On defining a winter wheat

Summary An international survey of wheat breeders and scientists was conducted to determine whether there was a common understanding of the term winter wheat. Response to photoperiod was mentioned by only seven of the 30 survey respondents. It was consequently suggested that it be excluded from any definition. Response to vernalization was mentioned by 28 of the 30 respondents. However, there was considerable variation in the method of quantifying this response and the degree of response necessary for wheat to be called winter. It was concluded that the only objective and internationally consistent definition of winter wheat was a genetic definition based on the complement of Vrn genes a wheat possesses. Varieties not possessing any of the dominant Vrn alleles appear to take a distinctively longer and more variable time to head when grown under non-vernalizing, long day conditions. These are genetically winter wheats.     

Relationship between allelic variation of Glu-1 and Gli-1/Glu-3 prolamin loci and gluten strength in hexaploid wheat

Summary Allelic variation of prolamin loci was examined in the F₂ from crosses between the hexaploid wheat varieties: Cajeme 71, Yécora 70, Ablaca, Anza, Pané 247 and Axona. Different allelic blocks for gliadins and LMW glutenin subunits were determined in Gli-1, Gli-2 and Glu-3 loci. A percentage of recombination of 1.5 ± 0.3 was determined between Gli-A1 and Glu-3 in the F₂ progeny of Yécora 70 x Axona. A significant positive association was found between gluten strength, measured by SDS-sedimentation volume, and the prolamins coded by Anza Gli-D1/Glu-D3 loci and Yécora 70 Gli-A1/Glu-A3 loci. Interactions between non homeologous loci Glu-1 and Gli-1/Glu-3 were also found.     

Chromosomal location of powdery mildew resistance genes in common wheat (Triticum aestivum L. em. Thell.) 3. Gene Pm22 in cultivar Virest

Summary Common wheat cultivar Virest possesses mildew resistance which is different from resistances expressed by currently documented mildew resistance genes, detected by response to eleven differential wheat powdery mildew isolates. F₂ populations from hybrids of the 21 Chinese Spring monosomic lines with Virest revealed one major dominant gene, located on wheat chromosome 1D. The new gene is designated Pm22. Italian cultivars Elia, Est Mottin, Ovest and Tudest also showed the disease response pattern corresponding to Virest.     

Genetic control of acquired high temperature tolerance in winter wheat

Summary The development of high temperature-tolerant wheat (Triticum aestivum L.) germplasm is necessary to improve plant productivity under high-temperature stress environments. The quantification of high temperature tolerance and the characterization of its genetic control are necessary for germplasm enhancement efforts. This study was conducted to determine the genetic control of acquired high temperature tolerance in common bread wheat cultivars. Reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by heat-stressed seedling leaves was used as a quantitative measure to characterize acquired high temperature tolerance. Eleven-day-old seedlings of 20 F₁ progeny produced through a complete 5×5 (Payne, Siouxland, Sturdy, TAM W-101, and TAM 108) diallel mating design were acclimated at 37° C for 24 hours, followed by a 2-hour incubation at 50° C. Under these test conditions, acquired high temperature tolerance ranged from a high of 75.7% for the genotype TAM W-101 × TAM 108, to a low of 37.3% for the genotype Payne × Siouxland. Partitioning of genotypic variance revealed that only the general combining ability component effect was statistically highly significant, accounting for 67% of the total genotypic variation. These results suggest that enhancing the level of high temperature tolerance in wheat germplasm is feasible utilizing existing levels of genetic variability and exploiting additive genetic effects associated with high temperature tolerance.Contribution of the Texas Tech College of Agric. Sci. Journal no T-4-386. This work was supported by USDA specific agreement No. 58-7MNI-6-114 from the Plant Stress and Water Conservation Laboratory, USDA-ARS, Lubbock, Texas, USA     

Monosomic analysis of fertility restoration in common wheat ‘Prof. Marchal’

Summary In common wheat (Triticum aestivum L.) a monosomic set of Chinese Spring and male-sterile Janus (with cytoplasm of T. timopheevi Zhuk.) were used to determine the chromosomal location of Rf-genes in Professeur Marchal. As revealed by test cross data, a major gene cofeerring fertility restoration was present in Prof. Marchal on chromosome 1B. A significant deviation towards sterility was observed in some fest cross progenies. Chromosome 1B of Chinese Spring appeared to carry a dominant restoring gene, which caused partial restoration of fertility.     

