Self-incompatibility in Spanish clones of apricot (Prunus armeniaca L.) tree

The present study is about some aspects of the reproduction physiology of twenty apricot clones ( Prunus armeniaca L.) grown in Abarán (Murcia, Spain). Self incompatibility of these clones was determined not only in field conditions in terms of the fruit set by means of self fertilization and free pollination, but also in laboratory conditions, by means of fluorescence microscopy of pollen germination on the stigma and of the growth of the pollen tube towards the egg. The only clone with signs of self incompatibility was ‘Moniquí Azaraque’. The clone with the lowest fertilization time was ‘Chicanos Archena’. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Compatibility and incompatibility in witloof-chicory (Cichorium intybus L.). 1. The influence of temperature and plant age on pollen germination and seed production

Summary For the production of inbred lines and F₁ hybrids in witloof-chicory information is wanted on characteristics such as the incompatibility system. These characteristics can only be studied properly if the influence of temperature and physiological status of the plant on pollen germination and seed production is known. Investigations were carried out with 9 self-incompatible (SI) and 6 self-compatible (SC) clones in glasshouses of the IVT phytotron at constant temperatures of 10, 14, 17, 20, 23 and 26°C. In general, in vivo pollen germination percentages were rather low after self pollination with an optimum for germination around 17–20°C. No seeds were formed at the lowest temperature (10°C) while seed production for SC clones was usually (rather) good at higher temperatures. At 26°C seed production in some clones decreased. Both pollen germination and seed production decreased at the end of the flowering period. There was a rather positive relationship at e.g. 17 and 20°C between pollen germination after selfing and seed production. When no pollen germination was observed, no seed formation occurred. When pollen grains did germinate, seed development would not necessarily occur in all cases. So this relationship only enables negative mass selection for SC.     

Selection for seed set capacity uncorrelated with flower heteromorphism in Primula vulgaris Hudson

Within-line pollinations were used when measuring the seed set of plants from seven early generation inbred lines of Primula vulgaris. One high seed setting plant and one low seed setting one were selected from each line and the seed set was evaluated on the offspring from selfings and within-line pollinations of these plants. Regression of offspring on parents for seed set was studied. The slope was estimated to be 0.17 ± 0.08, equivalent to an estimated heritability of around 34%. No significant differences in the slope of regression between the two reproduction methods (selfings or within-line pollinations) were detected. The realized improvement through one cycle of selection of high seed setting single plants in this early generation inbred material of P. vulgaris was 23.7%. Analysis of the seed set of within-line pollinated clones from late generation inbred lines of P. vulgaris revealed that only limited within-line variation remained after removal of the effects of the heteromorphic incompatibility system. It was concluded that selection of high seed setting single plants during early generations of inbreeding is efficient for improvement of seed set in future inbred lines of P. vulgaris to be used for hybrid seed production.     

Identification of cherry incompatibility alleles by microarray

We have developed a microarray for identification of sweet cherry incompatibility alleles. Using intron sequence information of the S-RNase gene, we have created a microarray chip that allows the specific recognition of the incompatibility alleles present in a cultivar. Most of the probes designed showed high specificity towards their alleles. In the original set of probes, cross-hybridization was observed between a few alleles with high sequence similarity. As our identification system is based on the combined hybridization information from both introns, we were able to identify false positive and unspecific probes which could be eliminated from our microarray. The optimized microarray was tested on cultivars with known alleles. The chip correctly identified all alleles tested. Furthermore, it was also possible to identify alleles in other cultivars where, so far, only one allele has been determined and also to determine in sour cherry the alleles originating from the sweet cherry parent. Our results demonstrate the great promise of microarray technology for this novel application.     

