Genetic nature of bushy plant type in the variant strain induced by grafting in Capsicum annuum L.

Summary To elucidate the genetic nature of bushy plant type in the variant strains derived from grafting, testcrosses were made on the one hand between one of the variant strains, G₅S₁₇, and both Yatsubusa and Spanish Paprika, and on the other hand between the two cultivars.The bushy strain has more nodes and branches on the main stem than the two cultivars.This bushy plant character was recessive to cv. Yatsubusa used as a scion and over-recessive to cv. Spanish Paprika used as a root stock.Such graft-induced change from recessive to over-recessive as bushy plant type was quite different from other varied characters such as, fruit shape, capsaicin content and guard cell size, which were generally intermediate between the two cultivars.     

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.     

Graft-induced change in fruit shape in Capsicum annuum L. I. genetic analysis by crossing

Summary Characteristics of fruit shape in the progeny from a graft-induced change were analysed. Non-pointed, typically inverted-blunt (two-lobed) fruit apex was observed in chimeric state within a scion of Yatsubusa grafted onto Spanish Paprika (inverted-blunt, three-or four-lobed fruit). This frequency of change in fruit shape was unstable in an early generation on the graft.     

Graft-induced changes in soybean storage proteins. I. Appearance of the changes

Summary Genetic changes induced by grafting were observed in soybean storage proteins, involving the 11S acidic subunit composition and Kunitz trypsin inhibitor. Changes from Gly ₁ Gly ₁to Gly ₁ gly ₁involved the 11S acidic subunit, and those from Ti ⁰Ti⁰ to Ti ³Ti⁰ involved the KTI in the first progeny (G₁S₁) in the scion (Gly ₁ Gly ₁ Ti ⁰Ti⁰, var. Kinzu) grafted onto var. Raiden (gly ₁ gly ₁ Ti ³ Ti ³). The progenies G₁S₂ and G₂S₁ from the seeds that had been changed segregated for both proteins. However, the segregation ratio in the progenies were different from those of the F₂'s from the sexual crosses between Kinzu and Raiden used for grafting. These findings show that the changes (changed genes) were transmitted to the progenies in an unstable manner.     

Inheritance of groat protein percentage in Avena sativa L. × A. Fatua L. Crosses

Summary Gene action and heritability of groat protein percentage were determined in F₁, F₂, and F₃ generations of nine crosses between three Avena sativa L. cultivars and three A. fatua L. selections. Relationships among groat protein percentage, grain yield, and 100-seed weight also were evaluated. The three A. sativa parents were Dal (high grain yield and intermediate groat protein percentage), Goodland (low grain yield and high groat protein percentage), and Stout (high grain yield and low groat protein percentage). The three A. fatua parents were chosen for the study on the basis of vigorous plant growth and high groat protein percentage. The study was conducted at Madison, Wisconsin in 1979 and 1980.There was partial dominance towards low groat protein percentage. Narrow sense heritability estimates for groat protein percentage were low in Dal and Goodland crosses and intermediate in Stout crosses. In the F₂ generation, groat protein percentage was significantly higher in shattering than in nonshattering plants in 1979, but not in 1980. There were significant, positive correlations between groat protein percentage, 100-seed weight, and grain yield in F₁ and F₂ generations, but they were not large numerically. Relationships among these traits were either negative or nonsignificant in the F₃ generation. Although our results indicated that selection for higher groat protein percentage is possible when a low protein A. sativa cultivar is used, most of our simple cross progenies from A. sativa x A. fatua crosses had weak straw and were susceptible to crown rust (Puccinia coronata Cda. var. avenae Fraser and Led.).     

Interaction among sporophytic S loci in self-incompatible garden chrysanthemums

Summary Certain parent-progeny crosses were studied to determine whether several S loci acted independently or epistatically to produce incompatibility in garden chrysanthemums, Chrysanthemum morifolium Ramat. The ratios of compatible: incompatible crosses with the original parent, as the pollen parent, were nearly 1:3, 1:1, and 1:1 for the I₁, backcross (BC), and BCF₂ generations, respectively. In particular, crosses between each progeny and the original parent showed that the number of compatible crosses was much higher than expected if each S locus acted independently. Therefore, interaction must have existed among pollen S alleles from different S loci. This information was used to demonstrate a method by which garden chrysanthemums could be inbred by sib mating in successive generations.Scientific Journal Series Paper Number 13,001 of the Minnesota Agricultural Experiment Station.     

