Identification of quantitative trait locus and prediction of candidate genes for grain mineral concentration in maize across multiple environments

Trace metal elements are essential in daily diets for human health and normal growth. Maize is staple food for people in many countries. However, maize has low mineral concentration which makes it difficult to meet human requirements for micronutrients. The objective of this study was to identify quantitative trait locus (QTL) and predict candidate genes associated with mineral concentration in maize grain. Here, a recombinant inbred line population was used to test phenotype of zinc (Zn), iron (Fe), copper (Cu) and manganese (Mn) concentrations in six environments and then a QTL analysis was conducted using single environment analysis along with multiple environment trial (MET) analysis. These two strategies detected a total of 64 and 67 QTLs for target traits, respectively. Single environment analysis revealed 13 QTL bins distributed on seven chromosomes. We found that five candidate genes associated with mineral concentration were located in the same intervals identified by Comparative mapping of meta-QTLs in our previous study. The genetic and phenotypic correlation coefficients were depended on the nutrient traits and they were significant between Fe and Zn, Fe and Cu, Fe and Mn in all environments. The results of this study illustrated the genetic correlation between maize grain mineral concentrations, and identified some promising genomic regions and candidate genes for further studies on the biofortification of mineral concentration in maize grain.     

Mapping of the <Emphasis Type="Italic">ms8</Emphasis> male sterility gene in sweet pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) on the chromosome P4 using PCR-based markers useful for breeding programmes

The nuclear male sterility gene ms8 is expected to facilitate the production of sweet pepper (Capsicum annuum L.) hybrids as it provides means for hybridization without the labor-intensive hand emasculation of female inbred lines. The development of molecular markers linked to ms8 locus will help the breeding practice for the selection of hybrid parental lines. In this study, F₂ population resulting from a cross between the sweet pepper male sterile line 320 and the male fertile variety Elf was used to identify DNA markers linked to the ms8 locus. With the use of RAPD–BSA technique, seven markers linked to the ms8 locus were found. Four of them were converted into SCAR markers. In addition, two COSII/CAPS markers linked to the ms8 locus were identified. Comparative mapping with reference pepper maps indicated that the ms8 locus is located on the lower arm of the pepper chromosome P4. Identified markers are useful for molecular breeding, however, at present markers tightly linked to ms8 locus are still lacking. Identification of molecular markers linked to the ms8 locus and determination of its chromosomal localization are useful for fine mapping and also provide the perspective for ms8 gene cloning.     

Assessment of the uniformity and stability of grapevine cultivars using a set of microsatellite markers

Solidity of microsatellite markers is a key issue for varietal identification, especially when they are used for legal purposes, what includes their probable future use in the distinctness, uniformity and stability testing of new varieties needed for the granting of Plant Breeders’ Rights. Nine grapevine microsatellites (VVS2, VVMD5, VVMD27, VVMD28, ssrVrZAG29, ssrVrZAG62, ssrVrZAG67, ssrVrZAG83 and ssrVrZAG112), which had previously demonstrated its capacity to discriminate any grapevine variety, have been assessed to evaluate its uniformity and stability. 19 varieties were selected, representative of a high diversity for morphological, agronomical, cultural and historical aspects, as well as for microsatellite allele variability. Then, for each variety, uniformity and stability were evaluated through the analysis of 50 plants from each of three different plots, and five plants from each of seven additional plots. Material from 4,137 plants of 229 plots of the 19 varieties was sampled in seven countries. Of 3,654 plants analyzed with the set of nine microsatellites, 3,299 were of the right variety and used for the survey. An average of 172 individual values was studied for each allele of each microsatellite of each variety, and none differences were detected that could not be explained as technical variations, with the exception of several putative chimeras in two varieties. Of the total of 171 variety x microsatellite combinations, only in one combination (‘Merlot’ x VVMD27) the number of off-types exceeded the threshold allowed. The remaining 170 combinations have been found uniform and stable according to internationally accepted rules.     

