Inheritance of seed coat colour in broad bean (Vicia faba L.)

Summary The inheritance of the seed coat colours violet, spotted, brown, green, red, black and beige was investigated in a 10×10 diallel cross between broad bean (Vicia faba L. major) lines. Spotted seed colour was dominant over any uniform seed coat colouring. Brown was dominant over black, green and normal (beige colour). Black and red seed parents behaved as recessive in all F₁ progenies. A 3 (coloured): 1 (normal) segregation ratio was observed in the F₂ of crosses of violet, brown, black, red and spotted seed coat parents to nornal seed coloured parents. Green x beige gave a segregation ratio of 9:7 in F₂. When two parents with different seed coat colour were involved in a cross, the F₂ showed a typical digenic segregation ratio thus demonstrating two unlinked and sometimes epistatic loci.Segregation of a multiallelic series at two loci explains all segregation ratios observed for seed coat colour in broad bean.     

Backcross breeding to increase seed retention in cocksfoot (Dactylis glomerata L.)

Summary The objective was to evaluate the effectiveness of the backcross breeding method to improve an existing variety (Hallmark) for higher seed retention.The recurrent parent was cv. Hallmark (H) and the donor parent was cv. Marta (M). Marta is an Italian cultivar with a high degree of seed retention. Two cycles of backcrossing with selection for higher seed retention were conducted. In each cycle, 1200 plants were grown. In both BC₁ F₁ and BC₂ F₁, 20 plants were selected for general features of H and for a high degree of seed retention. The 20 plants of BC₂ F₁ were intercrossed in 1989. The bulked population thus obtained (HS) was evaluated in 1989–90 together with H and M as spaced plants in a randomized complete block design with 4 replicates. Regarding seed retention, H had a score of 7.9, M of 1.7 and HS of 2.8, LSD (0.05)=0.8, on a scale from 1 to 9. Consequently HS had similar seed retention to M but similar ear emergence date, plant height and panicle morphology to H. The results confirm that seed shattering is under control of a single partially or completely dominant gene.     

The influence of genotype and environment on seed and embryo development in barley (Hordeum vulgare L.) after crossing with Hordeum bulbosum L.

Summary Seed and embryo development was studied in crosses between H. bulbosum and the barley genotypes VK 16032, Vada and Vogelsanger Gold and subsequently the F₁ and F₂ progenies from VK 16032 x Vada and VK 16032 x Vogelsanger Gold. Both seed and embryo development are strongly influenced by the barley genotype. Favourable environmental conditions can promote seed and embryo development in genotypes with existing good characters. Dominant inheritance for good seed development and incomplete dominance for large embryos is evident. Linkage between small embryo size and winter habit exists in Vogelsanger Gold.     

A new wilt-resistant parent for producing tomato rootstock seed

Summary Resistance to Verticillium wilt (VeVe) and Fusarium wilt, race 1 (II) has been bred into a genotype similar to that of GCR 66- a tomato rootstock seed parent used for the production of interspecific F₁ hybrid rootstock seed. The new seed parent is named GCR 115. It is proposed that the rootstock derived from GCR 115 be named Identistock KVF. The name Markerstock previously proposed in connection with GCR 66 has not been accepted by the registration authorities in the United Kingdom.     

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.     

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.     

Productivity of F hybrids of botanical varieties ofBrassica oleracea L.

Summary F₁ hybrids were obtained by making pair-crosses between nine botanical varieties ofBrassica oleracea. Although non-inbred parents were used, their yield was surpassed by all F₁ hybrids. The highest yields were shown by the crosses marrow-stem kale × sprouting broccoli and marrow-stem kale × cauliflower while the highest consumable yield (assessed by feeding plants to sheep) was that of F₁ hybrids marrow-stem kale × cauliflower and wild cabbage × cauliflower. A scheme for the production of F₁ hybrid seed is suggested, based upon an adaptation ofThompson's (1964) Triple-cross technique.     

Inheritance of firmness in raw cucumber (Cucumis sativus L.) fruit

Summary Inheritance of raw cucumber fruit texture (Magness-Taylor Fruit Pressure Tester firmness) was investigated over a 4-year period from 1971–1974. Results from 2 separate but related experiments suggested that firmness was quantitatively inherited with sufficient additive effects to permit gain from selection. In a selection study within 4 F₂ populations derived from crosses between firm (Chipper and Gy3) and soft (Mincu and Green F) fruit type cultivars, variation among and within F₃ and F₄ families was significant but overall family means were not significantly higher than the high parent in any of the 4 crosses. Narrow sense heritability estimates for fruit texture were 0.80 in the Mincu × Chipper population and 0.77 in the Green F × Chipper, Mincu × Gy3, and Gy3 × Green F crosses. In a separate experiment, generation means analysis was used to assess the mode of gene action in 2 crosses: Green F × Chipper, and Gy3 × Green F. Additive genetic effects accounted for 98.8% and 99.3% of the total genetic variation within each cross, respectively.Scientific Journal Series Paper No. 9794.     