Inheritance of tomato leaf curl virus resistance in Lycopersicon hirsutum f. glabratum

Summary Inheritance of resistance to tomato leaf curl virus (TLCV) was studied in the progenies derived from interspecific crosses between TLCV resistant Lycopersicon hirsutum f. glabratum line B 6013 and five susceptible cultivars (HS 101, HS 102, HS 110, Pusa Ruby and Punjab Chhuhara) of L. esculentum. P₁, P₂, F₁, F₂, B₁ and B₂ progenies of the five crosses were artificially inoculated with local strains of TLCV by means of the vector whitefly, Bemisia tabaci (Genn.). and the disease reaction was studied in all the crosses. Reaction of parents, F₁, F₂ and backcrosses suggests that resistance derived from L. hirsutum f. glabratum B 6013 is based on two epistatic genes, one from the wild parent and one from the cultivated one, resulting in a 13:3 segragation in the F₂.     

Inheritance of resistance to fruit rot (Phytophthora capsici Leon.) and induction of resistance in bell pepper (Capsicum annuum L.)

Summary Fruit rot in bell pepper caused by Phytopthora capsici Leon. is a limiting factor in its commercial production. Crosses were made between Waxy Globe, a small fruited hot type, resistant to fruit rot and four highly susceptible bell pepper commercial cultivars (Chinese Giant, California Wonder, Osh, Kosh and Yolo Wonder). Studies of the F₁'s, F₂'s and backcrosses indicated that Waxy Globe carries a dominant gene imparting resistance to fruit rot. After three backcrosses with California Wonder, lines were obtained combining the resistance gene of Waxy Globe with the large fruit size and low capsaicin of California Wonder.     

Inheritance of resistance to fruit rot (Phytophthora parasiticaDast.) in tomato (Lycopersicon esculentum Mill.)

Summary Fruit rot disease caused by Phytophthora parasiticaDast. is a limiting factor in tomato production in Himachal Pradesh. 30 to 60 per cent fruits are damaged by this disease. Crosses were made between EC 54725 (Lycopersicon pimpinellifolium), a small tyuited type, resistant to fruit rot and four highly susceptible tomato commercial cultivars (Gola, Sioux, S12, and Lalmani). Studies of F₁'s, F₂'s and back crosses indicated that EC 54725 carries a dominant gene imparting resistance to fruit rot.     

Inheritance of resistance to Pyrenochaeta lycopersici in tomato

Summary Tomato accessions (Lycopersicon sp.), along with commercial cultivars and breeding lines were grown in a field infested with the brown root rot (BRR) organism, Pyrenochaeta lycopersici and evaluated for resistance. Three L. esculentum Mill. accessions, P.I. 260397, P.I. 262906 and P.I. 203231, were resistant and were used as male parents in crosses designed to transfer resistance to tomatoes of fresh market type. Through analysis of parental generations and F₁ and F₂ progenies from three crosses the heritability of resistance in the broad sense was estimated to range from 25 to 43 percent. The minimum number of genes influencing resistance was estimated to be from 4 to 8.Florida Agricultural Experiment Stations Journal Series Paper no. 317.     

Selection for resistance to Plasmodiophora brassicae Wor. in oriental subspecies of Brassica rapa L.

Summary Selection for resistance to Plasmodiophora brassicae Wor. in oriental groups of Brassica rapa L.Two hundred and sixty-five cultivars of leafy, oriental bassicas were tested for resistance to 18 collections of Plasmodiophora brassicae, the causal agent of clubroot. The tests were conducted in the greenhouse at low and high level inoculum concentrations. Eleven cultivars of B. rapa pe-tsai, five cultivars of B. rapa pak-choy and three cultivars of B. rapa choy-sum consistently segregated for resistance at the lower concentration of inoculum (1000 spores/ml). All 265 cultivars were susceptible at the higher concentration (1 000 000 spores/ml). Three cultivars were used in pedigree and recurrent selection schemes for increased resistance. After three cycles of selfing resistant individuals, significantly more resistant S₃ lines were derived from each cultivar. Lines derived from two cultivars. Chinese White and PI 257236, continued to improve with each cycle of selection and demonstrated increased resistance to higher levels of inoculum (up to 1 000 000 spores/ml) New cultivars based on intercrosses of S₂ resistant individuals also had significantly better resistance than the original cultivar. After two cycles of selection in the third cultivar, PI 419007, resistance did not increase and its S₂ mass did not differ significantly from the original cultivar. Evidence that indicates resistance is pathotype-non-differential and offers an alternative to major gene, pathotype-differential types of resistance currently being introduced to the leafy oriental brassicas from other Brassica rapa groups.     

Increasing productivity in sweet almond using selected clones of bitter almond

Summary Eight controlled crosses were made between seven different sweet-kerneled almond cultivars (Prunus dulcis [Mill.] D. A. Webb), and five crosses were made between sweet x highly floriferous bitter almond clones. Sweet x bitter progenies out-yielded the sweet x sweet matings by more than three to one in the first year of production. This was attributable to greater cropping efficiency rather than to tree size or precocity. There was no pleiotropic association or association due to linkage between bitterness and yield. The selected Alnem (bitter) clones appear to be potentially useful progenitors for increasing almond yield capacity by conventional breeding methodology.     

