Durum Wheat Yield Research Articles

Durum Wheat Quality, Yield and Sanitary Status under Conservation Agriculture

In Mediterranean environments the adoption of Conservation Agriculture (CA) would allow growers to achieve environmental, agronomic and economic sustainability. We investigated the effect of different combination of crop establishment treatments and crop sequence (conventional tillage (CT) and durum wheat monocropping (WW); conventional tillage (CT) and durum wheat following faba beans (WF); zero tillage (ZT) and durum wheat monocropping (WW); zero tillage (ZF) and durum wheat following faba beans (WF) on yield, grain quality traits as well as on disease incidence and severity in durum wheat (var. Saragolla). The results of two years of data of a long-term experiment (seven-year experiment; split-plot design) are discussed. The CA approach (ZT + WF), which always induced the highest grain yields (6.1 t ha−1 and 3.3 t ha−1 in 2016 and 2017) thanks to an increased number of spikes m−2 (296 vs. 269 and 303 vs. 287 spikes m−2 in 2016 and 2017, respectively) as well as a more pronounced ear length, demonstrated significantly positive influences in terms of grain quality. It promoted grain protein accumulation (12.1% for ZT + WF vs. 11.4% for ZT + WW and 12.4% for ZT + WF vs. 10.6% for ZT + WW in 2016 and 2017) and improved the gluten quality (in terms of sodium dodecyl sulphate (SDS) sedimentation test) and colour of the grain. The abundance of crop residues determined a higher incidence and severity of Zymoseptoria tritici leaf symptoms under the CA system; nevertheless, the late appearance of infection was the main reason for not affecting yield and quality traits. The presence of faba beans (WF) in the rotation significantly reduced leaf symptoms in Z. tritici.

On farm analysis of the effect of the preceding crop on N uptake and grain yield of durum wheat (Triticum durum Desf.) in Mediterranean conditions

ABSTRACTOne of the challenges of eco-efficient agriculture is the development of operational farming practices to increase the level of agricultural production, maximize the efficiency of resource use and reduce environmental impacts. Based on the efficiency frontier concept and the decomposition of resource use efficiency, we used a three-quadrant framework allowing to carry a functional analysis of the cropping system. Using a data envelope approach, we established boundary curves which represent the maximum achievable performances (yield, N uptake) when N is the only limiting factor. This framework has been first implemented and tested using published data from 112 agronomic situations of rainfed durum wheat in experimental fields in northern Syria and then further applied on a data set of 245 agronomic situations of durum wheat in farmers’ fields in two grain-producing regions of Tunisia. The results demonstrated the impact of preceding crops: durum wheat following legumes or vegetable showed a higher potential for N uptake but with only a minor effect on its conversion into grains. This positive effect of diversified rotation on potential N uptake by durum wheat is partly of-set by increased N uptake gaps in farmer’s fields indicating a higher effect of other limiting factors.

A Maximin-minimax Approach for Identifying Drought Tolerant Genotypes Based on Yield Potential and Loss in Durum Wheat

Drought is the major cause of durum wheat yield losses in the Mediterranean and many other regions where the crop is not normally irrigated. Over three years (2010–13), 24 durum wheat genotypes representing diverse genetic materials were tested under drought and irrigated conditions. The main objectives were to assess the degree of genotypic variation for drought tolerance, characterize genotypic differences in response to drought, and identify sources of germplasm with greater drought tolerance than old and new cultivars. The percent reduction in average grain yield under drought conditions as compared to irrigated conditions was maximum (69%) during 2012–13, followed by 2010–2011 (33%) and 2011–2012 (15%). The average yields of genotypes under drought conditions differed significantly, which ranged from 1174 (correspond to old variety) to 2086 kg/ha (correspond to breeding line G2). The maximin-minimax approach, yield tolerance index (YTI) and three-dimensional (3-D) plot were used to classify genotypes for drought tolerance and yield productivity. Based on the results, two genotypes were identified as resistant and high yielding (G3 and G20), and eight genotypes (G2, G22, G8, G11, G15, G1, G9 and G5) were found to be high yielding and tolerant to drought conditions. Among the methods, the maximin–minimax approach appears to be more useful in identifying high yielding and drought tolerant genotypes as it seeks to minimize percentage yield loss while maximizing yield potential. In conclusion, considerable variability in yield and drought tolerance was observed for the durum wheat genotypes, which could be exploited at improving drought tolerance in durum wheat breeding program.

