Wheat Crosses Research Articles

Assessment of genes controlling Area under Disease Progress Curve (AUDPC) for stripe rust (P. Striiformis F. Sp. Tritici) in two wheat (Triticum Aestivum L.) crosses

Genetic effects on controlling stripe rust resistance were determined in two wheat crosses, Bakhtawar-92 x Frontana (cross 1) and Inqilab-91 x Fakhre Sarhad (cross 2) using Area under Disease Progress Curve (AUDPC) as a measure of stripe rust resistance. The resistant and susceptible genotypes for crosses were identified by initial assessment of 45 wheat accessions for stripe rust resistance. Mixed inheritance model was applied to the data analysis of six basic populations P1, F1, P2, B1, B2, and F2 in the crosses. The results indicated that AUDPC in cross 1 was controlled by two major genes with additive-dominance epistatic effect plus polygenes with additive-dominance epistatic effects (model E). Whereas in case of cross 2, it was under the control of two major genes with additive-dominance epistatic effect plus additive-dominant polygenes (model E-1). Additive effect was predominant then all other types of genetic effects suggesting the delay in selection for resistance till maximum positive genes are accumulated in the individuals of subsequent generations. Occurrence of transgressive segregants for susceptibility and resistance indicated the presence of resistance as well as some negative genes for resistance in the parents. The major gene heritability was higher than the polygene heritability in B1, B2 and F2 for the crosses. The major gene as well as the polygene heritability was ranging from 48.99 to 87.12% and 2.26 and 36.80% for the two crosses respectively. The highest phenotypic variations in AUDPC (2504.10 to 5833.14) for segregating progenies (BC1, BC2 and F2) represent that the character was highly influenced by the environment.

Characterization and mapping of complementary lesion-mimic genes lm1 and lm2 in common wheat

A lesion-mimic phenotype appeared in a segregating population of common wheat cross Yanzhan 1/Zaosui 30. The parents had non-lesion normal phenotypes. Shading treatment and histochemical analyses showed that the lesions were caused by light-dependent cell death and were not associated with pathogens. Studies over two cropping seasons showed that some lines with more highly expressed lesion-mimic phenotypes exhibited significantly lower grain yields than those with the normal phenotype, but there were no significant effects in the lines with weakly expressed lesion-mimic phenotypes. Among yield traits, one-thousand grain weight was the most affected by lesion-mimic phenotypes. Genetic analysis indicated that this was a novel type of lesion mimic, which was caused by interaction of recessive genes derived from each parent. The lm1 (lesion mimic 1) locus from Zaosui 30 was flanked by microsatellite markers Xwmc674 and Xbarc133/Xbarc147 on chromosome 3BS, at genetic distances of 1.2 and 3.8 cM, respectively, whereas lm2 from Yanzhan 1 was mapped between microsatellite markers Xgwm513 and Xksum154 on chromosome 4BL, at genetic distances of 1.5 and 3 cM, respectively. The linked microsatellite makers identified in this study might be useful for evaluating whether potential parents with normal phenotype are carriers of lesion-mimic alleles.

Mapping genes controlling anthocyanin pigmentation on the glume and pericarp in tetraploid wheat (Triticum durum L.)

A novel gene, designated Pg (purple glume), controlling anthocyanin pigmentation of the glume was identified and mapped in an F2 population from the durum wheat (Triticum durum) cross TRI 15744/TRI 2719. This gene was close to one of the two complementary dominant genes, controlling anthocyanin pigmentation of the pericarp (gene Pp3) in the centromere region of chromosome 2A; the other Pp gene (Pp1) was mapped on the short arm of chromosome 7B, near gene Pc controlling anthocyanin pigmentation of the culm and co-segregating with Pls (purple leaf sheath) and Plb (purple leaf blade). On the basis of the mapping results, the Pp3, Pc, Pls and Plb genes of T. durum were regarded as allelic to the T. aestivumPp3, Pc-B1, Pls-B1 and Plb-B1 loci. The likely allelism of Pp1 in T. durum and T. aestivum remains in dispute, the present durum Pp gene mapped to the short arm of chromosome 7B, whereas in common wheat it was reportedly located on the long arm.

