Authors:V. Oslovičová, J.R. Simmonds, J.W. Snape, Z. Gálová, Z. Balážová, and I. Matušíková
In this study we evaluate the genetic diversity of a selection of wheat accessions characteristically grown and adapted to mid-European environments, using various molecular marker systems. Thirty-three simple sequence repeat (SSR) markers were used alongside genic markers for known dwarfing genes, flowering time genes, and grain hardness genes, namely Rht-B1, Rht-D1, Ppd-D1, Vrn-A1, Vrn-B1, Vrn-D1 and Pinb-D1. In addition, variation was scored for the high-molecular-weight glutenin storage proteins, responsible for dough technological quality. A dendrogram was constructed using the UPGMA algorithm, based on the molecular data and the country of origin, giving an overview of their genetic similarity and relationships. The potential for the use of some agronomic traits in breeding, by providing a basis for multi-trait genetic selection in wheat breeding programs is discussed. Estimating the breeding values of crops using multiple genetic markers might help in breeding for varieties with good technological quality for growing under desired climatic conditions.
Authors:Q. Mo, C.Y. Wang, C.H. Chen, Y.J. Wang, H. Zhang, X.L. Liu, and W.Q. Ji
Thinopyrum ponticum (2n = 10x = 70) has donated rust resistance genes to protect wheat from this fungal disease. In the present study, the line ES-7, derived from the progeny of the crosses between common wheat cultivar Abbondanza and Triticum aestivum–Th. ponticum partial amphiploid line Xiaoyan784, was characterized by cytological, fluorescence in situ hybridization (FISH), genomic in situ hybridization (GISH) and EST-STS marker techniques. Cytological observations revealed that the configuration of ES-7 was 2n = 42 = 21 II. GISH and FISH results showed that ES-7 had two St chromosomes and lacked 5A chromosomes compared to common wheat. The 4A chromosome of ES-7 had small alterations from common wheat. Two EST-SSR markers BE482522 and BG262826, specific to Th. ponticum and tetraploid Pseudoroegneria spicata (2n = 4x = 28), locate on the homoeologous group 5 chromosomes of wheat, could amplify polymorphic bands in ES-7. It was suggested that the introduced St chromosomes belonged to homoeologous group 5, that is, ES-7 was a 5St (5A) disomic substitution line. Furthermore, ES-7 showed highly resistance to mixed stripe rust races of CYR32 and CYR33 in adult stages, which was possibly inherited from Th. ponticum. Thus, ES-7 can be used for wheat stripe rust resistance breeding program.
Authors:M.J. Ansari, R. Kumar, K. Singh, and H.S. Dhaliwal
Diploid wheat T. monococcum L. is a model plant for wheat functional genomics. A soft glume mutant was identified during manual screening of EMS-treated M2 progenies of a T. monococcum accession pau14087. The seeds in the mature spike of the mutant could be easily threshed manually. The soft glume mutant with high sterility, tapering and broader spikes had also tougher rachis than the wild type parent. Genetic analysis of crosses of the mutant with wild type indicated that the mutant was monogenic recessive. To map the soft glume mutant, a mapping population was developed by crossing the soft glume mutant with wild Triticum boeoticum acc. pau 5088, having tough glumes and hard threshing. The soft glume mutant was mapped between SSR markers Xgwm473 and Xbarc69 on 7AmL chromosome of T. monococcum, with a genetic distance of 1.8 cM and 8.3 cM, respectively. The soft glum mutant mapped on 7AmL, being distinct from a previously mapped soft glume mutant in wheat, has been designated as sog2. The work on fine mapping of sog2 gene is in progress.
Authors:N. Sinha, V. Priyanka, K.T. Ramya, T. Leena, J.A. Bhat, Harikrishna, N. Jain, P.K. Singh, G.P. Singh, and K.V. Prabhu
Abiotic stresses are major constraints to wheat productivity in many parts of the world. Tolerance to abiotic stresses can be achieved indirectly by selection for morpho-physiological traits. Physiological trait based breeding has been associated with improved performance under stress; and hence can combat and adapt wheat to drought and heat stress. Therefore, in the present study, phenotyping was carried out for agro-physiological traits in 52 diverse wheat germplasm lines under timely sown, rainfed and late sown environments for two years. Mean yield of the genotypes over the six environments were positively correlated with NDVI, days to maturity and negatively correlated with canopy temperature. The phenotypic data validated marker-trait associations of a number of meta-QTLs identified earlier for different physiological and agronomic traits. Six and seven meta-QTL genomic regions were found to be consistent in their expression for two years under rainfed/restricted irrigation and late sown environments, respectively. Expression analysis of the underlying candidate gene AK248593.1 in meta-QTL26 region revealed two folds higher expression in the NILs carrying the co-localized SSR markers. The linked markers of the thirteen meta-QTL regions associated with different traits can be used for effective transfer of the QTLs through marker assisted selection in wheat breeding programmes.
