Authors:László Fésüs, Attila Zsolnai, István Anton, and László Sáfár
The first results of the Hungarian sheep prion protein (PrP) genotyping programme are discussed in this paper. To obtain initial genotype frequency data 10 commercial (Hungarian Merino, German Mutton Merino, Merino Landschaf, German Blackheaded, Suffolk, Texel, Ile de France, Charollais, Lacaune, British Milksheep) and 4 indigenous (Gyimes Racka, Hortobágy Racka, Tsigaja, Cikta) breeds were sampled in 2003 and 2004, and the PrP genotypes were determined by microsequencing analysis with capillary electrophoresis. In all commercial breeds, a higher number of sheep were genotyped in 2005 (3648) and in 2006 (3834) within the breeding programme to increase scrapie resistance, and the estimated frequency data were compared to the initial figures to evaluate the efficiency of selection. The new developments arising from the identification of the so-called ‘atypical’ scrapie cases are also discussed.
Chlorophyll content is positively correlated with photosynthetic rate. However, little is known about the genetic correlation between grain yield and chlorophyll content in the same wheat mapping population. The primary goal of the study was to detect the genetic basis of grain yield and chlorophyll content and their possible roles in the genetic improvement of grain yield in wheat. Here, quantitative trait loci (QTLs) for grain yield and chlorophyll content were studied using a set of 168 doubled haploid (DH) lines derived from a cross between two elite Chinese wheat cultivars, Huapei 3×Yumai 57. The DH population and parents were evaluated for grain yield and chlorophyll content in three environments. A total of 11 additive QTLs and 6 pairs of epistatic QTLs were detected for grain yield and chlorophyll content. Loci, such as
on chromosomes (e.g. 2D, 4A, and 5D) simultaneously controling grain yield and chlorophyll content, showed tight linkages or pleiotropisms. Three novel major QTLs,
, closely linked with the PCR marker
on chromosome 5D, accounted for 10.32%, 12.95%, and 23.29% of the phenotypic variance, respectively. The favorable alleles came from Yumai 57.
Authors:R. Singh, D. Datta, Priyamvada, S. Singh, and R. Tiwari
The aim of this study was to develop a PCR based assay for an efficient selection of
resistance gene in breeding material. The two primer pairs designed from the
gene sequence amplified specific DNA fragments in the genotypes carrying
and did not give a signal with near isogenic line and other lines containing different
genes. The genetic linkage of these molecular markers to
gene was tested on a segregating F
population derived from cross between the stripe rust resistant genotype carrying
(FLW10) and the susceptible line WH542. The data demonstrated that the markers derived from
gene sequence are completely linked to
, which will enable to combine this gene with other stripe rust resistance genes in wheat breeding programmes.
L.) is one of the most economically important crops around the world. Diseases caused by fungi and viruses significantly reduce yield. The most important fungal diseases are leaf rust caused by
, and powdery mildew caused by
. The most economical and ecologically friendly way to avoid losses caused by these diseases is growing resistant varieties. Concerning practical breeding for powdery mildew and leaf rust resistance, simple, cheap and robust selection methods are required. Marker assisted selection (MAS) is of great potential to fulfil this demand. In this paper, we present development of a robust duplex marker for simultaneous selection of
, and presence of one of the following
Mla16, Mla19, Mla20, Mla21, Mla27
Authors:M. Sajjad, S.H. Khan, M.Q. Ahmad, A. Rasheed, A. Mujeeb-Kazi, and I.A. Khan
A panel of 94 diverse hexaploid wheat accessions was used to map quantitative trait loci (QTL) underlying the yield related traits on chromosome 3A. Population structure and kinships were estimated using unlinked SSR markers from all 21 chromosomes. Analysis of variance revealed significant difference among accessions; however, genotype × year interaction was non-significant for majority of yield related traits. A mixed linear model (MLM) approach identified six QTLs for four traits that individually accounted for 10.7 to 17.3% phenotypic variability. All QTLs were consistently observed for both study years. New putative QTLs for the maximum fertile florets per spike and spike length were identified. This report on QTLs for yield related traits on chromosome 3A will extend the existing knowledge and may prove useful in marker-assisted selection (MAS) for development of high yielding cultivars.
The location of major QTLs or even genes controlling abiotic stress tolerance is now possible by the application of marker-mediated techniques. This is achieved by exploiting precise genetic stocks, such as doubled haploids (DHs), recombinant substitution lines (RSLs) and recombinant inbred lines (RILs), along with the comprehensive genetic maps now available through the application of molecular marker techniques. These strategies are illustrated here showing how QTLs/genes affecting vernalization response, cold tolerance, osmotic adjustment, osmolite accumulation (free amino acids, polyamines and carbohydrates), salt tolerance and cold-regulated protein accumulation have been identified and located. Also, an example of marker-assisted selection (MAS) for frost tolerance is presented. Major loci and QTLs affecting stress tolerance in Triticeae have been mapped on the group 5 chromosomes, where the highest concentration of abiotic stress-related QTLs (vernalization response, frost tolerance, salt tolerance and osmolite accumulation) was located. A conserved region with a major role in osmotic adjustment has been located on the group 7 chromosomes.
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%.
Authors:I. Karsai, K. Mészáros, P. Szűcs, and et al.
The possibilities latent in molecular marker-based QTL analyses are presented through the example of studying winter survival and heading date in barley (Hordeum vulgare L.). The whole range of QTL experiments consists of several important steps, through which answers are found to the following questions: (1) How many QTLs are involved and where do they map, (2) How does the environment influence the effect of a QTL region (environment × QTL interactions), (3) When and where are the genes determining the given trait expressed (QTL dynamics), (4) What interactions occur between these QTLs and pathways leading to specific phenotypes, and (5) How consistent is the effect of a QTL region in different genetic backgrounds and in a wider range of germplasms (comparative mapping and association studies)? This knowledge then makes it possible to continue these experiments in the direction of marker-assisted selection and/or gene isolation through marker saturation of the relevant chromosomal regions and map-based cloning. The latter can give an insight into the exact mechanism through which the gene determines the phenotype.