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.     

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.     

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.     

Karyotypes and chromosome association in aneuploid varieties of Japanese garden iris,Iris ensata Thunb

Summary Karyotypes, chromosome association and pollen fertility of aneuploid varieties (2n=25), Ochibagoromo, Matsusakatsukasa and Isehomare in Iris ensata were analysed and compared with those of eu-diploid varieties (2n=24), Shishinden, Kachô and Asahimaru. The somatic chromosome complement of the aneuploid varieties consisted of 11 pairs and 3 singles of chromosomes and that of the eu-diploid varieties 12 pairs of chromosomes. The singles of chromosomes in the aneuploid varieties had similarity with one another and with a pair of chromosomes in the eu-diploid varieties. The high frequency of normal association was present in the eu-diploid varieties, and this indicated that 12 pairs of chromosomes had full homology between each other. In contrast, the mean chromosome association per cell in an aneuploid variety Ochibagoromo was 4.615_I+10.067_II+0.077_III+0.005_IV, indicating that the chromosome complement of this variety consisted of 11 pairs and 3 singles and that these singles had partial homology among them. The eu-diploid varieties exhibited high pollen fertility due to their regularity of chromosome association; the aneuploid varieties considerably lower fertility, i.e. 28.2% for Ochibagoromo, 31.8% for Isehomare and 43.8% for Matsusakatsukasa. The primary cause for the low fertility of these varieties seemes to be the partial homology among 3 single chromosomes. Finally, the origin and the development of the aneuploid varieties were discussed.     

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.     

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.     

Chromosome numbers of hybrid tuberous begonias

Summary The somatic chromosome numbers of 67 hybrid tuberous begonia cultivars (Begonia x tuberhybrida Voss) have been determined. The material concerned was collected in Belgium and England and represents several distinct groups, comprising both cultivars originated at the turn of this century and those introduced recently.The old Pendula group is characterized by the diploid chromosome number 28. Among the Multiflora group diploid, triploid and tetraploid cultivars are represented almost equally, while the investigated Multiflora maxima and large-flowered begonias proved to be tetraploid except for one triploid.Mitotic instability, to the extent reported by some authors, was not observed. The variation of the diploid number between 27 and 28, the triploid number between 41 and 42 and of the tetraploid number between 52 and 56 can be explained as a consequence of the fact that in the original hybridization wild tuberous species with 2n=26 and 2n=28 were involved.Publication 351, Laboratorium voor Tuinbouwplantenteelt, Landbouwhogeschool, Wageningen, the NetherlandsPublication 23, Rijksstation voor Sierplantenteelt, Melle, Belgium     

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.     

Morphology,cytology and forage potential of Pennisetum americanum (L.) K. Schum. x P. Purpureum Schum. amphidiploids

Summary F₁ hybrids between short-day photoperiod- sensitive maiwa bulrush millet, Pennisetum americanum (2n=14), and elephant grass, P. purpureum (2n=28), are triploid (2n=21), sterile, and can only be propagated vegetatively. Fertile amphidiploids, (2n=42, with 21 bivalents) were produced by colchicine treatment. Good seed set was obtained upon selfing the amphidiploids and the progeny exhibited variable pollen fertility and bivalent univalent and multivalent formation.Reciprocal crosses between elephant grass and the colchicine-induced amphidiploid failed to produce seeds. The maiwa millet x amphidiploid cross resulted in poor seed set and the reciprocal failed. Maiwa x amphidiploid hybrids were pollen sterile with 2n=21, rather than the expected 2n=28, indicating chromosome elimination.Morphologically, the amphidiploids and maiwa x amphidiploid hybrids closely resembled elephant grass and the F₁ hybrid. The amphidiploids showed no superiority over the F₁ hybrid and elephant grass in either forage yield or quality but one maiwa x amphidiploid genotype surpassed a promising local elephant grass selection in forage dry matter yield and flowered for a relatively short period.     

