Inheritance studies of characters associated with floating habit and their linkage relationship in rice

Summary Deep water rice varieties in general have certain peculiar characters which are associated with floating habit. These characters are (i) early nodal differentiation, (ii) nodal rooting, (iii) spreading habit, (iv) awned grains, (v) brown hull colour, (vi) red pericarp (red rice), and (vii) seed dormancy. Inheritance of these characters and linkage relationship of genes governing these characters were studied in a cross between Pankaj (non floating) and Nageribao (floating) rice varieties. Nageribao, a cultivar from Assam possesses these characters.Early nodal differentiation was observed to be controlled by a single dominant gene, designated as Nd. Nodal rooting was controlled by two dominant complementary genes, designated as Nr ₁ and Nr ₂. We found an inhibitory factor for spreading habit and one for brown hull colour in Pankaj; the operation of two dominant duplicate genes An ₁ and An ₂ for controlling awning characters, a single dominant gene Rd for red pericarp colour and a single dominant gene Gd for grain dormancy. Joint segregations between these characters resulted in the assignment of genes in the X linkage group of indica rices with estimated map distances based on the cross-over values. The genes An (awning), Es (spreading habit), Nr (nodal rooting) and Nd (nodal differentiation) were observed to be associated with each other. The gene for red pericarp (Rd) was observed to be linked with the grain dormaney gene Gd.     

Development of a triticale resistant to the greenbug: An historical perspective

Summary A greenbug [Schizaphis graminum (Rondani)] resistant strain of rye (Secale cereale L.) Insave F.A. from Argentina was crossed with Chinese Spring wheat (Triticum aestivum L.) and also with Elbon and Balbo cultivars of common rye. Juvenile plants of the primary wheat X rye hybrid were treated with colchicine. Partially fertile amphidiploids were obtained that are resistant to greenbug Biotypes B and C. F₁ and F₂ populations of seedling plants derived from crosses of Insave F.A. with Elbon and Balbo rye were tested for reaction to the greenbug to determine the genetic basis of inheritance. The results confirmed previous reports that resistance in Insave F.A. is conditioned by a single dominant gene.Deceased     

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).     

An assessment of thein vitro germination capacity of pollen grains of five tea hybrid rose cultivars

Summary Germination trials of pollen grains of the tea hybrid rose cultivars: Ferry Porche, Bronze Masterpiece, Queen Elizabeth, John F. Kennedy and Lady X, were carried outin vitro, to determine whether these cultivars are suitable as pollen donors in a breeding programme.Pollen grains of all five cultivars germinated poorly in a medium containing sucrose only. Addition of boric acid in the medium improved the germination percentages. The highest germinability was observed in Ferry Porche and Lady X on 15% sucrose+50 ppm boric acid, and 20% sucrose+100 ppm boric acid, respectively. Addition of calcium nitrate in the medium reduced germination percentages in all cultivars.The effect of pH of the medium on pollen grain germinability depended on the cultivar and the composition of the medium. On a medium free of boric acid, the pH values between 5.5 and 7.0 caused a significant increase in the germination percentages of pollen grains of Lady X and Queen Elizabeth. The addition of boric acid decreased the responsiveness of the pollen of all cultivars to the pH changes of the medium.The germination capacity of pollen grains of Lady X and Ferry Porche was not affected by incubation temperatures ranging between 20°C and 30°C.On the basis of the above results Lady X and Ferry Porche are considered the most suitable for pollen donors.     

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.     