Study of the parentage of grape cultivars by genetic interpretation of GPI-2 and PGM-2 isozymes

Summary Two highly variable enzyme systems of glucosephosphate isomerase (GPI) and phosphoglucomutase (PGM) were used to investigate the parentages of grape cultivars. Of 35 parent/offspring combinations that we investigated, 30 combinations gave alleles in the offspring which were presented in the reported parents, whereas 5 combinations gave alleles in the offspring which were not extractable from the reported parents. The Gpi-2 genotype of Hiro Hamburg and the Pgm-2 genotype of Pione indicated that Koshu Sanjaku and Cannon Hall Muscat may not have been the paternal parent respectively. The Gpi-2 genotype of New Niagara and the Gpi-2 and Pgm-2 genotypes of Beniyamabiko indicated that Niagara and a hybrid from DxK151 x Delaware may not have been the maternal parent respectively. The Gpi-2 genotype of Cannon Hall Muscat grown in Japan indicated that this cultivar may not have originated as a tetraploid sport of Muscat of Alexandria.     

Effect of ploidy on stomatal and other quantitative traits in plantain and banana hybrids

Summary Ploidy polymorphism occurs in the hybrid offspring derived from interspecific crosses between triploid plantains (Musa spp. AAB group) and diploid bananas (M. acuminata). Therefore,Musa breeders are interested in the determination of ploidy and its effects on phenotypic expression of quantitative traits. The aim of this research was to examine the reliability of stomatal and other phenotypic traits to determine ploidy in segregating plantainbanana hybrid families. Stomatal density and size were significantly correlated (P<0.01) with ploidy, although the correlation coefficients were not high (r=–0.49 and r=0.47, for stomatal density and size, respectively). High density of small stomata was correlated with low ploidy level, and vice versa. However, stomatal size and density were also influenced by a significant genotype effect (P<0.001) within the same ploidy level. Ploidy had an important effect on fruit traits and plant height in the hybrids of Obino l'Ewai×Calcutta 4, but this was not so clear in Bobby Tannap×Calcutta 4 hybrids. Obino l'Ewai derived tetraploids have medium to tall plants with large bunches and big fruits. Most of the tetraploids derived from Bobby Tannap have short stature due to the gene action of the dwarf,dw, allele. Also, a few selected diploids derived from Bobby Tannap outyielded their non-selected tetraploid full-sibs. In conclusion, chromosoem counting remains the only accurate proof of ploidy levels inMusa germplasm.     

Inheritance of late maturity α-amylase in wheat

Summary Two wheat cultivars that consistently show high levels of grain -amylase at harvest ripeness, in the absence of preharvest sprouting, were crossed with a control, low -amylase cultivar, and F₁, F₂ and BC₁ populations were developed. Grain of these populations was analysed for -amylase activity at harvest ripeness. Distribution and segregation patterns were consistent with control at a single locus with high -amylase the recessive allele. This mode of inheritance would make it extremely difficult to differentiate homozygous low -amylase lines from heterozygotes (low -amylase phenotype but carriers of high -amylase) and has important implications for wheat breeders. High -amylase, termed late maturity -amylase, was not linked with the awned inhibitor gene, B2, located on the long arm of chromsome 6B.     

Cytoplasmic relatedness of apple landraces and cultivars: a molecular analysis

Summary Mitochondrial DNA (mtDNA) diversity has been determined in apple landraces and cultivars, based upon restriction fragment length polymorphisms (RFLPs) for several mitochondrial genes. Our analysis includes three cultivars, Golden Delicious, McIntosh and Delicious, which represent the various patterns of mtDNA polymorphisms previously described (Ishikawa et al., 1992). A total of five RFLPs were detected, allowing classification of the apple genotypes into four cytoplasmic groups: GroupI, Golden Delicious-type; GroupII, McIntosh-type; GroupIII, Delicious-type; and Group IV, Dolgo Crab-type. European landraces and cultivars were assigned to Groups I, II, and III, while chinese crab apples were placed in either Group III or IV.     

