Sub-arm location of prolamin and EST-SSR loci on chromosome 1H<Superscript>ch</Superscript> from <Emphasis Type="Italic">Hordeum chilense</Emphasis>

Hordeum chilense Roem. et Schult. is a diploid wild South American barley that contains genes of interest for cereal breeding, many of them located on chromosome 1H^ch. In the current study, two H. chilense-wheat addition lines with deletions in the 1H^ch chromosome were used for sub-arm localization of five prolamin (glutenin and gliadin) loci and 33 EST-SSR marker loci on chromosome 1H^ch. The two sets of markers were distributed across five sub-arm chromosome regions. Three glutenin loci (Glu-H ^ch 2, Glu-H ^ch 3, Glu-H ^ch 4) together with the gliadin locus Gli-H ^ch 1 were located on the distal 20% of the 1H^chS arm, whereas the glutenin locus Glu-H ^ch 1 was on the proximal 88% region of 1H^chL. Among 33 EST-SSR marker loci, 7 (21.2%) were on the 1H^chS arm and, of them, 3 (9.1%) were on the distal 20% end and 4 (12.1%) on the proximal 80% region. The 26 loci (78.8%) on 1H^chL were distributed across three different regions: 18 (78.8%) in the proximal 88%, 3 (9.1%) in the distal 12% and 5 (15.2%) in a region less than 12% from the distal end. The deletions in the 1H^ch chromosome added to the common wheat background were thus shown to be useful for determining the sub-arm location of EST-SSR and prolamin loci. This could facilitate the identification of molecular markers linked to genes of agronomic interest and the isolation of such genes for use in common wheat improvement.     

Genetic analysis and associated SRAP markers for flowering traits of chrysanthemum (<Emphasis Type="Italic">Chrysanthemum morifolium</Emphasis>)

The inheritance of two flowering traits of chrysanthemum, initial blooming time and the duration of flowering, was investigated using segregation within an F ₁ population derived from a cross between the autumn-flowering ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ cultivars. The analysis, based on a single segregating generation and the major gene plus polygene mixed inheritance model, showed that the inheritance of both traits was compatible with the presence of two pairs of major genes displaying additivity–dominance–epistasis, with additivity predominating. As the heritability of both pairs of major genes was high (initial blooming time ~65%, duration of flowering ~72%), it should be possible to select for both traits in early breeding generations. A marker-trait association analysis based on sequence-related amplified polymorphism (SRAP) genotyping uncovered 10 (initial blooming time) and 12 (duration of flowering) markers significantly associated with phenotype, cumulatively explaining, respectively, 46 and 54% of the variation. Some potentially useful markers were identified.     

Soybean oil content QTL mapping and integrating with meta-analysis method for mining genes

Oil content of soybean was a valuable quantitative trait controlled by multiple genes. Eleven QTLs were detected by both CIM and MIM method with the population crossed between Charleston and Dong nong594 in recent 3 years (2007, 2008, 2009). Combining the QTLs collected over the past 20 years, an integrated map of oil-content major QTLs in soybean was established using soymap2, which was published in 2004, as a reference. Using the software BioMercator ver.2.1, QTLs were projected from their own maps onto the reference map. In total, ninety-eight QTLs were integrated into soymap2. A meta-analysis method was used to narrow down the confidence interval, and 20 consensus QTLs and their corresponding markers were obtained. Using a local version of GENSCAN, 10,137 sequences in the consensus QTL intervals were predicted. With BLAST, these predicted genes were compared to the International Protein Index database to mine the related genes. The results offer a basis for gene mining and molecular breeding in soybean.     

QTL identification of yield-related traits and their association with flowering and maturity in soybean

