Inheritance of agronomic traits from the Chinese barley dwarfing gene donors 'Xiaoshan Lixiahuang' and 'Cangzhou Luodama'

The inheritance of agronomic traits from the barley dwarfing gene donors ‘Xiaoshan Lixiahuang’ and ‘Cangzhou Luodamai’ was studied. The results indicated that dwarf plants, six‐row and short spikes, dense spikelets and naked kernels, respectively, were controlled by one pair of recessive genes, but a toothed awn was determined by one pair of dominant genes in both barley cultivars. The genes for the six characters in ‘Xiaoshan Lixiahuang’ were allelic to those in ‘Cangzhou Luodamai’. Genetic linkage was found among the genes for plant height, spike length and spikelet density. They were located on the long arm of chromosome 3 (3HL) in the order: plant height, spikelet density, spike length. The genes for naked kernels, six‐row spikes and tooth awns were independent of each other, and carried on the long arms of chromosomes 1(7H), 2(H) and 7(5H), respectively. The dwarfing genes were the same as the gene uz in Japanese and Korean barley cultivars.     

Inheritance of tolerance to zinc deficiency in barley

Barley (Hordeum vulgare L.) is often grown on alkaline zinc (Zn)‐deficient soils where reductions in yield and grain quality are frequently reported. Currently, the use of Zn‐based fertilizer along with Zn‐deficiency‐tolerant genotypes is considered the most thorough approach for cropping the Zn‐deficient soils; however, developing or breeding genotypes with higher Zn efficiency requires a good understanding of the inheritance of tolerance to Zn deficiency. This study was conducted to determine genetic control of this trait in barley. Two parental cultivars ('Skiff, moderately tolerant; and ‘Forrest’, sensitive), 185 F₂ plants, and 48 F₂‐derived F₃ families from this cross were screened to determine inheritance of tolerance to Zn deficiency using a visual score of deficiency symptoms. The segregation ratios observed indicated that greater tolerance to Zn deficiency in ‘Skiff compared with ‘Forrest’ at the seedling stage is controlled by a single gene with no dominance. The results also indicate that visual scores are useful for genetic analysis of tolerance to Zn deficiency.     

Inheritance of resistance to Pyrenophora teres f. teres in spring barley

The inheritance of seedling resistance to a Swedish isolate of Pyrenophora teres f. teres was investigated in four resistance sources of spring barley. Accessions CI 2330, CI 5791, CI 5822 and CI 9779 were used as resistance sources, and the cultivar ‘Alexis’ was used as a susceptible parent in different crosses. From the disease reaction in the F₁, F₂ and F₃ generations it was concluded that the resistance was governed by the same two complementary genes in CI 5791, CI 822 and CI 9776. One of these genes was present in CI 2330. The first three cultivars were highly resistant to the isolate used in this investigation. These results, when combined with earlier studies, suggest that CI 5791, CI 5822 and CI 9776 may be of great value as sources of resistance to barley net blotch. Spearman's rank correlation between the disease reaction of F₂ plants and their F₃ progeny was highly significant (r = 0.75; P ≥ 0.001) It is suggested that selection in the F₂ generation is effective. In a backcross breeding scheme, single plant reactions in F₁ or F₂ need to be confirmed in later generations.     

Inheritance and allelism of Russian wheat aphid resistance in several wheat lines

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko) has caused serious reduction in wheat production in 17 Western states of the United States since 1986. Inheritance of resistance to RWA in seven wheat lines and the allelism of the resistance genes in these lines with three known resistance genes Dn4, Dn5, and Dn6 were studied. The seven resistant lines were crossed to a susceptible wheat cultivar ‘Carson’ and three resistant wheats: CORWA1 (Dn4), PI 294994 (Dn5), and PI 243781 (Dn6). Seedlings of the parents, F₁, and F₂ were screened for RWA resistance in the greenhouse by artificial infestation. Seedling reactions were evaluated 21–28 days after the infestation using a 1–9 scale. The resistance level of all the F₁ hybrids was similar to that of the resistant parent, indicating dominant gene control. Only two distinctive classes were present and no intermediate types were observed in the F₂ population, suggesting qualitative, nonadditive gene action, in which the presence of any one of the dominant alleles confers complete resistance to RWA. Resistance in CI 2401 is controlled by two dominant genes. Resistance in CI 6501 and PI 94365 is governed by one dominant gene. Resistance in PI 94355 and PI 151918 may be conditioned by either one dominant gene or one dominant and one recessive gene. No conclusion can be made on how many resistance genes are in AUSVA1-F₃, since the parent population was not a pure line. Allelic analyses showed that one of resistance genes in CI 2401 and PI 151918 was the same allele as Dn4, the resistance gene in CI 6501 was the same allele as Dn6, and AUS-VA1-F₃ had one resistance gene which was the same allele as one of the resistance genes in PI 294994. One non-allelic resistance gene different from the Dn4, Dn5, and Dn6 genes in CI 2401, PI 94355, PI 94365, and PI 222668 was identified and should be very useful in diversifying gene sources in wheat breeding.     