Mapping QTLs for pre-harvest sprouting traits in the spring wheat cross ‘RL4452/AC Domain’

Pre-harvest sprouting (PHS) in spring wheat (Triticum aestivum L.) is a major downgrading factors for grain producers and can significantly reduce end-use quality. PHS resistance is a complex trait influenced by genotype, environment and plant morphological factors. A population of 185 doubled haploid (DH) lines from the spring wheat cross ‘RL4452/AC Domain’ were used as the mapping population to detect quantitative trait loci (QTLs) associated with three PHS traits, germination index (GI), sprouting index (SI) and falling number (FN). Six major QTLs linked with PHS traits were mapped on bread wheat chromosomes 3A, 3D, 4A (2 loci), 4B and 7D. ‘AC Domain’ alleles contributed to PHS resistance on 3A, 4A (locus-2) and 4B, and ‘RL4452’ alleles contributed resistance on 3D, 4A (locus-1) and 7D. QTLs detected on chromosome 4B controlling FN (QFN.crc-4B), GI (QGI.crc-4B) and SI (QSI.crc-4B) were coincident, and explained the largest amount of phenotypic variation in FN (22%), GI (67%) and SI (26%), respectively.

GENETIC STUDIES ON YIELD AND ITS COMPONENTS IN FOUR BREAD WHEAT CROSSES

Three experiments were carried out at Bahteem Agricultural Research Station during three successive seasons from 2005/2006 to 2007/2008. In 2005/2006 season using three wheat (Triticum aestivum L.) crosses namely; Gemmeiza 7 x Sids 1, Sakha 94 x Irena and Sids 1 x Sakha 94. Six populations (P1, P2, F1, F2, BC1 and BC2) for each cross were used in this investigation. The data were recorded on an individual guarded plants for number of spikes / plant, number of kernels / spike, 100-grain weight and grain yield / plant. Significant heterotic effects were obtained for number of spikes / plant, grain yield / plant and number of kernels / spike in the first cross while, heterotic increase in grain weight, grain yield / plant and number of kernels / spike seemed to be accounted for the heterotic response observed in the second cross. Also, significant heterotic effect was found for number of spikes / plant, grain weight and grain yield / plant in the third cross. Inbreeding depression estimates were significant for all studied attributes except for number of spikes / plant in the first cross. Over dominance towards the higher parent for number of spikes / plant, grain weight, grain yield / plant and number of kernels / spike were observed in the first cross. Meanwhile, over or partial dominance towards the lower parent was obtained for all characters in the third cross. On the other hand, partial dominance was observed for all characters (number of spikes / plant, grain weight, grain yield /plant and number of kernels / spike) in the second cross. F2 deviations (E1) were significant for all studied characters in the three crosses, except for number of spikes / plant in the first and second crosses, and grain weight in the first cross only. Moreover, backcross deviations (E2) were significant for all characters studied in all crosses, except for number of spikes / plant and for grain weight in the first cross, grain yield / plant in the first and the second ones. The additive gene effects were significant for all studied characters in the second and the third crosses, except for number of spikes / plant, grain weight , grain yield / plant and number of kernels / spike in the cross (Gemmeiza 7 x Sids 1). These results suggest the potential for obtaining further improvement in most studied character. In addition, dominance epistasis was significant for some of the studied attributes (number of kernels / spike, grain yield/ plant in the first and second crosses; and grain weight in the first and third ones; and number of spikes / plant in the third one). High to medium values of heritability were associated with high and moderate genetic advance as percentage of F2 mean in most characters. These results indicated that selection for the studied characters could be useful in the early generations.

Estimate of Heterosis and Combining Ability in Diallel Bread Wheat Crosses (Triticum aestivum L.)

Estimate of Heterosis and Combining Ability in Diallel Bread Wheat Crosses (Triticum aestivum L.)

