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Background and Aims. The study aims to explore the impact of advancements in wheat genetics on root structure and rhizosphere biology, which are still not fully understood. Specifically, we investigated various factors including the exudation of carboxylates, colonization by arbuscular mycorrhizal fungi, microbial activity, and root architecture in winter wheat varieties that have been released between 1965 and 2020. Methods. To conduct our study, we sowed fourteen different winter wheat varieties with four replicates on acidic Andisol at field conditions. Complete root systems and soil samples were extracted using a tractor-mounted hydraulic sampler tube of 3.5 cm diameter, which reached a depth of 60 cm. Results. In this sense, succinate showed a significant increase by 21%. Mycorrhizal colonization was inversely proportional to P concentrations and all varieties showed higher microbial activity at anthesis. The longest roots were found in varieties released after the year 2000, but no significant differences were found in other root architecture parameters. There was no clear pattern observed in root architecture or biological activity as a function of the year of release. Plant genetics moderated root architecture, carboxylate exudation, microbial activity, and mycorrhizal colonization, all of which are affected by high P concentrations. Conclusions. This study investigated plant-microorganism interactions, often overlooked due to root system analysis challenges. Older wheat varieties showed higher carboxylate exudation. We identified wheat varieties with potential for improved root systems and crop efficiency.

RESUMEN 'Chevignon' es una variedad de trigo de invierno, creada por la empresa ASUR Plant Breeding de Francia e introducida a Chile por el Programa de Mejoramiento de Trigo de INIA Carillanca. Es un trigo de altura mediana, ciclo intermedio, resistente a polvillo estriado (Puccinia striiformis West. f. sp. tritici Erikss) y oidio (Blumeria graminis D.C. f. sp. tritici Marchal), moderadamente resistente a polvillo de la hoja (Puccinia triticina f. sp. tritici Erikss y Henn) y muy buena tolerancia a septoria (Mycosphaerella graminicola (Fuckel) Sand). Es una variedad de alto rendimiento, con buenas características de calidad para panificación directa. Es de hábito de desarrollo invernal, de crecimiento rastrero al estado de plántula y de buena macolla terminal. Sus hojas son de color verde pálido, con hoja bandera semi curvada. La espiga es de color blanco, semi erecta, forma paralela, densidad alta y sin barbas. El grano es de forma redondeada, tamaño mediano, color rojo, pudiendo presentar ocasionalmente ciertos cambios de pigmentación en el endosperma. La altura de planta adulta varía entre 105 y 110 cm, con un promedio de 105 cm, y con una moderada resistencia a la tendedura. Su período vegetativo desde siembra a espigadura es más tardío que 'Maxwell' en alrededor de cinco días y más precoz que 'Bicentenario INIA' y 'Kiron INIA' en aproximadamente 8 a 10 días, respectivamente.

Water deficit is the most limiting factor for wheat production, so wheat-breeding programmes are currently focused on developing high-performance genotypes under such conditions. Carbon isotope dis...

Durum wheat landraces have huge potential for the identification of genetic factors valuable for improving resistance to biotic stresses. Tunisia is known as a hot spot for Septoria tritici blotch disease (STB), caused by the fungus Zymoseptoria tritici (Z. tritici). In this context, a collection of 3166 Mediterranean durum wheat landraces were evaluated at the seedling and adult stages for STB resistance in the 2016–2017 cropping season under field conditions in Kodia (Tunisia). Unadapted/susceptible accessions were eliminated to reach the final set of 1059 accessions; this was termed the Med-collection, which comprised accessions from 13 countries and was also screened in the 2018–2019 cropping season. The Med-collection showed high frequency of resistance reactions, among which over 50% showed an immune reaction (HR) at both seedling and adult growth stages. Interestingly, 92% of HR and R accessions maintained their resistance levels across the two years, confirming the highly significant correlation found between seedling- and adult-stage reactions. Plant Height was found to have a negative significant effect on adult-stage resistance, suggesting that either this trait can influence disease severity, or that it can be due to environmental/epidemiological factors. Accessions from Italy showed the highest variability, while those from Portugal, Spain and Tunisia showed the highest levels of resistance at both growth stages, suggesting that the latter accessions may harbor novel QTLs effective for STB resistance.

