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Muscadine grapes (Vitis rotundifoliaMichx.) are a specialty crop cultivated in the southern United States. Muscadines (2n=40) belong to theMuscadiniasubgenus ofVitis,while all other cultivated grape species belong to the subgenusEuvitis(2n=38). The berry color locus in muscadines has been mapped to a 0.8 Mbp region syntenic with chromosome 4 ofV. vinifera. In this study, we identified glutathione S-transferase4 (GST4) as a likely candidate gene for anthocyanin transport within the berry color locus. PCR and KASP genotyping identified a single intragenic SNP (C/T) marker corresponding to a proline to leucine mutation within the muscadineGST4(VrGST4) that differentiated black (CC and CT) from bronze (TT) muscadines in 65 breeding selections, 14 cultivars, and 320 progeny from two mapping populations. Anthocyanin profiling on a subset of the progeny indicated a dominantVrGST4action, with no allele dosage effect on total anthocyanin content or composition of individual anthocyanins. Proanthocyanidin content was similar in the seeds of both black and bronze genotypes, and seeds had much higherVrGST3expression and lowerVrGST4expression than skins.VrGST4expression was higher in post-veraison berries of black muscadines compared to pre-veraison berries, but no changes in gene expression in pre- and post-veraison berries were observed in the bronze muscadine cultivar.VrMybA1expression was higher in post-veraison berries of both black and bronze muscadines. These results suggest that berry pigmentation in muscadines is regulated by a mechanism distinct from theMybAgene cluster that is responsible for berry color variation inV. vinifera.

Linkage maps of muscadine grape generated using genotyping-by-sequencing (GBS) provide insight into genome collinearity between Muscadinia and Euvitis subgenera and genetic control of flower sex and berry color. The muscadine grape, Vitis rotundifolia, is a specialty crop native to the southeastern USA. Muscadine vines can be male, female, or perfect-flowered, and berry color ranges from bronze to black. Genetic linkage maps were constructed using genotyping-by-sequencing in two F1 populations segregating for flower sex and berry color. The linkage maps consisted of 1244 and 2069 markers assigned to 20 linkage groups (LG) for the ‘Black Beauty’ × ‘Nesbitt’ and ‘Supreme’ × ‘Nesbitt’ populations, respectively. Data from both populations were used to generate a consensus map with 2346 markers across 20 LGs. A high degree of collinearity was observed between the genetic maps and the Vitis vinifera physical map. The higher chromosome number in muscadine (2n = 40) compared to V. vinifera (2n = 38) was accounted for by the behavior of V. vinifera chromosome 7 as two independently segregating LGs in muscadine. The muscadine sex locus mapped to an interval that aligned to 4.64–5.09 Mb on V. vinifera chromosome 2, a region which includes the previously described V. vinifera subsp. sylvestris sex locus. While the MYB transcription factor genes controlling fruit color in V. vinifera are located on chromosome 2, the muscadine berry color locus mapped to an interval aligning to 11.09–11.88 Mb on V. vinifera chromosome 4, suggesting that a mutation in a different gene in the anthocyanin biosynthesis pathway determines berry color in muscadine. These linkage maps lay the groundwork for marker-assisted breeding in muscadine and provide insight into the evolution of Vitis species.