Heterosis in Some Crosses of Bread Wheat under Irrigation and Drought Conditions

Five bread wheat varieties with different characteristics were crossed in a half-diallel model in 2005/2006 season. The five parents and their 10 F1 hybrids were evaluated under normal and water stress conditions during 2006/2007 season, to estimate heterosis of some wheat crosses for drought tolerance and selecting the crosses which could be useful in breeding programs for drought tolerance. The results indicated that, the best crosses over their mid parents at water stress condition for days to heading was Sakha-61 x Sakha-93; for flag leaf area were Giza-168 x Gemmeiza-9 and Sakha-61 x Gemmeiza-9 and for plant height was Sakha-61 x Sakha-93. The best crosses over their mid parents at both normal and stress conditions for days to maturity was Sakha-61 x Gemmeiza-9; for flag leaf area were Giza-168 x Sakha-61, Sakha-8 x Gemmeiza-9 and Sakha-93 x Gemmeiza-9; for spikes/plant were Sakha-8 x Sakha-61, Sakha-8 x Gemmeiza-9 and Sakha-61 x Sakha-93; for kernels/spike were Giza-168 x Sakha-8, Giza-168 x Sakha-61, Giza-168 x Sakha-93 and Sakha-8 x Gemmeiza-9; for 100-kernel weight were Giza-168 x Gemmeiza-9, Sakha-61 x Sakha-93 and Sakha-93 x Gemmeiza-9 and for grain yield/plant were Giza-168 x Sakha-93, Sakha-8 x Gemmeiza-9 and Sakha-93 x Gemmeiza-9. The best crosses over their better parents at water stress condition for flag leaf area were Giza-168 x Sakha-8, Giza-168 x Gemmeiza-9 and Sakha-8 x Gemmeiza-9; for plant height were Giza-168 x Gemmeiza-9 and Sakha-8 x Sakha-61. The best crosses over better parents at both normal and stress conditions for plant height were Giza-168 x Sakha-8, Sakha-8 x Gemmeiza-9 and Sakha-93 x Gemmeiza-9; for spikes/plant were Sakha-8xSakha-61, Sakha-61 x Sakha-93 and Sakha-8 x Gemmeiza-9; forkernels/spike were Giza-168 x Sakha-61 and Giza-168 x Sakha-93 and for grain yield/plant were Sakha-61 x Sakha-93 and Sakha-93 x Gemmeiza-9. Estimation of useful heterosis over better parent for grain yield/plant proved that it never exceeds 10.16% at normal condition (cross Giza-168 x Gemmeiza-9) and 12.76% at stress condition (cross Sakha-93 x Gemmeiza-9). Useful segregate could be selected from such hybrids as hybrids wheat are still under experimentation in Egypt.

ESTIMATION OF SOME GENETIC PARAMETERS FOR SOME AGRONOMIC CHARACTERISTICS IN THREE CROSSES OF BREAD WHEAT

Six populations; P1, P2, F1, F2, BC1 and BC2 were used in this study to determine quantitative genetic parameters. The means of the six generations were recorded for number of days to heading , days to physiological maturity, plant height, number of spikes per plant, number of kernels per spike, 100-kernel weight and grain yield per plant in three crosses namely; Giza 168 × Gemmiza 10, Giza 168 × Sakha 69 and Sakha 69 × Giza 163 generated from four diverse parents. The experiment was conducted in 2005/06, 2006/07 and 2007/08 wheat-growing seasons at Sakha Agric. Res. Station. Analyzed data revealed that sufficient genetic variations were found among generations for all the characters studied in all crosses. The results of the genetic analysis showed that the genetic variance among F2 plants were genetically different for all studied characters in the three wheat crosses except for 100-kernel weight in the cross Giza 168 × Gemmiza 10. The additive, dominance and epistatic gene effects were important in controlling the inheritance of number of days to heading, number of spikes per plant, number of kernels per spike and grain yield. Heritability estimates in broad and narrow senses were generally moderate to high for most studied characters in the three crosses. The expected genetic advance estimates from selection in the F2 were low for days to heading and days to physiological maturity, 100-kernel weight in crosses Giza 168 × Gemmiza 10 and Giza 168 × Sakha 69 and for plant height in cross Sakha 69 × Giza 163. Average degree of dominance was less than unity for days to physiological maturity in cross Giza 168 × Gemmiza 10, for plant height in cross Giza 168 × Sakha 69 and for grain yield per plant in the three crosses indicating the presence of partial dominance. Significant heterosis estimates were obtained for days to heading, days to physiological maturity, plant height and 100-kernel weight in most crosses.