Contribution of main culm and tillers to grain yield of durum wheat: Influence of sowing date and plant traits

The question of whether tillers are a burden or a resource in durum wheat is of concern in the variable Mediterranean climates. The contribution of tillers to grain yield was investigated in commercial cultivars differing in time to anthesis, tillering and spike size, in response to three sowing dates:mid-autumn (recommended), winter, and early spring. The thermal time of phenological phases was calculated, and yield-components and floret production were analysed separately in main culm and tillers. Tiller spikes showed higher spikelet abortion coupled to lower spikelet fertility and mean kernel weight, so that grain yield was 40-60% lower than in main culm spikes. Despite this, tillers contributed 35 to 50% to plant yield. The sowing date affected tiller number rather than one tiller yield. In winter sowings (December), lower main culm yield was fully compensated by increased tiller yield, whereas shifts of sowing date to early spring (February) reduced tillering, which caused a yield loss ranging from 12 to 20%. Cultivars differed in one tiller yield rather than in tiller number, and higher grain yield of tillers was primarily due to increased grain recovery. A more equal partitioning of resources within main culm and tillers corresponded to better yield stability across sowing dates. Starting from this, we suggest that early anthesis, a long stem elongation phase, a high primordium initiation-rate and small spikes, could be positive traits for durum wheat yield stability in changing environments, since they allow plants directing more time and resources to floret production and grain filling both in main culm and tiller spikes. From a methodological point of view, our results show that the number of fertile florets per spike is highly correlated with the average floret number of five given spikelets.

The influence of seeding rate and micronutrients foliar application on grain yield and quality traits and micronutrients of durum wheat

A field experiment was conducted to evaluate the effect of seeding rate and foliar application of micronutrients and their synergistic effects on grain yield and quality traits of durum wheat. A split-split plot design was used with varieties assigned to the main plot, micronutrient to the sub plots and seeding rates to the sub-sub plots. Varieties were sown at seeding rate of 100, 125, 150 and 175 kg ha−1 and treated with ZnSO4 and FeSO4, applied foliarly at 25 kg ha−1 during anthesis stage. Significant differences among seeding rates, varieties and micronutrients and some of their interactions were observed. Higher seeding rate increased grain and biomass yields by 23.5% and 21.5%, respectively. Increasing seed rate from 100 to 175 kg ha−1 has reduced protein, gluten and Zeleny contents by 8.7%, 10.8% and 9.1%, respectively. FeSO4 × seeding rate interaction improved quality traits better than ZnSO4 interacted with seeding rate. Application of ZnSO4 and FeSO4 has increased Zn and Fe concentrations in the harvested grain. Agronomic biofortification could be an approach to overcome health problem related to Zn and Fe deficiency if used in combination with crop varieties with known genetic response to applied micro fertilizers.

Effects of pyraclostrobin on leaf diseases, leaf physiology, yield and quality of durum wheat under Mediterranean conditions