The ovular incompatibility system in Gasteria verrucosa (Mill.) H. Duval

Summary The nature and process of ovular incompatibility in Gasteria verrucosa was studied. Using different crossing programs and following the pollen germination and ovule penetration histochemically, an ovular gametophitic incompatibility system based on two or more loci is affirmed. Pollen tubes after self-and cross-pollination penetrate the micropyle. Although the percentage of seed setting reached about 60% after cross pollination no clear differences could be seen between the germination and ovule penetration of cross and self pollen.In the ovules, multiple penetration of micropyles and a preference for the first position ovules was observed. Results of semi-compatible crossings and mixed crossings indicated a gametophytic two or more loci incompatibility system. Ovular incompatibility was manifested by the degeneration of the sporophytic ovular tissues. In Gasteria verrucosa the system of ovular incompatibility does not seem to be restricted to the ovule.     

Determination of self-incompatible genotypes in sweet cherry (Prunus avium L.) accessions and cultivars of the German Fruit Gene Bank and from private collections

Sweet cherries are self-incompatible because of a gametophytic self-incompatibility system. S alleles in the style and pollen determine the crossing relationships. Knowledge of the S allele constitution of cultivars is very important for cherry growers and breeders, and recently, molecular methods have been developed to distinguish the S alleles in sweet cherries. The S allele genotypes of 149 sweet cherry cultivars and clones, including 126 not previously genotyped, were determined by using PCR analysis. Thirteen different S alleles in 40 combinations were distinguished and nine new incompatibility groups were documented. Two new S alleles were identified in five local sweet cherry processing cultivars from southwestern Germany using the second intron primers. The sequence of these alleles was determined and compared to all known sequences available in the NCBI database. The sequences obtained showed high similarities to the alleles S ₁₉ and S ₂₂, previously described only in wild cherries, Prunus avium L.     

Early generation selection for potato tuber quality in progenies of late blight resistant parents

Developing disease resistant cultivars is one of the major objectives for a potato (Solanum tuberosum L.) breeding program, but many resistant clones have not achieved commercial acceptance because of late maturity and non-marketable tuber characteristics. Selection for tuber quality should have greater emphasis inbreeding disease resistant cultivars. The objectives of this study were 1) to evaluate the ability of late blight (Phytophthora infestans (Mont.) de Bary) resistant parents to transmit chip-processing (tuber appearance, specificgravity, and chip-color) or tablestock (tuber appearance) quality to the offspring and 2) to compare selecting for tuber quality in single-hill versus eight-hill generations. We made crosses among eight unadapted potato cultivars (B0718-3,Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan, and Zarevo) with reported late blight resistance with adapted susceptible cultivars/breeding clones to generate 95populations (4,750 seedlings). Approximately 10% of the progeny from each cross were selected from single-hill plots based on tuber appearance, number, shape, and internal defects. These selected clones (408) were evaluated for tuber appearance, specific gravity, and chip-color. The same evaluations in the following year were made on tuber samples from eight-hill plots. Libertas and Tollocan were the best parents for transmitting chip-color; B0718-3, Zarevo, and Tollocan for transmitting tuber appearance; and Bzura, Libertas, and Zarevo for transmitting high specific gravity to the highest percentage of the offspring. Overall, 50% and 56% of the clones based on single- and eight-hill generation, respectively, were considered to possess chip-processing quality; over 90% of the clones had acceptable tablestock quality. A total of 71% of the clones possessing acceptable chip-processing and 95% of the clones possessing acceptable tablestock quality selected in both generations were identified in single-hill plots. The evaluation of tuber quality characteristics in single-hill generation not only permitted the identification of clones with acceptable chip-processing and tablestock, but also increased the amount of clonal information for the following generation of selection. In crosses between late blight resistant and susceptible clones, selection for tuber quality traits can be initiated in single-hill generation using a moderate selection intensity and precede late blight testing. This revised version was published online in August 2006 with corrections to the Cover Date.     