The twenty-first century,the century of plant breeding

To achieve global food security by 2050 primary production must almost be doubled, at least to 80 % by increasing production per unit land. The challenge to plant breeding is tremendous. It is necessary to convince the public of this challenge, who are already dealing with concerns about climate change, a scarcity of good arable land, the demands placed on land with regard to biomass production, scarcity of water and phosphorous as well as increasing consumption of meat. In terms of breeding, concerns are the very small number of major crops and low rates of breeding progress in self-pollinating cereals. Society and politicians can be easily distracted from the dire need to invest in basic breeding research and breeding applications when so many environmental concerns are being emphasized. A holistic approach to these problems is essential. The focus here is on both the obstacles to be overcome and the opportunities to ensure global food security by producing excellent germplasm by 2050. This can be achieved by new technologies and genomics as well as the continuing development of more traditional breeding methodologies.     

Detecting epistatic effects associated with cotton traits by a modified MDR approach

Genetic expression of a trait is complicated and it is usually associated with many genes including their interactions (epistasis) and genotype-by-environment interactions. Genetic mapping currently focuses primarily on additive models or marginal genetic effects due to the complexity of epistatic effects. Thus, there exists a need to appropriately identify favorable epistatic effects for important biological traits. Several multifactor dimensionality reduction (MDR) based methods are important resources to identify high-order gene–gene interactions. These methods are mainly focused on human genetic studies. Many traits in plant systems are not only quantitatively inherited but also are often measured in repeated field plots under multiple environments. In this study, we proposed a mixed model based MDR approach, which is suitable for inclusion of various fixed and random effects. This approach was used to analyze a cotton data set that included eight agronomic and fiber traits and 20 DNA markers. The results revealed high order epistatic effects were detected for most of these traits using this modified MDR approach.     

Mapping and marker-assisted breeding of a gene allelic to the major Asian rice gall midge resistance gene <Emphasis Type="Italic">Gm8</Emphasis>

Host plant resistance is the preferred management strategy for Asian rice gall midge (Orseolia oryzae), a serious pest in many rice-growing countries. Identification of simple sequence repeat (SSR) markers that are tightly linked to pest resistance genes can accelerate development of gene pyramids for durable/multiple resistance. Based on conventional and molecular allelism tests, we report herein that rice genotype Aganni possesses Gm8 gene, conferring hypersensitive independent (HR– type) resistance to gall midge biotypes GMB1, GMB2, GMB3, GMB4, and GMB4M. The gene Gm8 was mapped to chromosome 8 within a 400-kbp region, and the SSR markers RM22685 and RM22709 flank the gene closely. Using these closely linked flanking markers, nine other gall midge-resistant genotypes were identified as carrying the same gene Gm8. Through marker-assisted selection, Gm8 has been introgressed into an elite bacterial blight-resistant cultivar, Improved Samba-Mahsuri (IS).     

Genotype × environment interactions in populations possessing <Emphasis Type="Italic">Ga1</Emphasis>-<Emphasis Type="Italic">s</Emphasis> and <Emphasis Type="Italic">ga1</Emphasis> alleles for cross incompatibility in maize

Use of cross incompatibility in corn (Zea mays L.) by the Ga1-s allele may reduce cross-fertilization in specialty and conventional organic corn with pollen from genetically-modified (GM) corn. For effective use, information about environment, and genotype × environment effects on cross-fertilization by ga1 as well as heritability of cross incompatibility in maize is necessary. Our objective was to obtain this information. Four population pairs differing in their genotype at ga1 were evaluated for cross incompatibility with ga1 pollen in different environments. Populations were derived by crossing the recurrent parents B116, PHG35, ARZM16035:S19, and (CHZM05015:Mo17)Mo17 to Ga1-s donor parent Mo508W/Mo506W. Two replicates of each treatment were grown in the center of 952 m² fields planted with purple corn as an adventitious source of ga1/ga1 pollen. Open pollination was allowed and the amount of cross-fertilization estimated by averaging the percentage of purple seeds. Environment and genotype × environment effects were not significant. Contrasts to evaluate differences in cross-fertilization between Ga1-s and ga1 populations revealed that mean percentages of cross-fertilization in Ga1-s populations of B116, ARZM16035:S19, and (CHZM05015:Mo17)Mo17 were significantly lower than in ga1 populations. The estimated broad-sense heritability on an entry-mean basis for cross incompatibility was 0.81. Results suggest differences in genotype at ga1 played a major role in cross-fertilization of populations differing in their genotype at the ga1 locus. Incompatibility may be selected effectively over different environments and the Ga1-s system may be of value to reduce cross-fertilization with GM corn pollen.     

