Authors:T. W. Eschholz, R. Peter, P. Stamp, and A. Hund
Genetic variation in the flint maize (Zea mays L. conv. indurata) gene pool has decreased significantly since the introduction of hybrid breeding into Europe in the 1950s, leading to greater genetic vulnerability. Landraces, stored in gene banks, offer a valuable source to broaden the genetic basis again. The objective of this study was the genetic characterization of 166 Swiss landrace accessions originating from 7 Swiss regions (alpine valleys). The material was fingerprinted using a set of ten SSRs (Simple Sequence Repeat Markers). The resulting cladogram showed three main clusters comprising 95, 22 and 49 accessions, respectively. The largest group of accessions, from the Rhine valley of St. Gallen (RT), was present in all three main clusters. However, the majority of RT accessions was found in the first main cluster, together with those from the western neighbouring region (Linthtal) and from the southwestern neighbouring region (Wallis). Those from Tessin (southern Switzerland) were found mainly in one sub-cluster within the third main cluster. This is a very encouraging first step in appraising the genetic differences among accessions from Swiss regions.
Authors:A. A. Belousov, V. M. Sokolo, Y. M. Sivolap, V. P. Domenjuk, and N. J. Storcheus
The performance of
maize hybrids developed on the basis of recombined inbred lines (RIL) selected
from an F2 hybrid population using marker-assisted selection (MAS)
was studied. The task was to estimate the efficiency of DNA marker technology
for intrapopulation selection and to study the performance of hybrids produced
from marker-derived inbreds of the F2 population (GK 26 × Mo 17).
Two hundred RILs of marker origin were crossed with 3 unrelated testcross lines
from the Lacaune, Mindszentpuszta and Reid heterotic groups. An effective
marker test system and informative marker criteria were elaborated for
increasing MAS effectiveness. A two-locus system on the basis of linked SSR
markers proved to be the most effective. The genetic improvement effect
(ΔG) of the C1 population for plant productivity, plant height
and grain length ranged from 9.1 to 16.1%,
depending on the phenotypic trait and h2 level. The best hybrids
developed on the basis of RILs of marker origin outyielded the national check
for grain yield by 6.8-7.6%.
Wangshuibai is an indigenous scab resistance germplasm originated from Jiangsu, China. To characterize the genetic basis of scab resistance in this germplasm, QTLs for type I and type II resistances were detected using a recombinant inbred line (RIL) population created by single seed descent from Nanda2419 × Wangshuibai and a molecular marker map of more than 4000 cM constructed using RAPD, SSR and STS markers. The major QTLs for type I resistance in Wangshuibai were mapped to chromosomes 4BL and 5AS, and those for type II resistance were mapped to chromosomes 3BS. In addition, a QTL on chromosome 2B showed association with both types of resistance. These QTLs were verified with QTL nearisogenic lines. We found, by mapping QTLs for agronomical traits in the same population, that on chromosomes 4BL and 5AS the scab resistance QTLs co-located with QTLs for plant height, thousand grain weight or flag leaf width. However, these associations could be break down by recombinant selection. We concluded that Wangshuibai is a valuable scab resistance gene resources and marker assisted selection would be of great help for its better utilization.
Authors:L.R. Vemireddy, N. Ranjithkumar, A. Vipparla, M. Surapaneni, G. Choudhary, K.V. Sudhakarrao, and E.A. Siddiq
India bred high yielding rice varieties have enriched to a great extent the global rice germplasm since the mid-sixties. Systematic research efforts for development of cultivar-specific DNA fingerprints of major Indian rice cultivars, however, have not received due attention. The present investigation was aimed at development of DNA fingerprints for 90 high yielding rice varieties using hypervariable microsatellite (hvRM) markers. A panel of eight markers, viz. RM11313, RM13584, RM15004, RM5844, RM22250, RM22565, RM24260 and RM8207 was chosen from 52 polymorphic markers based on their highly polymorphic nature, SSR repeat type and number and ability to distinguish genotypes, in order to develop DNA fingerprints of 90 varieties. The remaining high polymorphic hvRM markers could be of immense value in future to distinguish new cultivars, in case they could not be distinguished by the 8 marker panel. Four of the 8 markers, viz. RM22250, RM13584, RM24260 and RM5844 were located in expressed genes and could be of value in DUS (Distinctness, Uniformity and Stability) testing. Thus we suggested, that this set of 8 loci could be used as standard for DNA fingerprinting of Indian rice cultivars.
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: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:W.T. Xue, A. Gianinetti, R. Wang, Z.J. Zhan, J. Yan, Y. Jiang, T. Fahima, G. Zhao, and J.P. Cheng
Crop seeds are the main staples in human diet, especially in undeveloped countries. In any case, the diet needs to be rich not only in macro-nutrients like carbohydrates and protein, but also in micro-nutrients. Nevertheless, both the macro- and micro-nutrients presented in seeds largely vary in consequence of field and environment conditions. In this research, 60 lines of a barley RILs population segregating for the SSR marker Hvm74, which is genetically linked to the GPC (grain protein content) locus (HvNAM-1), were studied in 4 environments (two growing years and two field managements) by carrying out a comprehensive profile of seed macro- (starch, total nitrogen and total soluble protein) and micro-nutrients (phytate, phenolics, flavonoids, Pi, Zn and Fe). Under field conditions, all the components were largely affected by the environment, but TN (total nitrogen) exhibited high genotype contribution, while micro-nutrients displayed higher genotype × environments interactions (GEI) than macro-nutrients. In order to approach the effects of carbon-nitrogen (C–N) balance on other seed components, two C/N ratios were calculated: C/TN (CNR1) and C/TSP (CNR2). CNR2 exhibited stronger negative correlations with all micro-nutrients. Hence, the significant GEI and its negative relationships with CNR2 highlighted the different characters of micro-nutrients in barley seeds.
Aerobic adaptation could be an important modification in the traditional rice to cope up with the increasing water scarcity problem. Identification of stable QTL for traits promoting adaptation to aerobic conditions can facilitate the development of water-efficient aerobic rice varieties with better yields. Filial and backcross populations derived from the crosses between high-yielding low-land (HKR47) and aerobic (MAS26) indica rice varieties, were evaluated for various physio-morphological traits including root traits (in case of net house evaluation). Under aerobic field conditions, grain yield per plant showed significant positive correlation with plant height, effective number of tillers/plant and panicle length in all the populations. Grain yield per plant also showed positive correlation with root length in both filial populations and with fresh and dry root weight in F2 population. Two parental rice varieties displayed polymorphism at 125 of the 803 SSR loci, which were used to map the QTL associated with traits promoting aerobic adaptation. A total of 14 QTL were detected, 10 of them were identified on chromosome 8. Study led to the identification of a number of promising plants with higher grain yield, better root length/biomass under managed aerobic conditions and possessing most of the identified QTL.
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.