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.     

Sequence of the S 9-RNase cDNA and PCR-RFLP system for discriminating S 1- to S 9-allele in Japanese pear

A new S ₉-allele was discovered in 6 Japanese pear cultivars, ‘Shinkou’, ‘Shinsei’, ‘Niitaka’, ‘Amanogawa’, ‘Nangetsu’ and ‘Nansui’. cDNA encoding S ₉-RNase, a stylar product of S ₉-allele, was cloned from pistils of ‘Shinkou’ and ‘Shinsei’ by 3' and 5' RACE. The S ₉-RNase gene had an open reading frame of 684 nucleotides encoding 228 amino acid residues. S ₉-RNase had a hypervariable (HV) region different from S ₁- to S ₈-RNase and shared higher similarity (95.2%) with apple S ₃-RNase than with 8 Japanese pear S-RNases (from 61.0% to 70.7%). Genomic PCR with primers ‘FTQQYQ’ and ‘anti-(I/T) IWPNV’ provided S ₁- to S ₉-amplicon (product), but could not discriminate the S ₂ from the S ₉ of ca. 1.3 kb. The S ₂ and S ₉ were distinguished by digestion with AflII and BstBI, respectively. The digestion with nine S-allele-specific restriction endonucleases, SfcI, AflII, PpuMI, NdeI,AlwNI, HincII, AccII, NruI and BstBI, distinguished S ₁ to S ₉, establishing that this PCR-RFLP system is useful for S-genotype assignments in Japanese pear harboring S ₁- to S ₉-allele. ‘Shinkou’, ‘Shinsei’, ‘Nangetsu’ and ‘Nansui’ assigned as S ₄ S ₉ were determined to be cross incompatible. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Identification of self-incompatibility (S) alleles in Latvian and Swedish sweet cherry genetic resources collections by PCR based typing

The Latvian and the Swedish sweet cherry (Prunus avium L.) genetic resources collections comprise valuable material for breeding. The collections represent local Latvian and Scandinavian genetic resources: semi-wild samples, landraces, and cultivars developed in local breeding programmes, as well as diverse germplasm from the northern temperate zone. The objective of this investigation was to determine which S ₁ –S ₆ alleles are most important in the sweet cherry genetic resources collections and to compare the identified allelic and genotypic frequencies in material of different origin. Accessions in the two collections were screened for the presence of the self-incompatibility (S) S ₁ to S ₆ alleles, using PCR based typing. Significant differences (P < 0.05) between screened collections were found in frequencies of S ₄ and S ₅ alleles. Analysis of allele combinations identified the high occurrence of selections with the S-genotype S ₃ S ₆ in both collections. Compared to the S-allele frequencies published for over 250 sweet cherry cultivars from Western and Southern Europe, the Latvian and Swedish germplasm appeared to have a high frequency of the S ₆ allele in both collections, and a relatively high frequency of the S ₅ allele in Latvian germplasm. This study represents the first comprehensive S-allele screening for the sweet cherry genetic resources collections in Latvia and Sweden. Both sweet cherry collections contain high proportion of accessions adapted to north central European growing conditions, not typical for the majority of the documented sweet cherry genetic resources, which explains differences in certain S-allele occurrence.     

Monogenic resistance in tomato to Fusarium oxysporum f. sp. lycopersici race 3

Summary Resistance to fusarium wilt, incited by Fusarium oxysporum (Schlecht.) f. sp. lycopersici (Sacc.) Snyder & Hansen race 3 in tomato (Lycopersicon esculentum Mill.) was discovered in LA 716, a L. pennellii accession. A resistant BC₁F₃ breeding line, E427, was developed from LA 716. E427 was crossed with the susceptible cv. Suncoast and F₁, BCP₁, BCP₂ (to Fla 7155, a susceptible parent) F₂, F₃, and BCP₂S₁ seeds were obtained. Segregation for resistance following root dip inoculation over three experiments indicated a single dominant gene controlled resistance. Five of the 12 BCP₁S₁'s segregated more susceptible plants, whereas one of the 12 segregated more resistant plants than expected (P<0.05). Three of 23 F₃ lines segregated more susceptible plants than expected while 1 of the 23 had more resistant plants than expected (P<0.05). Segregation in all other lines fit expected ratios. Five of the 23 F₃'s were homozygous resistant which was an acceptable fit to expectations (P=0.1–0.5). The gene symbol I ₃ is proposed for resistance to race 3 of the wilt pathogen. Deviations from expected ratios in data reported here and for other breeding lines indicate an effect of modifier genes and/or incomplete penetrance. Plant age at inoculation and seed dormancy did not affect results.Florida Agricultural Experiment Station Journal Series No. 8101.     