QTL mapping for milling, gluten quality, and flour pasting properties in a recombinant inbred line population derived from a Chinese soft×hard wheat cross

Improvement of processing quality is important for various wheat-based end products. A recombinant inbred line (RIL) population derived from a cross between the Chinese wheat cvv. PH82-2 (hard) and Neixiang 188 (soft) was sown at 3 locations across two seasons to map quantitative trait loci (QTLs) for milling, gluten quality, flour pasting properties, and Chinese white salted noodle (CWSN) qualities. One hundred and eighty-eight microsatellite loci, one rye secalin marker Sec1, one STS marker YP7A, one CAPs marker for the Pinb-D1b allele, and four glutenin subunit markers were used to genotype the population and construct a linkage map for subsequent QTL analysis. In total, 53 QTLs for 16 quality parameters were mainly mapped to glutenin loci Glu-A3 (Glu-A3a:Glu-A3d), Glu-B1 (Bx7+By9:Bx14+By15), and Glu-D1 (Bx2+By12:Bx5+By10), and the grain hardness (Pinb-D1a:Pinb-D1b) locus. The-high-molecular weight glutenin subunits (HMW-GS) 5+10 at the Glu-D1 locus showed large effects on mixograph peak time (MPT), mixograph 8 min width (MTxW), and weakening slope (WS), accounting for 43.1%, 24.2%, and 39.7% of the phenotypic variance, respectively. In contrast, the 1RS (1B.1R translocation) showed large negative effects on MTxW, explaining 42.2% of the phenotypic variance. Two important QTLs were detected for Rapid Viscosity Analyzer (RVA) parameters: one for RVA final viscosity (RFV) near the 1RS and the other for RVA setback (RSb) associated with the Glu-B1 locus, explaining 21.6% and 12.3% of the phenotypic variance, respectively. Two QTLs for noodle adhesiveness were identified: one occurred on chromosome 1A and the other was associated with Glu-B1. Two QTLs for noodle springiness, one associated with the 1RS showing a negative effect on noodle quality and the other mapped to the Ha locus on chromosome 5DS, accounted for 9.4% and 8.1% of the phenotypic variance, respectively. In addition, the Ha locus also showed large effects on flower protein content (FPC), mixograph peak width (MPW), and RVA parameters, especially RVA pasting temperature (RPT), explaining 71.5% of the phenotypic variance.

Gene effects and mean performance of nitrogen and phosphorus use in wheat after inoculation with arbuscular mycorrhiza fungi and Azotobacter chroococcum under low input conditions

The present investigation was conducted to study the impact of bio-inoculants under low input field conditions on the magnitude and direction of gene effects and the mean performance of nitrogen (N) and phosphorus (P) use in wheat. Three wheat cultivars suitable for different agro-ecological conditions, i.e. WH 147 (low mineral input), WH 533 (water deficit), Raj 3077 (high mineral input), and six generations (P1, P2, F1, F2, BC1and BC2) of three crosses, namely WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077, were evaluated in a randomized block design with three replications under low input field conditions (80 kg N + 40 kg P + 18 kg ZnSO4doses applied in each treatment) with three treatments, i.e. control, inoculation with arbuscular mycorrhiza fungi (AMF,Glomus fasciculatum) and dual inoculation with AMF andAzotobacter chroococcum(Azc). Bioinoculation with AMF and AMF+Azchad a positive impact on the mean performance of all the wheat crosses. The mean performance of AMF was maximum in the cross WH 147 × WH 533 for N and P response (%), N and P use index (%) and P content (ppm), whereas for N and P uptake it was maximum in the cross WH 147 × Raj 3077. The response and use index for N and P were better in the combined AMF+Azctreatment in all three crosses. The adequacy of the additive-dominance model for the phosphorus uptake (mg/plant) by all three crosses in all three treatments (i.e. control, AMF, AMF+Azc) suggested that additive (d) and dominance (h) gene effects mainly governed the inheritance of this trait. In all cases, digenic interactions were present, where the duplicate type of epistasis prevailed except for the P content in the control in the cross WH 147 × WH 533, where the complementary type of interaction was present. Pedigree selection in crosses WH 147 × WH 533 and WH 147 × Raj 3077 could be effective for breeding pure lines of wheat for sustainable agriculture (low input genotypes responsive to biofertilizers such as AMF andAzotobacter).