Two soybean recombinant inbred line populations, Jinpumkong 2 × SS2-2 (J × S) and Iksannamulkong × SS2-2 (I x S) showed population-specific quantitative trait loci (QTLs) for days to flowering (DF) and days to maturity (DM) and these were closely correlated within population. In the present study, we identified QTLs for six yield-related traits with simple sequence repeat markers, and biological correlations between flowering traits and yield-related traits. The yield-related traits included plant height (PH), node numbers of main stem (NNMS), pod numbers per plant (PNPP), seed numbers per pod (SNPP), 100-seed weight (SW), and seed yield per plant (SYPP). Eighteen QTLs for six yield-related traits were detected on nine chromosomes (Chrs), containing four QTLs for PH, two for NNMS, two for PNPP, three for SNPP, five for SW, and two for SYPP. Two highly significant QTLs for PH and NNMS were identified on Chr 6 (LG C2) in both populations where the major flowering gene, E1, and two DF and DM QTLs were located. One other PNPP QTL was also located on this region, explaining 12.9% of phenotypic variation. Other QTLs for yield-related traits showed population-specificity. Two significant SYPP QTLs potentially related with QTLs for SNPP and PNPP were found on the same loci of Chrs 8 (Satt390) and 10 (Sat_108). Also, highly significant positive phenotypic correlations (P < 0.01) were found between DF with PH, NNMS, PNPP, and SYPP in both populations, while flowering was negatively correlated with SNPP and SW in the J × S (P < 0.05) and I × S (P < 0.01) populations. Similar results were also shown between DM and yield-related traits, except for one SW. These QTLs identified may be useful for marker-assisted selection by soybean breeders.     

Analysis of rice blast resistance gene <Emphasis Type="Italic">Pi</Emphasis>-<Emphasis Type="Italic">z</Emphasis> in rice germplasm using pathogenicity assays and DNA markers

The Pi-z gene in rice confers resistance to a wide range of races of the rice blast fungus, Magnaporthe oryzae. The objective of this study was to characterize Pi-z in 111 rice germplasm accessions using DNA markers and pathogenicity assays. The existence of Pi-z in rice germplasm was detected by using four simple sequence repeat (SSR) markers (RM527, AP4791, AP5659-1, AP5659-5) closely linked to Pi-z, and was verified using pathogenicity assays with an avirulent strain (IE1k) and two virulent races (IB33 and IB49). Among 111 germplasm accessions evaluated, 73 were found to contain the Pi-z gene using both SSR markers and pathogenicity assays. The remaining 38 germplasm accessions were found to be inconsistent in their responses to the blast races IB33, IEIk and IB49 with expected SSR marker alleles, suggesting the presence of unexpected SSR alleles and additional R gene(s). These characterized germplasm can be used for genetic studies and marker-assisted breeding for improving blast resistance in rice.     

Morphology and SSR fingerprinting of newly developed <Emphasis Type="Italic">Cynara cardunculus</Emphasis> genotypes exploitable as ornamentals

The species Cynara cardunculus includes the globe artichoke (var. scolymus), the cultivated cardoon (var. altilis) and the wild cardoon (var. sylvestris). The three taxa are sexually compatible and originate fertile F ₁ progenies, which, given the high heterozygosity of the species, are highly segregating. We report the characterization of two F ₁ populations, one bred from a cross between globe artichoke and cultivated cardoon, and the other between globe artichoke and wild cardoon. Both populations featured a wide array of phenotypes in relation to several traits, and some of the newly developed genotypes are of interest for the ornamental market. The two populations were genotyped at 50 microsatellite (SSR) loci: in the globe artichoke × wild cardoon and globe artichoke × cultivated cardoon progenies 116 and 97 alleles were respectively detected. SSR pattern scores were used to produce an UPGMA dendrogram and a PCoA plot. A set of nine SSR loci, evenly dispersed across the genome, was shown to be sufficient to unambiguously identify each segregant. The molecular fingerprinting is useful for establishing the true to type correspondence of propagative materials in nurseries and ensures the effective correspondence between the real and the declared identity of a clone.     

Estimating genetic effects in maternal and paternal half-sibs from tetraploid-diploid crosses in <Emphasis Type="Italic">Musa</Emphasis> spp.

Ploidy manipulations and interspecific crosses have allowed considerable genetic progress in Musa breeding, but estimation of genetic parameters for parental selection remains a major challenge. This study aimed to determine the components of genetic variance and the relative contribution of genetic effects to phenotypic variation of yield and phenological traits in secondary triploid hybrids from tetraploid–diploid crosses. The hybrids were evaluated in two consecutive growth cycles on a tropical forest site. Non-genetic effects accounted for a large fraction of the variation observed for most traits, except bunch weight. Partitioning of genetic variance into additive and dominance components confirmed the predominant role of additive genetic effects on the expression of bunch weight, fruit filling time, fruit length, plant height, and number of leaves while primarily non-additive effects accounted for suckering behavior and fruit circumference. Maternal general combining ability (GCA) effects accounted for the additive genetic variation in plant height and number of leaves, suggesting that selection for these traits should be carried out in tetraploid clones. Conversely, paternal GCA effects were the primary causes of genetic variation for fruit filling time, bunch weight, and fruit length, suggesting that these characters should be selected for in diploid clones. Specific combining ability (SCA) effects were observed for all traits, except fruit filling time, suggesting that additional genetic gain could be achieved through recombinative heterosis for these traits.     

