Wheat Crosses Research Articles

Application of a low dose of gamma rays in wheat androgenesis

Gamma-rays of dose of 5 Gy using a 60 Co source was applied in a single wheat cross to study the effect on anther culture (AC) parameters. The female parent was a 6U g /6D mono-substitution line of cv. Trakia with resistance to pow- dery mildew and leaf rust, while the male parent was cv. Aglika, characterized as one of the best local varieties with high productivity and grain quality. Callus induction, plant regeneration, green and albino plants from the control (normal anther culture, 0 Gy) designated C, were compared with parameters studied in three other groups, derived from anthers irradiated with 5 Gy (designated AI), calli irradiated with 5 Gy (designated CI) and anthers and calli irradiated consecu- tively with 5+5 Gy (combined treatment group, designated ACI). Anther culture response of the four F1 group of plants was intermediate between the parents, with a slightly depressive effect of the dose irradiation in the AI and ACI groups. In general, the effect of the 5 Gy dose of irradiation on androgenesis was estimated to be negative for at least one group of haploid plants (AI), derived from irradiated anthers. Green plants were mostly reduced in the combined treatment group originating from irradiated calli and anthers.

Estimation of Gene Action , Heritability and Genetic Advance for Some Agronomic Traits in Three Bread Wheat Crosses

Estimation of Gene Action , Heritability and Genetic Advance for Some Agronomic Traits in Three Bread Wheat Crosses

Gene Action and Combining Ability in a Six Parent Diallel Cross of Wheat

Gene Action and Combining Ability in a Six Parent Diallel Cross of Wheat

QTL Analysis for Grain Pentosans and Hardness Index in a Chinese 1RS.1BL × non-1RS.1BL Wheat Cross

Pentosans are quantitatively minor constituents of wheat (Triticum aestivum L.), but they influence the end-use and nutritional qualities of grain cereals. Although several studies on the physicochemical properties and genetic basis of pentosans and pentosan-associated traits have been reported, the genetic architecture and determinants of pentosans remained ambiguous. In this research, 107 QTLs for pentosans and pentosan-associated traits were detected based on a population of recombinant inbred lines (RILs) derived from a 1RS/1BL translocation line × non-1RS/1BL translocation line. We identified seven stable expression QTLs for pentosans and one major QTL (Q.HI.scau-7D linked to xwmc634-7D) for hardness index (HI). Q.HI.scau-7D may be the gene responsible for the bimodal HI distribution map. More than one genetic location harbored QTLs for water-soluble pentosan (WSP), and the ratio of WSP content to water-insoluble pentosans (WIP) content (RWW) varied simultaneously, meaning that these loci harbored pleiotropic genes for WSP and RWW. WSP was the main factor in pentosans affecting wheat HI. This study gives a better understanding of the molecular genetics of pentosans and pentosan-related traits, and provides a certain theoretical basis for molecular genetics and breeding for pentosans.

Genetical Analysis of Self-Fertilized Generation Means in Two Durum Wheat Crosses

Six self-fertilized generations (P1, P2, F2, F3, B1S and B2S) of two crosses in durum wheat (Triticum durum Desf.), the first cross between Azeghar-1 and Um-Rabie-5 and the second cross between Leeds and Waha, were used to study gene action for the traits, heading time, flag leaf venation, plant height, peduncle length, number of spikes, spike length, grain yield, 100 grains weight and number of grains per spike. Two models were used in analyzing the components of the generation means, three –parameter model and six-parameter model. The results from the generation mean analysis showed that the three- parameter model was adequate for the inheritance of spike length and weight of 100 grains in the both crosses and number of spikes per plant in the second cross but there were additive, dominance and epistatic effects on the other characters in the both crosses.

Genetical Analysis of Self-Fertilized Generation Variances in Two Durum Wheat Crosses

Phenotypic variance in parents and third generation were analyzed to estimate the additive genetic variance, dominance genetic variance, environmental variance, average degree of dominance, heritability in broad sense, heritability in narrow sense and expected genetic advance from selection in F3 generation, of two crosses in durum wheat (Triticum durum Desf.), the first cross between Azeghar-1 and Um-Rabie-5 and the second cross between Leeds and Waha for traits, heading time, flag leaf venation, plant height, peduncle length, number of spike, spike length, grain yield, 100 grains weight and number of grains per spike. Average degree of dominance revealed the different types of dominance for the studied traits, the values of narrow sense heritability were high for plant height, peduncle length, number of spikes, grain yield and number of grains per spikes in both crosses, spike length and weight of 100 grains in first cross, and flag leaf venation in second cross.

