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Flint x dent is a common heterotic pattern exploited in maize (Zea mays L.) breeding programs across Europe. Two maize synthetics, EZS1, a mixture of Spanish open-pollinated flint varieties, and EZS2, crosses among North American dent-improved populations, were produced in Zaragoza, Spain. The synthetics showed heterotic behavior and were subjected to two cycles of [S.sub.1]-progeny intrapopulation selection for grain yield and lodging resistance before starting reciprocal recurrent selection. Our objectives were to partition the response to selection into additive and dominance effects after two cycles of intrapopulation selection, with generation mean analysis and diversity analysis. The entries resulting from a diallel mating design, without reciprocals, among the original and first two cycles for each population, were tested in live environments. The results showed that both populations were responsive to selection for improved grain yield, but only EZS2 was improved by selection against lodging. Diversity analysis was less conservative than the generation means model in detecting significant genetic effects. Genetic effects associated with selection for grain yield and lodging were mostly additive, but a significant dominance effect was detected in EZS2 for lodging. The improvement of the population cross did not match that of the populations per se, especially for EZS2. A loss of heterosis for the cross was detected, which might become unrecoverable if [S.sub.1] selection is continued. It was concluded that [S.sub.1] selection should be discontinued and that reciprocal recurrent selection should be initiated.

Malt quality traits of barley (Hordeum vulgare L.) may be suitable candidates for marker-assisted selection, as their evaluation involves laborious and costly procedures. Four regions of the genome were previously reported to affect several grain and malt quality traits in the two-row barley cross `Harrington'/`TR306'. This study used an independent set of lines derived from the same cross to verify the existence of quantitative trait loci (QTL) in these regions. Molecular marker genotypes were used to select 47 lines from among 410 Harrington/TR306 lines that had not been used in the original mapping experiment. Four groups of fines were selected on the basis of their genotype at marker loci in two regions on chromosome 7 (5H) with QTL affecting kernel weight and plumpness, grain protein, extract Β-glucan content, the difference between fine-grind and coarse-grind extract soluble protein, diastatic power, [Alpha]-amylase activity and fine-grind extract, and in regions on chromosomes 3 (3H) and 6 (6H) with QTL affecting extract Β-glucan content and fine-coarse difference. Grain and malt quality traits of these lines were determined from grain grown in five field environments in western Canada. The results confirmed the presence of QTL on chromosome 7 affecting all traits previously reported. Marker-based selection for two regions on chromosome 7 was effective in identifying phenotypically superior lines, and the magnitudes of the combined effects for these regions were close to the estimates calculated in the mapping experiment. The presence of QTL on chromosomes 3 and 6 could not be confirmed as categorically, but combined selection for extract Β-glucan content and fine-coarse difference at all four QTL regions was more effective than selection for only the two regions on chromosome 7., MALTING is an important end use of barley, with barley malt used mainly for brewing beer. Standard methods for assessing the suitability of barley for malting purposes involve analyses of [...]

We used the 'Baronesse'/'Full Pint' doubled haploid population to analyse the genetic factors controlling flowering date under South American conditions. Both parents have similar heading dates, but the population shows transgressive segregation. Two genes, eps2S on chromosome 2H and sdw1 on chromosome 3H, explained most of the phenotypic variation for anthesis date, with the later allele carried by 'Baronesse' and 'Full Pint' , respectively. Both effects were completely additive with no interaction. We studied three plant developmental periods: seedling emergence to tillering (Z10-Z20), tillering (Z20-Z30) and end of tillering to anthesis (Z30-Z49) under field conditions at three contrasting planting dates. Z10-Z20 was also measured under semi-controlled conditions. eps2S controlled Z30-Z49 periods, while sdw1 controlled Z20-Z30. Each of the two genes for the end-point phenotype-anthesis date-was a determinant of flowering at a different developmental stage. No gene x planting date interactions were detected. [ABSTRACT FROM AUTHOR]

