Incompatibility Reaction Research Articles

Two allelic genes responsible for vegetative incompatibility in the fungus Podospora anserina are not essential for cell viability

Vegetative incompatibility is a lethal reaction that destroys the heterokaryotic cells formed by the fusion of hyphae of non-isogenic strains in many fungi. That incompatibility is genetically determined is well known but the function of the genes triggering this rapid cell death is not. The two allelic incompatibility genes, s and S, of the fungus Podospora anserina were characterized. Both encode 30 kDa polypeptides, which differ by 14 amino acids between the two genes. These two proteins are responsible for the incompatibility reaction that results when cells containing s and S genes fuse. Inactivation of the s or S gene by disruption suppresses incompatibility but does not affect the growth or the sexual cycle of the mutant strains. This suggests that these incompatibility genes have no essential function in the life cycle of the fungus.

Induction of Ethylene Biosynthesis in Compatible and Incompatible Interactions of Soybean Roots with Phytophthora megasperma f. sp. glycinea and its Relation to Phytoalexin Accumulation

Summary Seedling roots of different varieties of soybean have been infected with various strains of the soybean pathogen Phytophthora megasperma f. sp. glycinea (Pmg), resulting in compatible and incompatible interactions. Infected roots displayed an increase in ethylene biosynthesis in all cases. Upon infection of the soybean cultivar Harosoy with Pmg race 1 or 3 or of cultivar Harosoy 63 with Pmg race 3, resulting in compatible interactions, the rate of ethylene biosynthesis started to increase ca. 6 h after infection and reached ca. 10–15-fold induction 11–12 h after inoculation. In the incompatible interaction of the soybean cultivars Maple Arrow or Harosoy 63 with Pmg race 1, however, ethylene production was stimulated 5–10-fold as early as 3 h after infection and reached its maximum, a ca. 50-fold induction, already 6 h after inoculation. Soybean roots treated with elicitor preparations from Phytophthora megasperma cell walls showed no increase in ethylene biosynthesis although they accumulated glyceollin, the main phytoalexin of soybean, to a similar degree as infected roots. Addition of 1-aminocyclopropane-1-carboxylic acid to soybean roots increased ethylene production without affecting glyceollin accumulation. We conclude that in soybean roots, an early burst of ethylene biosynthesis is a characteristic symptom of the incompatible reaction that cannot be mimicked by treatment with fungal elicitors.

Reproductive biology of the tamarillo,Cyphomandra betacea(Cav.) Sendt. (Solanaceae), and some wild relatives

Abstract Aspects of the reproductive biology of the tamarillo, Cyphomandra betacea (Cav.) Sendt., and some wild relatives, are described. Pollen of C. betacea stored atroom temperature appeared to remain viable for up to 1 week, but at 4°C was viable for several weeks. Flowers, seeds, and fruit of 10 taxa are described. Most taxa were found to be self-incompatible. All manifestations of the incompatibility reaction suggested that a gametophytic system of self-incompatibility is opemting in these species, as it does in other members of the Solanaceae. Fruit weight was significantly correlated with seed number in C. betacea.

Investigation of a self-compatible mutation in Solanum tuberosum clones inhibiting S-allele activity in pollen differentially

A self-compatible (SC) mutation, identified in dihaploid lines of Solanum tuberosum, was investigated. It has previously been proposed that this mutation arose by translocation of an S-allele (S1) to a new chromosomal location. When present in pollen grains of genotype Sx, it overcomes the incompatibility reaction normally seen on styles carrying the Sx allele. However, when present in S1-bearing pollen grains, the normal incompatibility reaction on styles carrying S1 is still observed. Using probes for the potato (S. tuberosum L.) S-linked glycoprotein (SLG) genes, it is shown that no sequence derived from SLG allele S1 can be linked to the presence of the SC mutation. The polypeptide product of the SLG allele S1 is also not detectable in SC mutant lines unless the S1 allele is also present. It is concluded that the SC mutation arose in a sequence other than that encoding the SLG S1 polypeptide, either in a part of the S-locus that is distinct from the S-gene, or at a different locus, giving rise to an inhibitor.

