Grass nitrogen (N) concentrations of dairy grasslands are higher on peat soil than on mineral soils. This can lead to increased N losses to air and water from dairy farming systems on peat soils. Our hypothesis was that the use of low-N perennial ryegrass (Lolium perenne L.) genotypes could be a means to lower grass N concentrations, when grown on peat soils. Our objective was to determine whether perennial ryegrass populations with different shoot tissue N concentrations, recorded on a sandy soil, would show different shoot tissue N concentrations and N use efficiencies (NUE) or N uptake efficiencies (NUptE) when grown on a peat soil. First, a pot experiment lasting 62 days was carried out with nine diploid and seven tetraploid populations, followed by a field experiment with two diploid and two tetraploid populations and a control lasting 30 months. Both experiments had three N fertilization levels. In the pot experiment, populations explained 3% of the variation in shoot tissue N concentration among tetraploids, 5 and 7% of the variation in NUE among diploids and tetraploids and 12% of the variation in NUptE among diploids. In the field experiment, populations explained 44% of the variation in NUptE. A higher NUE coincided with lower shoot tissue N concentrations among tetraploid populations in the pot experiment. We conclude that there is potential to alter the shoot tissue N concentrations of perennial ryegrass grown on peat soil, via selection for shoot tissue N concentrations and NUE.

Chenopodium quinoa W. is a species of South America with an exceptional nutritional content and wide agroclimatological adaptation. It has great genetic and phenotypic variability, however in Colombia there are few genetic improvement programmes that take advantage of its great genetic and productive potential. In Cundinamarca there are some adapted genotypes which have been selected by farmers. We evaluated 36 genotypes of Blanca de Jericó, Blanca Subachoque, Aurora, Púrpura and Tunkahuan from Cundinamarca, using eight ISSR markers. The analysis by the coefficient of Nei-Li at the level of similarity of 0.40 divided the population into three groups according their background genetic and the colour of oxalates. The percentage of polymorphic loci was higher than 90%. The average value of heterozygosity was 0.32, which is low given the selection processes that the evaluated germplasm has undergone. We found moderate genetic differentiation (Fst = 0.23). The analysis of molecular variance (AMOVA) showed higher variation (77%) groups than among groups (23%). The results revealed intra-population diversity, which suggests that farmers within their farms should undergo a more rigorous seed selection process. Our results demonstrate that ISSR markers are useful and powerful to assess the genetic relationships, polymorphism and genetic diversity of quinoa cultivars. The genetic characterization results reported in the present study will be promising for guiding the breeding of quinoa seed quality in Colombia.

New production from public and exclusive varieties released by the small grains breeding program at Virginia Tech generated cumulative discounted benefits of $41 million from 2000 to 2018. Fitted yields from field trials were combined with acreage estimates to generate weighted average yields based on adoption of new varieties. Benefits were estimated as the value of additional production from the release and adoption of improved varieties. Public varieties were responsible for most program benefits. The program was found to have a significant impact in Virginia and out-of-state, with much of these benefits due to public-private collaboration.

Badh2 of rice is considered to be the major gene responsible for the fragrance in rice. The wild type badh2 allele encodes betaine aldehyde dehydrogenase 2 (BADH2) enzyme while the mutated version of badh2 gene encodes non-functional BADH2 enzyme that leads to the accumulation of 2-acetyl-1-pyrroline (2AP), the principal fragrant compound in rice. There are many mutated recessive alleles causing fragrance in global rice germplasm, although the badh2.1 allele present in Basmati type rice is the most well-known among breeders. In this study, we attempted to reveal potential fragrance causing mutations, and the respective varieties carrying them, through in silico analysis based on the sequences available in the Rice SNP-Seek-Database of International Rice Research Institute. The sequences of 1878 rice accessions from 22 countries were analysed to identify mutations in each exon of badh2 comparatively with the non-fragrant ‘wildtype’ GenBank sequence in Nanjing11, Oryza sativa indica (EU770319.1). Results revealed that 63 varieties from 12 countries possessed the most prevalent allele, badh2.1 having an 8 bp deletion and three single nucleotide polymorphisms in the 7th exon. The second most prevalent allele in genotypes from Asia was badh2.7 having a ‘G’ insertion in the 14th exon. A novel allele with a T deletion in 9th exon was detected in a Thai rice accession. Rice varieties containing either badh2.1 or badh2.7 alleles could be identified with DNA markers for badh2.1 (frg) and badh2.7 (Bad2.7CAPS). The marker, Bad2.7CAPS, co-segregated with the fragrance phenotype in two crosses, confirming the possibility of employing it in marker assisted breeding.