Relationships between African species of the genus Cucumis L. Estimated by the production,vigour and fertility of F1 hybrids

Summary The production, vigour, and fertility of F₁ hybrids between nine African species of the genus Cucumis L. were studied as a measure of the relationships between the species. Hybrid plants were obtained from 29 out of the 72 possible cross combinations. Two F₁ hybrids died as seedlings, and 27 hybrids were raised to maturity. Pollen production and stainability varied greatly amongst these hybrids, as did fruit and seed set following self pollination and backcrossing with either parental species. The fruit shape of the hybrids was always intermediate between that of both parental species.Two species appeared to be closely related: C. prophetarum L. and C. anguria var. longipes A. Meeuse. Most other species produced highly to moderately fertile F₁ hybrids with at least one other species. C. metuliferus Naud. produced only sterile hybrids with C. zeyheri Sond. 2x. The results sustain the recent taxonomic classification of the genus (Jeffrey, 1980).     

Occurrence of aphid vector and genetic tolerance to infection by potyvirus in hot pepper

The productivity and marketable quality of hot pepper (Capsicum annuum var. annuum L.) are low in tropical regions mainly due to virus infections and lack of effective virus management strategies. The absence of effective virus management strategies could be attributed to lack of information on virus vectors and host resistance. Parental (P₁ and P₂) and progeny (F₁, B₁, B₂ and F₂) generations of five hot pepper crosses were grown in Ethiopia at three sites (Bako, Hawasa and Melkasa) to monitor number and species of potential aphid vectors, disease incidence levels with regards to natural infections by Potato virus Y (PVY) and Ethiopian pepper mottle virus (EPMV) complex, and to determine genetic tolerance of the crop to the viruses. Disease incidence was assessed before the flowering stage of the crop plants using visible disease symptoms due to infections by PVY and EPMV. The serological tests revealed presence of symptomless genotypes of the crop to the virus infections. Aphid species potentially transmitting the viruses, such as Acyrthosiphon pisum (Harris), Aphis fabae (Scopoli), and Myzus persicae (Sulzer), were identified from specimens caught by yellow water traps. The highest number of aphids from yellow water traps was recorded at a dense foliage growth stage of the crop at Melkasa. Highly significant variation was observed among generations of the five crosses in response to infections by PVY and EPMV complex. The most susceptible parents had the levels of disease incidences ranging from 80 to 90%, whereas their progenies had only below 30% incidence levels. The most tolerant parent remained symptomless to the natural infections of PVY- and EPMV-complex. Incidence levels in progenies of a cross from the most susceptible and tolerant parents remained below 20%. Based on serological test, the proportion of PVY-positive plants ranged from 0 to 75% and of EPMV-positive plants from 0 to 25%, with 0 to 17% co-infection by the two viruses. Availability of virus sources in the vicinity, efficiency of aphids in vectoring, weather conditions during the growth period, genetic tolerance and the growth stage of the crop affected natural infection by PVY- and EPMV-complex. Exploitation of the genetic potential of introduced elite genotypes and their progenies along with breeding elite local cultivars for resistance and excluding aphid vectors at young (seedling) stage of the crop plants could be helpful for minimizing losses in yield and quality of hot pepper due to infections by PVY- and EPMV-complex.     

Inheritance and transfer of multiple-flower character from Capsicum chinense into Capsicum annuum

Summary Capsicum annuum L. produces a single flower and thus a single fruit per branching node. In contrast, Capsicum chinense Jacq. yields two or more flowers per node. If genes for multiple-flowers per node could be transferred from C. chinese to C. annuum, it might be possible to breed C. annuum varieties with a more concentrated fruit set and potentially higher yield. Using progeny from an interspecific cross between C. annuum cv. NM 6-4 and C. chinense CA4, it has been determined that a minimum of five independently segregating chromosomal regions control the difference in flowering behavior between these two accessions. One of the segments is located on a translocated chromosome. Epistatic interactions among independent chromosomal regions appear to play a major role in the determination of this trait.Although it is unlikely that the multiple-flower character can be transferred to C. annuum in its full intensity while maintaining a horticulturally-acceptable phenotype, it may be possible to breed varieties which produce an average of more than 1.5 flowers per node, a value 50% higher than existing C. annuum varieties.     

