Genetics of self-compatibility in dihaploids of Solanum tuberosum L. 2. Detection and identification of all possible incompatibility and compatibility genotypes in six F1'S from interdihaploid crosses

Summary Two self-compatible (sc) dihaploids, G254 and B16, and one self-incompatible (si) dihaploid, G609, from Solanum tuberosum L. were intercrossed reciprocally. Segregation ratios sc : si : pc (pseudo-compatible) were determined in all 6 F₁'s in three successive years and critically tested and discussed. Genotypes at the S-locus could be assigned to the dihaploid parents and the S-allele on the translocation in sc G254 identified as S ₁. Using these genotypes all sc and si genotypes were derived which could be expected in the F₁'s.Incompatibility groups were detected in each F₁ from the results of complete diallels involving si plants. The genotype of each group was identified by test crosses. Compatibility groups could be both detected and identified by crossing in each F₁ the sc plants as females with the already identified si sibs. In this way a complete series of 6 si testers and corresponding sc genotypes was obtained involving four alleles at the S-locus and S ₁ and S _x on the translocation.Certative disadvantage of pollen carrying the translocation could be ruled out as a possible cause of unexpected ratios. The hypothesis of an S-bearing translocation as the cause of self-compatibility could account for all results on the assumption that translocation homozygotes are lethal and the S-allele on the translocation is active in the pollen only.The following bachelor students have contributed to the experimental data used in this article: Janny Olsder, J. Marelis, H. v.d. Brink, J. Sonneveld, D. Vreugdenhil, Digna van Ballegooijen and Els Staas-Ebregt.     

Genetics of self-compatibility in dihaploids of Solanum tuberosum L. I. Breeding behaviour of two self-compatible dihaploids

Summary Two highly fertile and self-compatible dihaploids (2ns=2x24) from Solanum tuberosum L. (2n 4x 48) were investigated to elucidate the genetic basis of their self-compatibility. To this end the two dihaploids were selfed and reciprocally intercrossed and the resulting I₁ and F₁ plants tested for self-compatibility. Reciprocal backcrosses of I₁-plants and F₁-plants were made. Complete diallels both within self-compatible and within self-incompatible F₁-plants were carried out as well as reciprocal matings between self-compatible and self-incompatible F₁-plants. From the wealth of data it could be concluded, that the dihaploids have two intact S-alleles, one being common to both. Six hypotheses were tested for explaining self-compatibility in these particular dihaploids. All but one had to be discarded. It is concluded that the self-compatibility most likely is brought about by the presence of an S-bearing translocation, which is not linked to the S-locus. The ratio sc :si in the F₁'s point either to certative disadvantage of translocation-bearing pollen or to lethality of translocation homozygotes. The importance of this self-compatibility mechanism for genetic and breeding research in potato is discussed.     

Inheritance of genetic markers from two potato dihaploids and their respective parent cultivars

Summary In the first inbred generation (I₁) of cv. Black 4495 a dark green, slowly growing mutant (coded ds) was found, whereas the I₁ of its self-compatible dihaploid, B16, comprised this ds mutant and in addition the mutants virescens (v) and yellow margin (ym). The occurrence of ds and ym might trace back to diploid S. phureja, one of the ancestors of Black 4495. No lethal mutants were observed in I₁ of B16. Analysis of I₁ of cv. Gineke revealed a simplex condition for virescence and either duplex or triplex heterozygosity for one lethal gene. On the other hand, the I₁ of its dihaploid, G254, segregated for virescence and for three different lethal genes. It is shown that both in B16 and in G254 homozygosity of an S-bearing translocation causes early death of embryo and endosperm, thus preventing seed development. From this study it appeared that the three lethal genes from G254 affect germination rate of the seeds. The genotypes at 11 loci of B16 and G254 are presented.Visiting scientists from Birmingham, England and Mlochow, Poland, respectively.     