Partial self-compatibility in ‘Tombul’ and ‘Montebello’ hazelnuts

Summary Self-pollination of hazelnut (Corylus avellana L.) cultivars in 1988 and 1990 revealed the existence of partial self-compatibility in Tombul and Montebello. Percent cluster set in these cultivars averaged 44 and 20%, respectively, but was less than 10% in 8 other cultivars investigated. Percent cluster set from pollination with Segorbe averaged 62 and 41% in 1988 and 1990, respectively. Self-pollination produced 40% fewer nuts per cluster and twice as many blanks as cross-pollination. All cultivars and selections have an active sporophytic incompatibility system.Evaluation of self-compatibility in seedlings from the cross Montebello × Compton revealed that the partial self-compatibility of the maternal parent was transmitted to some of the progeny. Self-pollination resulted in greater than 10% cluster set in two selections, OSU 41.134 and OSU 43.025, in both years, but only in 1988 in OSU 42.089 and Willamette. Three other selections had very low set in both years. Results of incompatible crosses with standard testers were generally in agreement with those of self-pollination, except that the S₂ tester induced greater set on 3 genotypes in 1988 and the S1 tester on 2 genotypes in 1990 than self-pollination. The partial self-compatibility of Montebello, OSU 41.134, and OSU 43.025 appears to be due to a failure of their stigmas to prohibit pollen tube growth in incompatible crosses. There is no evidence of a pollen-part mutation in Montebello, nor is there evidence that partial self-compatibility is due to the interaction of S-alleles, as Barcelona, which has the same alleles as these three genotypes, failed to set nuts in all incompatible crosses.     

Low light intensity and flower bud abortion in Asiatic hybrid lilies. I. Genetic variation among cultivars and progenies of a diallel cross

Summary When Asiatic lilies are forced during the winter period, additional light is needed to prevent flower bud abscission and flower bud blasting. Growth room experiments showed considerable differences among eight lily cultivars in their response to low light. Among these cultivars, Connecticut King and Enchantment appeared to be the most sensitive to low light conditions while Uncle Sam and Scout were the least sensitive.Analysis of an incomplete diallel cross between nine cultivars showed significant differences in general combining ability (GCA) for flower bud abortion, number of buds, forcing time, plant height and leaf scorch under winter greenhouse conditions. Enchantment had the highest positive GCA for bud abortion, indicating a high sensitivity to low light conditions. Uncle Sam had the lowest GCA. Pirate and Scout appeared to have a high GCA for sensitivity to leaf scorch. Connecticut King was found to be a probable source of cytoplasmic male sterility. The data suggest that male sterility is associated with better response to low light conditions.     

Genes for resistance to stripe rust in four spring wheat varieties

Summary Four spring wheat (Triticum aestivum L.) varieties differing in origin and reaction in the seedling stage to pathotype CDL-6 (extant in California) were intercrossed and examined in greenhouse conditions in F₁, F₂, and F₃ generations. Digenic and transgressive segregation was found in all crosses. The four varieties each had infection types (1 immune, 9 susceptible) and putative resistance genes as follows: Anza, IT 7, YrA; Glennson 81, IT 2, Yr9; Yecora Rojo, IT 6, YrC; and Ollanta, IT 4–6, YrL. Anza was classified as susceptible, Yecora Rojo and Ollanta as intermediate in seedling resistance, and Glennson 81 as resistant in the seedling stage.     

Genetic control of low temperature tolerance in germination of the common bean (Phaseolus vulgaris L.)

Summary Cultivars tolerant to low temperature during the germination and emergence stages and carriers of the grain quality standards demanded by consumers are needed to increase the success of irrigated common bean in Southern Minas Gerais State. To study the genetic mechanisms controlling these traits and assess the possibility of generating the desirable materials, a diallel cross involving ten cultivars including introductions and pure lines from the breeding program of ESAL was carried out. Speed of germination of the F₂ generation from the crosses was assessed under laboratory conditions at 12°C. The diallel analysis was carried out using Griffing's method IV (1956) and predictions of the cross potential were made by the methodology developed by Jinks & Pooni (1986). The results indicated that the parents differed in germination speed at low temperatures with Small White, A-488 and Rio Vermelho being the most tolerant and Carioca, ESAL 591 the most sensitive. No effect of the reciprocal crosses was observed either for germination percentage or germination speed. The parents A-488, Small White and Rio Vermelho showed the greatest general combining ability. Additive genetic effects predominated for both traits. Our results suggest that cold tolerance can be bred successfully into commercially acceptable cultivars.     