Validation of two models for self‐incompatibility in autotetraploid perennial ryegrass using high resolution melting‐based markers

Perennial ryegrass (Lolium perenne L.) displays a two‐locus gametophytic self‐incompatibility (SI) system that remains intact at the tetraploid level. Two models are plausible for SI in autotetraploids. In Model I: both alleles at the S locus and both at the Z locus in diploid pollen matching the female genotype results in incompatibility. In Model II: only one allele at S and one at Z locus in diploid pollen matching the female results in incompatibility. The goals were to determine which of the models best explains SI in our autotetraploid ryegrass population and to evaluate the efficiency of high‐resolution melting (HRM) genotyping for discriminating different iso‐allelic genotypes. The progeny of a cross between two autotetraploids was characterized with three HRM‐based markers co‐segregating with Z. Segregation ratios were used to make inferences about the mode of action of the SI system. The observed segregation differed significantly (P < 0.001) from the expected under Model I, but not from the expected under Model II (P = 0.463). Thus, Model II explains SI in this population, and HRM is an efficient tool to distinguish different iso‐allelic genotypic classes.     

Fast and reliable strawberry cultivar identification using inter simple sequence repeat (ISSR) amplification

ISSR amplification was evaluated for its applicability to strawberry varietalidentification. Eighteen primers based on various di- tri- or tetra- SSR motifswith 3 or 0 5'-selective nucleotides for anchoring were screened against thestrawberry genome by agarose gel electrophoresis. PCR conditions wereoptimised to obtain high quality patterns. Five primers that gave informativepatterns were selected and used to characterise, by polyacrylamide gelelectrophoresis, 30 strawberry varieties of various geographic and geneticorigins. A total of 390 bands, 113 of which were polymorphic (30%),were generated using these five primers. Genetic similarity between varietieswas estimated using Jaccard's coefficient of similarity. The associationsbetween varieties revealed by UPGMA analysis were consistent withpedigree data. With only one primer, all the varieties were distinguishedincluding those with a common pedigree. Banding patterns were highlyreproducible for DNA samples extracted from different tissues (leaves,sepals, and rhizomes) of the same plant, or from different plants (clones)of the same variety. ISSR technique is therefore a potentially useful tool forthe identification of strawberry varieties because it is simple, fast,cost-effective, highly discriminant and highly reliable.     

The effect of alternating temperatures on the self-incompatibility of some clones of Brussels sprouts (Brassica oleracea L. var. Gemmifera (DC.) Schulz)

Summary The influence of temperature on self-incompatibility of six S-homozygous clones of Brussels sprouts was studied. The clones were treated with constant temperatures of 14°, 17° and 20°C and alternating day and night temperatures of 17/14°, 20/14°, 23/14° and 26/14°C. To determine the degree of incompatibility the mean number of pollen tubes per style after selfing was calculated.The clone with the weak S-allele S-5 was less self-incompatible in the 23/14° and 26/14°C treatments than in the other treatments. The other clones with the weak S-alleles S-15 and S-45 remained sufficiently self-incompatible during all treatments. The clone with the rather strong S-39 showed the highest level of self-incompatibility at 26/14°C.In the two weakly self-incompatible clones with S-5 and S-39 a clear difference in self-incompatibility was found between young and old flowers. The strongly SI clones with S-39 showed no difference and in the two clones with S-15 the differences were small and significant in one case only.     

Self-incompatibility genotype identification and stability as influenced by inbreeding in red clover (Trifolium pratense L.)

Summary S allele genotypes of I₁ progenies from eight I₀ red clover (Trifolium pratense L.) clones were determined under isolated field conditions. Each I₁ progeny was vegetatively increased and isolated under a cage for pollination by honey bees. Clones within each I₁ progeny producing relatively large and small amounts of seed were classified homozygous and heterozygous, respectively, for S allele genotype. S allele genotypes were verified by extensive sib crosses in the greenhouse, and almost complete agreement was found with the field classification. I₂ progenies were reciprocally test-crossed with their parental I₀ clones to detect any changes in S specificity and also to confirm the previous S genotype classifications in the I₁ generation. It was concluded that the reliability of field and greenhouse sib classification of S genotypes is based on the strength of the incompatibility reaction in each particular clone. Most I₁'s showed a strong incompatibility reaction as evidenced by low seed set for heterozygous S genotypes, but one progeny showed a weak incompatibility reaction which resulted in S genotype misclassifications. An S specificity was changed in one I₂ progeny.Contribution from the Kentucky Agricultural Experiment Station. This paper (72-3-151) is published with the approval of the Director, Kentucky Agricultural Experiment Station, Lexington, Kentucky 40506, USA.     