This study aimed to identify whether and how sugarcane ( Saccharum spp.) breeding in Argentina modified nitrogen-use efficiency ( NUE), water-use efficiency ( WUE) and radiation-use efficiency ( RUE). Thirteen varieties were grown in two consecutive seasons. Trends in different traits were estimated by fitting the data to linear or bilinear regression models. There was a linear increase in NUE and WUE with the year of release throughout the 70-year span, whereas water use was not modified by sugarcane breeding. There was a positive and strong ( r > 0.90; P < 0.01) association between NUE and WUE and between sugar yield and NUE or WUE. Although RUE was not modified by sugarcane breeding, the amount of radiation intercepted by the crop increased with the year of release. Modern varieties had a higher maximum interception and needed fewer days to reach maximum interception than old varieties. This study suggests that applying ecophysiological knowledge would be instrumental in sugarcane breeding programmes in order to develop varieties with high resource-use efficiency and capable to adapt to global climate change. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between osmotic potential at full hydration (π100) and turgor loss point (ΨTLP) in wheat ( Triticum aestivum) to determine the potential of using π100 to predict ΨTLP under well-watered (WW) and drought (WS) conditions. Two methods for determining π100 were tested: pressure-volume (PV) analysis and freezing point osmometry. The study also measured π100 in a range of 38 field-grown wheat cultivars to determine whether there is genetic variation in π100 under field conditions. π100 correlated with ΨTLP using both methods under both water treatments, particularly WS. Genetic variation of π100 in the field, under rainfed conditions, was greater than controlled conditions and ranged from −0.94 to −1.95 MPa. Overall, the evidence supports development of π100 as a novel tool for plant breeders to screen large populations of wheat and identify genotypes with lower ΨTLP, an integrative trait that is related to drought tolerance. [ABSTRACT FROM AUTHOR]

The objective of this study was to analyse the genotypic variability of sugarcane resistance to the main aphid vector of the Sugarcane yellow leaf virus ( Sc YLV) ( Polerovirus, Luteoviridae), Melanaphis sacchari. We assessed the incidence of aphids in a field trial comparing 181 sugarcane cultivars. Based on the percentage of infested leaves, aphid incidence was scored every two weeks during three cropping seasons. Analysis of variance revealed highly significant genotype, and genotype × year variance, and high broad sense heritability. Using semivariograms, we showed that the alpha lattice design used in the field trial was able to cope with spatial correlation issues caused by the patchy nature of aphid infestations. Twenty-two aphid resistant cultivars were identified. A laboratory study of the development of M. sacchari on four of these 22 resistant cultivars confirmed the resistant status of three of them. We observed modest positive phenotypic and genetic correlations between the aphid incidence and the incidence of Sc YLV. The 22 cultivars resistant to M. sacchari showed twofold lower mean virus incidence than the remaining 159 cultivars. [ABSTRACT FROM AUTHOR]

Barley ( Hordeum vulgare) is an important component of heart-healthy whole grain diets because it contains β-glucan. All current US barley varieties with high β-glucan are spring habit and have waxy starch. Winter varieties have agronomic advantages but require low-temperature tolerance ( LTT). Vernalization sensitivity ( VS) is associated with higher levels of LTT. To rapidly develop fall-sown varieties with LTT and higher grain β-glucan, we therefore used marker-assisted selection ( MAS) at the WX and VRN- H2 loci. The MAS-derived lines, together with unrelated non-waxy germplasm developed via phenotypic selection ( PS), were used for a genome-wide association scan ( GWAS). The panel was phenotyped for grain β-glucan, LTT and VS. It was genotyped with 3072 single-nucleotide polymorphisms ( SNPs) and allele-specific primers. Marker-assisted selection fixed target alleles at both loci but only one of the target phenotypes (higher β-glucan percentage) was achieved. Variation for VS and LTT is attributable to (i) incomplete information about VRN-H1 at the outset of the project and (ii) unexpected allelic variation at VRN-H3 with a large effect on VS and LTT. [ABSTRACT FROM AUTHOR]