Estimation of genetic parameters for morpho-physiological traits under terminal heat tolerance in bread wheat (Triticum aestivumL.)

Winter wheat is adversely impacted by the effects of high temperature stress in many wheat-producing areas. Increasing productivity under heat stress conditions requires the development of high temperature-tolerant wheat cultivars. The identification and measurement of traits conferring high temperature tolerance and an understanding of genetic variability and gene regulation of these traits are essential for the development of high temperature-tolerant germplasm. Understanding the genetic basis of tolerance to high temperature is important for improving the productivity of wheat (Triticum aestivum L.) in regions where the stress occurs. The objective of this study was to estimate the genetic parameters for morpho-physiological characters viz. number of days to heading, days to maturity, tillers/plant, grain number, 1000 grain weight, grain yield, membrane stability and chlorophyll stability index under terminal heat stress which was created by delayed sowing of the crop. Four cultivars, DBW 16, Hindi 62 (heat-tolerant) and WH147, WH711 (heat-susceptible), were crossed as WH147 × DBW 16 and Hindi 62 × WH711 to produce F1, F2, and F3 populations, and their grain-filling duration (GFD) at 35 ° C day was determined as a measure of heat tolerance. Results indicated that significant variations were observed among different F 2 plant of both wheat crosses in respect of all yield attributes under heat stress environment. The SSR marker analysis was applied for the screening of the four parents for the polymorphism under stress condition. Products from 25 primer pairs among 50 simple sequence repeat (SSR) pairs were polymorphic between the parents. The polymorphic markers will be subjected for the genetic analysis of F 2 and F 3 population of the respective crosses under study.

Genetic control of flag leaf area in wheat (Triticum aestivum) crosses

The results indicated that the trait was mostly under control of one major gene in combination with polygenes (model D-2) for the two crosses during the first year. However, it was controlled by mixed epistasis of two major genes plus polygenes (model E-1) in cross 2 during the second year. Transgressive segregate on both upper and lower extremity of the trait in B 1, B2 and F 2 indicated the presence of both favorable and reversed genes in the parents. Higher major gene heritability (9.6 to 71.0) for the trait was recorded than the polygenes heritability (4.8 to 38.9) in the segregating generations (B 1, B 2 and F 2). Moderate to high environmental variations (14.4 to 85.0) in the trait for segregating generations revealed that FLA is influenced by the environmental fluctuations. Predominant additive effect over all other types of genetic effects suggests the delay in selection for FLA until maximum favorable genes are accumulated in the individuals.

Himalayan maize — potential pollen source for maize mediated system of chromosome elimination approach in DH breeding of bread wheat

To identify an efficient pollen source for maize mediated system of chromosome elimination, wheat genotypes (10 F1s) were pollinated with eight diverse Himalayan maize genotypes. Among these, two were composite varieties Early Composite (Check) and Bajaura Makka (L 201) and rest six were locally grown traditional open pollinated maize varieties collected from diverse regions of North-west Himalaya. The data were recorded for three haploid induction parameters viz. pseudo seed formation, embryo formation and regeneration. In most of the crosses, haploid embryos were produced, asserting the potential of wheat × maize system as a genotype non-specific system as compared to androgenesis and bulbosum technique, where the genotype specificity limits the development of haploid plants. Frequencies of all the three haploid induction parameters in different crosses of wheat × maize clearly indicated that both wheat and maize genotypes were behaving differently for different crosses. The line × tester analysis also ...

Comparative effect of auxin analogues on induction of polyhaploids in triticale and triticale wheat hybrids through wheat maize system

The study was designed to evaluate two auxins, 2,4-D and picloram for their effectiveness for induction of polyhaploids in triticale and triticale × wheat crosses and to standardize their optimum dose. Ten F1 and parental genotypes pollinated with maize were subjected to in vivo auxin treatment at three concentrations (100, 250 and 400 mg/l) by injecting at the tiller base of the crossed spikes so as to fill the hollow of their uppermost internode. Both auxins restulted in formation of embryo-carrying seeds, though the performance differed significantly for the three parameters of haploid induction at different concentrations. The highest seed formation, embryo formation, and regeneration frequencies in 2,4-D were recorded at 250, 400 and 250 mg/ l concentration, respectively, whereas, 400, 400 and 250 mg/ l concentration of picloram, respectively, were best for above traits. All the genotypes led to regeneration of haploid plants at 250 mg/l of both the auxins. On the basis of the three haploid induction parameters and overall success rates, the 250 mg/l concentration of both auxins was optimum.