Combining ability for grain chemistry quality traits in a white oat diallelic cross

There has been a strong demand for oat genotypes that contain caryopsis with high chemical quality which can suit the different market niches. Therefore, the objectives of this study were to assess the general (GCA) and specific combining ability (SCA) of white oat cultivars through diallelic crosses providing information about the genetic effects on expression of grain chemical quality components. Also, it was aimed to estimate the heterosis on F₁ and F₂ generations and the vigor loss due to inbreeding. During 2008, 21 hybrid populations F₁ and F₂ were obtained from artificial crossing among seven Brazilian white oat cultivars, following the complete diallel design, without considering the reciprocals. These populations and their parents were evaluated in the 2009 season in the experimental field in Capão do Leão, RS, Brazil. The higher values of mean squares associated to GCA indicates a strong contribution of additive genetic effects to the expression of grain chemical components. The parents tested showed a tendency to develop progeny with negative heterosis regarding protein, lipid, β-glucan and soluble dietary fiber in the grain, and positive for the content of nitrogen-free extract, total and insoluble dietary fiber. IAC 7 features a potential parent for obtaining grains with high protein and dietary fiber content, and low caloric content, fit to human diet. Meanwhile, UPF 15 and FAPA Louise can represent donors of alleles to increase lipid contents, while FAPA Louise and URS Guapa can be used to raise the grain nitrogen-free extract contents of lines intended for animal feeding.     

Identification and characterization of EST-SSRs in finger millet (<Emphasis Type="Italic">Eleusine coracana</Emphasis> (L.) Gaertn.)

In recent years, microsatellites have become the most used markers for studying population genetic diversity. The increased availability of the DNA sequences has given the possibility to develop EST-derived SSR markers. A total of 1,927 ESTs of Eleusine coracana available in the NCBI database were mined for SSRs. Di-nucleotides are the most occurring motifs accounting for more than 50% of the repeats, of which GA was the most abundant motif and tetra-nucleotides are the least occurring motifs. Of the 132 markers identified, 30 primer pairs based were synthesized. SSR markers were used for variety discrimination and genetic assessment in 15 finger millet accessions; 20 primers showed polymorphism and 13 primers were identified as having a PIC value above 0.5. On the basis of the distribution of these polymorphic alleles, the 15 accessions were classified into two groups. This study has demonstrated the potential of EST-derived SSR primer pairs in finger millet. These primers will serve as valuable source for further breeding programs.     

Development of mulberry varieties for sustainable growth and leaf yield in temperate and subtropical regions of India

Sericulture is an agro-based industry, which heavily depends on mulberry (Morus spp.) for its sustainability, as mulberry leaf is the only available feed for the silkworm Bombyx mori L. Sericulture, in West Bengal and other subtropical regions in India, suffers from lack of adequate quantity of quality mulberry leaf during the colder months, the best season for rearing the high yielding bivoltine silkworm hybrids. In order to develop mulberry varieties, which can sustain normal growth during these colder months to yield better, efforts have been made in different research institutes in India. The present report is part of such an effort in which accessions in germplasm bank were screened for better growth, leaf retention and leaf yield contributing associated traits. Twenty three selected parents were crossed, 3,500 seeds were sown, 2,700 seedlings were transplanted to progeny row trail, selected 210 hybrids were evaluated under primary yield trial and finally nine hybrids along with a control variety were studied in detail for all leaf yield contributing traits under final yield trial. Stability analysis was adopted to identify hybrids, which can yield stably across seasons. The hybrids CT-44 and CT-11 out yielding the control by 17.17 and 7.11% were selected as these hybrids yield 7.93 and 8.15 mt/ha leaf respectively during the colder months (February) for their direct use as cultivars in West Bengal and other subtropical areas of India to sustain bivoltine sericulture to produce quality and gradable silk fibers.