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.     

Breeding Philadelphus for double flower,purple center and low stature

Results from eight crosses involving seven cultivars are recorded. Double flower is a recessive character with variable expression and irregular inheritance. Purple centered corolla is a dominant character, also with variable expression. Two outstanding combinations for producing seedlings with low stature, small leaves and compact habit are Manteau d'Hermine x Dame Blanche and Frosty Morn x Erectus.Contribution No. 131, Genetics and Plant Breeding Research Institute, Canada Department of Agriculture, Central Experimental Farm, Ottawa, Canada     

Molecular and biological studies on male sterile cytoplasm in Cruciferae. II. The origin of Ogura male sterile cytoplasm inferred from the segregation pattern of male sterility in the F1 progeny of wild and cultivated radishes (Raphanus sativus L.)

Summary To determine the origin of Ogura male sterile cytoplasm in radish (Raphanus sativus L.), wild and cultivated radishes were crossed. Three types of progeny resulted from the F₁ hybrids between the wild radish from Kushikino with Ogura-type mtDNA and the cultivars (Uchiki-Gensuke or Comet). The segregation patterns of the male sterility were compared with those of Ogura cytoplasm. The male sterility induced in the F₁ hybrid was maintained by crossing with Uchiki-Gensuke, that maintains Ogura male sterility. In the two types of progeny, in which Comet (a restorer of Ogura cytoplasm) was used as one of the parents, both fertile and sterile plants segregated at the predicted ratio on the assumption that a single dominant fertility restoring gene exists in the restorer. From these results, we concluded that the Ogura cytoplasm is identical to that of the wild radish, and the former originated in a population of Japanese wild radish.     

Resistance to the glasshouse whitefly (Trialeurodes vaporariorum Westw.) in sweet pepper (Capsicum annuum L.)

Summary Fourteen cultivars, one F₁-hybrid and one half-wild type (Cind) of sweet pepper were tested on resistance to glasshouse whitefly. Several mutually significant levels of resistance were found. Most resistant appeared to be California Wonder, Severka M, Korál and Yolo Wonder. During the test sweet pepper plants were infested both with whiteflies and their parasite — Encarsia formosa, which caused the blackening of whitefly puparia. The blackened puparia are easily seen, enabling an easier and more rapid evaluation of the number of puparia present.     

Multifactor inheritance of seedcoat colour in greengram (Vigna Radiata (L.) Wilczek.)

Summary Seedcoat colour in greengram (Vigna radiata (L.) Wilczek.) is a useful marker for genetic studies and varietal identification. Its mode of inheritance was examined in five crosses among nine parents which differed for seedcoat colour. Four of the parents had sap green seedcoat colour while the others had raw sienna, brownish green, densely black spotted, black and greenish yellow seedcoat colour, respectively. At the F₂ generation, no more than 20 different colour classes were observed. The segregation in F₃ and backcross generations indicated that at least five major genes were involved in seedcoat colour inheritance. Sap green seemed to be dominant over raw sienna. The segregation ratios further indicated the role of non-allelic gene interactions (epistasis) in inheritance of seedcoat colour. Gene symbols were assigned to each colour and genotypes to each parent.     

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.     

Pleiotropic association of infection frequency and latent period of two barley cultivars partially resistant to barley leaf rust

Summary Cebada Capa, carrying four to six minor genes for a longer latent period (LP), was crossed to L94 and Vada, carrying no and five to six minor genes for a longer LP respectively. Of each of 68 F3-lines the infection frequency (IF) and the LP of ten just-heading plants were assessed. There appeared to be a strong association between IF and LP, whereby the relationship between IF and LP of both crosses could be described by a single linear regression equation. The data strongly suggest that the genes for increased LP pleiotropically decrease the IF. The possibility of a close linkage between genes for reduced IF and genes for increased LP, although unlikely, could not be excluded.     