Mapping QTLs for pre-harvest sprouting tolerance on chromosome 2D in a synthetic hexaploid wheat×common wheat cross

Based on segregation distortion of simple sequence repeat (SSR) molecular markers, we detected a significant quantitative trait loci (QTL) for pre-harvest sprouting (PHS) tolerance on the short arm of chromosome 2D (2DS) in the extremely susceptible population of F2 progeny generated from the cross of PHS tolerant synthetic hexaploid wheat cultivar 'RSP' and PHS susceptible bread wheat cultivar '88-1643'. To identify the QTL of PHS tolerance, we constructed two SSR-based genetic maps of 2DS in 2004 and 2005. One putative QTL associated with PHS tolerance, designated Qphs.sau-2D, was identified within the marker intervals Xgwm261-Xgwm484 in 2004 and in the next year, nearly in the same position, between markers wmc112 and Xgwm484. Confidence intervals based on the LOD-drop-off method ranged from 9 cM to 15.4 cM and almost completely overlapped with marker interval Xgwm261-Xgwm484. Flanking markers near this QTL could be assigned to the C-2DS1-0.33 chromosome bin, suggesting that the gene(s) controlling PHS tolerance is located in that chromosome region. The phenotypic variation explained by this QTL was about 25.73-27.50%. Genotyping of 48 F6 PHS tolerant plants derived from the cross between PHS tolerant wheat cultivar 'RSP' and PHS susceptible bread wheat cultivar 'MY11' showed that the allele of Qphs.sau-2D found in the 'RSP' genome may prove useful for the improvement of PHS tolerance.

Differential Gene Expression in Uppermost Internode between Wheat Hybrid and Its Parents

Heterosis is defined as the advantage of hybrid performance over its parents in growth and productivity. Previous studies showed that differential gene expression in hybrids and their parents is responsible for the heterosis. Plant hormones, espe-cially GAs are found to be related to heterosis in development of shoot and plant height. However, information on systematic identification and characterization of the differentially expressed genes in shoots of hybrid and their parents are not found, and molecular evidence for the contribution of plant hormone to plant heterosis are also absent. The purpose of this paper was to in-vestigate the differential gene express in stems of hybrid and their parents, and further, to investigate the possible role of genes participating hormone signaling in the formation of heterosis of plant stem. Using a wheat cross combination that exhibited vig-orous heterosis in plant height, the differential gene expression in upper-most internode of wheat hybrids and their parents was analyzed by cDNA-AFLP. Ninety-eight differentially expressing cDNA fragments were obtained, which were sequenced and analyzed by Blast-x. Reverse Northern hybridization was performed in order to test the expression pattern of isolated ESTs in hybrid and their parents. The differentially expressed genes included a cdc2 gene and a PAS1 gene, which were induced by GAs and CTKs respectively and participated in plant cell division. The cdc2 gene was up-regulated in hybrid while the expression of PAS1 in hybrid was near the higher parent. The differentially expressed genes also included kinase participating in signal trans-duction, genes involved in metabolism and genes related to transcription regulations. It can be inferred that numerous genes were differentially expressed in the upper-most internode of hybrids and their parents, including genes participating in cell division and cell expansion, kinase related to signal transduction and so on. Reverse Northern blot analysis indicated that the expression pattern in our cDNA-AFLP analysis is credible. Since it has been much reported that genes participating in cell division and cell expan-sion are involved in plant stem growth and elongation, and genes that participate in gibberellins signals have been proved to be up-regulated in wheat hybrid and contributed to heterosis in wheat plant height, it can be modestly speculated that the differential expression of genes involved in phytohormone signals may be related to heterosis in wheat intenode elongation and plant height.

Pm23: a new allele of Pm4 located on chromosome 2AL in wheat

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the major diseases of common wheat (Triticum aestivum) worldwide. The powdery mildew resistance gene Pm23, identified in the common wheat Line 81-7241 and originally assigned to wheat chromosome 5A, was relocated on chromosome 2AL with the aid of molecular markers. Mapping of microsatellite markers in two wheat crosses segregating for Pm23 and Pm4b, respectively, in combination with the reported mapping of Pm4a, indicated that the three genes were all linked to the marker Xgwm356 with a distance of 3-5 cM. Allelism between Pm4b and Pm23 was then confirmed, when the progenies of a cross between VPM1 (Pm4b) and Line 81-7241, were shown to be all resistant to a B. graminis isolate avirulent to the both parents. Pm23 is therefore a new allele of the Pm4 locus, and was redesignated as Pm4c.