Transfusion of type-A and type-B blood to cats

Summary Although nearly all domestic shorthair and longhair cats have type-A blood (> 99%), the frequency of blood type B in various feline breeds ranges from 0 to 59%. All blood-type-B cats have strong natural alloantibodies, predominantly of the IgM class, whereas blood-type-A cats have low alloantibody titers of the IgG and IgM classes. We therefore studied the efficacy and safety of transfusing 20 ml of matched and mismatched 14C-potassium cyanate-labeled blood to cats. In autologous and allogeneic matched transfusions of blood-type-A and type-B cats, the half-life of labeled erythrocytes proved to be similar (29 to 39 days). In contrast, type-B erythrocytes transfused into 5 blood-type-A cats had a mean (± sd) half-life of only 2.1 ± 0.2 days and induced minor transfusion reactions. Half of the type-A blood given to 4 blood-type-B cats was destroyed within minutes to 6 hours (mean ± sd = 1.3 ± 2.3 hours), depending on the alloantibody titer. After 1 day, none of the labeled erythrocytes were detected. Mismatched transfusions in blood-type-B cats caused marked transient reactions including systemic anaphylactic signs (hypotension, bradycardia, apnea, urination, defecation, vomiting, and severe neurologic depression) and hemolytic signs (hemoglobinemia and pigmenturia) associated with severe reduction in plasma alloantibody titer and complement activity. We conclude that the rapid destruction of type-A erythrocytes transfused into blood-type-B cats predominantly occurs intravascularly and is complement- and IgM-mediated, whereas type-B erythrocytes administered to blood-type-A cats are mostly extravascularly hemolysed by a process involving small amounts of IgG and IgM, but without marked complement activation. Thus, any first or subsequent AB-mismatched transfusions are ineffective and life threatening. We therefore recommend the practice of blood typing or cross-matching prior to transfusing blood in cats to prevent any incompatibility reactions and to assure efficacy.

Mycelial Incompatibility and Molecular Markers Identify Genetic Variability in Field Populations ofSclerotinia sclerotiorum

Sixty-three sclerotial strains of Sclerotinia were obtained from transects in two fields of canola (Brassica napus) in Ontario. Mycelial pairings of the strains in all combinations on agar medium produced either an incompatible reaction in which a reaction line between the two strains developed in the interaction zone, or a compatible reaction in which no reaction line developed. The reaction line was a distinct discontinuity between the two strains, visible as a red line on the colony reverse in pairings made on medium amended with red food coloring. Among the 33 strains from the first field, six mycelial compatibility groups (MCGs) were recognized, the largest group including 19 strains (...)

TheFusarium solani-Induced Expression of a Pea Gene Family Encoding High Cysteine Content Proteins

Two pea genes, pI39 and pI230, which are specifically induced by two forma specials of Fusarium solani, encode closely related proteins with predicted molecular masses (Mr) of 8.2 and 8 kDa, respectively. Both proteins contain a signal sequence and are cleaved to mature proteins of Mr 5 kDa as indicated by an in vitro translation system. The mature proteins contain about 17% cysteine residues and have the potential to form four disulfide bonds. The two proteins share extensive homology in their signal sequences but much less homology as mature proteins. The cysteine residues of the mature proteins are highly conserved, suggesting functional importance. Southern hybridization suggests these genes belong to a multigene family. The relative accumulations of mRNA levels indicate that the two genes are expressed somewhat differentially. In both the compatible (susceptible) and incompatible reactions between F. solani and pea tissue, pI39 mRNA accumulates more slowly than pI230 mRNA and accumulates to relatively high levels after 24 hr of inoculation. The increase in accumulation of pI230 mRNA occurs within 6 hr and thus correlates with an initial suppression of the growth of both the compatible and incompatible pathogen, which is cytologically observable at 6 hr. pI39 and pI230 belong to a distinct class of pathogenesis-related proteins characterized previously, which are associated with and thus may contribute to nonhost resistance in plants.