Identification of self-incompatibility alleles and pollen incompatibility groups in sweet cherry by PCR based s-allele typing and controlled pollination

A total of 17 pollen incompatibility groups in sweet cherry (Prunusavium L.) were identified among 46 accessions by PCR based S-alleletyping analysis and by controlled test pollinations. Two putativeS-alleles different from S ₁ to S ₆,S _z and S _y were identified. Five S-genotypes, S ₁ S ₅, S ₁ S ₆,S ₂ S ₆, S ₄ S ₆, andS ₅ S ₆, combinations of S ₁ toS ₆ alleles that had not previously been identified from cultivars in NYSAES, were positively confirmed by PCR based S-genotyping analysis. Also, the S-genotypes of cultivars in some pollen incompatibility groups that had previously been incorrectly reported have been clarified. Several popular cultivars, which were previously used as testers for S-allele typing analysis, were found to have been inaccurately genotyped. In addition, the S-genotypes and self-incompatibility groups of some relatively recentlyintroduced cultivars were identified. The molecular typing system ofS-genotypes based on PCR is a useful and rapid method for identifying newS-alleles and incompatibility groups in sweet cherry.     

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.     

Molecular markers linked to the <Emphasis Type="Italic">fin</Emphasis> gene controlling determinate growth habit in common bean

The S-genotypes of 16 apricot (Prunus armeniaca L.) cultivars native to China were determined by the S-allele PCR approach and the results were confirmed by cross-pollination tests among these cultivars. Primer combination EM-PC2consFD + EM-PC3consR, based on the conserved regions C2 and C3 of Rosaceous S-RNase genes, was the most useful primer combination for identifying Chinese apricot S-alleles. Twelve S-RNase alleles were identified using this primer combination, and they were defined as follows: S ₉ was 657 bp, S ₁₀ was 266 bp, S ₁₁ was 464 bp, S ₁₂ was 360 bp, S ₁₃ was 401 bp, S ₁₄ was 492 bp, S ₁₅ was 469 bp, S ₁₆ was 481 bp, S ₁₇ was 487 bp, S ₁₈ was 1337 bp, S ₁₉ was 546 bp and S ₂₀ was 1934 bp. S ₁₁–S ₂₀ were new S-RNase genes deposited in GenBank under accession numbers DQ868316, DQ870628-DQ870634, EF133689 and EF160078, respectively. Our findings contribute to a more efficient breeding program of Chinese apricot and further studies on the S-RNase genes.     

Solanum phureja genes are expressed in the leaves and tubers of aneusomatic potato dihaploids

Summary The expression of leaf isozymes and tuber patatin in dihaploids derived from the Solanum tuberosum cv. Pentland Crown was investigated. Seven of the dihaploids were aneusomatic containing additional chromosomes from the S. phureja dihaploid inducer. Of these, four genotypes expressed leaf isozymes characteristic of the S. phureja dihaploid inducer, and the tubers of three aneusomatic dihaploids contained a S. phureja form of patatin. Aneusomatic dihaploids in which the proportion of cells containing additional S. phureja chromosomes was relatively small (i.e. 1–15%) did not express leaf isozyme markers or patatin bands characteristic of the dihaploid inducer or showed only faint expression of one or two markers. However, those with a high proportion of cells containing additional chromosomes (50–55%) had a range of strongly expressed leaf isozymes that were characteristic of the dihaploid inducer and also expressed the S. phureja tuber patatin.One dihaploid genotype was exclusively euploid (2n<24), yet is expressed a S. phureja leaf isozyme marker and S. phureja tuber patatin, suggesting recombination or chromosome substitution between the genome of the S. phureja dihaploid inducer and the cultivar Pentland Crown.     