Genetic diversity is a valuable asset for crop improvement. In this study, a total of 50 rice genotypes were screened for salinity tolerance at the reproductive stage using gravel-based hydroponics, soil, controlled mini-field and field methods. Different morpho-agronomic, physiological markers and tolerance indices were used to classify tolerant and susceptible genotypes. Our results showed high genetic variability in response of rice genotypes to salinity using different screening methods. The significant effect (P < 0.01) of salinity include increased Na+ sequestration in the flag leaf, increased unfilled grains (except for the field method) and reduced pollen fertility, total yield, panicle length and the average number of filled grains per panicle. Plant height (except for the soil method) and K+ ion concentration in the flag leaf were not significantly affected by salinity (P > 0.05). Genetic diversity analysis indicated that the germplasm evaluated exhibits moderate diversity (PIC ${\overline{\bf X}}$ = 0.2085). Cluster analysis using single nucleotide polymorphisms showed that the genetic make-up of rice germplasm somehow did not necessarily indicate their over-all tolerance or susceptibility to salinity. This study proved that the controlled mini-field method is the most advantageous among the screening methods while geometric mean productivity, stress tolerance index and yield index are the tolerance indices that can be classified as better predictors of salinity tolerance considering the yield potentials of the genotypes. The genotypes Nona Bokra and Mushkan 41 can be used for breeding in the future through low Na+:K+ ratio while Damodar and Bhura Rata 4-10 for breeding salt-tolerant cultivars with higher yield potentials.

Twenty-two sweet potato [Ipomoea batatas (L.) Lam.] clones with a wide range in metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] tolerance were used to establish narrow sense heritability estimates (h2) using a greenhouse procedure. The heritability estimates were obtained from simple linear regressions (h2 = 2b) of injury rating, shoot fresh weight, and change in shoot fresh weight of offspring against the same responses of parents at metribuzin concentrations of 0, 0.3, and 0.6 ppm in the potting medium and averaged data for the two concentrations. These values ranged from 0.85 to 1.0, indicating that a recurrent mass selection process should be an appropriate approach to developing metribuzin-tolerant cultivars. Several highly tolerant clones were identified.

Evaluating quality traits is important to the selection of elite lines in Brassica napus L. In this study, the quality traits of 488 global collections of B. napus L were evaluated for two consecutive years under central Chinese growing conditions, and a series of phenotypic data was obtained. The measured total glucosinolate content (GLC) and erucic acid content (ERU) values for 95.5% of the accessions were consistent with the original values, and large variations in quality traits were found among these accessions, thus enabling selection for these characters. In general, Chinese accessions tended to have a higher oil content (OC) than foreign accessions, while compared with winter and spring accessions, semi-winter accessions tended to have the highest OC. The mean GLC and ERU of Chinese rapeseed accessions showed gradual downward trends over time, and the genotypic variation in ERU accounted for 98.44% of the total variation, which was the highest among all 10 of the quality traits. Additionally, the heritability for ERU was largest among all 10 of the quality traits. Significant correlations were observed between different traits; OC had significantly (P < 0.01) negative correlation coefficients with oleic acid content, whereas OC had significantly (P < 0.01) positive correlation coefficients with ERU. Principal component analysis revealed that there was no clear boundary among materials of different geographic origins and different ecotypes according to the first two principal coordinates, respectively. This information about variations in quality traits revealed in this study could identify parents for improved rapeseed breeding.