Genetics of self-compatibility in dihaploids of Solanum tuberosum L. 4. Linkage between an S-bearing translocation and a locus for virescens

Summary Three dihaploids of Solanum tuberosum (two self-compatible, one self-incompatible) were found to be heterozygous for a monogenic recessive virescent mutant. Intercrossing resulted in the expected 3 : 1 ratio only in crosses involving one self-compatible and one self-incompatible parent. Self-compatible x self-compatible matings produced F₁'s in which 6:1 was found. The same ratio was observed in the self progeny of the two self-compatible dihaploids. This significant deviation could be explained by assuming linkage (25% crossing-over) between v and an S-bearing translocation. This translocation causes self-compatibility in the dihaploids used and early lethality when homozygous.     

Genetics of self-compatibility in dihaploids of Solanum tuberosum L. 5. The S-genotype of tetraploid potato cultivar gineke

Summary Investigations of the genetics of self-compatibility and self-incompatibility in dihaploids and diploid derivatives from cv. Gineke revealed the presence of S ₁, S₂ and S ₃ at the S-locus of Gineke and in addition an S ₁-allele on a translocation. By means of a complete tester set involving the S-alleles S ₁, S₂ and S ₃ (all from Gineke) and S ₄ (from Black 4495) it was demonstrated that some Gineke dihaploids were compatible with all six testers. This indicated a fourth S-allele in Gineke, which differs from those in the tester series and was therefore assigned S ₅. Additional evidence was obtained from an analysis of F₁'s from crosses of two S ₅-bearing dihaploids and one of the testers. So the S-genotype of cv. Gineke was identified as S ₁S₂S₃S₅/S₁, the second S ₁ being the S-allele on a translocated fragment.     

A new secondary reciprocal translocation discovered in Chinese wheat

A new wheat-rye secondary reciprocal translocation involving T1RS·7DL and T7DS·1BL was detected by chromosome C-banding and genomic in situ hybridization (GISH). The meiotic configuration analysis combined with C-banding and GISH on F₁ hybrids of this newly discovered translocation with T1RS·1BL and Chinese Spring Dt7DS indicated that the new translocation probably resulted from a secondary reciprocal translocation between the primary translocation T1RS·1BL and 7D in the progenies of Aifeng3//Mengxian201/Neuzucht. On the basis of the cytological analysis of progenies and recombinant inbred lines (RILs) (derived from a cross between T1RS·7DL, T7DS·1BL and T1RS·1BL), the translocation chromosomes T1RS·7DL and T7DS·1BL transmitted readily, and appeared in most of the progenies.     

The inheritance of partial self-compatibility in Brassica oleracea L.: Results from a half diallel homozygous for a moderately recessive S-allele

Summary In a study of partial self-compatibility in Brassica oleracea, flower number, seeded siliqua and seed production were recorded on self-and cross-pollinated inflorescences of the progenies of a half diallel between six in bred Brussels sprout plants homozygous for the same moderately recessive incompatibility allele S₄₅.On both self-and cross-pollinated inflorescences significant amounts of additively controlled genetic variation were found for seed set per flower. For cross-pollinated inflorescences this was also the case for the two components of seed set, seeded siliquae per flower and seeds per seeded siliquae, but for self-pollinated ones only seeded siliquae production showed significant additive variation. Considerable heterosis and gene interaction were always present and a simple additive dominance model did not explain the variation.Two of the parents transmitted lower levels of partial self-compatibility to their progenies and, in one of these, dominant genes appeared to be responsible. The most important feature determining the production of self seeds was found to be the number of flowering sites at which the incompatibility mechanism failed rather than the number of seeds produced at each site.     

Effects of resistance genes,heat tolerance genes and cytoplasms on expression of resistance to Pseudomonas solanacearum (E.F. Smith) in potato

Summary Effects of resistance genes and heat tolerance genes on expression of resistance to bacterial wilt caused by Pseudomonas solanacearum were investigated in 30 F₁ progenies from parents with different levels of bacterial wilt resistance and heat tolerance. A race 1 and a race 3 isolate of the bacterium were used for inoculation under screenhouse conditions at two locations. Results obtained indicated that with reduction in levels of parental resistance, resistance in the F₁ progenies was also reduced. Under hot conditions, a reduced heat tolerance in the genetic background also resulted in lower levels of resistance expression. The effect of heat tolerance tended to diminish at lower temperatures leaving the effect of resistance genes more consistent. There existed a strong interaction between resistance genes and genes for heat tolerance. The nature of resistance to bacterial wilt in potato and implications for breeding for resistance are discussed.Effects of reciprocal crosses on expression of resistance to a race 1 isolate under hot screenhouse conditions, were studied in 5 sets of reciprocal F₁ progenies involving different resistant and susceptible parents. The reciprocal differences observed were not significant suggesting absence of cytoplasmic effects on expression of resistance.     