Hybrids of <Emphasis Type="Italic">Passiflora</Emphasis>: <Emphasis Type="Italic">P. gardneri</Emphasis> versus <Emphasis Type="Italic">P. gibertii,</Emphasis> confirmation of paternity,morphological and cytogenetic characterization

Two new varieties of interspecific hybrids of Passiflora have been developed from the cross between P. gardneri versus P. gibertii, both registered under the Passiflora Society International. Twelve putative hybrids were analyzed. Hybridization was confirmed using RAPD and SSR markers. Primer UBC11 (5′-CCGGCCTTAC-3′) generated informative bands. Primer SSR Pe75 has amplified species-specific fragments and a heterozygote status was observed with two parent bands 300 and 350 bp. The molecular markers generated have been analyzed for the presence or absence of specific informative bands. Based on the morphological characterization, we have identified two hybrid varieties: P. ‘Gabriela’ and P. ‘Bella’. P. ‘Gabriela’ produced flowers in bluish tones, bluish petals on the adaxial and abaxial faces, light blue sepals on the adaxial and light green on the abaxial faces, corona with the base of filaments in intense lilac color and white apex. P. ‘Bella’ produced flowers in lilac tones, intense lilac petals on the adaxial and abaxial faces, dark lilac sepals with whitish edges on the adaxial and light green on the abaxial faces, corona with the base of filaments in intense lilac color and white apex. The cytogenetic analysis verified that the hybrids have the same chromosomal number as the parents (2n = 18); the formation of bivalents between the homeologous chromosomes (n = 9) was observad, leading to regular meiosis, which allows the sexual reproduction and use of these hybrids in breeding programs.     

Breeding value of selected blackcurrant (<Emphasis Type="Italic">Ribes nigrum</Emphasis> L.) genotypes for early-age fruit yield and its quality

The study was conducted in the years from 2011 to 2013 at the Research Institute of Horticulture in Skierniewice, Poland. The aim of the research was to assess the breeding value, based on the effects of general and specific combining abilities (GCA and SCA), of 15 parental genotypes of blackcurrant in terms of fruit yield and quality. The plant material consisted of F₁ generation seedlings obtained by crossing, in a factorial mating design of twelve maternal (‘Bona’, ‘Big Ben’, ‘Chereshnieva’, Kupoliniai’, ‘Gofert’, ‘Tines’, ‘Sofievskaia’, ‘Tihope’, ‘Ores’, ‘Ruben’, ‘Titania’ and D13B/11) and three paternal cultivars (‘Ceres’, ‘Foxendown’ and ‘Saniuta’). It was found that the cultivars ‘Ruben’, ‘Big Ben’, ‘Gofert’ and D13B/11 had significant positive effects of GCA on fruit yield at least in two consecutive years. ‘Ruben’, ‘Saniuta’ and D13B/11 had positive GCA effects on fruit weight. For ‘Chereshnieva’, ‘Gofert’, ‘Tines’, ‘Sofievskaia’, ‘Tihope’, ‘Titania’, ‘Ceres’ and Saniuta’ positive GCA effects were estimated for soluble solids content, whereas ‘Ruben’, ‘Ceres’, ‘Gofert’ and ‘Ores’ had positive GCA effects on the ascorbic acid content in fruit. This indicated a high breeding value of these parental genotypes in terms of the evaluated traits. The significantly positive values of SCA, estimated for the crossing combinations: ‘Big Ben’?×?‘Saniuta’, ‘Ruben’?×?‘Foxendown’, ‘Titania’?×?‘Ceres’, ‘Kupoliniai’?×?‘Saniuta’, ‘Gofert’?×?‘Foxendown’, ‘Gofert’?×?‘Saniuta’, ‘Tines’?×?‘Ceres’ and ‘Tihope’?×?‘Foxendown’ for at least two traits describing fruit yield and quality, were evidence of the interaction of both these parental genotypes in the creation of new dessert-type cultivars of blackcurrant.