Quantitative trait loci ( QTLs) for salt tolerance with additive, epistatic and QTL × treatment interaction effects at seedling stage in wheat were identified. A set of 131 recombinant inbred lines derived from cross Chuan 35050 × Shannong 483 were evaluated under salt stress and normal conditions. Wide variation was found for all studied traits. A total of 18 additive and 16 epistatic QTLs were detected, among which five and 11 were with significant QTL × treatment effects. Ten QTL clusters were identified, and each may represent a single gene or closely linked genes. The locus controlling shoot K+/Na+ concentration ratio and shoot Na+ concentration on chromosome 5A may be identical to Nax2. The interval Xgwm6-Xgwm538 on chromosome 4B for total dry weight was also identified in a previous study, both near the marker Xgwm6. The marker Xgwm6 may be useful for marker-assisted selection. Six pairs of homoeologous QTLs were detected, showing synteny among the A, B and D genomes. These results facilitate understanding the mechanisms and the genetic basis of salt tolerance in wheat. [ABSTRACT FROM AUTHOR]

Development of effective molecular markers linked to Pm21 deriving from Haynaldia villosa is critical for wheat breeding of powdery mildew resistance. In this study, we designed 12 pairs of conserved-intron scanning primers ( CISPs), using intron-containing conserved genes located on the short arm of Brachypodium distachyon chromosome 3 (3 Bd S) aligned with cDNA or expressed sequence tags ( ESTs) of Triticeae crops. Of 12 CISP primer pairs, 11 amplified DNA both in H. villosa and in wheat, and four displayed H. villosa chromosome 6 VS-specific polymorphisms. Six non-polymorphic DNAs were further sequenced for designing internal primers, and five additional 6 VS-specific markers were obtained. Of the total nine 6 VS-specific co-dominant markers, six could effectively trace Pm21 in F2 population derived from the hybrid between the T6 AL.6 VS line and ' Yangmai 158'. This study demonstrated that Brachypodium genomic information could be powerfully utilized to develop molecular markers in H. villosa or other Triticeae species. [ABSTRACT FROM AUTHOR]

Nitrogen (N) fertilization is essential to maximize crop production. However, around half of the applied N is lost to the environment causing water and air pollution and contributing to climate change. Understanding the natural genetic and metabolic basis underlying plants N use efficiency is of great interest to reach an agriculture with less N demand and thus, more sustainable. The study of ammonium (NH4+) nutrition is of particular interest, because it mitigates N losses due to nitrate (NO3-) leaching or denitrification. In this work, we studied Brachypodium distachyon, the model plant for C3 grasses, grown with NH4+ or NO3- supply. We performed gene expression analysis in the root of the B. distachyon reference accession Bd21 and examined the phenotypic variation across 52 natural accessions through analysing plant growth and a panel of 22 metabolic traits in leaf and root. We found that the adjustment of primary metabolism to ammonium nutrition is essential for the natural variation of NH4+ tolerance, notably involving NH4+ assimilation and PEPC activity. Additionally, genome-wide association studies (GWAS) indicated several loci associated with B. distachyon growth and metabolic adaptation to NH4+ nutrition. For instance, we found that the GDH2 gene was associated with the induction of root GDH activity under NH4+ nutrition and that two genes encoding malic enzyme were associated with leaf PEPC activity. Altogether, our work underlines the value of natural variation and the key role of primary metabolism to improve NH4+ tolerance., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Light quality influence on barley development is poorly understood. We exposed three barley genotypes with either sensitive or insensitive response to two light sources producing different light spectra, fluorescent bulbs, and metal halide lamps, keeping constant light intensity, duration, and temperature. Through RNA-seq, we identified the main genes and pathways involved in the genotypic responses. A first analysis identified genotypic differences in gene expression of development-related genes, including photoreceptors and flowering time genes. Genes from the vernalization pathway of light quality-sensitive genotypes were affected by fluorescent light. In particular, vernalization-related repressors reacted differently: HvVRN2 did not experience relevant changes, whereas HvOS2 expression increased under fluorescent light. To identify the genes primarily related to light quality responses, and avoid the confounding effect of plant developmental stage, genes influenced by development were masked in a second analysis. Quantitative expression levels of PPD-H1, which influenced HvVRN1 and HvFT1, explained genotypic differences in development. Upstream mechanisms (light signaling and circadian clock) were also altered, but no specific genes linking photoreceptors and the photoperiod pathway were identified. The variety of light-quality sensitivities reveals the presence of possible mechanisms of adaptation of winter and facultative barley to latitudinal variation in light quality, which deserves further research., (© 2023. Springer Nature Limited.)