Genetic and cytogenetic studies with a male sterile mutant of common wheat (Triticum aestivum)

Summary Genetic and cytogenetic studies were done on a male sterile mutant of the wheat variety Probus. Association of the 4A chromosome carrying the ms gene was studied in the F₁ of the male sterile Probus with Chinese Spring ditelo 4AS, with Transec and with line T4AS-DRS respectively. The presumption that the genetic male sterility of the mutant was due to a terminal deletion of the short arm of chromosome 4A could be confirmed.Linkage studies showed that the ms gene was at 17 map units from the dwarfing gene (Rht3) of Minister dwarf. This allows selection of short male sterile plants at the seedling stage.     

Inheritance of aroma in rice

Summary Inheritance of an aroma was worked out in crosses between Brimful from Nepal as an aromatic rice and leading Japanese varieties Koshihikari and Nipponbare as non-aromatic ones. The F₂ pattern of segregation for aroma to non-aroma was 3:13 indicating one dose gene for aroma and one dose inhibitor gene in two crosses. This ratio was confirmed by genetic behavior of F₃ populations.     

Chromosomal location of genes controlling 6-phosphogluconate dehydrogenase,glucose-6-phosphate dehydrogenase and glutamate dehydrogenase isozymes in cultivated rye

Summary The 6-phosphogluconate dehydrogenase (6-PGD), glucose-6-phosphate dehydrogenase (G-6-PD) and glutamate dehydrogenase (GDH) zymogram phenotypes of wheat, rye and their aneuploid derivates were determined. At least three genes involved in the production of 6-PGD isozymes were located on chromosome arms 4RL, 6RL and 2RL of Imperial rye, King II rye and Dakold rye. Evidence was obtained that at least one gene located on chromosome arm 5RS controls G-6-PD isozyme activities in these varieties of rye and one gene involved in the production of GDH isozymes was located on chromosome arm 2RS of Imperial, King II and Dakold rye. The results indicate that the 6-PGD isozymes exist as dimers and monomers. No possible structure of the G-6-PD and GDH could be determined.     

Cytoplasmically controlled cold tolerance in a cytoplasmic-genetic male sterile line of rice

Summary The cytoplasmic-genetic male sterile line, Krishna-A with Kalinga-I cytoplasm was developed in rice through repeated backcrossing the completely pollen sterile F₁ of the cross Kalinga-I/Krishna with the recurrent male parent cv. Krishna. The germination percentage and root-shoot length in Krishna-A at 12°C and 9°C indicated a higher degree of tolerance to low temperature than the cold tolerant female parent Kalinga-I. The high yielding cold tolerant variety Kalinga-I was developed from a cross involving the cold tolerant variety Dunghansali and the high yielding variety IR 8. It is inferred that tolerance to low temperature during germination in Krishna-A was inherited from the cytoplasm of cv. Dunghansali through Kalinga-I besides male sterility. The cytoplasmic control of cold tolerance is reported here for the first time in rice literature. The male sterile line Krishna-A because of its tolerance to low temperature would be suitable for the development of hybrid rice especially for areas where low temperature is a problem during germination.     

Structure of variation among morphological and physiological traits in three pearl millet composites

Summary The plant breeder's task of improving and stabilizing many plant traits simultaneously is complicated by interrelationships that occur among the traits. Factor analyses were conducted on three phenotypically diverse pearl millet [Pennisetum glaucum (L.) R. Br.] composites to describe the structure of relationships among yield, morphological, and physiological traits. Approximately 1000 S₀ spaced-plants from each composite were evaluated for 20 traits, and random samples of 289 S₁ progenies from each composite were evaluated for 18 of these traits. Factors extracted in S₀ and S₁ populations identified unique sets of traits that were interrelated along axes of (a) biological yield, (b) panicle size, (c) dry matter partitioning and (d) compensation between number and size of seeds. Several plant traits had large loading coefficients on the Biological Yield and also, but with opposite signs, on the Dry Matter Partitioning factor. The traits having large loading on these two factors differed between space-planted and normal-density stands, showing that environmental conditions contributed to the associations observed among traits. Correlations of S₁ with parental S₀ factor scores for the Biological Yield, Panicle Size and Seed Paramters factors produced significant correlation coefficients, indicating that these trait complexes had a genetic basis. The implications of these results for millet breeding are discussed.     