Quantitative resistance to Botrytis cinerea from Solanum neorickii

Tomato (Solanum lycopersicum) is susceptible to gray mold (Botrytis cinerea). Quantitative resistance to B. cinerea was previously identified in a wild relative, S. neorickii G1.1601. The 122 F₃ families derived from a cross between the susceptible S. lycopersicum cv. Moneymaker and the partially resistant S. neorickii G1.1601 were tested for susceptibility to B. cinerea using a stem bioassay. Three putative quantitative trait loci (pQTL) were detected: pQTL3 and pQTL9 reducing lesion growth (LG) and pQTL4 reducing disease incidence (DI). For each pQTL, a putative homologous locus was identified recently in another wild tomato relative, S. habrochaites LYC4. pQTL3 was confirmed by assessing disease resistance in BC₃S₁ and BC₃S₂ progenies of S. neorickii G1.1601. pQTL4 was not statistically confirmed but the presence of the S. neorickii resistance allele reduced DI in all three tested populations. The reduction in LG of pQTL9 was not confirmed but rather, this locus conferred a reduced DI, similar to observations in the QTL study using S. habrochaites. The results are discussed in relation to other disease resistance loci identified in studies with other wild tomato relatives.     

Stabilization of new types of diploids (2n=22, 24) through selfing of aneuploids (2n=21, 22) derived from crossing of sesquidiploids (2n=29, AAC) and Brassica campestris (2n=20 AA)

Summary Aneuploids with 2n=21 and 2n=22 derived from crossing of sesquidiploids (2n=29, AAC) and Brassica campestris (2n=20, AA) were selfed successively in order to follow the changes in chromosome number of the progenies for three consecutive generations. Progenies with 2n=22, 23 and 24 obtained after selfing of S₀ generation and the succeeding S₁, S₂ and S₃ generations were analyzed in terms of pollen stainability, % seed set as well as cytogenetically based on meiotic behaviour with the aim of determining the possibility of addition of one or more alien chromosomes into n=10 species which may lead to differentiation of single or plural disomic addition lines. The generation of aneuploids with 2n=21 progressed in such a way that most plants seem to revert to the 2n=20 chromosome number of B. campestris after selfing. From 2n=22 aneuploids, however, the succeeding progenies showed high frequency of plants with two additional chromosomes which accounted for 50.6% and 52.9% of total S₃ progenies via 2n=22 and 2n=24 S₂ generations, respectively. The meiotic behaviour of these progenies indicated evidence for a rule governing the frequency distribution of chromosome number among these addition lines and high possibility to breed such disomic plants with 2n=22. A method of selecting stable aneuploids was suggested in addition to the possible role of pollination biology at various processes of such breeding program.     

Identification of S-alleles in almond using multiplex PCR

The S-genotypes of eight almond (Prunus dulcis Miller (D.A. Webb)) cultivars from different geographical origins and of nine new selections from the CEBAS-CSIC (Murcia, Spain) breeding program were determined using single and multiplex PCR with different sets of specific oligonucleotide primers. The results of PCR using the AS1II- and AmyC5R-specific primers showed amplification in a single reaction of 10 different self-incompatibility alleles and of the self-compatibility allele S _f. However, the amplified fragments of the S _f allele were of similar sizes to those amplified from the S ₃ self-incompatibility allele. For this reason, a specific PCR primer CEBASf was designed from the intron sequence of S _f. A multiplex-PCR reaction using the AS1II, CEBASf and AmyC5R primers permitted unequivocal identification of the 10 self-incompatibility alleles and of the self-compatibility allele. Multiplex PCR opens the possibility to identify new S-alleles using different sets of primers. The applications of these PCR markers in the almond-breeding programs are discussed.     

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.     