Comparison of Selection Methods for the Development of White‐Seeded Lines from Red × White Soft Winter Wheat Crosses

There has been increasing interest in developing soft white winter wheat (Triticum aestivum L.) cultivars for areas that have traditionally grown only soft red winter wheat. To develop white wheat segregates in a red wheat breeding program requires deliberate breeding decisions. The objectives of this study were to assess differences in agronomic, disease, and milling and baking quality traits between red and white progeny in 11 red × white crosses and to determine the optimal time and method for identifying white segregates from red × white crosses. Red and white progeny from the 11 populations were evaluated in replicated experiments at three locations in 2005–2006. White progeny produced significantly (p < 0.05) lower grain yields than red progeny in two of five environments studied. Deoxynivalenol level was significantly (p < 0.05) higher in white than in red progeny in the three environments in which it was measured. Flour yield, flour lactic acid solvent retention capacity, and softness equivalent were significantly (p < 0.05) lower for white progeny than for red progeny. To determine the optimal generation for selection of white lines, early‐generation bulk selection was compared with single seed descent in three populations at two locations. Although there were significant (p < 0.05) differences between selection methods within populations, neither breeding method was consistently superior across the three populations. Simulated selection of superior white lines based on agronomic and milling and baking quality showed no significant differences between the selection methods.

Mapping quantitative trait loci controlling pre-harvest sprouting resistance in a red × white seeded spring wheat cross

Hard white wheat (Triticum aestivum L.) is a value-added product because of its processing advantages over red wheat; however, white wheat tends to be more susceptible to pre-harvest sprouting (PHS). To identify quantitative trait loci (QTLs) associated with PHS tolerance, we developed a doubled haploid (DH) mapping population from the cross AC Domain (red seeded) × White-RL4137 (white seeded). A genetic map was constructed using microsatellite markers located on chromosome groups 3, 4, 5 and 6. A population of 174 DH lines was characterized for important aspects of PHS including sprouting index, germination index, Hagberg falling number and seed coat colour. A total of 11 QTLs were identified on group 3 chromosomes and on chromosome 5D. Seven QTLs associated with the PHS traits were found to be co-incident with seed coat colour on chromosomes 3A, 3B and 3D. The 5D PHS QTL was notable because it is independent of seed coat colour.

BRS Minotauro - Triticale Cultivar

The triticale cultivar BRS Minotauro was developed by the Brazilian Agricultural Research Corporation Embrapa. It is a result of a cross of Brazilian wheat and rye with hexaploid triticale. BRS Minotauro is hexaploid, has a medium cycle, medium to tall plant stature, adapts extremely well to cultivation conditions in the south of Brazil, with an average grain yield of 3,790 kg ha -1 , i.e., 9% higher than the mean yield of the controls, and has a high yield stability in different environments.

Molecular mapping of quantitative trait loci for yield and yield components in spring wheat (Triticum aestivum L.)

An F1 derived doubled haploid (DH) population of 402 lines from the adapted spring wheat cross Superb (high yielding)/BW278 (low yielding) was developed to identify quantitative trait loci (QTL) associated with yield and yield components. A subset of the population (186 lines) was evaluated in replicated field trials in 2001 and 2002 at six locations in Manitoba and Saskatchewan, Canada. Agronomic parameters, grain yield and yield components including 1,000 grain weight, harvest index, average seed weight spike(-1), seed number spike(-1) and spikes number m(-2) were measured. A genetic map was constructed with 268 microsatellite marker loci and included two morphological genes, reduced plant height, Rht-B1b, and the presence/absence of awns, B1. Composite interval mapping was conducted to estimate the location and effect of QTL associated with the evaluated traits. A total of 53 QTL were identified on 12 chromosomes for the 9 evaluated traits with the coefficient of determination ranging from 0.03 to 0.21 of the total variation. The increase in yield and yield components ranged from 4.5 to 17.1% over the population mean. The five grain yield QTL were detected on chromosomes 1A, 2D, 3B, and 5A and showed a combined increase of 34.4%, over the population mean. The alleles from Superb were associated with increased yield for four of the five QTL. This study identified potential chromosome segments for use in marker-assisted selection to improve yield and yield components in spring wheat.

GENETIC ANALYSIS OF TWO EGYPTIAN WHEAT CROSSES (Triticum aestivum, L.)