Male-sterility in nigerian bulrush millets (Pennisetum americanum (L.) K. Schum)

Summary The occurrence of three male-sterile plants is reported. One in a population of ex-Bormu, an improved recommended variety of day-length neutral gero bulrush millet and the two others in the selfed progeny of a population of maiwa bulrush millet, a short-day photoperiod-sensitive type. Tests confirmed the cytoplasmic-genic nature of the male-sterility in the gero population. No tests could be conducted for maiwa.The transfer of male-sterility from the male-sterile Tift 23A bulrush millet, obtained from the United States, into a maiwa population is also reported. After six backcrosses the maiwa genotype appeared to have been reconstituted against the background of a male-sterility inducing cytoplasm. Maiwa male-sterility maintainer plants have also been identified.     

Genetical analysis of contribution of low-molecular-weight glutenin subunits to dough strength in common wheat (Triticum aestivum L.)

To evaluate the effect of low-molecular-weight glutenin subunit (LMW-GS) genes on dough strength, locus-specific primers of LMW-GS genes and gliadin bands tightly linked to LMW-GS genes were analyzed in common wheat. Segregation analysis of the F₂ progeny from a cross between Haruhikari, a good bread-making quality cultivar, and Asakaze-komugi, a poor bread-making quality cultivar, showed that dough strength significantly correlated with one amplified LMW-GS gene located at the Glu-B3 locus from Haruhikari. There was no specific reference to the gliadin bands identified as promising markers in the cross under study. The LMW-GS gene of Haruhikari had a seven amino-acid deletion in the repetitive domain relative to Asakaze-komugi, as well as six amino-acid substitutions, three of which would be expected to cause changes in hydrophilicity. The presence of the LMW-GS gene and other LMW-GS genes tightly linked to it may affect the dough strength of wheat.     

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     

Stability of forage yield and quality in pearl millet hybrids heterogenous for rust resistance

Summary The susceptible pearl millet hybrid Tifleaf 1, the resistant hybrid Tifleaf 2, and two experimental 3-way hybrids with different proportions of resistant and susceptible plants were evaluated for rust resistance and forage yield and quality in 1990, 1991, and 1992. Different environmental conditions were obtained by varying planting date, planting density, and fungicide applications across three years of evaluation in the field. Rust severity of forage was negatively correlated with late season green yield, dry matter yield, in vitro dry matter digestibility, and digestible dry matter yield. The stability across environments of the 3-way hybrids was intermediate between resistant Tifleaf 2 and susceptible Tifleaf 1 for rust severity and the yield and quality measurements negatively correlated with rust severity. Mixtures of resistant and susceptible plants would probably provide greater control of rust than measured in these small-plot experiments. Although a mixture of resistant and susceptible plants appears to provide an alternative to monogenic control of rust in forage pearl millets, identification and utilization of additional sources of resistance would be beneficial to improve the performance of 3-way hybrids.     

Inheritance of resistance to powdery mildew (Erysiphe graminis f. sp. hordei) in eleven primitive barley varieties

The inheritance of the powdery mildew resistance of eleven primitive barley varieties was investigated. crosses with varieties with identified resistance genes revealed that at least three different genes are present in a group of six genotypes from Greece (Hor736, Hor847, Hor878, Hor1159, Hor1379 and Hor1873) and one from Turkey (Hor1188). One dominant gene is common to these seve genotypes and in the Greek accessions a second gene is present. The expression of this second gene was respectively dominant in the crosses with Hor736 and Hor1159, recessive in the crosses with Hor878 and Hor1873, and depended on the employed powdery mildew isolate in the crosses with Hor847 and Hor1379. The detected genes differ from the resistance genes of the crossing partners, viz. Ml-al2, Ml-(Ab), Ml-(CP) and Ml-(1402). The accessions from China (Hor824 and Hor4021) each possess two resistance genes which differ from Ml-a12, Ml-(La) and Ml-(CP). The major gene is common to both accessions and is either identical, allelic or closely linked to a gene in the variety Nigrate. The Columbian accession Hor1894 possesses one resistance gene linked to a resistance gene in Nigrate but this gene differs from the Ml-a locus. The variety Palestine (Hor3997) possesses two resistance genes of which one is allelic or closely linked to Ml-(at).