The effect of gibberellic acid on fruit and seed set in crosses of garden and winter hardy Rosa accessions

Summary The effect of gibberellic acid (GA₃) was studied on a wide range of crosses between various garden roses and two hardy breeding lines. Although there were fewer seeds per fruit, fruit set was higher in most crosses when GA₃ was applied to the stigma at the rate of 250 ppm ten days after pollination. However, higher fruit set did not result in more seeds per pollination for many crosses and seemed to be related to the degree of male parentage. Both parents used had a major effect on pollination success. Recently developed Rosa cultivars have a narrow genetic base and the use of distantly related cultivars as parents would possibly give a high seed set and greater numbers of progeny.Contribution No. 335/90.08.01R, Experimental Farm, L'Assomption; Contribution No. Ro 44, Research Program Service, Ottawa.     

Inheritance of closed flower in pepper

Summary Progenies of pepper (Capsicum annuum L.) crosses between the closed flower pepper line UFBG 8209-1 and cultivars Permagreen and Early Calwonder representing the normal, open flower type, were evaluated in a field experiment. The F₁ generation was open flowered. Backcrosses and F₂ generations indicated that the closed flower trait was controlled by a single recessive gene.Florida Agricultural Experiment Stations Journal Series No. 4918.     

Graft-induced variants as a source of novel characteristics in the breeding of pepper (Capsicum annuum L.)

A line with genetic changes that was obtained from selfed seeds of the scion of an intraspecific pepper graft was used as a source of new characteristics in this breeding experiment. Five new variant lines and several sublines were bred by the use of this graft-induced variant strain and two other cultivars. Gradual introduction of the desired quantitative traits and selection resulted in combinations which significantly outperform the parental lines. Our breeding aim was to combine the two-lobed fruit shape that is characteristic for the graft-induced variants with thick pericarp, high sugar content, large fruit size, and significantly reduced or eliminated pungency in the new variants. A bushy plant type, typical for the graft-induced variants could be maintained in some selected sublines. The use of the three different genotypes resulted in many favorable combinations of quantitative traits, and lines were selected with the most valuable new characteristics. However, not all of these expressed the two-lobed fruit apex of the graft-induced variants. Our results reveal that the new characteristics which are induced by grafting are stable, new traits, and can be used as a novel genetic source in the breeding of pepper. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluation of globe artichoke and related germplasm for resistance to artichoke latent virus

Summary A total of 280 globe artichoke (Cynara scolymus L.) clones were assessed for reaction to naturally occurring artichoke latent virus (ALV) in field trials. Also, the reaction of 17 seed progenies of crosses which produced ALV-resistant clones in the field, 20 self progenies of parental genotypes common to these crosses, self progenies of 17 artichoke cultivars, and 7 accessions ofC. cardunculus andC. syriaca were evaluated in the glasshouse following mechanical inoculation with ALV. The local and systemic presence of ALV, and the relative virus content in infected plants were determined by ELISA.All cultivars and most of the otherC. scolymus material tested (clones and seed progenies) proved to be highly susceptible to ALV. Ten progenies were less susceptible to mechanical inoculation as shown by the moment the virus could be detected, and a slow rate of accumulation of viral antigen. Some plants in two seed progenies possessed apparently a high resistance as could be concluded from the failure of ALV to spread or to multiply in plant.Accessions ofC. cardunculus andC. syriaca were also highly susceptible to ALV. However, an interspecific hybridC. cardunculus x C. syriaca presented the highest level of resistance, the plants remained free of local and systemic infection. Ratios of resistant to susceptible plants in self progenies of resistant plants suggested that this resistance was dominant.     

Nuclear RFLP between pepper cultivars (Capsicum annuum L.)

Summary Forty one nuclear probes, distributed across the different linkage groups of the previously published map, were used to examine restrition fragment length polymorphism between cultivated peppers. Total DNA from thirteen accessions of Capsicum annuum var. annuum and one accession of C. baccatum var. pendulum was separately cut with ten restriction enzymes. The analyses were restricted to only one enzyme per probe to reduce the polymorphism redundancy. Nei & Li's genetic distances between accessions were calculated from the 141 resultant nuclear DNA restriction fragments. The genetic variation was larger between C. annuum and C. baccatum than between C. annuum cultivars. Large fruited related accessions closely clustered together. Distances between the small fruited cultivars were larger than within the bell pepper group. A correspondence analysis performed on differences between the global RFLP patterns of each accessions of C. annuum revealed the particular genomic structure of four small fruited cultivars: Criollo de Morelos 334, H3, Perennial and Doux Long des Landes. The percentage of probes revealing at least one RFLP with at least one enzyme ranged from zero to fifty percent for all the pairwise comparisons of C. annuum accessions. 82 presumptive loci were detected with a mean number of 1.46 alleles per locus within C. annuum and 1.83 within all the accessions. This result indicates that molecular markers will be more usable in intraspecific study of C. annuum than isozyme markers.