Durum wheat landraces have huge potential for the identification of genetic factors valuable for improving resistance to biotic stresses. Tunisia is known as a hot spot for Septoria tritici blotch disease (STB), caused by the fungus

Phytoene synthase 1 (Psy1) and lipoxygenase 1 (Lpx-1) are key genes involved in the synthesis and catalysis of carotenoid pigments in durum wheat, regulating the increase and decrease in these compounds, respectively, resulting in the distinct yellow color of semolina and pasta. Here, we reported new haplotype variants and/or allele combinations of these two genes significantly affecting yellow pigment content in grain and semolina through their effect on carotenoid pigments. To reach the purpose of this work, three complementary approaches were undertaken: the identification of QTLs associated to carotenoid content on a recombinant inbred line (RIL) population, the characterization of a Mediterranean panel of accessions for Psy1 and Lpx-1 genes, and monitoring the expression of Psy1 and Lpx-1 genes during grain filling on two genotypes with contrasting yellow pigments. Our data suggest that Psy1 plays a major role during grain development, contributing to semolina yellowness, and Lpx-1 appears to be more predominant at post-harvest stages and during pasta making.

Refereed/Peer-reviewed It is well known that phosphorus (P) addition helps mitigate the adverse effects of water deficit stress on plants. However, the efficiency of spring wheat genotypes in the use of both components has not been addressed. The objective of this study was to evaluate the combined effect of P and water limiting conditions over phosphorus use efficiency (PUE) and water use efficiency (WUE) to categorize different spring wheat genotypes. Eight spring wheat genotypes were selected based on their yield tolerance index score (YTI) obtained from a previous screening of 384 wheat genotypes. They were evaluated for their ability to use P and water. Plants were grown under semi-controlled conditions on an Andisol with soil P-concentration of 3.4 mg P kg−1 (-P), which was enriched to 30 mg P kg−1 (+P). Irrigation was applied at two levels: well-watered (+W) and 30% +W (water-stressed, -W). Wheat was grown until the end of its phenological cycle. The P and water scarcity produced a delay in wheat development, especially in the first vegetative stages. Genotypic differences in growth, development, P accumulation, and yield were observed in response to P and water limiting conditions. The lowest performance in plant growth and grain yield was regarded when the P and water restrictions were applied. However, differences were observed in terms of PUE and WUE. In this sense, spring wheat genotypes were grouped into three and four classes for PUE and WUE, respectively. The most efficient genotype for all the conditions was “QUP2418”, which obtained the highest score in the consolidated PUE and WUE ranking. On the contrary, “FONTAGRO 92″ and “F6CL091337″ were the most inefficient genotypes. Strong correlations were observed between PUE components and WUE, enabling the future selection of co-adapted wheat genotypes efficient in the use of P and water.

RESUMEN 'Kiron INIA' es un nuevo cultivar de trigo (Triticum aestivum L.) obtenido en el Programa Nacional de Trigo, Centro Regional de Investigación (CRI) Carillanca, del Instituto de Investigaciones Agropecuarias (INIA). Es un trigo de altura mediana, de ciclo tardío, resistente al polvillo estriado (Puccinia striiformis West. f. sp. tritici Erikss) y al oidio (Blumeriagraminis D.C. f. sp. tritici Marchal), y moderadamente sensible al polvillo de la hoja (Puccinia triticina. f. sp. tritici Erikss y Henn) y septoria (Mycosphaerella graminicola (Fuckel) Sand). Es un cultivar invernal de alto rendimiento, con buenas características de calidad para panificación directa, que heredó un alelo de tolerancia a la acidez del suelo de un parental. Sus hojas son de color verde ligeramente pálido, con hoja bandera semi erecta, de abundante cerosidad (glauescencia) en el haz. La espiga es de color blanco, decumbente, forma paralela, densidad alta, compacta y con barbas en todo su longitud. El grano es de forma redondeada, tamaño mediano, y color rojo pálido. La altura de la planta adulta varía entre 95 cm y 105 cm, con un promedio de 100 cm, y con un tallo de muy buena resistencia a la tendedura. Es un trigo de alto rendimiento (12,9 t ha1), superando incluso al testigo comercial en diferentes localidades y estaciones.