Postulation of leaf-rust resistance genes in Czech and Slovak barley cultivars and breeding lines

Leaf‐rust resistance (Rph) genes in 61 Czech and Slovak barley cultivars and 32 breeding lines from registration trials of the Czech Republic were postulated based on their reaction to 12 isolates of Puccinia hordei with different combinations of virulence genes. Five known Rph genes (Rph2, Rph3, Rph4, Rph7, and Rph12) and one unknown Rph gene were postulated to be present in this germplasm. To corroborate this result, the pedigree of the barley accessions was analysed. Gene Rph2, as well as Rph4, originated from old European cultivars. The donor of Rph3, which has been mainly used by Czech and Slovak breeders, is ‘Ribari’ (‘Baladi 16’). Rph12 originates from barley cultivars developed in the former East Germany. Rph7 in the registered cultivar ‘Heris’ originates from ‘Forrajera’. A combination of two genes was found in 10 cultivars. Nine heterogeneous cultivars were identified; they were composed of one component with an identified Rph gene and a second component without any resistance gene. No gene for leaf rust resistance was found in 17 of the accessions tested. This study demonstrates the utility of using selected pathotypes of P. hordei for postulating Rph genes in barley.     

Inheritance of nitrogen and phosphorus utilization efficiency in spring barley at the vegetative growth stages under high and low nutrition

Inheritance of the nitrogen and phosphorus utilization efficiencies (NUE and PUE, respectively) and that of the tolerance (T) to limited NP nutrition was investigated in spring barley crosses at the vegetative growth stages. Plants were grown in sand-vermiculite cultures under high and low NP nutrition. In a diallel set (Ps and F₂s), both general combining ability (GCA) and specific combining ability (SCA) effects were significant for the variation in NUE and PUE, while the variation in T was mainly associated with GCA effects. The contribution of nonadditive genes for the utilization efficiencies was found to increase under nutrient shortages. Overdominance of genes was detected. The characters exhibited low heritabilities (0.10-0.42). Generation means analysis in two cross-combinations revealed significant effects of epistatic gene interactions. It was assumed that the involvement of both the dominance effects and epistatic interactions would not facilitate selection efforts to improve the characters in spring barley at its vegetative growth. Such selection should be performed among families of later generations. The genotype-nutrition interactions observed suggest that selection under diverse nutrition rates would be necessary for the more precise evaluation of barley efficiency under less favourable soil fertility.     

Inheritance and allelism for resistance to Russian Wheat Aphid in an Iranian Spring Wheat

Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is an important pest of wheat (Triticum aestivum L.) in the United States of America. Developing adapted wheat cultivars with genetic resistance to RWA is an effective control strategy. Genetic studies were conducted to determine the mode of inheritance of gene(s) conferring resistance to RWA in an Iranian landrace wheat line, G 5864. For the inheritance study, G 5864 was crossed with the susceptible wheats ‘Yecora Rojo’ and ND 2375. Seedlings of F1, reciprocal F1, F2, BC1 to the susceptible parent (BCS), and BC1 to the resistant parent (BCR) were screened for RWA reaction. Several phenotypic segregation ratios were tested in the F2 populations for goodness of fit; the 9:3:3:1 ratio (resistant: rolled leaves: stunted plants: susceptible) was an acceptable fit in all cases. Thus, resistance in G 5864 seemed to be controlled by two independent dominant genes with additive gene effects. The allelic relationships of gene(s) in this line with genes in other resistant lines, PI 137739 (Dn1), PI 262660 (Dn2), PI 372129 (Dn4), PI 294994 (Dn5), and PI 243781 (Dn6), were also studied. Segregation patterns observed in G 5864 × resistant (R × R) F2 populations were inconclusive. However, no susceptible plants were observed in these F2 populations. If previous reports concerning the number of resistance genes present in the other resistant lines are correct, then given the high manifestation of resistance observed in G 5864, and given the absence of susceptible plants in the R × R F2 populations, it is indicated that RWA resistance in G 5864 is either controlled by different alleles at the same loci as the other resistance genes, or that G 5864 shares a resistance gene with each of the other resistant lines. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tracing sources of dwarfing genes in barley breeding in China