Understanding how human perception is related to physicochemical attributes strengthens identification of ripeness and marketability parameters for peaches and nectarines [Prunus persica (L.) Batsch]. Six peach and nectarine cultivars (Amoore Sweet, Bowden, Effie, Loring, Souvenirs, and White River) and three advanced breeding selections (A-827, A-850, and A-865) were harvested from trees grown at the University of Arkansas System Division of Agriculture Fruit Breeding Program in Clarksville, AR. Physical and chemical characteristics of the genotypes at harvest were as follows: fruit weight of 134.4 to 330.2 g, firmness of 7.8 to 35.8 N, soluble solids of 7.5% to 14.7%, pH of 3.3 to 4.8, titratable acidity of 0.2% to 1.1%, total sugars of 1.7 to 10.4 g/100 g, and total organic acids of 0.1 to 0.9 g/100 g. Overall, A-865 had the lowest fruit weight (134.0 g) and pH (3.3), and the highest firmness (35.8 N), soluble solids (14.7%), titratable acidity (1.1%), total sugars (10.4 g/100 g), and total organic acids (0.8 g/100 g). ‘White River’ had the largest fruit (330.2 g) and pit (11.06 g). A-850 (63.6) had the highest soluble solids/titratable acidity ratio, and ‘Bowden’ (12.7) had the lowest. A trained descriptive sensory panel (n = 10) was used to create a lexicon for Arkansas-grown fresh-market peaches and nectarines. The panel evaluated the fruit for aroma (n = 4), external appearance (n = 8), internal appearance and pit attributes (n = 6), basic tastes (n = 3), aromatics while eating fruit (n = 5), feeling factors (n = 2), and texture (n = 6). Principal component analysis explained 63.4% of the data variance attributed to texture and acidity. Of all of the physicochemical attributes, firmness had the most significant correlations with the descriptive sensory attributes, followed by fruit weight. Firmness was negatively correlated (r = −0.70 to 0.81) to fruit size, fuzziness, amount of bruises on the flesh, pit size, and moisture release, and positively correlated (r = 0.68–0.84) to sourness, green/unripe aromatics, flesh hardness, flesh crispness, and fibrousness between the teeth. Fruit weight was positively correlated (r = 0.67–0.75) to fruit and pit size, overripe aromatics, and moisture release. Significant correlations between descriptive sensory appearance, basic tastes, aromatics, and texture attributes with physicochemical attributes provide an indication of ripeness and marketability parameters for peaches and nectarines. These descriptive attributes are quality factors that impact consumer purchases and perception of fresh-market peaches and nectarines.

Understanding how consumer perception is related to physiochemical attributes assists in the identification of harvest and marketability parameters for muscadine grapes (Vitis rotundifolia Michx.). Three muscadine cultivars (Ison, Nesbitt, and Summit) and three advanced breeding selections (AM-9, AM-74, and AM-83) were harvested from vines at the University of Arkansas System Division of Agriculture Fruit Research Station in Clarksville, AR. The physiochemical (physical and composition) and sensory attributes (descriptive) of the genotypes were evaluated at harvest. Significant differences between genotypes were observed for berry weight (9.25–14.38 g), soluble solids (12.73% to 15.40%), pH (2.88–3.33), titratable acidity (0.54% to 1.01%), soluble solids/titratable acidity ratio (13.12–28.49), skin firmness [0.85–1.48 Newtons/millimeters (N·mm−1)], and flesh firmness (0.89–2.14 N). Total sugars (6.17–9.75 g/100 g) and total organic acid (0.50–0.84 g/100 g) levels were not significantly different for these genotypes. A trained descriptive sensory panel (n = 8) evaluated the fruit attributes for aroma (n = 9), external appearance (n = 7), internal appearance (n = 3), basic tastes (n = 3), aromatics (n = 10), feeling factors (n = 2), and texture (n = 7). The descriptive sensory panel detected differences among genotypes for external appearance, internal appearance, and basic taste attributes, more specifically with desirable attributes rather than unfavorable. However, the panelists found no differences among genotypes for texture attributes. Of the physiochemical attributes, total sugars had the most significant correlations with the descriptive sensory attributes, followed by soluble solids/titratable acidity ratio. Total sugars were correlated to 12 attributes (three aromas, two exterior appearances, two basic tastes, four aromatics, and one feeling factor) and soluble solids/titratable acidity was correlated to five attributes (one aroma, one basic taste, two aromatics, and one feeling factor). A lexicon of terms for descriptive sensory attributes for fresh-market muscadine grapes was established. This lexicon can be used for other research and breeding efforts, as well as establishing the relationship between the physiochemical and descriptive sensory attributes.