Wide compatibility in rice (Oryza sativa L.)

Summary Wide compatible varieties (WCVs) show normal spikelet fertility in crosses with Indica and Japonica rice varieties. Crosses of Indica and Japonica varieties frequently show high spikelet sterility which prevents exploitation of heterosis for grain yield. We screened 41 rice varieties for the wide compatibility trait by crossing each with three Indica and three Japonica testers. Varieties giving fertile F₁ hybrids with both groups of testers were classified as WCVs. Seven varieties viz., BPI-76 (Indica); N 22; Lambayeque-1 and Dular (Aus); Moroberekan, Palawan and Fossa HV (Japonicas), were identified as WCVs. The frequency of WCVs was higher among Aus and Japonicas. The wide compatibility trait in varieties: Dular and Moroberekan was controlled by a single dominant gene linked with the Est-2 and Amp-3 loci (mean recombination 32.0%). Est-2 and Amp-3 showed complete linkage. Pgi-2 was found to be linked with Est-2 and Amp-3 (mean recombination 16.1%). Est-2 and Amp-3, showed a tighter linkage with C ⁺ (mean recombination 4.1%). Pgi-2 showed a lower linkage with C ⁺ (mean recombination 17.3%). The recombination values between the WC gene in Dular and C ⁺ was much higher than those reported in Japan for the WC gene (S₅ ⁿ) from Ketan Nangka. It is possible that the WC gene from Dular is different from that in Ketan Nangka. Linkage intensities with the WC gene were not strong enough to be of use for indirect selection for the wide compatibility trait. A search for a more closely linked isozyme or DNA marker was proposed.     

Fertility,plant morphology,and transmission rates of the extra chromosome in single and double trisomics of Solanum tuberosum L. Group Tuberosum

Summary Initial single and double trisomics of S. tuberosum Group Tuberosum cv. Gineke were successfully crossed with and backcrossed to clones obtained through inbreeding of self-compatible dihaploids of the same variety. Some trisomics showed reduced flowering or flower abnormalities and contributed therefore only to a small extent. Berry-set and seed-set varied considerably. There was no relation between these phenomena, nor was there any relation between either berry-or seed-set and the identity of the extra chromosome in the female parent. Seed-set seemed to be influenced by the male parent. When a more inbred male parent was used in the crosses with trisomics this often resulted in less seed per cross. There was no clear relation between seed-set and stainability of the pollen grains, but both the strong selection for good pollen and the high level of self-compatibility, have apparently contributed to the success of the crosses. The double trisomic plants yielded less seed than most single trisomics. Only three of the single trisomics produced stainable pollen and two of them yielded progeny when used as male parent in crosses or selfings.In the progenies several of the trisomic types could be distinguished on the basis of plant morphology in the young seedling stage. For ten different trisomics the morphotype is being described. The average rate of female transmission of the extra chromosome was about twenty per cent, but there was a wide variation, both between and within the various trisomic types. The results indicated that for chromosomes 3 and 8 the rate of transmission was higher than the average value. In one out of two trisomic types male transmission of the extra chromosome occurred, with a rate of 4.7%. The possible causes for the observed differences in female transmission of the extra chromosome are being discussed.     

Use of molecular markers to accelerate the breeding of common bean lines resistant to rust and anthracnose

The main goal of this work was to introduce resistance genes for rust, caused by Uromyces appendiculatus, and anthracnose, caused by Colletotrichum lindemuthianum, in an adapted common bean cultivar through marker-assisted backcrossing. DNA fingerprinting was used to select plants genetically closer to the recurrent parent which were also resistant to rust and to race 89 of C. lindemuthianum. DNA samples extracted from the resistant parent (cv. Ouro Negro), the recurrent parent (cv. Rudá), and from BC₁, BC₂ and BC₃ resistant plants were amplified by the RAPD technique. The relative genetic distances in relation to the recurrent parent varied between 9 and 59% for BC₁, 7 and 33% for BC₂, and 0 and 7% for BC₃ resistant plants. After only three backcrosses, five lines resistant to rust and anthracnose with, approximately, 0% genetic distance in relation to the recurrent parent were obtained. These lines underwent field yield tests in two consecutive growing seasons and three of them presented a good yield performance, surpassing in that sense their parents and most of the reference cultivars tested.     