A two-year field experiment was conducted to study the putative “health” effects of pyraclostrobin along with its fungicidal action on two durum wheat (Triticum turgidum L. subsp. durum) cultivars under rainfed, Mediterranean conditions. Five foliar treatments were applied: single applications [100 g active ingredient (ai) ha−1] at the end of tillering (BBCH 31, T31) and the flag leaf stage (BBCH 39, T39), application (100 g ai ha−1) at both growth stages (a total of 200 g ai ha−1; T31+39), chemical control [TCC; a tank mixture of myclobutanil (60 g ai ha−1) and fenpropimorph (750 g ai ha−1) at BBCH 31, 39 and 69 (end of flowering) growth stages] and untreated control (TUC). The two predominant foliar diseases [powdery mildew (PM) caused by Blumeria graminis f. sp. tritici, and Septoria tritici blotch caused by Zymoseptoria tritici] were assessed five times, initiating at BBCH 30, and the area under disease progress curve (AUDPC) was calculated. At the end of flowering (BBCH 69), physiological traits were determined on flag leaf [nitrogen concentration (Leaf N), chlorophyll content as assessed by SPAD-502 (SPAD), specific leaf area (SLA)] and canopy [canopy temperature depression (CTD)]. Also, carbon and nitrogen isotopes were measured on flag leaf [carbon isotope discrimination (ΔFL), 15N natural abundance (δ15NFL)] and mature grains (ΔG and δ15NG) at BBCH 69 and 99 (harvest maturity), respectively.Pyraclostrobin applications suppressed both foliar diseases as AUDPC revealed. The T31+39 was the most effective treatment leading to highest grain and protein yields (GY and PY) while T31 ranked second in yields indicating that early suppression of foliar diseases (T31, T31+39) was the most beneficial. The negative correlations between yields and ΔFL-G, a measure of flag leaf isotopic signature on grains, signified the importance of the prolongation of flag leaf photosynthesis as a result of foliar diseases suppression. On the other hand, foliar treatments had no significant effect on grain quality. The high-yielding cv. Elpida was tolerant to powdery mildew, water conservative during grain filling and more dependent on carbohydrates translocation to filling grains (higher ΔFL-G). The high-yielding growth season also showed higher grain protein concentration and vitreousness as a result of the lower diseases pressure, which was mirrored in higher flag leaf N, SLA and CTD. Concluding, the positive yield response of durum wheat to pyraclostrobin was not due to a “plant health” effect but owing to foliar diseases suppression, which allowed prolonged flag leaf photosynthesis.

Genomic selection for grain yield and quality traits in durum wheat

The prediction accuracies of genomic selection depend on several factors, including the genetic architecture of target traits, the number of traits considered at a given time, and the statistical models. Here, we assessed the potential of single-trait (ST) and multi-trait (MT) genomic prediction models for durum wheat on yield and quality traits using a breeding panel (BP) of 170 varieties and advanced breeding lines, and a doubled-haploid (DH) population of 154 lines. The two populations were genotyped with the Infinium iSelect 90K SNP assay and phenotyped for various traits. Six ST-GS models (RR-BLUP, G-BLUP, BayesA, BayesB, Bayesian LASSO, and RKHS) and three MT prediction approaches (MT-BayesA, MT-Matrix, and MT-SI approaches which use economic selection index as a trait value) were applied for predicting yield, protein content, gluten index, and alveograph measures. The ST prediction accuracies ranged from 0.5 to 0.8 for the various traits and models and revealed comparable prediction accuracies for most of the traits in both populations, except BayesA and BayesB, which better predicted gluten index, tenacity, and strength in the DH population. The MT-GS models were more accurate than the ST-GS models only for grain yield in the BP. Using BP as a training set to predict the DH population resulted in poor predictions. Overall, all the six ST-GS models appear to be applicable for GS of yield and gluten strength traits in durum wheat, but we recommend the simple computational models RR-BLUP or G-BLUP for predicating single trait and MT-SI for predicting yield and protein simultaneously.

No-till durum wheat yield success probability in semi arid climate: A methodological framework

The aim of this study is to develop a framework for the evaluation of no-till (NT) yield success probability as a decision tool for farmers or decision makers. The effect of soil management on durum wheat yield has been tested on many long-term field experiments. Results of these researches were collected in a unique dataset to evaluate the success of NT management in comparison to conventional tillage (CT) as influenced by the aridity index, crop residue management and cropping system. A total of 519 observations of long-term experiments (>3years) regarding durum wheat in a number of areas with semi arid climate were included in the present study. The relative ratio of yield under NT and CT was correlated to the aridity index (Ai) for different cropping systems and residue management strategies. No-till performed better with lower values of the Ai. When NT and CT yields were the same, the Ai value was defined as the Ai threshold, and this value resulted as being strongly dependent upon crop management.The developed framework, in any given site, allows us (i) to know the threshold for different managements tecniques, (ii) to estimate the probability of success in adopting NT and CT soil management techniques; (iii) to predict the best management with reference to Ai variation.