Race-specific resistance to Xanthomonas oryzae pv. oryzae conferred by bacterial blight resistance gene Xa-10 in rice ( Oryza sativa) involves accumulation of a lignin-like substance in host tissues

When seedling leaves of rice ( Oryza sativa L.) cultivars carrying the Xa-10 gene for bacterial blight resistance were infiltrated with suspensions of cells from races 2 or 5 of Xanthomonas oryzae pv. oryzae , a rapid, race-specific incompatible reaction occurred: the leaf tissue became dark greenishbrown, and the rate of bacterial multiplication decreased compared to compatible interactions. By 48–72 h after inoculation, the affected area was dark brown. Lignin-like phenolic compounds accumulated throughout the incoulation site in the incompatible combination, beginning by 18–24 h after inoculation and reaching a maximum by 72 h. With the Xa-4 resistance gene, incompatible reactions involved localized water soaking, inhibition of lesion development, and deposition of a lignin-like polymer around the perimeter of the infiltration site. Compatible interactions between cultivars with either Xa-4 and race 2 or Xa-10 and race 1 were similar: both displayed a uniformly water-soaked, yellow-green, spreading lesion by 24–48 h after inoculation. Lignin-like substances were detected by 96–120 h following inoculation and were limited to the perimeter of the infiltration site. Infiltration of cultivars containing the Xa-10 gene with water or UV-killed bacteria elicited no responses. The phenotypes conferred by resistance genes Xa-4 and Xa-10 were distinguished rapidly by histological reactions.

Acute Hemolytic Transfusion Reaction in an Abyssinian Cat With Blood Type B

After receiving a transfusion with unmatched blood, an anemic Abyssinian cat developed an acute hemolytic transfusion reaction. Similar to many other purebred cats, the recipient had type B blood with strong serum anti-A alloantibodies, whereas the donor had blood type A. Subsequent transfusions with type B blood proved effective and without adverse reactions. This case of a clinical A-B incompatibility reaction emphasizes the need for blood typing and/or crossmatching prior to transfusing cats.

Self‐Incompatibility in Papaver rhoeas L.: inhibition of incompatible pollen tube growth is dependent on pollen gene expression

summaryIn order to gain an insight into the cellular activities which lead to the inhibition of pollen tube growth following a self‐incompatible response, we have been studying the effects of various metabolic inhibitors on pollen–stigmatic extract interactions in vitro. The results indicate that both transcription and glycosylation are required for the full inhibition of pollen tube growth during an incompatible response in Papaver rhoeas. The ability of actinomycin D to partially alleviate an incompatible reaction suggests that during the response, pollen gene expression is induced; we have found that this is indeed the case and have identified novel proteins produced in the pollen which are associated with the incompatibility response. These findings give a clear indication that de novo transcription of pollen genes which are specific to this response, play an important role in the inhibition of pollen tube growth in this species. This provides a significant step towards the elucidation of the mechanism whereby pollen tube growth is arrested following an incompatible reaction in this species.