Confirming parentage and clonal identity is an important aspect of breeding and managing germplasm collections of clonally propagated, outcrossing crops, like blackberry (Rubus subgenus Rubus). DNA fingerprinting sets are used to identify off-cross progeny and confirm clonal identity. Previously, a six-simple sequence repeat (6-SSR) fingerprinting set was developed for blackberry using a small number of samples. The usefulness of the 6-SSR fingerprinting set for pedigree confirmation had not been evaluated. Therefore, it was used in this study to validate parentage for 6 and 12 biparental populations from the University of Arkansas (UA) and US Department of Agriculture Agricultural Research Service (USDA-ARS), Horticultural Crops Research Unit (HCRU) breeding programs, respectively. Twenty-seven of the 489 individuals in these breeding populations were identified as off-cross. The 6-SSR fingerprinting set was sufficient for parentage confirmation; however, a total of 61 plants distributed across 28 sets of genotypes could not be distinguished from each other. An 8-SSR fingerprinting set with improved resolution was subsequently developed and used to evaluate 177 Rubus accessions from the USDA-ARS National Clonal Germplasm Repository, UA, and USDA-ARS HCRU programs. The 8-SSR fingerprinting set distinguished all samples expected to have unique genotypes and identified differing DNA fingerprints for two sets of accessions suspected to have identical fingerprints. Cluster analysis grouped the accessions from the eastern and western US breeding programs based on geography and descent. Future work will focus on establishing a database of DNA fingerprints for germplasm identification and for determining pedigree relationships between blackberry accessions.

Toxic concentrations of aluminium cations and low phosphorus availability are the main yield-limiting factors in acidic soils, which represent half of the potentially available arable land. Brachiaria grasses, which are commonly sown as forage in the tropics because of their resilience and low demand for nutrients, show greater tolerance to high concentrations of aluminium cations (Al3+) than most other grass crops. In this work, we explored the natural variation in tolerance to Al3+ between high and low tolerant Brachiaria species and characterized their transcriptional differences during stress. We identified three QTLs (quantitative trait loci) associated with root vigour during Al3+ stress in their hybrid progeny. By integrating these results with a new Brachiaria reference genome, we identified 30 genes putatively responsible for Al3+ tolerance in Brachiaria. We observed differential expression during stress of genes involved in RNA translation, response signalling, cell wall composition, and vesicle location homologous to aluminium-induced proteins involved in limiting uptake or localizing the toxin. However, there was limited regulation of malate transporters in Brachiaria, which suggests that exudation of organic acids and other external tolerance mechanisms, common in other grasses, might not be relevant in Brachiaria. The contrasting regulation of RNA translation and response signalling suggests that response timing is critical in high Al3+-tolerant Brachiaria., We identified QTLs, genes, and molecular responses in high and low tolerant Brachiaria grasses associated with aspects of the response to aluminium stress, such as regulation, cell wall composition, and active transport.

Brachiaria humidicola (BH) (syn. Urochloa humidicola) is an important forage grass in the tropics due to its capacity to grow in nutrient‐deficient soils, tolerate waterlogging, and inhibit soil nitrification. A major objective of BH breeding is to improve its nutritional quality. Therefore, a rapid and low‐cost method is needed to assess main quality parameters such as neutral detergent fiber (NDF), acid detergent fiber (ADF), in vitro dry matter digestibility (IVDMD), and crude protein (CP). This study developed models using near infrared reflectance spectroscopy (NIRS) to predict concentrations of these parameters toward breeding. Samples were collected from BH trials located in different regions of Colombia, scanned for NIRS (400–2,500 nm), analyzed with wet chemistry as reference values, and used to build the chemometric models. Results from wet chemistry showed wide variability in terms of dry matter percentage for NDF (51.6–76.2%), ADF (26.1–46.1%), IVDMD (41.5–78.3%), and CP (2.8–12.8%). The NIRS models were validated using an independent set of samples and have coefficients of determination (R2) and one minus the variance ratio (1 – VR) values in the range of .9 and .95, suggesting a good correlation between reference‐lab and NIRS‐predicted values. The standard errors of cross validation (SECV) for IVDM, NDF, ADF, and CP were 1.59, 1.18, 0.74, and 0.53%, respectively. Prediction efficiency (ratio of performance to standard deviation, RPD) for all parameters was above 3.0, except for CP (2.6). Calibrations obtained present an adequate adjustment and predictive tendency, making them suitable for selection and BH breeding.