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.     

A new tomato rootstock seed parent

A new tomato rootstock seed parent which combines the characters green stem, potato leaf and long style in a Lycopersicon esculentum genotype has been produced. This will facilitate seed production of the interspecific F₁ hybrid rootstock which is used for grafted crops, and also permit the positive identification of any off-types which arise from accidental self-pollination of the seed parent. The new seed parent has been named GCR 66. It is proposed that rootstocks derived from this type of seed parent shall be called Markerstocks. GCR 66 is very similar to the cultivar Ailsa Craig in its agronomic characters and will be useful for studies with the tomato when pollination needs to be accurately controlled.     

Comparison of heritabilities derived from single F2 seed populations and bulk seed from F2 plant populations for oleic,linoleic and linolenic acids in oilseed rape

Summary The heritabilities for oleic, linoleic and linolenic acids in oilseed rape (Brassica napus) were determined using single F₂ seeds on F₁ plants and bulk seed samples of F₂ plants. The heritabilities by the use of single F₂ seeds were found to increase, remain constant, or decrease relative to those obtained from F₂ plant populations, depending on the fatty acid and the cross. However, the change in heritabilities was not great in most cases. Therefore the half-seed technique could be used for early generation selection for these fatty acids.     

Genetic nature of low capsaicin content in the variant strains induced by grafting in Capsicum annuum L.

Summary The genetic nature of low capsaicin content in variant strains induced by grafting was elucidated by crossing the G₅S₂₃ strain with the two cultivars, Yatsubusa (Capsicum annuum L. var. fasciculatum Ilish) and Spanish Paprika (C. annuum L. grossum Sendt) originally used for grafting. Decreased capsaicin synthesis was a stable characteristic for at least several generations from G₅S₁₆ to G₅S₂₃ and was transmitted to the progenies of crosses. This fact shows that the decreased capsaicin synthesis is a genetic trait in the graft-induced variant strains. The genetically dependent characteristic of pungency of the G₅S₂₃, Yatsubusa and Spanish Paprika were analysed by High Perfomance Liquid Chromatography measurement and tasting assay.Cross experiment between the G₅S₂₃ strain, hot parent Yatsubusa and sweet parent Spanish Paprika showed that pungent and sweet for pungency chracteristics are generally controlled by at least two pairs of genes. Although segregation of capsaicin content and pungency was clearly demonstrated in F₂ progenies from reciprocal crosses between the G₅S₂₃ strain and Spanish Paprika, F₂ progenies from reciprocal crosses between G₅S₂₃ and Yatsubusa were all hot and did not develop low capsaicin plants.     

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 neurotoxin (ODAP) content, flower and seed coat colour in grass pea (Lathyrus sativus L.)

Summary A strong epidemiological association is known to exist between the consumption of grass pea and lathyrism. A neurotoxin, -N-Oxalyl-L-, -diaminopropanoic acid (ODAP) has been identified as the causative principle. This study was undertaken to investigate the mode of inheritance of the neurotoxin ODAP, flower and seed coat colour in grass pea. Five grass pea lines with low to high ODAP concentration were inter-crossed in all possible combinations to study the inheritance of the neurotoxin. Parents, F₁ and F₂ progenies were evaluated under field condition and ODAP analyzed by an ortho-phthalaldehyde spectrophotometric method. Many of the progenies of low x low ODAP crosses were found to be low in ODAP concentration indicating the low ODAP lines shared some genes in common for seed ODAP content. The F₁ progenies of the low ODAP x high ODAP crosses were intermediate in ODAP concentration and the F₂ progenies segregated covering the entire parental range. This continuous variation, together with very close to normal distribution of the F₂ population both of low x low and low x high ODAP crosses indicated that ODAP content was quantitatively inherited. Reciprocal crosses, in some cases, produced different results indicating a maternal effect on ODAP concentration. Blue and white flower coloured lines of grass pea were inter-crossed to study the inheritance of flower colour. Blue flower colour was dominant over the white. The F₂ progenies segregated in a 13:3 ratio indicating involvement of two genes with inhibiting gene interactions. The gene symbol LB for blue flower colour and LW for white flower colour is proposed.     

Inheritance of N2 fixation efficiency in cowpea

Summary Host plant genetics of N₂ fixation in the cowpea (Vigna unguiculata (L.) Walp.) — Rhizobium symbiosis was investigated in the field with a mixed strain inoculum and in the greenhouse with a single strain inoculum. Five cowpea genotypes, including H-Brown Crowder and L-Bush Purple Hull, were used to generate populations for genetic studies. Diallel analysis for general combining ability (GCA), specific combining ability (SCA) and reciprocal effects was carried out for the N₂ fixation variables nitrogenase activity, nodule number, nodule weight, and top dry weight, in the field study. Generation mean analysis and heritability estimates were performed on the greenhouse population which included P₁ (H-Brown Crowder), P₂ (L-Bush Purple Hull), F₁, F₁. F₂, BC₁, and BC₂. Positive and significant correlations were observed between nitrogenase activity and both nodule weight and nodule number. Correlation coefficients between top dry weight and the other 3 variables were not significant. Estimates of SCA were highly significant for all variables except top dry weight, while those of GCA were significant only for nodule weight. Generation mean analysis revealed that additive gene action was more prominent than dominance and interallelic gene action for nodule number and nitrogenase activity, while the opposite was true for nodule weight and top dry weight. Narrow sense heritability estimates were moderately high for nodule number (0.55) and nitrogenase activity (0.62), and low for nodule weight (0.39) and top dry weight (0.17).Texas Agricultural Experiment Station Technical Article 20385. Research supported in part by a grant under USAID PASA AG/TAB 610-9-76 (USDA-CSRS-701-15-59).     