Mycelial interactions in Sclerotinia sclerotiorum

Mycelial interactions were examined among 35 isolates of Sclerotinia sclerotiorum and two Asian species, Sclerotinia asari and an unnamed, Japanese species. Pairings were scored as compatible when strains merged to form one colony and incompatible when strains grew to form two distinct colonies. Incompatible mycelial pairings resulted in an interaction zone in which a distinct reaction line and abundant aerial mycelium or thin mycelium were observed with some variation among replicates. All pairings of a strain with itself were compatible. Of the 31 strains of S. sclerotiorum tested, 21 were mycelially incompatible with all others. Among the remaining 10 strains of S. sclerotiorum, there were four mycelial compatibility groups consisting of two or three strains each. Pairings of S. asari with all other strains resulted in a unique incompatible reaction, a mycelium-free interaction zone. Two of three strains of the Japanese species were intercompatible, but pairings of each of the three strains with all other strains were incompatible. Microscopically, mycelial interactions in pairings of strains were complex. Anastomosis between paired strains was not always observed. This may be due in part to the conversion of many hyphal tips, in both compatible and incompatible interactions, to sites of microconidiogenesis no longer capable of hyphal fusion. Incompatible pairings were followed by hyphal deterioration in one or both strains; hyphal deterioration was not observed in compatible interactions. Of the 31 strains tested, 4 strains of S. sclerotiorum produced apothecia. Pairings between single ascospore isolates within each strain were compatible, as were pairings with the parent isolate. Mycelial interactions of single ascospore isolates with other strains were identical to those of the parent isolate, indicating that the parent fruitbody was homozygous for any determinant(s) of mycelial incompatibility. The data from this study suggest that a high level of mycelial incompatibility exists among strains of S. sclerotiorum, comparable to levels of vegetative incompatibility reported in other ascomycetes, that the extent of mycelial incompatibility indicates that genetic heterogeneity exists within the species, and that mycelial compatibility/incompatibility reactions may be an effective way of categorizing intraspecific heterogeneity.

Ferrous sulfate combined with ascorbic acid does not significantly reduce acetaldehyde accumulation in the blood of alcoholized rats treated with disulfiram or betalactam antibiotics

Adult female SPF Sprague-Dawley rats treated orally by gavage with disulfiram (1 g/kg b.wt.) or betalactam antibiotics (3.38 mmol/kg b.wt.) with a 1-methyltetrazole-5-thiol side chain (cefmenoxime, latamoxef, cefotetan, cefoperazone, cefamandole) produced a marked, statistically significant rise of acetaldehyde in the blood 1 and 3 hr following IP administration of ethanol [2 g/kg b.wt., 20% (g/v) solution]. This accumulation of blood acetaldehyde remained unchanged or was reduced only very slightly by a mixture of iron sulfate [Fe(II)SO 4·7H 2O, 2.64 mg/kg b.wt.] and ascorbic acid (6.67 mg/kg b.wt.) injected intravenously. This slight decrease is considered to be due to a formation of a complex between ferrous sulfate and agents (disulfiram and the betalactam antibiotics as well as their metabolites) producing acetaldehyde by inhibition of acetaldehyde metabolizing enzymes. A possible coaction of ascorbic acid cannot be explained satisfactorily; ascorbic acid may support cellular redox potentials. The combination of ferrous sulfate and ascorbic acid was used for examination since both chemicals are recommended to reduce adverse symptoms of an ethanol incompatibility reaction in the course of a therapy with the mentioned antibiotics or disulfiram. Since acetaldehyde augmentation in the blood is regarded as a cause of complaints and because the acetaldehyde rise was not depressed significantly by ferrous sulfate and ascorbic acid it can be concluded that these two agents are not potent enough for a rational therapy of ethanol incompatibility symptoms initiated by the investigated drugs.

The progamic phase in Cichorium intybus L. Pollen tube growth in the style, incompatibility reaction and gametophytic competition

Pollen germination and tube growth were studied following compatible, incompatible and pseudo-compatible pollinations in chicory. Pollen germination begins 3 minutes after compatible pollinations. The earliest pollen tubes reach the ovary 17 minutes later. Many of the later germinating pollen tubes are arrested and burst at the stigma papillae. In the transmitting tissue inhibitional effects due to negative interactions between pollen tubes are frequently observed. Complete self-incompatibility results in total inhibition of germination. In case of pseudo-self-compatibility, some pollen germinate but germination and stigma penetration are delayed and often result in pollen bursting. There is no self-incompatibility reaction in the transmitting tract but if the pollen tubes reaching this tissue are relatively numerous, negative interactions between them occur as after compatible pollinations. An hypothesis is presented which attributes the negative interactions between pollen tubes to the diffusion of a substance from the growing pollen tubes. This substance would also provoke pollen bursting on the stigma.