Authors:A. Sudaric, M. Vrataric, I. Rajcan, T. Duvnjak, and M. Volenik
The rate of genetic gain in the quantity and quality of soybean grain depends considerably on the genetic diversity of the selected parental components. Genetic diversity assessment is a crucial aspect of breeding that maximizes genetic improvement. The objectives of this study were to evaluate the genetic diversity of the selected soybean germplasm using genetic markers, as well as to compare the effectiveness of breeding procedures with and without the use of genetic markers in parental selection. The genetic relationships within the selected soybean germplasm were estimated using 14 simple sequence repeats (SSRs). The agronomic performance (grain yield, protein and oil content in the grain) of the parental components and derived lines was determined in field trials. Based on SSR marker data and phenotypic data, an association was found between the agronomic performance of the derived lines and the genetic distance between the parental lines. Crosses between more diverse parents resulted in derived lines with greater values for grain yield and grain quality compared with the parents than crosses between similar parents. The results indicated the usefulness of genetic marker information in parental selection, contributing to breeding efficiency.
Authors:F.M. Zhao, Y. Tan, L.Y. Zheng, K. Zhou, G.H. He, Y.H. Ling, L.H. Zhang, and S.Z. Xu
Chromosome segment substitution lines (CSSLs) are powerful tools to combine naturally occurring genetic variants with favorable alleles in the same genetic backgrounds of elite cultivars. An elite CSSL Z322-1-10 was identified from advanced backcrosses between a japonica cultivar Nipponbare and an elite indica restorer Xihui 18 by SSR marker-assisted selection (MAS). The Z322-1-10 line carries five substitution segments distributed on chromosomes 1, 2, 5, 6 and 10 with an average length of 4.80 Mb. Spikilets per panicle, 1000-grain weight, grain length in the Z322-1-10 line are significantly higher than those in Nipponbare. Quantitative trait loci (QTLs) were identified and mapped for nine agronomic traits in an F3 population derived from the cross between Nipponbare and Z322-1-10 using the restricted maximum likelihood (REML) method in the HPMIXED procedure of SAS. We detected 13 QTLs whose effect ranging from 2.45% to 44.17% in terms of phenotypic variance explained. Of the 13 loci detected, three are major QTL (qGL1, qGW5-1 and qRLW5-1) and they explain 34.68%, 44.17% and 33.05% of the phenotypic variance. The qGL1 locus controls grain length with a typical Mendelian dominance inheritance of 3:1 ratio for long grain to short grain. The already cloned QTL qGW5-1 is linked with a minor QTL for grain width qGW5-2 (13.01%) in the same substitution segment. Similarly, the previously reported qRLW5-1 is also linked with a minor QTL qRLW5-2. Not only the study is important for fine mapping and cloning of the gene qGL1, but also has a great potential for molecular breeding.
Authors:B. Kumar, K.S. Hooda, R. Gogoi, V. Kumar, S. Kumar, A. Abhishek, P. Bhati, J.C. Sekhar, K.R. Yathish, V. Singh, A. Das, G. Mukri, E. Varghese, H. Kaur, V. Malik, and O.P. Yadav
Maydis leaf blight (MLB), a serious foliar fungal disease of maize, may cause up to 40% losses in yield. The present studies were undertaken to identify the stable sources of MLB resistance, its inheritance study, and testing of MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes. A set of 112 inbred lines were screened under artificially created epiphytotics conditions at three hotspot locations. Analysis across multi-locations revealed significant effects of genotypes and environments, and non-significant effects due to genotypes × environment interaction on disease incidence. A total of 25 inbred lines with stable resistance were identified across multi-locations. Inheritance of resistance was studied in six F1s and two F2s of resistant and susceptible parents. The null hypothesis of segregation of resistance and susceptible for mono and digenic ratios in two F2 populations was rejected by Chi-square test. The non-significant differences among the reciprocal crosses depicted the complete control of nuclear genome for MLB resistance. Partial dominance in F1s and normal distribution pattern in F2s of resistant and susceptible parents suggested polygenic nature of MLB resistance. Correlation studies in F2 populations exhibited significant negative correlation between disease score and days to flowering. Five simple sequence repeats (SSRs) markers, found associated to MLB resistance in different studies were unable to differentiate amongst MLB resistance and susceptible parents in our study. This emphasizes the need of fine mapping for MLB resistance in Indian germplasm. The identified stable sources of resistance and information on inheritance study can be used further in strengthening of resistance breeding against MLB.