Toxic concentrations of aluminium cations and low phosphorus availability are the main yield-limiting factors in acidic soils, which represent half of the potentially available arable land. Brachiaria grasses, which are commonly sown as a forage in the tropics because of their resilience and low demand for nutrients, have a greater tolerance to high concentrations of aluminium cations than most other grass crops. In this work, we explored the natural variation in tolerance to aluminium cations (Al3+) between high and low tolerant Brachiaria species and characterised their transcriptional differences during stress. We also identified three QTLs associated with root vigour during Al3+ stress in their hybrid progeny. By integrating these results with a new Brachiaria reference genome, we have identified 30 genes responsible for Al3+ tolerance in Brachiaria. We also observed differential expression during stress of genes involved in RNA translation, response signalling, cell wall composition and vesicle location genes homologous to aluminium-induced proteins involved in limiting uptake or localizing the toxin. However, there was limited regulation of malate transporters in Brachiaria, which are associated with external tolerance mechanisms to Al3+ stress in other grasses. The contrasting regulation of RNA translation and response signalling suggests response phasing is critical to Al3+ tolerance.HIGHLIGHTWe identified QTLs, genes and molecular responses in high and low tolerant Brachiaria grasses associated with aspects of response to aluminium stress, such as regulation, cell-wall composition and active transport.

Rubusfruits are high-value crops that are sought after by consumers for their flavor, visual appeal, and health benefits. To meet this demand, production of red and black raspberries (R. idaeusL. andR. occidentalisL.), blackberries (R. subgenusRubus), and hybrids, such as Boysenberry and marionberry, is growing worldwide.Rubusbreeding programmes are continually striving to improve flavor, texture, machine harvestability, and yield, provide pest and disease resistance, improve storage and processing properties, and optimize fruits and plants for different production and harvest systems. Breeders face numerous challenges, such as polyploidy, the lack of genetic diversity in many of the elite cultivars, and until recently, the relative shortage of genetic and genomic resources available forRubus. This review will highlight the development of continually improving genetic maps, the identification of Quantitative Trait Loci (QTL)s controlling key traits, draft genomes for red and black raspberry, and efforts to improve gene models. The development of genetic maps and markers, the molecular characterization of wild species and germplasm, and high-throughput genotyping platforms will expedite breeding of improved cultivars. Fully sequenced genomes and accurate gene models facilitate identification of genes underlying traits of interest and enable gene editing technologies such as CRISPR/Cas9.

Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR–BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR–BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR–BBML as candidate genes for the apomictic function of parthenogenesis.

Rhizoctonia foliar blight, caused by Rhizoctonia solani, is an important disease of Brachiaria spp. in tropical America. Host-plant resistance is an attractive option for disease management. In this study, we evaluated three inoculum types (mycelium-infected agar disc, microdiscs suspensions, and microencapsulated-mycelium suspensions) in order to identify a rapid and accurate method for mass screening of Brachiaria genotypes for resistance to Rhizoctonia spp. in greenhouse trials. Visual damage score, area under the disease progress curve, and percent chlorophyll loss were estimated to determine the most accurate and precise method for evaluating Rhizoctonia resistance. The microencapsulated-mycelium solution (0.75 g/ml in potato dextrose broth sprayed on plants 30 days after planting) caused greater foliar damage than the other inoculum types and allowed effective discrimination between resistant and susceptible genotypes. The effectiveness of spray-applied, microencapsulated-mycelium was further corroborated by the evaluation of 350 genotypes not previously selected for resistance to Rhizoctonia spp., which varied significantly in their reaction to R. solani. The microencapsulated-mycelium methodology has several advantages over existing methods, including its high-throughput capacity, efficient use of time and space, ease of quantification of inoculum, and consistent results over replicate trials. This methodology could be applied to assess resistance to Rhizoctonia spp. in other crops.