Application of the concepts of test value and varietal value to the study of genetic advance in recurrent selection: A synthesis

Summary The concepts of varietal ability and value in test of a genotype or group of genotypes are specified according to the type of variety (clones, hybrids, lines, synthetics) and the testing system (phenotype, S₁, General combining ability (GCA), line value, General synthesizing ability (GSA)). Varietal ability and value in test are to be considered as any quantitative characters for which it is possible to define additive effects, dominance effects and epistasis. For diploids in recurrent selection, only additive effects and additive× additive epistasis for varietal value contribute to genetic advance. Genetic advance depends on the covariance between the testing value of the parents and the test value of the progeny by intercrossing. Such a parent-offspring covariance is, in the absence of epistasis and inbreeding, one half of the covariance between additive effects in test of the parents and additive effects in test of their progenies. This allows one to express directly the genetic advance in varietal value according to the type of variety and to the testing system used in recurrent selection. The case of biallelic populations is considered; it allows some discussions on the relative values of components of variance of varietal and test values.     

Compatibility and incompatibility in witloof-chicory (Cichorium intybus L.). 2. The incompatibility system

Summary In witloof-chicory fertilization is frequently prevented by the action of an incompatibility mechanism. In two experiments the incompatibility system was investigated. In the IVT phytotron at a constant temperature of 17 C reciprocal crosses were made between unrelated plants followed by diallel crosses between the F1 plants and backcrosses with the parents.Analyses of the results of the above crosses strongly suggest that in witloof-chicory a one locus sporophytic incompatibility system occurs with different dominance and codominance relationships between S-alleles in pollen and style.     

山东地区乳房炎和非乳房炎牛奶中金黄色葡萄球菌的分离鉴定与耐药分析

为了解山东地区不同类型牛奶中金黄色葡萄球菌流行情况和耐药特征,对37个牧场的乳房炎和非乳房炎奶样进行细菌分离鉴定及MIC测定试验。采用常规方法与PCR技术进行金黄色葡萄球菌的分离鉴定,微量肉汤稀释法进行MIC测定,卡方检验进行数据差异显著性分析。①共分离到150株金黄色葡萄球菌,检出率为11.26%(150/1332),且乳房炎奶样显著高于非乳房炎(P=0.009);②12种药物的MIC与EUCAST分布趋势大致相同;③分离菌株对青霉素(91.38%)耐药最严重,且乳房炎/非乳房炎奶样差异显著(P=0.047);④116株分离菌株中多重耐药(≥3)菌株为34(29.31%)株,乳房炎/非乳房炎奶样差异不显著(P=0.611);⑤威海对6种药物的耐药率在60%以上,其他地区仅对1~2种药物的耐药率在50%以上。乳房炎奶样的金黄色葡萄球菌检出率显著高于非乳房炎;分离菌株对青霉素严重耐药且乳房炎奶样多重耐药问题突出;不同地区均呈现不同程度的耐药。     

新疆野扁桃自交不亲和SFB与S-RNase蛋白间相互作用的研究

利用酵母双杂交系统研究新疆野扁桃自交不亲和性花粉SFB蛋白与花柱S-RNase蛋白间的相互作用。以野扁桃花药为实验材料,根据实验要求和基因的结构特点,利用已克隆到的SFB和S-RNase基因,有针对性的截短,构建酵母双杂交载体。研究结果显示,成功构建了酵母双杂交重组表达载体,PtSFB17、PtS16-RNase和PtS17-RNase各蛋白之间并没有发现存在相互作用,据此推测PtS16-RNase蛋白和PtS17-RNase蛋白不在PtSFB17蛋白的识别谱中,协同非我识别模型在新疆野扁桃中同样存在。新疆野扁桃自交不亲和性PtSFB17、PtS16-RNase和PtS17-RNase各蛋白间并无相互作用。     