There are many quality targets in cereals that could generate step-change improvements in nutritional or food-processing characteristics. For instance, levels of acrylamide, soluble and insoluble fibre, antioxidants, allergens and intolerance factors in food are, to a large extent, determined by the genetics of the raw materials used. However, improvements to these traits pose significant challenges to plant breeders. For some traits, this is because the underlying genetic and biochemical basis of the traits is not fully understood but for others, there is simply a lack of natural genetic variation in commercially useful germplasm. One strategy to overcome the latter hindrance is to use wide crosses with more exotic germplasm; however, this can bring other difficulties such as yield loss and linkage drag of deleterious alleles. As DNA sequencing becomes cheaper and faster, it drives the research fields of reverse genetics and functional genomics which in turn will enable the incorporation of desirable traits into crop varieties via molecular breeding and biotechnology. I will discuss the evolution of these techniques from conventional genetic modification to more recent developments in targeted gene editing and the potential of biotechnology to complement conventional breeding methods. I will also discuss the role of risk assessment and regulation in the commercialisation of GM crops.

More than 3200 new mutant varieties have been bred and used by millions of farmers, which has significantly contributed to world food security. A lot more mutants have also served as tools for gene discovery and functional analysis. Recent genomic approaches including TILLING (Targeting Induced Local Lesions In Genome) have enabled screening of mutations at the molecular level. This review describes the molecular nature of chemically and physically induced mutations and their repercussions. Analyses of TILLING reports indicate that chemically induced mutations are mostly nucleotide substitutions, but that mutation frequencies fluctuate among plant species ranging from one DNA lesion per 300 kbp in Arabidopsis to one DNA lesion per 30 kbp in bread wheat, which reciprocate with an increase in ploidy levels. The majority (>95%) of chemically induced DNA lesions are silent or missense mutations. Mutations induced by physical mutagens seem to be more diverse, including single-nucleotide substitutions, insertions, inversions and translocations, although short deletions ( < 15 bp) are relatively more predominant. The proportion of complex mutations (translocation, inversions, etc.) may increase with an increase in the linear energy transfer of radiations. In addition, the implications of these findings for the roles of induced mutants in breeding and gene function analysis are briefly discussed.

Nicaragua is located in the Mesoamerican diversity centre for common beans (Phaseolus vulgaris L.). Yet, there is insufficient knowledge of the molecular characteristics of most common bean landraces in Nicaragua. The objectives of the present study were to investigate the genetic diversity of common bean landraces and to identify promising sources of genetic variation for breeding purposes. Two cultivars and 40 landraces never studied before were selected from a collection based on the geographic origin, seed coloration and information provided by farmers. Fourteen microsatellite markers distributed in different linkage groups were analysed. The study revealed that there is a high genetic diversity (mean 8.9 alleles per locus). The populations showed structuring into three groups where seed weight had a strong relationship with population clustering. At least 20% of the populations hold promising allelic variation and potential for good market acceptance that could be maximized in breeding programmes. Additionally, four markers revealed a high correlation with seed length, width and weight, suggesting that marker-assisted selection for these yield-determinant traits could be straightforward. Nonetheless, more marker–trait associations should be addressed in order to enforce this practice.

Introduction. Chinese jujubeoriginated in China and has become a leading fruit tree in the northernpart of China with total production of 4,250,000 t in 2009 and totalplanting area of 1,500,000 ha. Among the reported 944 Chinese jujubecultivars or strains, ‘Zanhuangdazao’ is the unique natural triploid cultivar;it is characterized by big fruit, high yield and good adaptabilitycompared with the other diploid cultivars. Therefore, our groupbegan polyploid breeding through colchicine induction starting in2000. Cultivar origin. ‘Chenguang’ is a new Chinese jujubecultivar induced by colchicine on the stem apex of the diploid ‘Linyilizao’.Through three years of top-grafting and purification, its characteristicswere observed in grafted and top-grafted experimental orchards continually.In 2009, ‘Chenguang’ was released by the Hebei Forestry CultivarExamination and Approval Committee and became the unique tetraploid Chinesejujube cultivar in the world to date. Cultivar characteristics.The somatic chromosome number, botanical character, phenologicalphase, productivity and adaptability are given. ‘Chenguang’ is suitablefor growing in Shanxi, Hebei, Shandong Province, where the annual averagetemperature is 12–14 °C and rainfall is above 400 mm, or similar soiland climate conditions. Main cultural techniques. Propagation,the training system, fruit setting and disease control are explainedand recommended.