To study the origin ofdwarfing genes used in barley breeding inChina, pedigree data of more than 350 dwarfand semi-dwarf cultivars and entriesdeveloped since 1950 were collected. Theresults showed that 68.4% of them werederivatives of just six accessions:`Chibadamai' (CBDM), `Xiaoshanlixiahuang'(XSLXH), `Cangzhouluodamai' (CZLDM),`Aiganqi' (AGQ), `Zhepi 1' and `Yanfu Aizao3' (YFAZ 3). Therefore, these sixaccessions are considered the main donorsof dwarfing genes to barley cultivars bredin China. `CBDM', `XSLXH' and `CZLDM' arelandraces and were used between 1950 and1980. `AGQ', `Zhepi 1' and `YFAZ 3' arereleased cultivars used since 1980. `CBDM',`XSLXH', `CZLDM' and `AGQ' carry the samedwarfing gene uzu on chromosome arm3HL. `Zhepi 1' and `YFAZ 3' likely aremutations at the sdw 1 locus.     

Resistance to powdery mildew in selections from Tunisian landraces of barley

Two-hundred and thirty-two accessions of barley landraces collected from Tunisia were screened for resistance to powdery mildew. A number of race-specific genes were detected using the detached leaf technique. Among the 232 accessions tested, 169 were susceptible to powdery mildew, 20 were resistant and 43 showed differential reactions to the three isolates of powdery mildew used. An attempt was made to determine the number of genes, the types of gene, the types of gene action and the gene loci in 20 resistant accessions. Three types of cross were made: (1) the accessions were crossed to the susceptible variety ‘Pallas’, (2) the accessions were crossed with ‘Pallas’ isolines, and (2) accessions with identical powdery mildew reaction patterns were intercrossed. Three isolates of Erysiphe graminis f. sp. hordei were used: Bzm-1, KM 18-75, R13C. A number of different resistance genes were detected among the 19 resistant accessions. Surprisingly, segregation indicating single genes only were detected with the isolates used. Some of these genes could be associated with loci already known. In 19 cases a dominant and in one a recessive mode of inheritance was detected. The recessive gene was not located at the mlo locus. This investigation represents the first systematic study of race-specific genes for powdery mildew resistance in Tunisian landraces. The newly identified sources of resistance may be used in many strategies of breeding for disease resistance.     

Inheritance and allelism of resistances to the Russian wheat aphid in seven wheat lines

Summary Studies were conducted to determine the inheritance and allelic relationships of genes controlling resistance to the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), in seven wheat germplasm lines previously identified as resistant to RWA. The seven resistant lines were crossed to a susceptible wheat cultivar Carson, and three resistant wheats, CORWA1, PI294994 and PI243781, lines carrying the resistance genes Dn4, Dn5 and Dn6, respectively. Seedlings of the parents, F₁ and F₂ were screened for RWA resistance in the greenhouse by artificial infestation. Seedling reactions were evaluated 21 to 28 days after the infestation using a 1 to 9 scale. All the F₁ hybrids had equal or near equal levels of resistance to the resistant parent indicating dominant gene control. Only two distinctive classes were present and no intermediate types were observed in the F₂ segregation suggesting major gene actions. The resistance in PI225262 was controlled by two dominant genes. Resistance in all other lines was controlled by a single dominant gene. KS92WGRC24 appeared to have the same resistance gene as PI243781 and STARS-9302W-sib had a common allele with PI294994. The other lines had genes different from the three known genes.     

Inheritance of partial resistance to spot blotch in barley

Diallel crosses (without reciprocals) were made among 10 different barley genotypes with genetic variability for spot blotch resistance. Forty‐five F₁ hybrids and their parents were assessed for their combining abilities for the disease resistance. Three experiments, two in a growth chamber on detached leaf and seedlings tests and one in the field on adult plant stages, were undertaken using a randomized complete block design with five replicates. A mixed conidial suspension of nine virulent isolates of the pathogen was used for inoculation. Statistical analysis showed genetic variability for spot blotch resistance. Results showed that the cultivar Banteng, the Ethiopian line CI‐5791 and the Syrian line 79‐SIO‐9 had partial resistance in all experiments. General combining ability was significant, with either positive or negative values. Resistant genotypes show favourable GCA‐effects, and they could therefore be successfully used for breeding purposes.     