Nitrification, the biological oxidation of ammonium to nitrate, weakens the soil's ability to retain N and facilitates N-losses from production agriculture through nitrate-leaching and denitrification. This process has a profound influence on what form of mineral-N is absorbed, used by plants, and retained in the soil, or lost to the environment, which in turn affects N-cycling, N-use efficiency (NUE) and ecosystem health and services. As reactive-N is often the most limiting in natural ecosystems, plants have acquired a range of mechanisms that suppress soil-nitrifier activity to limit N-losses via N-leaching and denitrification. Plants' ability to produce and release nitrification inhibitors from roots and suppress soil-nitrifier activity is termed 'biological nitrification inhibition' (BNI). With recent developments in methodology for in-situ measurement of nitrification inhibition, it is now possible to characterize BNI function in plants. This review assesses the current status of our understanding of the production and release of biological nitrification inhibitors (BNIs) and their potential in improving NUE in agriculture. A suite of genetic, soil and environmental factors regulate BNI activity in plants. BNI-function can be genetically exploited to improve the BNI-capacity of major food- and feed-crops to develop next-generation production systems with reduced nitrification and N2O emission rates to benefit both agriculture and the environment. The feasibility of such an approach is discussed based on the progresses made.

A powdery mildew resistance gene was introgressed from Aegilops speltoides into winter wheat and mapped to chromosome 5BL. Closely linked markers will permit marker-assisted selection for the resistance gene. Powdery mildew of wheat (Triticum aestivum L.) is a major fungal disease in many areas of the world, caused by Blumeria graminis f. sp. tritici (Bgt). Host plant resistance is the preferred form of disease prevention because it is both economical and environmentally sound. Identification of new resistance sources and closely linked markers enable breeders to utilize these new sources in marker-assisted selection as well as in gene pyramiding. Aegilops speltoides (2n = 2x = 14, genome SS), has been a valuable disease resistance donor. The powdery mildew resistant wheat germplasm line NC09BGTS16 (NC-S16) was developed by backcrossing an Ae. speltoides accession, TAU829, to the susceptible soft red winter wheat cultivar ‘Saluda’. NC-S16 was crossed to the susceptible cultivar ‘Coker 68-15’ to develop F2:3 families for gene mapping. Greenhouse and field evaluations of these F2:3 families indicated that a single gene, designated Pm53, conferred resistance to powdery mildew. Bulked segregant analysis showed that multiple simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers specific to chromosome 5BL segregated with the resistance gene. The gene was flanked by markers Xgwm499, Xwmc759, IWA6024 (0.7 cM proximal) and IWA2454 (1.8 cM distal). Pm36, derived from a different wild wheat relative (T. turgidum var. dicoccoides), had previously been mapped to chromosome 5BL in a durum wheat line. Detached leaf tests revealed that NC-S16 and a genotype carrying Pm36 differed in their responses to each of three Bgt isolates. Pm53 therefore appears to be a new source of powdery mildew resistance.

Farmers’ Varietal Identification in a Reference Sample of Local Phaseolus Species in the Sierra Juarez, Oaxaca, Mexico. Farmer-named varieties are often the basis of in situ diversity assessment, collections for ex situ conservation, and on-farm improvement programs. Such varieties play an important role in sustainable agriculture because of their adaptation to local environmental conditions and consumer tastes. The importance of these varieties has stimulated interest in understanding farmers’ varietal classifications. We investigated the empirical basis of, and agreement among, farmers’ bean variety classification in a community in the Sierra Juarez, Oaxaca, Mexico. A reference sample of 300 local seeds of three Phaseolus species was sorted by nine farmers into named varieties. Nuclear and chloroplast microsatellite markers and seed morphology data were used to a) establish species identities; and test the hypotheses that b) farmer varieties reflect morphological and genetic structures; and c) there is agreement among farmers in variety classification. Because all farmers sorted the same set of seeds the variation in individual farmers’ classifications could be documented and compared. Our results indicate an empirical basis for farmer varieties, but without stringent classification rules. Varietal names underestimated diversity present at the community level because of the intravarietal variation present in farmer classifications. There was low classification agreement among farmers, although broad morphological and genetic patterns were present. The variation in farmers’ classifications of this Phaseolus diversity resulted in both synonymy and homonymy across classifications. The goal of farmers may not be to maintain the same variety across households, but to form a version of a broad type that best fits their own needs and circumstances at one point in space and time. Thus, in both work with farmers and collections of their Phaseolus varieties for ex situ conservation it should not be assumed that same-named seed lots are redundant units of diversity. Morphological and/or molecular data should, therefore, supplement farmer varietal names in assessments of in situ crop diversity, while ex situ collections would benefit from the inclusion of multiple accessions of the same variety from different farmers, repeated over time.