Molecular marker-assisted selection for yield-enhancing genes in the progeny of “9311×<Emphasis Type="Italic">O. rufipogon</Emphasis>” using SSR

Oryza rufipogon (IRGC105491) is a wild relative of cultivated rice, it contains two favorable yield-enhancing genes (yld1.1 and yld2.1) on chromosomes 1 and 2, respectively, which are capable of improving the yield of hybrid rice by 18 and 17%, respectively. SSR markers RM9, RM24, RM5 and RM306 are flanking yld1.1, while RM166 and RM208 are mapped in the close region to yld2.1. These molecular markers tightly linked to the two yield-enhancing genes were used to screen the plants of backcross population between 9311 (one of the top-performing parental lines in super hybrid rice seed production in China) and O. rufipogon. The results were as follows: (1) in BC₂F₁ population, the percentage of the individuals which contain both of the O. rufipogon alleles at marker loci RM166 and RM9 was 16.8%; (2) 1.5% individuals of total BC₃F₁ population have all the six linked markers (RM166, RM9, RM5, RM208, RM24, RM306); (3) in BC₄F₁ population, the percentage of the individuals which contain both of the two O. rufipogon alleles at marker loci RM166 and RM9 was 18.0%. Based on marker genotypes, the individuals, that contain multiple O. rufipogon markers, were selected and used for further backcross and self cross. Many 9311-type lines with yield-enhancing genes and high yield potential were obtained. After three times self-crossing a stable improved 9311 line was obtained. The results indicated that these molecular markers are feasible for marker-assisted selection (MAS) to screen rice individuals with high yield potential.     

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.     

Selection for seed set in crosses of Avena sativa L. × A. Abyssinica Hochst.

Summary Precoz oat line, discovered in a mass planting of wild oats in Colombia, is a tetraploid belonging to Avena abyssinica. It crossed easily with Kyto, but not with Bacata, both hexaploid oat cultivars. Pentaploid hybrid plants of Precoz × Kyto and Precoz × Bacata had 35 chromosomes, tended to have seven bivalents and 21 univalents at meiosis, and were completely sterile, Colchicine treatment of pentaploid F₁ plants produced decaploid tillers from which five amphiploid seeds were obtained. Selection for high percentage of seed set in the third and fourth amphiploid generations of Precoz × Kyto gave fifth generation plants with 80–100% fertility. The chromosome numbers of these plants approximated the octoploid level. Some derivatives from crosses of third generation amphiploids with hexaploid cultivars had the hexaploid chromosome number and good fertility.Pentaploid hybrid plants and amphiploid derivatives from them were as early in heading as Precoz when tested at either 12-or 15-hour photoperiods. This suggests that the photoperiod response from Precoz is dominant and has good penetrance.Journal Paper no J-7408, Project 1752.     

Expression of late maturity α-amylase in wheat containing gibberellic acid insensitivity genes

Summary Two wheat cultivars, Spica and Lerma 52, which consistently produce high levels of -amylase during the later stages of grain development (late maturity -amylase), were crossed with a set of four near-isogenic lines carrying the tall (rht) allele or one of the dwarfing genes Rht1, Rht2 or Rht3 (GA-insensitive alleles). The F₁ and F₂ populations were developed and analysed for grain -amylase and plant height. The Rht3 gene exhibited the strongest influence on plant height and strongly inhibited new -amylase synthesis during the later part of grain ripening. By comparison, Rht1 and Rht2 had a less pronounced effect but still significantly reduced the expression of late maturity -amylase. These observations suggest that gibberellic acid is involved either directly or indirectly in this phenomenon. The implications of the effect of dwarfing genes on expression of late maturity -amylase are discussed in relation to cultivar improvement and to the identification and control of high -amylase germplasm.     

Genetics of a high-selfing trait in pigeonpea

Summary A true-breeding line characterized by free filaments of anthers and modified keel petal was derived from F₂ population of an intergeneric cross between Cajanus cajan (L.) Millsp. and Atylosia lineata W. & A. This variant, designated as partial cleistogamy, favours a high level of self-fertilization. The inheritance of this trait was studied in the F₁, F₂, F₃, and BC₁F₁ generations of three crosses. The results suggest that the partial cleistogamy trait is governed by a single recessive gene, designated as pct.