Evidence of allelism between genes Pm8 and Pm17 and chromosomal location of powdery mildew and leaf rust resistance genes in the common wheat cultivar'Amigo'

TIBL-1RS wheat-rye translocation cultivars utilized in wheat programmes worldwide carry powdery mildew resistance gene Pm8. Cultivar‘Amigo’possesses resistance gene Pm17 on its TIAL-1RS translocated chromosome. To be able to use Pm17efficiently in breeding programmes, this gene was transferred to a TIBL-1RS translocation in line Helami-105, and allelism between Pm8 and Pm17was studied. The progenies of the hybrids in the F₂ generation and F₃ families provided evidence that the two genes are allelic. Genetic studies using monosomic analyses confirmed that in cultivar‘Amigo', Pm17 and leaf rust resistance gene Lr24 are located on a translocated chromosome involving 1 A and 1B, respectively.     

Inheritance of resistance to Rhynchosporium secalis in spring barley (Hordeum vulgare L.)

The inheritance of durable resistance of selected spring barley varieties to Rhynchosporium secalis was investigated. Data from the F₂ generation of a 4 × 4 diallel, without reciprocals and the F₄ generation of three crosses selected out of this diallel, suggest that resistance in this sample of varieties tested is complex in inheritance. Significant additive effects were detected indicating that the resistance level of barley cultivars may be improved by the hybridisation of suitable varieties. However, the genes conferring resistance seem to be concealed by the expression of one completely dominant resistance gene in our set of varieties. These results are partly in conflict with previous results on the inheritance of resistance to R. secalis in the breeder's line ‘11258/2286₁₃A’ indicating that the effectiveness of this resistance gene may be greatly influenced by the genetic background of the current population of R. secalis.     

Inheritance and chromosome location of Alp, a gene controlling aluminum tolerance in 'Dayton' barley

Aluminum (Al) toxicity is a major limiting factor in acid soils and more adequate genetic tolerance is needed to improve barley adaptation and production in affected regions. To study the inheritance and chromosome location of the Alp gene controlling Al tolerance in ‘Dayton’ barley the primary trisomics of sensitive ‘Shin Ebisu 16’ were crossed to ‘Dayton’. Parental, F₁ and F₂ seedlings were grown in nutrient solution containing 0.03, 0.06 and 0.09mM Al. and classified for tolerance by haematoxylin staining of the roots. In diploid F₂ progeny, Alp was inherited as a single gene, dominant at 0.06mM and recessive at 0.09 mM concentrations, as indicated by the 3:1 and 1:3 (tolerant: sensitive) segregation ratios, respectively. Segregation of the trisomic Frderived F₂ seedlings at 0.06mM Al deviated significantly from the 3:1 only for the triplo 4/‘Dayton’ cross. Data for this cross fit the expected trisomic ratios, indicating that the Alp gene is distally located from the centromere on chromosome 4. These results confirm that tolerance is simply inherited, but expression of tolerance is dependent on Al concentration and allele dose.     

Inheritance of reduced plant height in the sunflower line Dw 89

The objective of the present research was to study the inheritance of reduced plant height in the sunflower line Dw 89. Plants of the cytoplasmic male sterile version of this line, cmsDw 89 (mean plant height of 47.4 cm) were crossed with plants of the restorer line RHA 271 (mean of 120.9 cm). F₁ plants averaged 120.4 cm, which indicated dominance of standard over reduced plant height. F₂ plants followed a segregation pattern of 1 : 15 (reduced : normal height), suggesting that reduced plant height in Dw 89 is controlled by alleles at two loci, designated Dw1 and Dw2. Class assignment in the F₂ was confirmed through the evaluation of the F₃ generation. Backcrosses to Dw 89 segregated with 1 : 3 (reduced : normal height) ratios, which confirmed the digenic inheritance of the trait. The evaluation of plant height distributions in F₃ families suggested possible genetic interaction between the Dw1 and Dw2 loci.     