Infestations of Italian ryegrass are problematic in both conventional and organic wheat production systems. The development of wheat cultivars with superior competitive ability against Italian ryegrass could play a role in maintaining acceptable yields and suppressing weed populations. Research was conducted in North Carolina to identify indirect methods of selection for Italian ryegrass suppressive ability (hereafter referred to as weed suppressive ability) of winter wheat cultivars that correlate well with Italian ryegrass-to-wheat biomass ratios. Two winter wheat cultivars (Dyna-Gro Baldwin and Dyna-Gro Dominion) and one experimental wheat line (NC05-19684) with differing morphological traits were overseeded with varying densities of Italian ryegrass. Wheat height measured throughout the growing season in weed-free plots was strongly associated with weed suppressive ability, but high wheat tillering capacity had no significant effect on weed suppressive ability in the lines tested in this study. Italian ryegrass seed head density during grain fill was strongly correlated (r= 0.94) with Italian ryegrass-to-wheat biomass ratio, the generally accepted measure of weed suppressive ability. Visual estimates of percent Italian ryegrass biomass relative to the plot with the highest level of Italian ryegrass infestation in each replicate were also strongly correlated with weed suppressive ability at all growth stages, especially during heading (r= 0.87) (Zadoks growth stage [GS] 55). Measurements from nonimaging spectrophotometers and overhead photographs taken from tillering (Zadoks 23 to 25) to early dough development (Zadoks 80) were unreliable estimates of end-of-season Italian ryegrass-to-wheat biomass ratios because they failed to account for wheat cultivar differences in biomass, color, and growth habit. Italian ryegrass seed head density and visual estimates of Italian ryegrass biomass during grain fill are appropriate indirect methods of selection for weed suppressive ability in breeding programs.

Brachiaria grasses are sown in tropical regions around the world, especially in the Neotropics, to improve livestock production. Waterlogging is a major constraint to the productivity and persistence of Brachiaria grasses during the rainy season. While some Brachiaria cultivars are moderately tolerant to seasonal waterlogging, none of the commercial cultivars combines superior yield potential and nutritional quality with a high level of waterlogging tolerance. The Brachiaria breeding program at the International Center for Tropical Agriculture (CIAT), has been using recurrent selection for the past two decades to combine forage yield with resistance to biotic and abiotic stress factors. The main objective of this study was to test the suitability of normalized difference vegetation index (NDVI) and image-based phenotyping as non-destructive approaches to identify Brachiaria hybrids tolerant to waterlogging stress under field conditions. Nineteen promising hybrid selections from the breeding program and three commercial checks were evaluated for their tolerance to waterlogging under field conditions. The waterlogging treatment was imposed by applying and maintaining water to 3 cm above soil surface. Plant performance was determined non-destructively using proximal sensing and image-based phenotyping and also destructively via harvesting for comparison. Image analysis of projected green and dead areas, NDVI and shoot biomass were positively correlated (r ≥ 0.8). Our results indicate that image analysis and NDVI can serve as non-destructive screening approaches for the identification of Brachiaria hybrids tolerant to waterlogging stress.