Global food security could be imperilled by the combined pressures from the effects of continually evolving climatic conditions, demographics and other socio-economic factors, the demands of the livestock, bioenergy and fibre industries for food-based substrates, the static or decreasing availability of natural resources for agriculture and the impracticality of increased use of economically and environmentally costly agricultural inputs. The optimal harnessing of plant genetic resources for food and agriculture (PGRFA) in manners that translate their repertoire of hidden potentials into significantly enhanced crop productivities has been severally identified as crucial to achieving the required considerably significant increases in food production. The scope of the problems and the plausible means for addressing them compel the devising of novel and more efficient ways for deploying PGRFA in need-based crop improvement programmes. We posit a continuum approach to the management of PGRFA which links seamlessly the effective conservation and access to PGRFA through their use in developing superior and resilient crop varieties to the provision of their high-quality seeds and planting materials to the growers. To achieve the mainstreaming of this paradigm, we propose the institutionalization of overarching national PGRFA strategies that prescribe result-oriented action plans spanning above three components of the management of PGRFA for a country's priority crops. We also describe the strategy as a means for identifying and assigning responsibilities to critical stakeholders and providing for the governance of all aspects of PGRFA activities over specific time frames. Steps to developing and adopting a national PGRFA strategy are also suggested.

Guava (Psidium guajava) and araçá (Psidium spp.) plants are important for the Brazilian economy, as their fruit is both accepted by the consumers, and makes a beneficial contribution to the human diet thanks to their content in vitamin C, carotenoids and phenolic compounds. Here, we report the content in the fruit of free ascorbic acid, lycopene, β-carotene, flavonoids and phenolic compounds, and the total antioxidant activity present in a collection of guava and araçá accessions curated at the Embrapa Semiarido germplasm bank. Guava fruits with a red-coloured pulp flesh contained a significant amount of carotenoids, especially lycopene, and a high concentration of phenolic compounds. These compounds were largely responsible for the antioxidant activity of the araçá accessions. Among the guava accessions, phenolic compounds were also responsible for the antioxidant activity. High levels of free ascorbic acid were present in most accessions. In both guava and araçá, there is substantial potential to develop cultivars with a good level of consumer acceptability.

Hordeum chilense Roem. et Schultz. is a diploid wild barley native to Chile and Argentina. The high crossability of this species with other members of the Triticeae tribe promoted the development of the new species × Tritordeum Ascherson et Graebner. Hexaploid tritordeum was developed from the hybrid derived from the cross between H. chilense (used as female parent) and durum wheat. The interest of H. chilense is based on the presence of traits potentially useful for wheat breeding, including high endosperm carotenoid content, septoria tritici blotch resistance and abiotic stress tolerance. Besides, the variability at cytoplasm level is also important in this species. The development of common wheat–H. chilense alloplasmic lines (nucleus from wheat and cytoplasm from H. chilense) results in fertile or male sterile genotypes, depending on the accession donating the cytoplasm. Furthermore, these alloplasmic lines constitute an ideal system for deepening our knowledge on nuclear–cytoplasm interactions. In conclusion, H. chilense is an interesting source of variability for wheat breeding.