The impact of climate change requires developing and validating models that help to project possible scenarios that must adapt to new varieties. This study seeks to validate and calibrate the Decision Support System for Agrotechnology Transfer (DSSAT) model as a tool that facilitates the characterization of the behavior of new varieties in the face of new scenarios generated by climate change. The determination of genetic coefficients of three bread wheat (Triticum aestivum L.) varieties was considered in the methodology; this was done with the database of the historical records of the Instituto de Investigaciones Agropecuarias (INIA) Wheat Breeding Program for the 2000 to 2011 period. Once the adjustment level of the model was dealt with, it was feasible to obtain genetic coefficients of three spring wheat varieties (Pandora-INIA, Kipa-INIA, and Millan-INIA); days from planting to anthesis variable exhibited RMSE values fluctuating between 3.5 and 9.7 depending on the variety. For total duration of days to maturity, 'Millan-INIA' exhibited a very good adjustment (RMSE = 0.25) as compared to 'Pandora-INIA' (RMSE = 1.35) and 'Kipa-INIA' (12.22). Furthermore, the coefficient of determination of the genetic coefficients indicates that the varieties have minimum vernalization requirements; these are similar to the photoperiod between 'Pandora-INIA' and 'Millan-INIA' and lower in the case of 'Kipa-INIA'. Thermal requirements for grain filling, biomass production, and plant height did not exhibit any important differences among varieties. Finally, the methodology allowed calibrating the DSSAT model and achieving a good predictive level of yields for the three varieties. The plant development parameters must be studied in greater detail because of the low association between simulated and observed values.

A greenhouse experiment was carried out to assess the effect of the inoculation with rhizobacterial strains on the tolerance to water stress in wheat genotypes (Triticum aestivum L.) under two different water regimes. A drought resistant (Fontagro 8) and a susceptible (Fontagro 98) genotype were studied. Soil water content was kept at 100% and 45% field capacity. The treatments were inoculations with AG-70 (Bacillus sp.), AG-54 (Pseudomonas sp.), and a mixture of both (AG-70 + AG-54); a control treatment consisting of an autoclaved nutritive solution. When applied to Fontagro 8 genotype, the AG-70 + AG-54 treatment resulted in a higher increase in shoot (88%) and root dry weight (211%) compared to the control under drought conditions. The same treatment applied on the susceptible genotype (Fontagro 98) resulted in increases of 73% and 129% in shoot and root dry weight, respectively. In addition, the inoculated plants showed significant increases in root length, stomatal conductance and chlorophyll index. The AG-54 and AG-70 treatments increased NPK contents in the drought-resistant genotype, while the AG-54 and AG-70 + AG-54 treatments increased the P content in the susceptible genotype. The treatments that showed the most positive effects on the biological quality parameters of the soil (microbial activity, microbial respiration and urease enzyme activity) were AG-54 and AG-70 + AG-54. Therefore, the use of AG-70 and AG-54, applied separately or combined, increased tolerance to water stress in both wheat genotypes and constitute a biotechnological tool for the production of crops in water-deficit ecosystems.

RESUMEN Pionero INIA es la primera variedad de trigo doble propósito liberado por el Programa Nacional de Trigo del INIA Carillanca. Es una variedad de invierno (Triticum aestivum L.) producto de la selección de germoplasma recibido de la Empresa Saaten Union Research de Francia. Mostró excelente adaptabilidad para siembras tempranas, en zonas de inviernos largos y primaveras húmedas. La altura promedio de planta adulta alcanza los 90 cm, siendo clasificado como una variedad de trigo enano a semi enano. El rendimiento promedio, en diferentes localidades y varios años de evaluación, fue significativamente superior al testigo Kumpa INIA, destacándose por su resistencia a enfermedades y tipo agronómico. Sus características de calidad molinera y de almidón permiten utilizarlo en la industria galletera, ganadera y acuícola.