Widespread introgression of Solatium phureja DNA in potato (S. tuberosum) dihaploids

Dihaploids were assumed to be of parthenogenic origin but cv. ‘Pentland Crown’ dihaploids produced at the Scottish Crop Research Institute (SCRI), Dundee, Scotland, are known to contain DNA from the S. phureja dihaploid inducer. This study investigates whether inducer DNA occurs in dihaploids of cultivars ‘Aminca’, ‘Brio’, ‘Lizen’ and ‘Sirtema’, produced at INRA, Ploudaniel, France. Two microsatellite markers and five simple sequence repeat 5′-anchored polymerase chain reaction (PCR) primers were used to generate markers. Markers originating from the dihaploid inducer were detected in 13 of the 19 INRA dihaploids and in some dihaploids from each cultivar. Greater introgression occurred in ‘Lizen’ dihaploids than in ‘Brio’ dihaploids, suggesting that the female (S. tuberosum) parent influences introgression. The percentage of INRA dihaploids containing inducer DNA was similar to that for ‘Pentland Crown’ dihaploids (c. 65%). The micro-satellite markers provided the first evidence of the transfer of specific, potentially useful, genes from the inducer to the dihaploid offspring. Interspecific introgression during dihaploid induction is more widespread than previously thought and researchers should be aware that it may influence the results of research using dihaploids.     

Breaking breeding barriers in Lycopersicon. 3. Inheritance of self-compatibility in L. peruvianum (L.) Mill.

Summary A brief survey is given of the genetics of self-compatibilith in species with a one-locus gametophytic system of incompatibility.A study has been made of the genetics of the self-compatibility found in L. peruvianum.From the results of various test crosses and selfings and of cytological research it is concluded that self-compatibility in L. peruvianum can be based on different types of S-allele mutations, on addition of an S-allele bearing chromosome fragment, or on genes modifying the S-allele expressivity.The results further indicate that generation of new S-alleles is a frequently occurring phenomenon in inbred material of L. peruvianum and that pollen with an S-allele mutation or an extra chromosome fragment is less vital than normal pollen.A short notation for incompatibility genotypes is given.     

Medium, Explant and Genotype Factors Influencing Shoot Regeneration in Oilseed Brassica spp.

The effects of culture media, explants and genotypes on shoot regeneration in oilseed Brassica species were examined in this study. The maximum shoot regeneration frequency was obtained in Murashige and Skoog medium supplemented with 3 mg l^?1 6‐benzylaminopurine and 0.15 mg l^?1 1‐naphthaleneacetic acid. The addition of 2.5 mg l^?1 AgNO₃ was very beneficial to shoot regeneration in B. napus and Ag₂S₂O₃ (10 mg l^?1) was even superior to AgNO₃ (2.5 mg l^?1). Explant age, explant type and carbon source also significantly affected shoot regeneration. Four‐day‐old seedlings of cotyledonary explants showed the maximum shoot regeneration frequency and number of shoots per explant. Of the four explants – peduncles, hypocotyls, cotyledons and leaf petioles – cotyledons produced the highest shoot regeneration frequency (56.67 %). Four carbon sources – glucose, maltose, starch and sucrose – were compared for their respective effects on shoot regeneration from cotyledonary explants. Sucrose appeared to be the best carbon source for shoot regeneration with the highest shoot regeneration frequency (76.00 %). Considerable variation in shoot regeneration from cotyledonary explants was observed both between and within Brassica species. The shoot regeneration frequency ranged from 10.00 % for cv. R5 (B. rapa) to 83.61 % for cv. N1 (B. napus). Two B. napus, one B. carinata and one B. juncea cultivars exhibited shoot regeneration frequency higher than 70 %. In terms of the number of shoots produced per explant, B. rapa showed the highest variation, ranging from 5.64 for cv. R3 to 1.33 for cv. R5. Normal plantlets were regenerated from all induced shoots and developed normally. The regenerated plants were fertile and identical with the source plants.     