Non-allelic interaction scaling test (A, B, and C) coupled with joint scaling test χ2 and six parameters model were applied to test the adequacy of genetic model and estimates the genetic components for days to heading, flag leaf area, (cm)2 number of spikes / plant, number of grains/spike, 1000-grain weight (g.) and grain yield plant (g.) using six generation (P1, P2, F1, B1, B2 and F2) of two wheat crosses; 1. sids1 X Gemmeiza 7 and 2. Gemmeiza 9 X Sakha 92, A randomized complete block design with three replications was used. The obtained results indicated the importance of additive genetic variance (D) in the genetic control of days to heading and flag leaf area for Gimmeiza 9 X Sakha 92 and number of spikes / plant in two crosses. Heritability in narrow sense was more than 0.50. While the dominance genetic variance (H) was found to be the prevalent type controlling for the remaining crosses in the studied characters and the value of (H/D)0.5 was more than one for these characters and heritability in narrow sense was less than 0.50. The non allelic interaction (A, B and C) coupled with joint scaling test (χ2) revealed that simple genetic model was adequate for explaining the inheritance of number of spikes/plant for Gemmeiza 9 X Sakha 92, epistasis played a great role of controlling remaining characters in two crosses. Additive (d) and additive X dominance (J) were significant for days to heading and number of grains / spike (1st and 2nd crosses), 1000 grain weight and grain yield / plant for 2nd cross. The digenic interaction type dominance X dominance (L) controlling days to heading (1st, and 2nd crosses), number of spikes/plant (1st cross), number of grains/spike, 1000-grain weight and grain yield / plant for 2nd cross. Understanding the type of gene action controlling mechanism of the yield and yield components couped with the reproduction system are considered the main limiting factors for choosing the appropriate breeding method. These information are of great interest for plant breeder to release high yielding wheat cultivars as well as early mature ones.

Variations in the crossability of common wheat cultivars with cultivated barley

Differences in crossabilities of 23 common wheat cultivars, Triticum aestivum, were investigated by crossing those with cultivated barley, Hordeum vulgare cv. ‘Betzes’. Simultaneously, the wheat cultivars were crossed with rye, Secale cereale, in order to clarify the relationship between the crossabilities of wheat with barley and rye. Common wheat cultivars were used as female parents in both crosses, and number of embryos and seeds in wheat-barley and wheat-rye crosses were counted. Crossabilities of wheat with barley ranged from 0 % to 27.1 %, which were classified into five classes based on t-tests between all of the cross combinations. The highest class consisted of two cultivars, ‘Aobakomugi’ (27.1 %) and ‘Norin 61' (19.0%). Correlation between the crossabilities of wheat with barley and rye was not significant (r = 0.437, P > 0.05). However, after the crossability values of the two cultivars, ‘Aobakomugi’ and ‘Nobeokabouzu', were excluded, the coefficient was highly significant (r= 0.629, P < 0.01), since these cultivars showed only high crossabilities with barley or rye, respectively. These data suggest that the crossability of wheat with barley is also controlled by Kr alleles, which are known to control crossability with rye. However, there are exceptional wheat cultivars, in which crossability gene(s) other than the Kr system exist, that need to be considered.

Variations in the crossability of common wheat cultivars with cultivated barley

Differences in crossabilities of 23 common wheat cultivars, Triticum aestivum, were investigated by crossing those with cultivated barley, Hordeum vulgare cv. ‘Betzes’. Simultaneously, the wheat cultivars were crossed with rye, Secale cereale, in order to clarify the relationship between the crossabilities of wheat with barley and rye. Common wheat cultivars were used as female parents in both crosses, and number of embryos and seeds in wheat-barley and wheat-rye crosses were counted. Crossabilities of wheat with barley ranged from 0 % to 27.1 %, which were classified into five classes based on t-tests between all of the cross combinations. The highest class consisted of two cultivars, ‘Aobakomugi’ (27.1 %) and ‘Norin 61' (19.0%). Correlation between the crossabilities of wheat with barley and rye was not significant (r = 0.437, P > 0.05). However, after the crossability values of the two cultivars, ‘Aobakomugi’ and ‘Nobeokabouzu', were excluded, the coefficient was highly significant (r= 0.629, P < 0.01), since these cultivars showed only high crossabilities with barley or rye, respectively. These data suggest that the crossability of wheat with barley is also controlled by Kr alleles, which are known to control crossability with rye. However, there are exceptional wheat cultivars, in which crossability gene(s) other than the Kr system exist, that need to be considered.