Introduction. Tejocote (Crataegus spp.) is an edible fruit species that some Mesoamerican cultures have cultivated since pre-Hispanic times in Mexico; however, this fruit crop has not undergone formal breeding. It is unknown whether morphological markers associated with fruit size exist to be used for indirect selection; this could be important, because this species has a large cycle. Our research aimed at studying phenotypic correlations between leaf and stomata characters with fruit weight; such correlations might be used as morphological markers for selection of superior germplasm for fruit weight. Materials and methods. Pearson’s correlation coefficients of 36 leaf variables and three leaf stomata variables with fruit weight were calculated in 94 genotypes of four different species. Results. As expected, the correlations calculated for each species and for the species pool differed. However, the number of veins in leaves of reproductive shoots was positively correlated with fruit weight (P ≤ 0.05) in the two most important horticultural species. On the other hand, C. mexicana was the best option for selecting superior germplasm, and the most significant variables correlated with fruit weight in this species were leaf major axis length of large vegetative shoots, leaf elongation ratio and number of veins of reproductive shoot leaves. Discussion. These variables could be good selection indices or morphological markers that can be used for early screening of germplasm for yield potential.

Introduction. Wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most important disease of banana worldwide, causing severe yield losses in commercial and local consumption cultivars. Chemical control is currently the most used method to manage the Fusarium wilt of banana, although it is toxic, expensive and dangerous. Therefore, control through genetic improvement is widely encouraged. Hence, breeding was carried out to develop banana hybrids with putative resistance. Materials and methods. Hybridization of identified resistant diploids with commercial triploids and tetraploids was carried out; it resulted in development of 22 hybrids with improved agronomic characters. In a second step, screening of these hybrids for resistance to Foc race 1 was attempted using the double cup method of challenge inoculation with the pathogen in the roots of the hybrids at optimum level. Host responses of the susceptible and resistant hybrids were examined under greenhouse conditions through biochemical and isozyme analysis. Results. Six hybrids among the 22 hybrids with improved agronomic characters were selected based on their yield and they were evaluated for resistance. Three of them were resistant to Foc and the others were susceptible. The resistance mechanism involving the relation of enzymes such as peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine lyase (PAL), and biochemicals such as phenols, proline and lignin showed relatively higher activity in resistant hybrids and parents than susceptible ones. Isozyme analysis of PO and PPO carried out using selected resistant and susceptible hybrids revealed the induction of specific isoforms in the resistant hybrids upon challenge inoculation. Conclusion. Three hybrids were identified as potential hybrids with good yield and resistance to Foc race 1.

UK agriculture is undergoing significant change with reduced subsidies for food production, increasing consumer demands for food safety and traceability, and environmental concerns including climate and demographic change. The International Treaty on Plant Genetic Resources for Food and Agriculture adopted by the United Nations Food and Agriculture Organisation supports the use of genetic resources for research and breeding. Mining genetic resources for useful genetic variation is perceived as a major benefit of genebanks. However, utilization by breeders may be constrained by poor characterization of genetic resources, a widening gap between improved and unimproved material, and the disruption of well- adapted genotypes during introgression. Breeders working with grasses and forage legumes for sustainable agriculture are fortunate in the wealth of genetic variation available both within the primary species of interest and among related species. New DNA technologies allow more targeted approaches to the use of these genetic resources. Possibilities for gene transfer between related species using conventional techniques expand the available gene pools while potential use of genetic transformation extend these even further.

Genealogical data have been used very widely to construct indices with which to examine the contribution of plant breeding programmes to the maintenance and enhancement of genetic resources. In this paper we use such indices to examine changes in the genetic diversity of the winter wheat crop in England and Wales between 1923 and 1995. We find that, except for one period characterized by the dominance of imported varieties, the genetic diversity of the winter wheat crop has been remarkably stable. This agrees with many studies of plant breeding programmes elsewhere. However, underlying the stability of the winter wheat crop is accelerating varietal turnover without any significant diversification of the genetic resources used. Moreover, the changes we observe are more directly attributable to changes in the varietal shares of the area under winter wheat than to the genealogical relationship between the varieties sown. We argue, therefore, that while genealogical indices reflect how well plant breeders have retained and exploited the resources with which they started, these indices suffer from a critical limitation. They do not reflect the proportion of the available range of genetic resources which has been effectively utilized in the breeding programme: complex crosses of a given set of varieties can yield high indices, and yet disguise the loss (or non-utilization) of a large proportion of the available genetic diversity.