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.     

The effect of chromosome doubling on fertility,meiotic behaviour and crossability of Solanum etuberosum × S. pinnatisectum

Summary Doubling the chromosome number of sterile F₁ hybrids of S. etuberosum × S. pinnatisectum resulted in fertile allotetraploid hybrids (code 4x-EP) with nearly normal chromosome pairing at meiosis. Many seeds were obtained from selfing and sibbing, but seed set varied considerably. The 4x-EP hybrids were successfully crosses as females with S. stoloniferum and S. polytrichon and as males with S. verrucosum. The crosses with S. stoloniferum and S. polytrichon were carried out reciprocally and unilateral incompatibility was detected. Crosses of 4x-EP hybrids as males onto S. phureja and S. tuberosum cv. Gineke produced parthenocarpic berries only. Nearly 1700 flowers of colchicine-doubled S. pinnatisectum × S. bulbocastanum and the trispecific hybrid (S. acaule × S. bulbocastanum) × S. phureja did not yield a single berry after pollination with a pollen mixture from 20 4x-EP plants.It is concluded that the use of the bridging species S. pinnatisectum and either S. stoloniferum, S. polytrichon or S. verrucosum may enable gene transfer from the non-tuberous Etuberosa species to potato cultivars.     

Correlation of stylar ribonuclease zymograms with incompatibility alleles in sweet cherry

Summary Protein stylar extracts of 16 cultivars of sweet cherry (Prunus avium), from the 10 different incompatibility groups to which incompatibility alleles have been assigned, were separated on acrylamide gels using isoelectric focusing (IEF) and were stained for ribonuclease activity. When two cultivars from the same incompatibility group were analyzed they gave identical zymograms and the cultivars of the 10 different incompatibility groups gave in all eight distinct zymograms. The ribonuclease polymorphism could be correlated with the reported S allele constitutions of the cultivars. Three ribonuclease bands were identified that each consistently corresponded to one of the six known incompatibility alleles (S ₁, S₂ and S ₆), a fourth band apparently corresponded to S ₃ and to the combination of S ₄ and S ₅, and a fifth band to S ₄ and S ₅ in other combinations. Thus, it seems that S alleles of cherry have ribonuclease activity and that IEF is useful for distinguishing S allele constitutions. The ribonuclease pattern of Summit, a cultivar of unknown incompatibility group, indicated its incompatibility genotype to be S ₁S₂, and this was confirmed by controlled pollination. The same band corresponded to S ₄ and S ₄', the mutant allele in self-compatible cultivars. IEF and ribonuclease staining promise to be useful tools for exploring the incompatibility relationships of cherry cultivars and perhaps of other self-incompatible Prunus crops.     

Heritability and gain from selection for quantitative resistance to Xanthomonas campestris pv. vesicatoria in Capsicum annuum L.

Summary Breeding for disease resistance in peppers (Capsicum spp.) to the bacterial spot pathogen (Xanthomonas campestris pv. vesicatoria (Doidge) Dye) has been based on either qualitative or quantitative evaluation methods. Quantitative evaluation of components of resistance, lesion number and lesion diameter, has been useful for determining quantitative resistance, but few breeders have applied these methods in routine selection programs. This study was aimed at determining the heritability and gain from selection for resistance to the bacterial spot pathogen based on three components of resistance. Random selections from a diverse intermated population of Capsicum annuum L. were self-pollinated for two generations to create S₁ and S₂ families. Thirty S₁ families, corresponding S₂ families and four homozygous check lines were evaluated. At forty-two days after seeding, two different leaves of each plant were inoculated by leaf infiltration with low concentrations (5×10³ colony forming units) of Group 2 (XCV PT, race 1) and 4 (XCV P, race 1) of the bacterium, respectively. After 15 days, lesion number cm^-2 and lesion diameter were measured. Total lesion area was calculated. Narrow-sense heritabilities for lesion number, lesion diameter, and total lesion area were 0, 43, and 31%, respectively, with Group 2, and 26, 43, and 33%, respectively, with Group 4. Actual S₂ gain from 20% selection pressure in the S₁ was approximately 50%, when selection towards resistance was based on total lesion area.