Simultaneous improvement of grain yield and protein content in durum wheat by different phenotypic indices and genomic selection.

Simultaneous improvement of protein content and grain yield by index selection is possible but its efficiency largely depends on the weighting of the single traits. The genetic architecture of these indices is similar to that of the primary traits. Grain yield and protein content are of major importance in durum wheat breeding, but their negative correlation has hampered their simultaneous improvement. To account for this in wheat breeding, the grain protein deviation (GPD) and the protein yield were proposed as targets for selection. The aim of this work was to investigate the potential of different indices to simultaneously improve grain yield and protein content in durum wheat and to evaluate their genetic architecture towards genomics-assisted breeding. To this end, we investigated two different durum wheat panels comprising 159 and 189 genotypes, which were tested in multiple field locations across Europe and genotyped by a genotyping-by-sequencing approach. The phenotypic analyses revealed significant genetic variances for all traits and heritabilities of the phenotypic indices that were in a similar range as those of grain yield and protein content. The GPD showed a high and positive correlation with protein content, whereas protein yield was highly and positively correlated with grain yield. Thus, selecting for a high GPD would mainly increase the protein content whereas a selection based on protein yield would mainly improve grain yield, but a combination of both indices allows to balance this selection. The genome-wide association mapping revealed a complex genetic architecture for all traits with most QTL having small effects and being detected only in one germplasm set, thus limiting the potential of marker-assisted selection for trait improvement. By contrast, genome-wide prediction appeared promising but its performance strongly depends on the relatedness between training and prediction sets.

Evaluation of seed yield of durum wheat (Triticum durum) under drought stress and determining correlation among some yield components using path coefficient analysis

Water deficit affects can have negative effects on grain formation. I investigated the relationships between the characters of durum wheat (Triticum durum) and yield under drought stress and identified the most effective components of yield. I used 49 durum wheat genotypes (43 exotic and 6 local lines), in a lattice design (7×7) replicated twice, during tillering, stem elongation, anthesis and grain filling. There were positive correlations among harvest index (r=0,849), plant height (r=0,695), tillering (r=0,689), peduncle length (r=0,466) and grain yield. The number of seeds per spike (0,432), spike length (0,410) and 1 000 seed weight (0,385) had the highest direct effect on yield.

Влияние сроков посева на урожайность пшеницы твердой озимой в условиях северной Степи

Влияние сроков посева на урожайность пшеницы твердой озимой в условиях северной Степи

Switching from conventional tillage to no-tillage: Soil N availability, N uptake, 15N fertilizer recovery, and grain yield of durum wheat

This 2-year study, performed in a typical Mediterranean environment on three soil types (two Inceptisols and one Vertisol), aimed to improve understanding of the factors that play a major role in determining crop response when soil management shifts from conventional tillage (CT) to no-tillage (NT). The effects of NT on the soil nitrogen (N) availability, N uptake, 15N fertilizer recovery, and grain yield of durum wheat were evaluated in comparison to CT under five different N fertilization rates (0, 40, 80, 120, and 160 kg N ha−1).Compared to CT, NT negatively affected grain yield in one of the two years but only in the two Inceptisols. On average, a considerable grain yield advantage of CT over NT (approximately +0.6 Mg ha−1 of grain) was observed with no N fertilization. This benefit decreased progressively when N fertilizer rate increased to the point that at 120 kg ha−1 of N applied differences between CT and NT were negligible. The differences between the two tillage systems in both grain yield and N uptake were attributable more to differences in the native soil mineral N (that materialized already during the vegetative phase of the crop cycle) than to differences between CT plants and NT plants in efficiency in taking up N from fertilizer. The differences between CT and NT for many of the traits observed in durum wheat plants increased with decreasing soil fertility and in particular with decreasing soil total N. In conclusion, the shift from CT to NT, which should be accompanied in any case by an increase in the N fertilization rate to take into account the reduction in soil N available for the crop, was less problematic in the Vertisol, which is more fertile and better structured than the two Inceptisols.