Effect of genetic blends of dry beans (Phaseolus vulgaris) of different Plant architecture on apothecia production of Sclerotinia sclerotiorum and white mold infection

Summary The determinate Phaseolus vulgaris L. cvs Dark Red Kidney Charlevoix, and near-isogenic Great Northern Nebraska 1 were grown in blends with the indeterminate GN Nebraska 1 in white mold (Sclerotinia sclerotiorum) disease field nurseries. A critical difference between Charlevoix and indeterminate GN Nebraska 1 is that the latter has a greater leaf area closer to the soil surface, and this is associated with increased numbers of apothecia beneath the canopy and higher disease severity. White mold infection and apothecia number/m² beneath the canopy of the blends containing Charlevoix were significantly reduced in comparison with the severely infected, homogeneous, indeterminate GN Nebraska 1. A reduction of white mold infection for the indeterminate GN Nebraska 1 was not observed in blends grown under severe or moderate white mold incidence, but did occur under slight incidence in blends containing 65% and 75% Charlevoix.No significant difference for seed yield occurred between the blends and homogeneous cultivars planted in four experiments under severe, moderate, slight and zero white mold incidence, respectively, except in Experiment 1 under moderate white mold incidence, the blend of 50% indeterminate GN Nebraska 1 and 50% Charlevoix exceeded the yield of the indeterminate GN Nebraska 1. Mean weight of white (GN Nebraska 1) and red seed (Charlevoix) increased and decreased, respectively, in some blends due to the more vigorous growth of the indeterminate GN Nebraska 1.Published as Paper No. 5341, Journal Series, Nebraska Agric. Exp.t Station. Research was conducted un under Project 20–3.     

Limited but specific variations of seed storage proteins in Japanese common wheat (Triticum aestivum L.)

The electrophoretic banding patterns ofgliadin in common wheat lines derived fromJapan were determined byacid-polyacrylamide gel electrophoresis. For the 107 wheat lines used in our study,27 different patterns were identified, 13corresponding to the -gliadin, 8 tothe , -gliadin and 6 to the-gliadin. The gliadin patterns ofJapanese wheat cultivars and landracesgreatly differed from the patterns of wheatlines from other countries, and thevariation seen in wheat lines from Japanwas limited to 46 patterns. Sevencollection or breeding areas in Japanshowed different frequencies in theirgliadin patterns. Combining the gliadinpatterns with high molecular weightglutenin subunit compositions, 67combinations were observed. One gliadinpattern consisting of -gliadinpattern F, , -gliadinpattern H and -gliadin pattern Dwas frequently found in many Japanese wheatlines, though the other patterns werelimited to only one or two wheat lines.     

Chromosome location of genes for resistance to powdery mildew in common wheat (Triticum aestivum L.) 1. Mlk and other alleles at the Pm3 locus

Summary Several wheat cultivars/lines were inoculated with isolates of Erysiphe graminis tritici to identify new genes/alleles for resistance. The wheats were tested with 13 isolates that had been characterized from responses on differential lines with known resistance genes. Gene Mlk which occurs in cultivars Kolibri, Syros, Ralle and several other European common wheats was found to be an allele at the Pm3 locus and is now designated Pm3d. The mildew resistance in an old Australian wheat, W150, is conferred by a single gene also allelic to Pm3 and now designated Pm3e. The near-isogenic line Michigan Amber/8^*Cc possesses another allele now designated Pm3f. A Syrian land variety of common wheat shows mildew resistance that is conditioned by the combination of genes Pm1 and Pm3a. Finally, two accessions of Triticum aestivum ssp. sphaerococcum appeared to possess the Pm3c allele.     

Crossability relationships of andean potato varieties of three ploidy levels

Summary The formation of triploids in 4x×2x crosses was studied in primitive potato varieties from the Andes of Peru and Bolivia. Triploid frequencies were as high as 80–100% in some crosses, although the actual number of seeds was low. The triploid block varied according to the tetraploid parent, and was never entirely absent. The likelihood of triploid formation was studied in 4x×2x crosses where pollen from both tetraploids and diploids of known genotype was used. Even though the diploids were chosen for their non-production of 2n gametes, as detected in pollen grain size, 66% of the hybrids were tetraploid. The amount and probability of gene-flow between the tetraploid and diploid gene-pools, either directly through 2n gametes or through triploid bridges was examined. Most of the 20 cultivars of S. x chaucha produced seed in crosses with tetraploids and diploids, although the fertility of the latter crosses was four times higher. The female fertility of some of the triploids thus allows them to exchange genes with the tetraploids and diploids, although gene-flow occurs more rapidly through direct transfer from diploids to tetraploids via 2n gametes.     