Half-sib progeny evaluation and selection of potatoes resistant to the US8 genotype of Phytophthora infestans from crosses between resistant and susceptible parents

The objectives of this study were to evaluate the use of potato (Solanum tuberosum L.) late blight (Phytophthora infestans (Mont.) de Bary) resistant parents in cultivar development and identify superior clones possessing moderate to high late blight resistance combined with acceptable maturity and tuber quality. Ninety-five crosses were made between eight unadapted parents with reported late blight resistance (B0718-3, Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan and Zarevo) and susceptible parents (cultivars or advanced breeding clones) adapted to North American growing conditions. A total of 408 field selected clones were assessed for late blight resistance in the greenhouse and in the field using a mixture of US8 P. infestans isolates (A2 mating type, metalaxyl resistant) that overcame all known R-genes except R8 and R9. Clones with ≤ 10% infected foliar area in the greenhouse test or ≤ 0.30 RAUDPC (relative area under the disease progress curve) value in the field in 1998 were re-tested in 1999. A total of 118 (29% of 408) putative late blight resistant clones were selected. The eight late blight resistant parents differed in both the ability to transmit late blight resistance and in the level of resistance transmitted to the progeny. The Tollocan and B0718-3 families (half-sib progeny) had the greatest degree of resistance and frequency of resistant clones. Scott-Knott cluster analysis ranked 79 clones (67% of 118) in the high and moderate late blight resistant groups. Among these 79 clones, 19 clones had vine maturity equal to or earlier than mid-season combined with acceptable tuber quality. Further selection in 2000 resulted in eight advanced selected clones (six from Tollocan and two from B0718-3 families) with the same level of resistance as the parent combined with vine maturity and tuber quality equivalent to Atlantic, a standard cultivar for chip processing in North America. The results indicate that this breeding approach can be used to select parents for late blight resistance breeding and to identify superior clones with high levels of late blight resistance and marketable vine maturity and tuber quality. This revised version was published online in July 2006 with corrections to the Cover Date.     

Exploitation of the incompatibility mechanism for the production of F1 hybrid forage grasses

Summary The utility of the two locus (SZ) incompatibility system for the production of F₁ hybrids in forage grasses is examined in relation to its mode of action at the tetraploid level and in dihaploids. Schemes are proposed for producing tetraploid populations with a high level of within population incompatibility or of single or double cross hybrids from the dihaploids.     

Inheritance of anther-culture response in perennial ryegrass (Lolium perenne L.)

Genetic control of the capacity to respond to anther culture in perennial ryegrass was studied in F₁ offspring from crosses between 11 clones selected for anther-culture response (‘inducers’) and 10 clones selected from breeding material on the basis of good agronomic performance. Large differences in anther-culture response were observed between the two types of parent, with inducer clones producing an average of 10.7 green plants per 100 anthers, compared with only 0.3 for breeding clones. Hybrid populations produced an average of 2.2 green plants per 100 plated anthers, which is 7.3 times the response of the breeding material. This improvement was mainly due to a 9.4-fold increase in the percentage of green plants regenerated from hybrid populations to 4.7% compared to an average of 0.5% from breeding clones. Most of the GCA (general combining ability) in the experiment was contributed by the breeding material, constituting 55.8, 100.0 and 36.7% of genetic variation among hybrids for embryo formation, regeneration and green plant percentage, respectively. Any remaining genetic variation among hybrids was predominantly due to SCA (specific combining ability) effects, with percentages of 44.2 and 63.3%, respectively, for embryo and green plant formation. These results are discussed with respect to the possible exploitation of genes controlling anther-culture response for haploid production in breeding programmes of perennial ryegrass.