I, six-row type, and Meritxa0×xa0H93174006 or Mxa0×xa0H, two-row type), containing 200 and 127 recombinant inbred lines (RILs), were phenotyped for leaf Δ13C and agronomic traits under rain-fed environments in Alberta, Canada. A transgressive segregation pattern for leaf Δ13C was observed among RILs. The broad-sense heritability (H2) of leaf Δ13C was 0.8, and there was no significant interaction between genotype and environment for leaf Δ13C in the Wxa0×xa0I RILs. A total of 12 QTL for leaf Δ13C were detected in the Wxa0×xa0I RILs and 5 QTL in the Mxa0×xa0H RILs. For the Wxa0×xa0I RILs, a major QTL located on chromosome 3H near marker Bmag606 (9.3, 9.4 and 10.7xa0cM interval) was identified. This major QTL overlapped with several agronomic traits, with W89001002003 alleles favoring lower leaf Δ13C, increased plant height, and reduced leaf area index, grain yield, harvest index and days to maturity at this locus or loci. This major QTL and its associated marker, when validated, maybe useful in breeding programs aimed at improving WUE and yield stability of barley on the Canadian Prairies.

Mycorrhizal inoculation and nitrogen fertilization affect the physiology and growth of spring wheat under two contrasting water regimes

AimsMost plants benefit from mycorrhizal symbiosis through their improved abilities to take up nutrients and water. Information on the interactive effects of fungal inoculation, nitrogen (N) fertilization and drought on water use efficiency (WUE) and productivity of Canadian wheat varieties is scanty.MethodsIn this study, we investigated the effects of arbuscular mycorrhizal fungi (AMF) inoculation, N fertilization and water regime (well-watered (WW) vs water-deficit (WD)) on WUE, phosphorus (P) and N uptake and growth of spring wheat (Triticum aestivum var. Superb) in a greenhouse experiment.ResultsThe specific leaf area (SLA) of flag leaves was significantly increased by AMF inoculation under the two water regimes but was lowered under N fertilization and drought conditions. The AMF inoculation significantly enhanced relative water content under WD. The WUE and instantaneous WUE (WUEi) were enhanced by N fertilization and AMF inoculation under both water regimes. Combined N fertilization and AMF inoculation significantly increased N concentrations in stem and grain, plant height, biomass and grain yield under WD. The P concentrations in stem and grain were increased under WD, irrespective of other treatments applied. The WUE and grain N, stem N, and P concentrations were positively correlated.ConclusionsPlant physiological characteristics were negatively affected by WD, while N fertilization and AMF inoculation enhanced plant performance under WD, including the increase of N and P concentrations in different componments of spring wheat.

Physiological characterization of recombinant inbred lines of barley with contrasting levels of carbon isotope discrimination

Background and AimsCarbon isotope discrimination (Δ13C) in C3 plants used as an indirect measure of water-use efficiency (WUE) provides a tool for selecting crops with high WUE under dry environments.MethodsWe evaluated the physiology and Δ13C of a set of 8 F5 recombinant inbred lines (RILs) with contrasting levels of leaf Δ13C derived from two parents, ‘W89001002003’ (low Δ13C) and ‘I60049’ (high Δ13C) of six-row barley (Hordeum vulgare L.) in a greenhouse and under field conditions in three locations (Lacombe, Vegreville and Castor). In the greenhouse experiment, seven days of water deficit was imposed at the stem elongation stage followed by re-watering to pre-deficit level.ResultsA significant negative relationship between WUE and leaf Δ13C was observed. Under water-deficit conditions, both photosynthetic rate (A) and stomatal conductance (gs) were significantly reduced with a strong positive correlation (r = 0.89) between the two, and the variation in gs was proportionally greater than A. The low leaf-Δ13C RIL ‘147’ maintained the highest A and gs among ten genotypes (RILs and parents) under water-deficit conditions. Leaf Δ13C was positively correlated with biomass and grain yield in the field trials. Multivariate analysis of leaf Δ13C, harvest index and plant height discriminated genotypes into three clusters: drought sensitive, drought tolerant and an intermediate type.ConclusionsThe study suggests that it is possible to select low Δ13C lines such as RIL ‘147’, which is able to maintain or produce high yields under low moisture conditions on the Canadian Prairies

Genotype, environment and G × E interaction influence (1,3;1,4)‐β‐d‐glucan fine structure in barley (Hordeum vulgare L.)

BACKGROUNDnThe structure of β-glucan influences its use in cereal-based foods and feed. The objective of this study was to determine the effect of environment (E) and genotype (G) on β-glucan fine structure and its genetic control in two-row spring barley with normal starch characteristics.nnnRESULTSnA population of 89 recombinant inbred lines, derived from the cross of two-row spring barley genotypes Merit × H93174006 (H92076F1 × TR238), was characterized for concentration and structure of grain β-glucan in two environments. Results showed that concentrations of β-glucan, DP3, DP4 and DP3 + DP4 were positively correlated with each other, suggesting no preference for DP3 or DP4 subunit production in high- or low-β-glucan lines. The concentrations of β-glucan, DP3, DP4 and DP3:DP4 ratios were significantly influenced by genotype and environment. However, only DP3:DP4 ratio showed a significant effect of G × E interaction. Association mapping of candidate markers in 119 barley genotypes showed that marker CSLF6_4105 was associated with β-glucan concentration, whereas Bmac504 and Bmac211 were associated with DP3:DP4 ratio. Bmac273e was associated with both β-glucan concentration and DP3:DP4 ratio.nnnCONCLUSIONnThe grain β-glucan concentration and DP3:DP4 ratio are strongly affected by genotype and environment. Single-marker analyses suggested that the genetic control of β-glucan concentration and DP3:DP4 ratio was linked to separate chromosomal regions on barley genome.

Nud locus and the effects on seedling vigour related traits for genetic improvement of hulless barley.

Abstract nSome hulless barley varieties have been reported to be associated with poor vigour, which can limit their yield and make them unattractive to growers. A study was conducted to determine the linkage relationship of the locus