Interspecific cross of Brassica oleracea var. alboglabra and B. napus : effects of growth condition and silique age on the efficiency of hybrid production, and inheritance of erucic acid in the self-pollinated backcross generation

Interspecific hybrids were produced from reciprocal crosses between Brassica napus (2n = 38, AACC) and B. oleracea var. alboglabra (2n = 18, CC) to introgress the zero-erucic acid alleles from B. napus into B. oleracea. The ovule culture embryo rescue technique was applied for production of F₁ plants. The effects of silique age, as measured by days after pollination (DAP), and growth condition (temperature) on the efficiency of this technique was investigated. The greatest numbers of hybrids per pollination were produced under 20°/15°C (day/night) at 16 DAP for B. oleracea (♀) × B. napus crosses, while under 15°/10°C at 14 DAP for B. napus (♀) × B. oleracea crosses. Application of the ovule culture technique also increased the efficiency of BC₁ (F₁ × B. oleracea) hybrid production by 10-fold over in vivo seed set. The segregation of erucic acid alleles in the self-pollinated backcross generation, i.e. in BC₁S₁ seeds, revealed that the gametes of the F₁ and BC₁ plants carrying a greater number of A-genome chromosomes were more viable. This resulted in a significantly greater number of intermediate and a smaller number of high-erucic acid BC₁S₁ seeds.     

New self-incompatibility alleles in apricot (Prunus armeniaca L.) revealed by stylar ribonuclease assay and S-PCR analysis

Apricot (Prunus armeniaca L.) shows gametophytic self-incompatibility controlled by a single locus with several allelic variants. An allele for self-compatibility (S_C) and seven alleles for self-incompatibility (S₁–S₇) were described previously. Our experiments were carried out to ascertain whether the number of allelic variants of apricot S-locus was indeed so small. Twenty-seven apricot accessions were analysed for stylar ribonucleases by non-equilibrium pH gradient electrofocusing (NEpHGE) to determine their S-genotype. To validate the results of electrofocusing, the applicability of the S-gene-specific consensus PCR primers designed from sweet cherry sequences was tested. NEpHGE revealed 12 bands associated with distinct S-alleles in newly genotyped cultivars. Cherry consensus primers amplified 11 alleles out from 16 ones, which indicated that these primers could also recognize most of the S-RNase sequences in apricot, and provided an efficient tool to confirm or reject NEpHGE results. By combining the protein and DNA-based methods, complete or partial S-genotyping was achieved for 23 apricot accessions and nine putatively new alleles (provisionally labelled S₈–S₁₆) were found. Their identity needs to be confirmed by pollination tests or S-allele sequencing. This study provides evidence that similarly to other Prunus species, the S-locus of apricot is more variable than previously believed.     

Monosomic analysis of stem rust resistance in the wheat cultivar Almus

Summary Monosomic analysis of resistance to stem rust, race 11 (isolate G 425) was carried out in the cultivar Almus (GDR) possessing a 1B/1R translocation. F₂ progenies of monosomic and disomic F₁ plants of Almus crossed with 21 monosomic lines of Chinese Spring were tested. Two lines (1B and 6B) differed significantly from the disomic segregation ratio by a higher number of resistant plants and two other lines (1D and 6A) by a lower number of resistant plants. The results fitted a hypothesis comprising the interaction of two genes for resistance and two inhibitors.     

Transfer of resistance to race 2 of Plasmodiophora brassicae from Brassica napus to cabbage (B. oleracea ssp. capitata). III. First backcross and F2 progenies from interspecific hybrids between B. napus and B. oleracea ssp. capitata

Summary The first backcross and F₂ progenies from triploid F₁ and tetraploid F₁ hybrids between B. napus and 2x and 4x B. oleracea ssp. capitata (cabbage) were studied for their general morphology, resistance to race 2 of the clubroot pathogen, chromosome number and meiotic chromosome behavior. No linkage was apparent between resistance and the major morphological characters. Unreduced gametes played a large part in the successful formation of seed of the B₁ and F₂ progeny. B₁ plants with low chromosome numbers were selected for use in recurrent backcrosses. The potential use of anther culture to extract gametic progenies from resistant B₁ and F₂ plants with higher chromosome numbers was suggested. The presence of homoeologous pairing observed in all the plants is considered advantageous for selecting suitable progeny in later generations.     