Incompatibility in Dendrobium (Orchidaceae)

A unique self-incompatibility system in Dendrobium is demonstrated by more than 1700 pollination experiments. The majority (72%) of the 61 species that were self-pollinated showed self-sterility. In contrast with many other orchid genera Dendrobium showed high incompatibility in interspecific pollinations. Self-and interspecific incompatibility is expressed by flower abscission and not by inhibition of pollen germination or pollen tube growth. The incompatibility system is gametophytic and complementary, and it is likely that the auxin content in the pollinia triggers the incompatibility reaction. Microscopical investigations on the detached cells of the stigma (here called eleutherocytes) after compatible and incompatible pollinations, suggest that the incompatibility response is probably controlled by these cells.

Mating type and mating strategies in Neurospora

In the heterothallic species Neurospora crassa, strains of opposite mating type, A and a, must interact to give the series of events resulting in fruiting body formation, meiosis, and the generation of dormant ascospores. The mating type of a strain is specified by the DNA sequence it carries in the mating type region; strains that are otherwise isogenic can mate and produce ascospores. The DNA of the A and a regions have completely dissimilar sequences. Probing DNA from strains of each mating type with labelled sequences from the A and the a regions has shown that, unlike in Saccharomyces cerevisiae, only a single copy of a mating type sequence is present in a haploid genome. The failure to switch is explainable by the physical absence of DNA sequences characteristic of the opposite mating type. While the mating type sequences must be of the opposite kind for mating to occur in the sexual cycle, two strains of opposite mating type cannot form a stable heterokaryon during vegetative growth; instead, they fuse abortively to give a heterokaryon incompatibility reaction, which results in death of the cells along the fusion line. The DNA sequences responsible for this reaction are coextensive with those sequences in the A and a regions which are necessary to initiate fruiting body formation. The genus Neurospora also includes homothallic species--ones in which a single haploid nucleus carries all the information necessary to form fruiting bodies, undergo meiosis, and produce new haploid spores. One such species, N. terricola, contains one copy each of the A and the a sequences within each haploid genome.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of hypersensitive cell collapse: correlation of increased lipoxygenase activity with membrane damage in leaves of Phaseolus vulgaris (L) inoculated with an avirulent race of Pseudomonas syringae pv. phaseolicola

Increases in lipolytic acyl hydrolase and lipoxygenase isoenzyme activities in leaves of Phaseolus vulgaris (L.) cv. Red Mexican during the incompatible reaction to Pseudomonas syringae pv. phaseolicola race 1 cells coincided with electrolyte leakage characteristic of the early stages of the hypersensitive response. Increase in lipoxygenase activity was inhibited by cycloheximide. Evolution of ethane indicated that membrane-lipid peroxidation had occurred in vivo. Superoxide dismutase (SOD) and peroxidase (POX) activities also increased in the incompatible combination, but at 12 h after inoculation, somewhat later than lipoxygenase. It is possible that SOD and POX were induced as a protective response of the cells against active oxygen species produced as a consequence of lipoxygenase action. The role of lipoxygenase in initiating processes that lead to hypersensitive cell death is discussed.

Time-course alteration of lipoxygenase activity in blast-infected rice leaves.

To reveal the relationship between the resistance to rice blast disease on rice plants and the amount of oxygenated C-18 unsaturated fatty acids isolated from rice plant as anti-blast substances, the change of the activity of lipoxygenase (LOX) which participates in the synthesis of these compounds in rice leaves was investigated. Although LOX activity in rice leaves was sensitive to the water-spraying resulted in a little increment, it has been clearly and largely enhanced by blast infection. The pattern of change in LOX activity with days after inoculation depended on the combination of rice cultivar and the race of rice blast fungus. In rice leaves shown incompatible reaction, LOX activity increased rapidly from the first day of spray-inoculation and reached to the maximum two or three days after, and declined thereafter. In the compatible combination, the highest activity was observed seven days after inoculation, although LOX activity rose temporarily in two or three days. Rice cultivars having higher level of field resistance showed higher LOX activity than that with low level of it. In addition, LOX activity in mature leaves was also greater than that of the just expanded young leaves of all cultivars examined.