Environmental and Genetic Variation for Yield-Related Traits of Durum Wheat as Affected by Development.

Phenology has a profound effect on adaptation and productivity of crops. The impact of phenology on tillering and fertility traits of durum wheat (Triticum turgidum L. subsp. durum Desf.) was evaluated with the aim of specifying which group of flowering genes (Vrn, Ppd, or eps) was involved in their control. A recombinant inbred line population was grown under four contrasting conditions of vernalization and daylength. Phenotyping was carried out according to robust phenological models dissecting both phenological and yield related traits. Whole-genome profiling was performed using the DArT-Seq technology. The genetic variability for tillering was mainly related to the genetic variability for vernalization sensitivity, as shown by the many quantitative trait loci (QTLs) identified in non-vernalized plants associated to both tillering and phenological traits. No effects of photoperiod sensitivity on spikelet number were detected in short-day-grown plants, apparently because of limited genetic variability in photoperiod sensitivity of the population. Earliness per se was involved in control of spikelet number via final leaf number, with these traits genetically correlated and sharing some QTLs. Chaff weight and number of kernels per g chaff were negatively associated and related to anthesis date under most conditions. QTL mapping uncovered novel loci involved in phenological control of tillering and fertility traits, and confirmed the presence of several well-established loci. Phenotyping of both phenology and kernel number according to a robust physiological model amplified the possibility of identifying genetic factors underlying their variations. Also, isolating known flowering gene cues by manipulation of environmental conditions provided the opportunity for each group of genes to be expressed without confounding effects of the others. This information helps to predict the consequences of either genetic manipulation of flowering genes and changes in environmental conditions on the potential yield of durum wheat.

Оценка генетического разнообразия сортов твердой пшеницы (Triticum durum Desf.) с использованием микросателлитных маркеров

Durum wheat (Triticum durum Desf.) is an important crop both in the world and in Kazakhstan. Durum wheat is used as a valuable raw material in bakery and pasta production. Effective breeding strategies require knowledge of the genetic diversity level of cultivars. Polymorphism of the twenty-nine durum cultivars was analyzed using 7 microsatellite markers. The total number of alleles was 20 and the effective allele number was an average of 2.8. The average polymorphic information content (PIC) value was 0.3658 and ranged from 0.1267 in Xgwm219 to 0.5457 in Xgwm247. The genetic diversity indices of Shannon and Nei were equal to 0.7174, 0.4243, respectively. The level of genetic diversity was relatively high. The genetic distance between cultivars was calculated. Also, with the help of microsatellite markers, a cluster analysis of the studied cultivars was conducted. The results of the study make it possible to assess the level of genetic polymorphism in the studied cultivars and indicate that the used markers are informative. Polymorphic markers were selected for the following studies on the durum genetic diversity. The obtained information will be used in breeding programs aimed at increasing yield and adaptability of durum wheat. Key words: Triticum durum, genetic resources, genetic diversity, microsatellites, SSR.

Combining ability analysis of some yield and quality traits in durum wheat (Triticum durum Desf

Combining ability analysis of some yield and quality traits in durum wheat (<i>Triticum</i> <i>durum</i> Desf

Assessment of heritability and genetic advance for agronomic traits in durum wheat (Triticum durum Desf.)

In order to evaluate the amount of heritability for desirable agronomic characteristics and the genetic progress associated with grain yield of durum wheat (Triticum durum Desf.), a split plot experiment was carried out with four replications during three cropping seasons (2009-2012). Three sowing dates (as environmental factor) and six durum wheat varieties (as genotypic factor) were considered as main and sub factors respectively. Analysis of variance showed interaction effects between genotypes and environments in days to ripening, plant height, spike length, number of grains per spike, number of spikes per unit area, grain mass and grain yield. The grain yield showed the highest positive correlation with number of grains per spike also grain mass (91 % and 85 %, respectively). A relatively high heritability of these traits (82.1 % and 82.2 %, respectively) suggests that their genetic improvement is possible. The maximum genetic gain (19.6 %) was observed for grain mass, indicating this trait should be a very important indicator for durum wheat breeders, although the climatic effects should not be ignored.