Breeding for quantitative resistance to potato cyst nematode (Globodera pallida) in tetraploid potatoes using dihaploids and unreduced gametes

Summary Dihaploids were produced from tetraploids resistant to potato cyst nematode (Globodera pallida (Stone)). High levels of resistance were found in the dihaploids and three were used to produce tetraploid progenies by crossing them with susceptible tetraploid cultivars. One dihaploid, PDH505, produced more highly resistant offspring than the other two, PDHs 417 and 418. The latter gave progenies whose levels of resistance were similar to those obtained from susceptible dihaploids crossed with resistant tetraploids.The differences between the progenies of the resistant dihaploids were probably due to different modes of unreduced gamete formation (PDH505 producing gametes by first division restitution (FDR) and PDHs 417 and 418 by second division restitution (SDR)) although cytological studies would be necessary to confirm this. The methods by which dihaploids could be utilised in a tetraploid potato breeding programme are discussed in relation to the mode of unreduced gamete formation.     

Characterization of graft-induced change in capsaicin content of Capsicum annuum L.

Summary Capsaicin contents were measured in the progenies from the test crosses between the strain, G₅S₁₇ derived from fruit with the graft-induced change in fruit shape and the original two cultivars, Yatsubusa (Capsicum annuum L. var fasciculatum Ilish) and Spanish Paprika (C. annuum L. var. grossum Sendt) used for grafting.The strain, G₅S₁₇ contained a lower amount of capsaicin than the original pungent cultivar Yatsubusa used as scion. The characteristic of the lowered capsaicin content in the strain has been stably inherited through seed propagation, and has also been transmitted to the progenies from the crosses with the original two cultivars used for scion or stock. These features in the capsaicin content agreed with those in fruit shape in the graft-induced change.     

Breaking breeding barriers in Lycopersicon. 2. Breakdown of self-incompatibility in L. peruvianum (L.) Mill.

Summary Attempts were made to break the self-incompatibility in L. peruvianum by selection of mutated S-alleles through large-scale self-pollination on clones with pollen which was mutagenically treated in different stages of development. Besides self-compatibility was searched for in inbred lines.The self-incompatibility in L. peruvianum was found to be very strict indeed. From more than 22,000 self-pollinations on 5 clones 1527 seeds were obtained, seed set being very erratic. The possible causes of this seed set are discussed. From 1527 seeds 1036 plants were raised and tested for self-compatibility.In the progenies of 4 clones from 823 plants tested, 7 were more or less self-compatible. It is concluded that this self-compatibility was spontaneous and not the result of the mutagenic treatment.In the progeny of the fifth clone plants were found which reacted as self-compatible at a temperature of about 40°C and as self-incompatible at lower temperatures. It is suggested that this character—a high temperature sensitive incompatibility reaction—is governed by one recessive gene.In inbred lines plants were found with a stable form of self-compatibility and also plants with a high temperature sensitive incompatibility reaction.The problems of an incompatibility research on inbred material are discussed. A brief survey is given of some of the characters found in inbred L. peruvianum.     

Crossability and cytology of hybrid progenies in the cross between Brassica campestris and three wild relatives of B. oleracea,B. bourgeaui,B. cretica and B. montana

Summary Crossability and cytology were examined in F₁, F₂, B₁ and hybridsplants of F₁ hybrids of Brassica campestris and three wild relatives of B. oleracea, B. bourgeaui, B. cretica and B. montana, respectively. The F₂ plants were obtained after self-and open pollination of the F₁ hybrids. The B₁ and hybrid plants were produced after the F₁ hybrids backcrosses with B. campestris and crossed with B. napus, respectively. After crossing the F₁ hybrids, many seeds of the F₂, B₁ and hybrid plants were harvested. Multivalent formation was high in the chromsome configuration for the PMCs of F₂, B₁ and hybrid plants, suggesting that crossing over might occur between them. Many different types of aneuploids were obtained in the progenies of the F₂, B₁ and hybrid plants. It is suggested that different types of normal egg cells may be produced by one-by-one or little-by-little chromosome addition. The possibility is discussed of gene transfer from B. bourgeaui, B. cretica and B. montana, to cultivated plants, B. campestris and B. napus.