Gene Effects for Yield and Yield Components in Some Bread Wheat Crosses

Gene Effects for Yield and Yield Components in Some Bread Wheat Crosses

Estimation of Genetic Parameters for Earliness and Grain Yield Characters in Three Bread Wheat Crosses

Estimation of Genetic Parameters for Earliness and Grain Yield Characters in Three Bread Wheat Crosses

Production of doubled haploids in spring wheat varieties and crosses

Production of doubled haploids in spring wheat varieties and crosses

Genetic model analysis on seedling and maturity traits in wheat under rainfed conditions

An experiment was conducted to access the genetic variability among early vigour and quantitative traits under limited moisture in F2 generation of a 5 × 5 diallel cross of bread wheat. The results indicated that there was significant genotypic variation among the genotypes. Additive dominance model revealed full fitness of the data for RL, DSW, FRW, DRW, spike length, and 1000-grain weight but was partially fit for SL, FSW, R/S, tillers per seedling, plant height, tillers per plant, spikelets per spike, and grain yield per plant. The partially adequate models for these plant characters might be due to the presence of non-allelic interaction, linkage, and non-independent distribution of the genes in the parents. Additive genes coupled with moderate to high narrow sense heritability were involved in the heritage of all the traits, which indicated a higher scope of selection in early generations.

EFFICINCY OF THREE BREEDING METHODS ON TWO BREAD WHEAT CROSSES

EFFICINCY OF THREE BREEDING METHODS ON TWO BREAD WHEAT CROSSES

Inheritance of stem strength and its correlations with culm morphological traits in wheat (Triticum aestivumL.)

Yao, J., Ma, H., Zhang, P., Ren, L., Yang, X., Yao, G., Zhang, P. and Zhou, M. 2011. Inheritance of stem strength and its correlations with culm morphological traits in wheat ( Triticum aestivum L.). Can. J. Plant Sci. 91: 1065–1070. The genetic effect of stem strength and its correlation with culm morphological traits were investigated in a 7×7 diallel cross of wheat involving seven parents (Ningmai 8, Ningmai 9, Yangmai 5, Yangmai 9, Yangmai 11, Sumai 3, and Wangshuibai) during the crop season of 2009–2010. Significant differences were observed among genotypes for stem strength. The estimates of general combining ability (GCA) pointed out that the best general combiners for stem strength were Ningmai 8 and Yangmai 9. The additive-dominance model was adequate for stem strength, and it was controlled by the over dominance type of gene action. Ningmai 8, followed by Yangmai 5, possessed maximum recessive genes, whereas Wangshuibai had maximum dominant genes. Stem strength could be controlled by three genes with low narrow sense heritability. A statistical analysis showed that stem strength is highly significantly correlated with nine culm morphological traits except for diameter of the first basal internode.

Triticum aestivum × Triticum timopheevii introgression lines as a source of pathogen resistance genes

A collection of introgression lines was obtained from crosses of common wheat (Triticum aestivum L.) cultivars with tetraploid wheat Triticum timopheevii (Zhuk.). Evaluation of resistance to fungal diseases revealed the lines with resistance to leaf and stem rusts, powdery mildew, spot blotch, and loose smut, the most widespread in Siberian region of Russia. Localization of the T. timopheevii genome fragments by means of microsatellite markers determined higher frequency of substitutions and translocations on chromosomes 1А, 2A, 2B, 5A, 5B and 6B. Molecular mapping of the loci determining leaf rust resistance revealed two independent loci on chromosomes 5B and 2A. The major locus on 5BS.5BL-5GL translocated chromosome accounting 64% of the phenotypic variance of the trait was found to be closely linked to microsatellite markers Xgwm814 and Xgwm1257. The other, minor locus, controlling 11% of the trait was mapped next to Xgwm312 on chromosome 2A. Microsatellite markers located near these genes may be used for controlling the transfer of valuable traits in new wheat cultivars.

Identification of genetic factors controlling kernel hardness and related traits in a recombinant inbred population derived from a soft × ‘extra-soft’ wheat (Triticum aestivum L.) cross

Kernel hardness or texture, used to classify wheat (Triticum aestivum L.) into soft and hard classes, is a major determinant of milling and baking quality. Wheat genotypes in the soft class that are termed 'extra-soft' (with kernel hardness in the lower end of the spectrum) have been associated with superior end-use quality. In order to better understand the relationship between kernel hardness, milling yield, and various agronomic traits, we performed quantitative trait mapping using a recombinant inbred line population derived from a cross between a common soft wheat line and a genotype classified as an 'extra-soft' line. A total of 47 significant quantitative trait loci (QTL) (LOD≥3.0) were identified for nine traits with the number of QTL affecting each trait ranging from three to nine. The percentage of phenotypic variance explained by these QTL ranged from 3.7 to 50.3%. Six QTL associated with kernel hardness and break flour yield were detected on chromosomes 1BS, 4BS, 5BS, 2DS, 4DS, and 5DL. The two most important QTL were mapped onto orthologous regions on chromosomes 4DS (Xbarc1118-Rht-D1) and 4BS (Xwmc617-Rht-B1). These results indicated that the 'extra-soft' characteristic was not controlled by the Hardness (Ha) locus on chromosome 5DS. QTL for eight agronomic traits occupied two genomic regions near semi-dwarf genes Rht-D1 on chromosome 4DS and Rht-B1 on chromosome 4BS. The clustering of these QTL is either due to the pleiotropic effects of single genes or tight linkage of genes controlling these various traits.