Effect of contrasting crop rotation systems on soil chemical, biochemical properties and plant root growth in organic farming: first results

Organic farming is claimed to improve soil fertility. Nonetheless, among organic practices, net C-inputs may largely vary in amount and composition and produce different soil conditions for microbial activity and plant-root system adaptation and development. In this study, we hypothesised that, in the regime of organic agriculture, soil chemical and biochemical properties can substantially differ under contrasting crop rotation systems and produce conditions of soil fertility to which the plant responds through diverse growth and production. The impact of 13 years of Alfalfa-Crop rotation (P-C) and Annual Crop rotation (A-C) was evaluated on the build up of soil organic carbon (SOC), active (light fraction organic matter, LFOM; water soluble organic carbon, WSOC) and humic fraction (fulvic acids carbon, FAC; humic acids carbon, HAC), soil biochemical properties (microbial biomass carbon, MBC; basal respiration, dBR; alkaline phosphatase AmP; arylsulfatase ArS; orto-diphenoloxidase, o-DPO) and the amount of available macro-nutrients (N, P, and S) at two different soil depths (0-10 cm and 10-30 cm) before and after cultivation of wheat. We also studied the response of root morphology, physiology and yield of the plant-root system of wheat. Results showed that the level of soil fertility and plant-root system behaviour substantially differed under the two crop rotation systems investigated here. We observed high efficiency of the P-C soil in the build up of soil organic carbon, as it was 2.9 times higher than that measured in the A-C soil. With the exception of o-DPO, P-C soil always showed a higher level of AmP and ArS activity and an initial lower amount of available P and S. The P-C soil showed higher rootability and promoted thinner roots and higher root density. In the P-C soil conditions, the photosynthesis and yield of durum wheat were also favoured. Finally, cultivation of wheat caused an overall depletion of the accrued fertility of soil, mainly evident in the P-C soil, which maintained a residual higher level of all the chemical and biochemical properties tested.

THE USE OF AMMI MODEL FOR INTERPRETING GENOTYPE × ENVIRONMENT INTERACTION IN DURUM WHEAT

SUMMARYDurum wheat (Triticum durum) is one of the most important cereal crops in the Mediterranean region; however, its cultivation suffers from low yield due to environmental constrains. The main objectives of this study were to (i) assess genotype × environment (GE) interaction for grain yield in rainfed durum wheat and to (ii) analyse the relationships of GE interaction with genotypic/meteorological variables by the additive main effects and multiplicative interaction (AMMI) model. Grain yield and some related traits were evaluated in 25 durum wheat genotypes (landrace, breeding line, old and new varieties) in 12 rainfed environments differing in winter air temperature. The AMMI analysis of variance indicated that the environment had highest contribution (84.3% of total variation) to the variation in grain yield. The first interaction principal component axis (IPCA1) explained 77.5% of GE interaction sum of squares (SS), and its effect was 5.5 times greater than the genotype effect, indicating that the IPCA1 contributed remarkably to the total GE interaction. Large GE interaction for grain yield was detected, indicating specific adaptation of genotypes. While the postdictive success method indicated AMMI-4 as the best model, the predictive success one suggested AMMI-1. The AMMI biplot analysis confirmed a rank change interaction among the locations, indicating the presence of strong and unpredictable rank-change location-by-year interactions for locations. In contrast to landraces and old varieties, the breeding lines with high yield performance had high phenotypic plasticity under varying environmental conditions. Results indicated that the GE interaction was associated with the interaction of heading date, plant height, rainfall, air temperature and freezing days.