In situ conservation of crop genetic resources is an important complement to ex situ conservation, yet little is known about how small-scale farmers perceive diversity in their own fi elds. In this study, we investigated the role of farmers from a community in the Sierra Juarez, Oaxaca, Mexico, in managing Phaseolus bean diversity in their fi elds. We collected seeds from 287 plants in 10 fi elds in the village of Santa Maria Jaltianguis and evaluated the diversity present in the collection at 10 nuclear and three chloroplast DNA (cpDNA) microsatellite markers. Following a STRUCTURE analysis, three core population clusters were identifi ed in the collection, a fi nding corroborated by morphological observations, principal coordinate analysis, and neighbor-joining tree construction using molecular data. The fi rst two populations were identifi ed as Phaseolus vulgaris L. ecogeographic races Mesoamerica and Jalisco and the third population as related species Phaseolus coccineus L. and Phaseolus dumosus Macfad. Each of the fi elds sampled consisted predominantly of a single Phaseolus species or ecogeographic race, but there was also evidence of low levels of gene fl ow between races Jalisco and Mesoamerica. Our data suggest farmers in Santa Maria Jaltianguis recognize existing inter- and intraspecies diversity in Phaseolus, its differential adaptation, its capacity to exploit a broad range of growing environments, and its potential to buffer the community against socioeconomic and climatic changes.

The International Center for Tropical Agriculture (CIAT) forage-breeding program utilizes recurrent selection on specific combining ability (RS-SCA) with a non-inbred tester in a synthetic, fully sexual breeding population to develop improved apomictic Brachiaria (Trin.) Griseb cultivars. This breeding scheme was designed to accumulate nonadditive, heterotic effects over cycles of selection and recombination. Various approaches for accelerating genetic gain in the context of recurrent selection for improved apomictic forage grasses are being considered as the breeding program enters the fourth cycle of RS-SCA. The identification of a molecular marker linked to the genetic factor controlling apomictic reproductive mode makes feasible the alternate breeding methods including reciprocal full-sib recurrent selection (RFRS) in two complementary populations, both segregating for apomixis. The establishment of complementary populations based on natural heterotic patterns enhanced through RS-SCA is an important prerequisite for the initiation of RFRS in Brachiaria. The RFRS scheme proposed in this chapter should result in accelerated genetic gains compared to RS-SCA and facilitate the implementation of additional forms of marker assisted selection (MAS) in Brachiaria and other apomictic grasses when well-saturated molecular maps become available.

One of the very few published articles dedicated to the investigation of Wat’s Dyke, Margaret Worthington Hill’s article stemming from her University of Manchester M.Phil thesis was originally published in a special issue of the Bulletin of the John Rylands Library published by Manchester University Press. Guest-edited by Gale R. Owen-Crocker, the theme was Anglo-Saxon Texts and Contexts (Worthington 1997). Her article is re-printed here with the permission of the author and with the support and permission of the guest-editor, the current editors of that journal, and Manchester University Press. This version has been revised for style (including the removal of footnote citations and the inclusion of a Bibliography) and includes new photographs taken by this journal’s editors to illustrate the character of the monument at key locations mentioned in the text. The article remains an invaluable resource for those studying Wat’s Dyke and it might be profitably read in conjunction with the published fieldwork and dating of Wat’s Dyke at Gobowen (Shropshire) by Malim and Hayes (2008). Margaret spoke eloquently about her long-term research on Offa’s Dyke and Wat’s Dyke at the first meeting of the Offa’s Dyke Collaboratory in Shrewsbury in April 2017 and attended the Offa’s Dyke Conference at Oswestry in September 2018. In this context, it is a particular privilege to include her important study in the first volume of the Offa’s Dyke Journal, thus recognizing her longstanding contribution to the study of Britain’s longest early medieval linear earthworks.

Earlier fieldwork by the University of Manchester (see ANTIQUITY 64:51–8) identified the important early medieval port of Quentovic. This note reports on the final two seasons of work, which clarified the phasing and extent of this major wic settlement, and on the radiocarbon dates from key features.