ESTIMATION OF GENETIC PARAMETERS FOR GRAIN YIELD AND ITS COMPONENTS IN THREE BREAD WHEAT CROSSES UNDER LOW INPUT OF NITROGEN FERTILIZER

Six populations (P1, P2, F1, F2, BC1 and BC2) of three bread wheat(Triticum aestivum L.) crosses, mamely Gemmeiza 9 x MayonS//CrowS/VeeS (cross I), Attila/Sids 1 x Sakha 94 (cross II) and Mayon S//Crow S/VeeS x Attila /Sids 1 (cross III) were used to estimate genetic parameters for grain yield/plant and certain related characters under two nitrogen fertilizer levels; (40 Kg N/Fed [low level] and 75 Kg N/Fed (recommended level]). Results revealed that heterosis values were positive and significant relative to better-parent in the three crosses under the two nitrogen levels for most of the studied characters. Meanwhile, heterosis values were negative and significant for number of kernels/spike in the first and the third crosses under low level of nitrogen N1, and the third cross under recommended level N2 and for kernel weight in the second cross under N1. In the second and third crosses under N2, positive and significant inbreeding depression values were recorded for all studied characters in the first cross except for kernels/spike under both N1 and N2, for kernels/spike in the second cross under both N1 and N2, for spikes/plant and grain yield in the third cross under N1 and N2, whereas negative significant values were obtained for kernels/spike in the third cross and for kernel weight in the second and third ones under both levels of nitrogen. Over-dominance above the higher parent was detected for spikes/plant and grain yield in all crosses under the two levels of nitrogen, for kernels/spike in the first cross under N2 as well as in the second cross under N1 and N2 and for kernel weight in the first cross under two levels. The other types of dominance were also studied. Scaling tests (A, B, C and D) indicated the presence of non-allelic gene interactions for all studied characters in all crosses under both levels of nitrogen. Additive genetic variance was highly significant for all traits in the three crosses under N1 and N2. Dominance variance was significant for all characters in all crosses, except for kernels/spike and kernel weight in the second cross under N1 and for all characters except for kernels/spike in the first cross, for kernel weight in the second cross and for all characters except for kernel weight in the third one under N2. Epistasis effects were present for most studied traits in the three crosses under both levels of nitrogen. F2 deviations (E1) was significant for kernel weight in all crosses, spikes/plant in the second and third crosses and grain yield in the second cross under N1 as well as for spikes/plant and kernel weight in all crosses and grain yield in the first and second crosses under N2. Back-cross deviations (E2) were significant for kernel/spike and grain yield in the first cross, for kernel weight in the second cross and for all characters in the third cross under N1 as well as for spikes/plant and grain yield in the first cross, for kernels/spike and kernels weight in the second cross and for all characters except for spikes/plant in the third cross under N2. Broad sense heritability estimates were relatively high under both N1 and N2. Selection in segregating generation could be effective to produce lines that have high yielding ability under low level of nitrogen fertilizer (40 kg N/fed).

English

Leaf rust is a major disease of wheat crop in the world as a whole. This study was undertaken to find the genetic effects of adult plant leaf resistance in wheat (Triticum aestivum L.). Three wheat crosses were developed from three resistant and one susceptible parent. Six populations (P1, P2, F1, F2, BC1 and BC2) of each cross were grown under field conditions and were artificially inoculated with isolates of mixture of leaf rust prevalent races. Leaf rust intensity and reaction type were observed and the coefficient of infection was computed. Generation means and variance analyses were performed for the estimation of additive, dominance and epistatic genetic effects. Additive and dominance, as well as epistatic genetic effects, are involved in the inheritance of leaf rust resistance. However, the narrow sense heritability estimates were low, which also exhibited the presence of epistatic genetic effects. Thus, selection of resistant adult plant in later segregating generations would be useful for the development of high yielding wheat genotypes.   Key words: Wheat, leaf rust, Puccinia recondite, genetic studies, Pakistan.