Genetic analysis of hexaploid wheat,Triticum aestivum using intervarietal chromosome substitution lines—protein content and grain weight

Summary The 21 intervarietal chromosome substitution lines of the cultivar Hope in Chinese Spring were used to analyse the genetic differences between the two cultivars Hope and Chinese Spring in grain protein content and grain weight.Only one chromosome of Hope, 5D, significantly influenced grain protein content of Chinese Spring. Its influence was of only minor effect and was to decrease protein content expression of Chinese Spring. It has been postulated that the genetic control of protein content, in this instance, is most likely due to many genes each of small effect.Five chromosomes of Hope influenced the 1000 grain weight value of normal Chinese Spring, all increasing its expression. Chromosomes 1A, 4A and 5B were of major effect and 3A and 6A of comparatively minor effect. A minimal estimate of five genes determines the difference in grain size between these cultivars. The possible evolutionary significance of the contribution of the A genome of bread wheat to grain size determination is discussed. On the basis of certain findings of this study, proposals are made for breeding for increased grain size in hexaploid wheat.     

Genetic analysis of resistance of three melon lines to Sphaerotheca fuliginea

Summary The inheritance of resistance of three melon lines to Sphaerotheca fuliginea race 1 has been studied. Negro possesses one dominant gene for resistance. Resistance in Amarillo is mainly controlled by one gene, and resistance in Moscatel Grande seems to be controlled by two genes. These four genes are different from each other and allelism tests showed that the gene present in Negro is different from those described before in PMR5, PI 124111 and PI 124112. The main gene present in Amarillo is different from those carried by PMR5 and PI 124111 and the two genes carried by Moscatel Grande are different from the one present in PMR5.     

Segregation and linkage analysis of DNA markers in microspore derived and F2 populations of oilseed rape (Brassica napus L.)

Summary The segregation of RFLP and RAPD markers was compared in two oilseed rape (Brassica napus L.) breeding populations from the cross Topas x R4, the latter being a low linolenic mutation line. A total progeny of 68 F₂ and 40 microspore derived plants were studied with 25 markers. The results indicated a significant excess of Topas alleles at five RAPD loci in the microspore derived population. This suggests that genomic regions which probably affect microspore culture ability do not have identical distribution in the two population types.     

Chemically induced sterility in wheat for hybrid seed production

Summary The gametocidal effects of RH-531, RH-532, and RH-2956 were studied with three rates and times of foliar application on two spring wheat (Triticum aestivum L.) varieties, Anza and Yecora 70. RH-531 and RH-532 applied at or before booting stage caused rather large reduction in plant height while RH-2956 had a small effect on height. Application of any of the three chemicals on Anza at meiotic stages reduced self-pollination (SP) fertility by 97–99%. If 90% SP fertility reduction is acceptable, the application time could vary from premeiosis to postmeiosis for Anza. Yecora 70 was less sensitive than Anza to gametocide treatments. The lowest SP fertility obtained in Yecora 70 with RH-531, RH-532, and RH-2956 was by treatment at booting (4 kg/ha), at premeiosis (2 kg/ha), and heading (8 kg/ha), and the corresponding SP fertility reductions were 74, 89, and 71%. Pollen stainability-determined by aceto-carmine, IKI, and Alexander's stains-was not affected by gametocide treatment and was not useful in evaluating sterility induced by these chemicals. For the RH-531-treated Anza and Yecora 70 and the RH-532-treated Anza, more than 94% of the seeds produced by open-pollination on treated plants were from self-or sib-pollination as determined by progeny testing. However, RH-532-treated Yecora 70 and RH-2956-treated Anza and Yecora 70 did result in more crossed seeds, with a maximum of 20% outcrossing. It was believed that spike compactness induced by the chemicals and the related poor flower opening were the major limitations for outcrossing. Artificial pollinations made to the test varieties showed that RH-531 induced both male and female sterility and was undesirable for practical use. RH-532, however, could be applied at the booting stage to avoid severe female sterility, and RH-2956 clearly was the best of the three chemicals, with the female fertility very close to those of the untreated checks of both Anza and Yecora 70. Of the three chemicals, RH-2956 gave the highest percentage of hybrid plants in the progeny of hand-or open-pollinated spikes. Its practical use for hybrid seed production, however, will depend largely on improvement of methods to increase cross pollination in wheat.     