Different physiological traits have been proposed as key traits associated with yield potential as well as performance under water stress. The aim of this paper is to examine the genotypic variability of leaf chlorophyll, stem water-soluble carbohydrate content and carbon isotope discrimination (Δ(13)C), and their relationship with grain yield (GY) and other agronomical traits, under contrasting water conditions in a Mediterranean environment. The study was performed on a large collection of 384 wheat genotypes grown under water stress (WS, rainfed), mild water stress (MWS, deficit irrigation), and full irrigation (FI). The average GY of two growing seasons was 2.4, 4.8, and 8.9 Mg ha(-1) under WS, MWS, and FI, respectively. Chlorophyll content at anthesis was positively correlated with GY (except under FI in 2011) and the agronomical components kernels per spike (KS) and thousand kernel weight (TKW). The WSC content at anthesis (WSCCa) was negatively correlated with spikes per square meter (SM2), but positively correlated with KS and TKW under WS and FI conditions. As a consequence, the relationships between WSCCa with GY were low or not significant. Therefore, selecting for high stem WSC would not necessary lead to genotypes of GY potential. The relationship between Δ(13)C and GY was positive under FI and MWS but negative under severe WS (in 2011), indicating higher water use under yield potential and MWS conditions.

Wheat (Triticum aestivum L.) genetic improvement objectives include obtaining cultivars capable of expressing their maximum potential yield and quality in diverse environments. This make necessary to know and define the environment in which a variety can express its maximum potential yield and quality. The objective of this study was to assess which method is the most efficient to study cultivars response in multiple environments. For this, we analyze the adaptability, stability, and genotype x environment (GxE) interaction effect, grain yield, sedimentation, and wet gluten content of 13 spring wheat cultivars sown in six environments in the central-south and southern zones of Chile during two seasons. The data were analyzed by regression analysis, additive main effects and multiplicative interaction (AMMI), and the sites regression (SREG) model. By this was thus established that SREG analysis is the most efficient for this type of study since, in addition to analyzing stability, adaptability, and effect (GxE), it allows identifying the best cultivar. In this case, 'Pandora-INIA' stands out by exhibiting the best yield (7.38 t ha-1), high sedimentation (36.95 cm³), and wet gluten (41.54%) indices in all the environments, and this positions it as a variety having both high yield and quality.Dentro de los objetivos del mejoramiento genético del trigo (Triticum aestivum L.) figura la obtención de variedades capaces de expresar su máximo potencial de rendimiento y calidad en diversos ambientes. Por lo cual es necesario conocer y definir el ambiente en que una variedad puede expresar al máximo su potencial de rendimiento y de calidad. El objetivo de este trabajo fue determinar una metodología eficiente para analizar la respuesta de diversos cultivares de trigo a distintos ambientes. Para ello se analizó la adaptabilidad, estabilidad y la interacción Genotipo x Ambiente (GxE) de 13 variedades de trigo de primavera, sembradas, en seis ambientes de la zona centro sur y sur de Chile, durante dos temporadas, evaluando rendimiento de grano, sedimentación y contenido de gluten húmedo. Los resultados fueron sometidos a análisis de regresión, análisis de efectos principales aditivos e interacción multiplicativa (AMMI) y modelo de regresión de sitios (SREG), estableciendo que el análisis SREG es el más eficiente para este tipo de estudio, ya que además de analizar estabilidad, adaptabilidad y efecto (GxE), permite identificar cuál es la mejor variedad. 'Pandora-INIA' presentó el mejor rendimiento (7,38 t ha-1), altos índices de sedimentación (36,95 cm³) y gluten húmedo (41,54%) en todos los ambientes, siendo la variedad que presenta en conjunto alto rendimiento y alta calidad.