The role of soils in the analysis of potential agricultural production: A case study in Lebanon

Maintaining cereal production in the Bekaa valley in Lebanon presents a serious challenge. Lack of water is the driving force of agricultural research which is mainly focused on introduction of drought resistant cultivars, application of conservation tillage and supplemental irrigation. In this context forty-eight experimental plots were laid out for three years in a statistical split plot design. The statistical analyses showed that aboveground biomass and yield were significantly affected by irrigation for barley but not for the yield of durum wheat. Effects of soil tillage practices and introduction of new cultivares were not significant.A soil survey indicated that the implicit assumption of soil homogeneity of the agronomic design was correct for surface soil but that two different soil types (Cambisols and Fluvisols) had to be distinguished considering subsoil conditions and corresponding rooting patterns. Therefore, the main objective of this paper was to determine the effects of different soil types on crop response and, in addition, to assess how physically-based modeling can predict future effects of climate change on crops and soils. Simulation model SWAP was validated for local conditions using measurements of soil water contents, aboveground biomass and yield of wheat. Considering two rather than one soil type for the experimental area resulted in different conclusions for both crops as to the effectivity of both conservation tillage and irrigation, demonstrating that a distinction of only one soil type results in misleading results. The validated model was applied to estimate yields considering climate change, focusing on the application of supplemental irrigation. Yields for “Mikii3” a durum wheat cultivar are expected to increase by appr. 14% in both soils due to climate change. More importantly, only 3 supplemental irrigations would be needed for the deep soil requiring 5% more water as compared with current climate trend, while the shallow soil needs 13 irrigations, corresponding with a need for 35% more water. This is highly significant from an economic point of view and supports the relevance of distinguishing two soil types.It was demonstrated the synergy of joint research by the agronomic and soil science community and the need for executing a soil survey in future when planning agronomic experiments, including a hydrological soil characterisation.

Differential representation of albumins and globulins during grain development in durum wheat and its possible functional consequences

Durum wheat (Triticum turgidum ssp. durum (Desf.) Husn.) is an economically important crop used for the production of semolina, which is the basis of pasta and other food products. Its grains provide proteins and starch for human consumption. Grain development is a key process in wheat physiology; it is highly affected by a number of enzymes that control the metabolic processes governing accumulation of starch and storage proteins and ultimately grain weight. Most of these enzymes are present in the albumin/globulin grain fraction, which represents about a quarter of total seed proteins. With the aim to describe the dynamic profile of the albumin/globulin fraction during durum wheat grain development, we performed a proteomic analysis of this subproteome using a two-dimensional differential gel electrophoresis (2D-DIGE)-based approach and compared six developmental stages. A total of 285 differentially (237 over- and 48 under-) represented spots was identified by nanoLC-ESI-LIT-MS/MS, which were associated with 217 non-redundant Triticum sequence entries. Quantitative protein dynamics demonstrated that carbon metabolism, energy, protein destination/storage, disease/defense and cell growth/division functional categories were highly affected during grain development, concomitantly with progressive grain size increase and starch/protein reserve accumulation. Bioinformatic interaction prediction revealed a complex network of differentially represented proteins mainly centered at enzymes involved in carbon and protein metabolism. A description of 18 proteins associated with wheat flour human allergies was also obtained; these components showed augmented levels at the last developmental stages. By providing a comprehensive understanding of the molecular basis of durum wheat grain development, yield and quality formation, this study provides the foundation and reveals potential biomarkers for further investigations of durum wheat breeding and semolina quality. Biological significanceA 2D-DIGE-based comparative analysis of the albumin/globulin fraction from durum wheat caryopses at six developmental stages was performed to describe the dynamic subproteomic changes associated with grain development. Quantitative variations of 217 differentially proteins demonstrated that highly affected are the functional categories of carbon metabolism, energy, protein destination/storage, disease/defense and cell growth/division, which displayed a general over-representation, consistently with concomitant occurrence of grain size increase and starch/protein reserve accumulation. Bioinformatics revealed a complex protein network centered mainly at enzymes involved in carbon and protein metabolism. Differentially represented proteins and corresponding functional categories highly resembled those previously identified as variable in developing bread wheat grain. This suggests that the main differences in kernel hardness between durum and bread wheat probably do not depend on proteomic changes in corresponding albumins/globulins, but on other specific factors affecting the interaction between the starch granules and the endosperm protein matrix in the kernel.