Interspecific incompatibility due to stylar barriers in tuber-bearing and closely related non-tuber-bearing Solanums

The phenomenon of interspecific incompatibility between various wild tuber-bearing and closely related non-tuber-bearing Solanum species was studied. One area of investigation included an examination of possible protein interactions in the incompatibility reaction using SDS electrophoresis. Pollen tube inhibition and morphology were examined in conjunction with biochemical analysis. Two sets of crosses were examined: interspecific tuber-bearing species crosses and interspecific tuber-bearing × non-tuber-bearing species crosses. These crosses had consistent pollen tube inhibition in the upper one-third of the style. The upper third of the styles of incompatibly pollinated, compatibly pollinated, and unpollinated styles was studied under fluorescence microscopy to observe pollen tube growth and morphology. Interspecific tuber-bearing × non-tuber-bearing species crosses demonstrated consistent pollen tube inhibition just below the stigma with frequent pollen tube swelling and bursting and extensive callose deposition along the pollen tube wall. Interspecific tuber-bearing species crosses had pollen tube inhibition further down the style with pollen tube tip tapering and extensive callose deposition. Stylar proteins of the lower two-thirds of the styles were analyzed with SDS electrophoresis. No unique protein differences were found to be specifically associated with the interspecific incompatibility reaction in this portion of the style.

The Importance of a2-Antiplasmin in the Defibrination Syndrome

Two coagulation abnormalities may result in a marked decrease in plasma fibrinogen caused by prominent defibrination. The two conditions that cause defibrination with a bleeding diathesis are disseminated intravascular coagulation (DIC) and primary fibrinogenolysis (PF).1 Various conditions may be associated with DIC. These include serious infections; complications of pregnancy, such as abruptio placentae or toxemia (PIH); malignancy, such as carcinomas or acute promyelocytic leukemia; marked tissue injury, such as brain injury and incompatible hemolytic transfusion reaction; and venomous snakebite. The cause of PF differs from DIC. Primary fibrinogenolysis is associated with cirrhosis, since the liver normally removes plasminogen activator from the circulation. Other conditions associated with PF are extensive cardiovascular or pulmonary surgery and metastatic carcinoma of the prostate, releasing plasminogen activator into the circulation. The recent utilization of tissue plasminogen activator to cause thrombolysis of coronary artery and cerebral artery thrombi causes local fibrinogenolysis. The laboratory parameters used

Allelic Composition of Cotton at the Le1 and Le2 Loci.

Cotton (Gossypium spp.) zygotes bearing a Le2dav allelle in combination with Le1 and/or Le2 undergo a physiological reaction resulting in embryo or seedling in viability. All F1 hybrids between cultivated tetraploid cotton (G. hirsutum L. and G. barbadense L., 2n = 4x = 52) and a Le2dav homozygote are inviable. A breeding procedure being developed for mass extraction of doubled haploids of cotton relies on the “bio‐elimination” of F1 hybrids by this complementary lethal system. Success is contingent on the absence of le1le2 gametes from a prospective parent because these alleles are fully compatible with Le2dav. The primary objective of this research was to determine the frequency of le1 and le2 in a representative sample of USA‐developed G. hirsutum cultivars. A secondary objective was to determine if the timing of the incompatibility reaction was consistent across genetic backgrounds. Fifty‐two cultivars were tested by observing the frequencies of nonviable vs. viable progeny and the timing of necrosis following two types of matings: (i) cultivar ✕ le1le1Le2davLe2dav and (ii) (cultivar ✕ le1le1le2le2) ✕ le1le1Le2davLe2dav. All 52 cultivars were found to be Le1Le1Le2Le2, indicating that the frequencies of alleles le1 and le2 are zero, or nearly so, in USA‐developed G. hirsutum germplasm. Results on necrotic development indicated that the cumulative dosage of alleles Le1 and Le2 affected the onset of necrosis in the presence of Le2dav. Because alleles le1 and le2 are rare in American upland cottons, the doubled‐haploid breeding system will be applicable to these stocks.