Resistance to bird cherry-oat aphid (Rhopalosiphum padi L.) in winter wheat varieties

Summary In Hungary the bird cherry-oat aphid (Rhopalosiphum padi L.) is the most frequent aphid species in winter wheat (Triticum aestivum L.). Estimations of infestation by R. padi as well as measurements of grain yield and thousand-kernel mass were carried out in 26 winter wheat genotypes in conditions of naturally infested and not infested (protected) control plots. The experiment was performed in isolated conditions in two field cages covered by nets. The aphids overwintered on wheat and got into cage, extremely quickly multiplied, therefore there was no need to apply any artificial aphid infestation. Highly significant differences were demonstrated among genotypes in infestation severity of R. padi as well as in losses of grain yield and thousand-kernel mass. The most resistant variety GK Zombor had 25% infestation, and the most susceptible one GK Lili had 79.2%. The reduction of grain yield of the most tolerant genotypes (GK Korány, Downy, Mv 4, Jubilejnaja 50, Mv 8, GK Kincsö and GK Zombor) was 26–33%, and that of thousand-kernel mass was 23–30%. The most sensitive genotypes (GK Lili, GK Örzse, GK Koppány and Mv 13) suffered 58–63% losses in yield, and 40–50% in thousand-kernel mass. A close correlation was found between infestation of R. padi in different wheat genotypes and losses of grain yield (r=0.7572, P<0.001). Also there were tolerance differences among genotypes even within the same level of infestation. The reductions of thousand-kernel mass correlated very closely with the reductions of grain yield (r=0.9212, P<0.001), that makes screening possible by reductions of thousand-kernel mass. These results have found application in breeding. The leaf pubescence of the varieties studied did not generally influence the infestation by R. padi.     

Effects of the Russian wheat aphid on osmotic potential and fructan content of winter wheat seedlings

Summary The effect of an autumn Russian wheat aphid, Diuraphis noxia (Mordvilko), infestation on winter wheat, Triticum aestivum L., was investigated using osmotic potential, fructan content and field survival measurements to estimate coldhardiness. An average infestation of 147 aphids per plant, under simulated hardening conditions, increased the osmotic potential of Froid and Brawny (more or less coldhardy varieties, respectively) seedlings by 0.236 and 0.345 MPa, respectively. A natural field infestation averaging 9.7 aphids per plant reduced fructan contents of Froid and Brawny seedlings by 22.60 and 59.10 g kg^-1 dry wt., respectively. Similar trends occurred after a natural freeze period. Field survival and yield results indicate that the autumn infestation reduced the winter survivability of Brawny by 54% and reduced grain yields by 1217 kg ha^-1; survival and yield of infested Froid were not significantly affected. PI 372129, a D. noxia resistant winter wheat genotype was not affected by an infestation in regard to these parameters. These studies suggest that coldhardiness in Froid and Brawny was reduced by D. noxia though only the less hardy Brawny had a significantly reduced winter survivability and grain yield. Therefore, the effects of an autumn D. noxia infestation on some winter wheat genotypes may interact with a winter climate and increase the potential for winterkill.     

Congruity backcrossing as a means of creating genetic variability in self pollinated crops: seed morphology of Phaseolus vulgaris L. and P. acutifolius A. Gray hybrids

Summary Seeds of early generations of three reciprocal congruity-backcross (CBC) pedigrees, developed by backcrossing Phaseolus vulgaris-P. acutifolius hybrids to each of the parent species in alternate generations, exhibited a preponderance of traits (size, shape, color, and pattern) of the cytoplasmic parent. The large size of Red Cloud (V₁), the P. vulgaris parent common to all of the pedigrees, dominated pedigrees with V₁ as the cytoplasmic parent, while the small size and rounded or square shapes of the tepary parents, wild P. acutifolius var. acutifolius PI 263590 or G400445 (A₁₉), wild P. acutifolius var. latifolius PI 406622 (A₁₀), or cultivated P. acutifolius var. latifolius Serowi PI 319443 (A₉), were the majority phenotypes when P. acutifolius was the cytoplasmic parent. Continuing through the second cycle of CBC, that is the second backcross with each of the parent species or the fourth backcross, began an amelioration of the apparent cytoplasmic effect on gene expression, as reciprocal pedigrees became more alike, usually with intermediate expression of parental traits or the appearance of new traits. The large seed size of V₁ was recovered in hybrids with P. acutifolius cytoplasm and the kidney shape of V₁ became rare in hybrids with P. vulgaris cytoplasm. Although the tepary-bean parents represented two subspecies and both cultivated and wild P. acutifolius, the three sets of reciprocal-hybrid pedigrees with P. vulgaris Red Cloud are surprisingly similar. It may be that the exotic parent used to develop a CBC pedigree should be selected more for combining ability in the interspecific cross than for specific economic traits. While the number of generations (six or more) required to produce fertile, intermediate CBC hybrids (that did not require embryo rescue) may preclude routine use of this method by practical plant breeders, the crossability of advanced hybrids with both parental species and the amount of variability apparent in advanced-hybrids progenies suggests that CBC would be valuable for maintaining exotic germplasm in immediately useful forms.