α-Tomatine and other steroidal glycoalkaloids in fruits of tomato lines resistant to the glasshouse whitefly (Trialeurodes vaporariorum Westw.)

Summary The total steroidal alkaloid compositions of the mature-harvested fruits of the tomato cultivar Allround (Lycopersicon esculentum), of the species L. hirsutum glabratum, resistant to the glasshouse whitefly (Trialeurodes vaporariorum), and of four resistant lines were determined by capillary gas chromatography. The contents of -tomatine in the red-ripe fruits of Allround and in those of the lines were low (5 mg/kg fresh weight). The green-mature fruits of the wild species had a high content (3390 mg/kg fresh weight) of -tomatine. The total alkaloid profiles of Allround and of the lines were similar. Comparison of flame ionisation detector response with thermoionic detector response indicated that in addition to tomatidine, the aglycone of -tomatine, a small amount of one other steroidal alkaloid might be present in Allround and in the lines. The wild species contained five compounds which possibly are steroidal alkaloids.The safety level of -tomatine in tomatoes is discussed. It was concluded that, in respect of the glycoalkaloids of the mature-harvested fruits, the resistant tomato breeding lines are as safe for human cosumption as the standard cultivar.     

Combining ability for femaleness and yield in single and 3-way crosses of pickling cucumbers intended for once-over harvest

Summary Single and 3-way cross hybrids derived from 13 parental lines of pickling cucumber were used to estimate general and specific combining ability for femaleness and yield. Parental lines 551F, 368G, 581H, and 5802A exhibited the highest general combining ability effects in both single and 3-way crosses for total yield and marketable yield. Additive effects of genes were found to be relatively more important than nonadditive effects for both femaleness and yield. Cucumber breeders might develop high yielding cultivars based on high general combining ability for yield in parental arrays; moreover, the general performance of the parental lines in single crosses could be used to predict high yielding 3-way hybrid crosses.     

Traditional seed maintenance and origins of the French lucerne landraces

Summary As for other forage crops the notion of variety is quite recent in lucerne (Medicago sativa L.). Up to 1950 in France, farmers cultivated landraces whose origins were geographically defined. Seed production was a by-product of forage production. Usually, seeds were harvested on the second or third crop, in old lucerne fields. Natural selection created landraces adapted to local conditions. In some years, climatic conditions, especially in northern regions, were unfavourable to seed production. In the exchanges and trades of seeds between French regions, the genetic origin of the seeds was omitted, the geographical origin was only mentioned. Even if France usually exported lucerne seeds, imports occurred in bad years. Seeds were imported from European countries and from North and South America. Varieties from America were poorly adapted to the French conditions for forage production. These foreign varieties have probably intercrossed with the local landraces but no data is available to know to what extent. Among the various French landraces, five main types were defined using morphological characters: Flamande in the north, three types (Poitou, Marais de Luçon, Marais de Challans) in the west, and Provence in the south. These landraces have been widely used in breeding since 1950. Even though these five landraces are, up to now, maintained, the other landraces have probably been lost (no more cultivated and not in genebanks), replaced by registered varieties.     

Breeding for resistance to yellow disease of hyacinths. II. Influence of flowering time,leaf characters,stomata and chromosome number on the degree of resistance

Summary Analysis of an incomplete diallel design with 14 hyacinth cultivars and 4 wild accessions of Hyacinthus orientalis showed a significant GCA component for resistance to yellow disease. The late flowering hyacinth cultivars King of the Blues and Marconi and the early flowering Hyacinthus orientalis 70129 were found to be the best combiners for yellow disease resistance. Within a cultivar, the degree of earliness itself was not associated with the degree of resistance. Correlation coefficients of leaf characters and degree of resistance showed that hyacinths with short and/or narrow leaves are generally more resistant than those with long and/or broad leaves. Tetraploid cultivars with few, large stomata tend to be susceptible, diploid ones with many small stomata tend to be the more resistant.