Authors:E. Nagy, I. Timár, Z. Hegyi, T. Spitkó, and L. Marton
The chemical composition of maize makes it suitable for a wide range of nonconventional uses, including utilisation as a new source of energy for the 21st century as a raw material for biofuel. The aim of the experiments was to amalgamate the application of genetic markers with conventional breeding methods to produce maize hybrids whose starch content and ecostability satisfied the demands of industrial use, while having yield potential and agronomic traits on a par with those of hybrids currently cultivated. The chemical quality of 220 lines was evaluated using the NIR spectrometric technique, and the five maize inbred lines with the lowest and highest starch contents were selected for genetic marker studies. The variety identification of the lines was carried out using the isoenzymes stipulated by UPOV. The following SSR (simple sequences repeat) markers were tested: phi 095, umc 1057, nc 004, phi 096, nc 007, umc 1564, phi 85, y1 SSR, umc 1178, nc 009, phi 070, umc 1066, umc 1741, umc 1069, phi 033, phi 061, wx, phi 032, phi 084 and phi 062. The analysis of the fragment patterns revealed three SSR markers that appeared to be correlated with the starch content of the maize lines. These were the primer pairs
y1 SSR, umc 1069
. These results are only of a preliminary nature, however, as the incorporation of starch is probably regulated by several genes, and the studies suggest it is also influenced by several environmental factors. It also appears likely that the bioethanol yield is determined not only by the starch content, but also by other parameters. Further research should thus be expanded to include investigations into the structural and fermentability traits of starch molecules, including the characterisation of these traits using genetic markers.
Authors:S.M. Pirseyedi, A. Kumar, F. Ghavami, J.B. Hegstad, M. Mergoum, M. Mazaheri, S.F. Kianian, and E.M. Elias
Fusarium head blight (FHB) damage in durum wheat (Triticum turgidum L. var. durum Desf., turgidum) inflicted massive economic losses worldwide. Meanwhile, FHB resistant durum wheat germplasm is extremely limited. ‘Tunisian108’ is a newly identified tetraploid wheat with FHB resistance. However, genomic regions in ‘Tunisian108’ that significantly associated with FHB resistance are yet unclear. Therefore, a population of 171 backcross inbred lines (BC1F7) derived from a cross between ‘Tunisian108’ and a susceptible durum cultivar ‘Ben’ was characterized. Fusarium graminearum (R010, R1267, and R1322) was point inoculated (greenhouse) or spawn inoculated (field) in 2010 and 2011. Disease severity, Fusarium-damaged kernel (FDK) and mycotoxins were measured. Analysis of variance showed significant genotype and genotype by environment effect on all traits. Approximately 8% of the lines in field and 25% of the lines in greenhouse were more resistance than Tunisian108. A framework linkage map of 267 DArt plus 62 SSR markers was developed representing 239 unique loci and covering a total distance of 1887.6 cM. Composite interval mapping revealed nine QTL for FHB severity, four QTL for DON, and four QTL for FDK on seven chromosomes. Two novel QTL, Qfhb.ndsu-3BL and Qfhb.ndsu-2B, were identified for disease severity, explaining 11 and 6% of the phenotypic variation, respectively. Also, a QTL with large effect on severity and a QTL with negative effect on FDK on chromosome 5A were identified. Importantly, a novel region on chromosome 2B was identified with multiple FHB resistance. Validation on these QTL would facilitate the durum wheat resistance breeding.
Authors:T. Harangozó, Gy. Pernesz, A. Veres, K. Tóth-Lencsés, L. Heszky, and E. Kiss
The aim of this paper was to find possible link between molecular and morphological similarities of 38 Hungarian white grape varieties. Three aspects of morphological and molecular similarity were assessed in the study: comparison of the ordered variety pairs, assessment of molecular and morphological mean similarity differences and separation of varieties into similar groups by divisive cluster analysis to define (DIANA). Molecular similarity was calculated from binary data based on allele sizes obtained in DNA analysis. DNA fingerprints were determined at 9 SSR loci recommended by the European GrapeGen06 project. Morphological similarity was calculated on the basis of quantitative morphological descriptors. Morphological and molecular similarity values were ordered and categorized after pairwise comparison. Overall correlation was found to be weak but case by case assessment of the variety pairs confirmed some coincidence of molecular and morphological similarity. General similarity position of each variety was characterized by Mean Similarity Index (MSI). It was calculated as the mean of n-1 pair similarity values of the variety concerned. Varieties were ordered and compared by the difference of the index. Five varieties had low morphological and high molecular MSI meaning that they share several SSR marker alleles with the others but seems relatively distinct according to the expression of their morphological traits. Divisive cluster analysis was carried out to find similar groups. Eight and twelve cluster solutions proved to be sufficient to distinct varieties. Morphological and molecular similarity groups partly coincided according to the results. Several clusters reflected parent offspring relations but molecular clustering gave more realistic results concerning pedigree.