11 paginas, 6 tablas, 2 figuras. The definitive version is available at www.blackwell-synergy.com

Grain yield and plant height of 80 recombinant chromosome substitution lines (RCSLs) of barley were measured in six environments with contrasting available moisture profiles. Two environments were in OR, USA (Moro and Pendleton) during one growing season (2004), and four in Chile (Cauquenes and Santa Rosa) during two growing seasons (2004/2005 and 2007/2008). From the yield data obtained in the different environments, yield adaptability (Finlay–Wilkinson slope) and stability (deviations from regression) were calculated. Two commercial cultivars (Harrington and Baronesse) were used as checks in all environments. Marker-quantitative trait associations were identified using 47 simple sequence repeats (SSRs) and the general linear model (GLM) implemented in TASSEL. The mean plant height and grain yield of the 80 RCSLs differed greatly across environments, reflecting differences in water availability. In all environments, there were significant differences (P

Association mapping has been proposed to identify polymorphisms involved in phenotypic variations and may prove useful in identifying interesting alleles for breeding purposes. Using this approach, a total of 382 cultivars and advanced lines of spring wheat obtained from three breeding programs (Chile, Uruguay and CIMMYT) were evaluated for plant height (PH), kernels per spike (KS), 1,000 kernel weight (TKW), grain yield and carbon isotope discrimination (Δ13C) and tested for genotyping-by-sequencing-derived SNP markers across the hexaploid wheat genome. A Bayesian clustering approach via Markov chain Monte Carlo was performed to examine the genetic differentiation (F ST) among different genetic groups. The results indicated the existence of two distinct and strongly differentiated genetic groups. Cluster I contained 215 genotypes (56.3 %), over 60 % (137/215) of which were collected from CIMMYT. Cluster II showed the highest F ST value, according to 95 % credible interval. Linkage disequilibrium (LD) among SNPs was calculated for the A, B and D genomes and at the whole-genome level. LD decayed over a longer genetic distance for the D genome than for the A and B genomes. In the A and B genomes, LD declined to 50 % of its initial value at about 2 cM. In the D genome, LD was much more extensive, declining to 50 % of its initial value only at 22 cM. In the whole genome, LD declined to 50 % of its initial value at an average of 4 cM. Important genomic regions associated with complex traits in spring wheat were identified. Selection on these regions may increase the efficiency of the current breeding programs. Although most of the associations were environment specific, some stable associations were detected for Δ13C, KS, PH and TKW. Chromosomes 1A, 3A, 4A and 5A were the most important chromosomes, as they comprised quantitative trait loci (QTL) for Δ13C, a trait that can be used as an indirect tool for increased water-use efficiency in wheat. Environment-specific genomic regions were detected, indicating the presence of QTL-by-environment interaction. To produce suitable genotypes under contrasting water availability conditions, QTL × E interactions (and genotype-by-environment interaction) should be considered in the current spring wheat breeding program.

In Chile, durum wheat is cultivated in high-yielding Mediterranean environments, therefore breeding programs have selected cultivars with high yield potential in addition to grain quality. The genetic progress in grain yield (GY) between 1964 and 2010 was 72.8 kg ha&minus, 1 per year. GY showed a positive and significant correlation with days to heading, kernels per unit ground area and thousand kernel weight. The gluten and protein content tended to decrease with the year of cultivar release. The correlation between the &delta, 13C of kernels and GY was negative and significant (&minus, 0.62, p &lt, 0.05, for all cultivars, and &minus, 0.97, p &lt, 0.001, excluding the two oldest cultivars). The yield progress (genetic plus agronomic improvements) of a set of 40&ndash, 46 advanced lines evaluated between 2006 and 2015 was 569 kg ha&minus, 1 per year. Unlike other Mediterranean agro-environments, a longer growing cycle together with taller plants seems to be related to the increase in the GY of Chilean durum wheat during recent decades.