Parial resistance in the barley (Hordeum vulgare L.) cultivar 'Chikurin Ibaraki 1' to two PAV-like isolates of barley yellow-dwarf virus: allelic variability at the Yd2 gene locus

The Japanese barley cultivar, ‘Chikurin Ibaraki 1’, is partially resistant to the PAV serotype of barley yellow-dwarf virus (BYDV), but its induced mutant line, Ea52, is susceptible. The inheritance of resistance in cv. ‘Chikurin Ibaraki 1’ to BYDV-PAV was investigated. The F, and F2 plants of crosses of cvs ‘Chikurin Ibaraki 1’, Ea52, ‘Vixen’, carrying the Yd2 gene of resistance, and ‘Plaisant’, a susceptible French cultivar, were tested in growth chamber and field conditions. Isolate RG, against which ‘Chikurin Ibaraki 1’ is partially resistant in growth chamber and field conditions, and isolate 2t, which overcomes the partial resistance of ‘Chikurin Ibaraki 1’ in field conditions (Chalhoub et al. 1994) were used. The segregation of F2 plants of crosses between ‘Chikurin Ibaraki 1’ and the susceptible cultivars to isolate RG (one resistant to three susceptible) suggests that the resistance of ‘Chikurin Ibaraki 1’ is controlled by a single recessive gene. All 537 F2 plants of ‘Chikurin Ibaraki 1’בVixen’ tested with isolate RG in growth chamber and field conditions were resistant. The F2 plants of this cross were all resistant to isolate 2t in growth chamber conditions but segregated with a ratio of one resistant to three susceptible in field conditions owing to the susceptibility of ‘Chikurin Ibaraki 1’ to this isolate. Results suggest that the resistance gene in ‘Chikurin Ibaraki 1’ is tightly linked or allelic with the Yd2 gene in ‘Vixen’. However, it differs from this gene in ‘Vixen’ in that it can be overcome by isolate 2t in field conditions.     

Inheritance of heading time in spring barley evaluated in multiple environments

The inheritance of heading time of spring barley was studied in three extremely early genotypes IB, RL and ‘Mona’ (M), which is homozygous recessive for the early maturity ea8 (=ea_k) gene conferring extreme earliness under short daylengths and is relatively photoperiod insensitive, and five (GP, MA, PS, NU and BA) spring genotypes that are early to intermediate for heading time. Frequency distributions of F₂ generations grown at Ouled Gnaou, Morocco (32°15′ N), an environment which maximizes differences between photoperiod‐insensitive and photoperiod‐sensitive genotypes, indicated that across populations many loci were segregating in a complex Mendelian manner. IB and RL were both homozygous recessive for the ea8 gene, which conferred an early heading time. RL had partially dominant alleles at second locus (Enea8), which enhanced its earliness. Recovery of only progeny within the parental range of genotypes for heading time from the crosses of RL/M and IB/M suggests that numerous loci remained suppressed, perhaps latent, given their diverse parentage. The ea8 recessive homozygote in RL suppressed another unidentified locus which, when homozygous recessive in the absence of the ea8 recessive homozygote, conferred extreme earliness in one short daylength environment (Ouled Gnaou, Morocco) but was undetected in another environment (Davis, CA, USA). Epistatic gene action and genotype × environment effects strongly influenced heading time. In addition to a genetic system consisting of single‐locus recessive homozygotes conferring photoperiod insensitivity, a second genetic system, based on dominant alleles at one or a few loci, derived from the early heading Finnish landrace ‘Olli’, also confers extremely early heading time under short daylengths and relative photoperiod insensitivity in the genotype GP.     

Genetic analysis of the nitrogen and phosphorus utilization efficiencies in mature spring barley plants

Inheritance of the efficiency of nitrogen and phosphorus utilization in grain production was studied in diallel hybrids of spring barley. Effects of varied NPK fertilization and soil moisture on the genetic variance was evaluated at maturity in pot‐ and field‐grown plants. A preponderance of general combining ability effects was found for the efficiency ratios and utilization efficiencies, suggesting that the generative efficiency indices were mainly controlled by an additive genetic system. However, the relatively high narrow‐sense heritabilities (0.33‐0.81) found under optimal conditions tended to decline to 0.00‐0.36 following water and nutrient shortages. The importance of non‐additive gene effects for utilization efficiencies was demonstrated in the field under reduced nutrition. This leads to the conclusion that the involvement of additive gene action should facilitate selection efforts only under favourable environments. Selection delayed until later hybrid generations should be used when trying to improve the nutrient efficiency of barley under less favourable nutrition conditions.