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Premise Pollen dispersal plays a critical role in gene flow of seed plants. Most often, pollen dispersal is measured using paternity assignment. However, this approach can be time-consuming because it typically entails genotyping all pollen donors, receptors, and offspring at several molecular markers. Methods We developed a faster, simpler protocol to track paternity, using pollen receptors and grouped pollen donors that possess rare alleles. We tested this approach using wind-pollinated Amaranthus tuberculatus and insect-pollinated Solanum lycopersicum. After screening potential markers for rare alleles, we grew both species in experimental arrays under field conditions. Results All tested A. tuberculatus seeds and 97% of S. lycopersicum fruits could be assigned to the grouped pollen donors using each of two markers. From these results, we could infer paternity of untested offspring and assess pollen dispersal patterns in each array. Discussion By combining rare alleles and grouped pollen donors, we could assess pollen dispersal for both species and across all arrays after genotyping a small number of pollen donors and a representative subset of offspring. While directly applicable to A. tuberculatus and S. lycopersicum, this approach could be used in other species to assess pollen dispersal under field conditions.

Tomato spotted wilt virus (TSWV) and Phytophthora infestans (late blight) in tomato (Solanum lycopersicum) have a worldwide distribution and are known to cause substantial disease damage. Sw-5 (derived from S. peruvianum) and Ph-3 (derived from S. pimpinellifolium) are, respectively, TSWV and late blight resistance genes. These two genes are linked (within 5 cM on several maps) in repulsion phase near the telomere of the long arm on chromosome 9. The tomato lines NC592 (Ph-3) and NC946 (Sw-5) were crossed to develop an F2 population and subsequent inbred generations. Marker-assisted selection (MAS) using three polymerase chain reaction-based codominant markers (TG328, TG591, and SCAR421) was used in F2 progeny with the goal of selecting for homozygous coupling-phase recombinant lines. From 1152 F2 plants, 11 were identified with potential recombination events between Ph-3 and Sw-5; of those, three were male sterile (ms-10). F3 progeny were generated from the remaining eight F2 recombinants, and resistance to both pathogens, or Ph-3 and Sw-5 in coupling phase, was confirmed in three of those. Recombination was suppressed fivefold in our F2 population to 1.11 cM between genes when compared with published maps of the same region. However, MAS was an efficient tool for selecting the desirable recombination events for these two pathogen resistance genes.

Moderately elevated temperature effects on flower development were examined in nine tomato cultivars (Lycopersicon esculentum Mill.). Plants were grown under high (HT, 32/28 °C day/night temperatures) and control (CT, 26/22 °C) temperature conditions. Fate of flowers developed was categorized as seeded fruit, parthenocarpic fruit, undeveloped flowers, or aborted flowers. Although HT decreased seeded fruit set in all nine cultivars, the degree of sensitivity and the pattern of reaction to the elevated temperature differed among cultivars. FLA7156 was the most tolerant cultivar, although under HT seeded fruit set was less than half that at CT (22.5% compared to 46.8%). The remaining cultivars had very few or no seeded fruit set at all at HT. The percentage of parthenocarpic fruit increased at HT compared to CT in all cultivars. Aborted flowers also increased in FLA7156, NC8288, NCHS1 and NC46E, but did not change in ‘Piedmont’, NC279HS, and NC403HS, or decreased in ‘Fresh Market 9’ and TH318. Reduction of flower abortion and increase of parthenocarpic fruit set can be advantageous traits for breeding of high temperature tolerant tomato cultivars.

Incidence of parthenocarpic fruit, undeveloped flowers and flower abortion in tomato plants ( Lycopersicon esculentum Mill.) were compared under optimal temperature (OT, 28/22°C day/night) and chronic, mild high temperature conditions (HT, 32/26°C). Seeded fruits were found only under OT conditions, where 37±9% of all flowers developed into seeded fruit. However, flower aborted was also higher under OT, with an additional 24±7% of flowers aborted under optimal temperature conditions, compared to only 4±1% of flowers aborted under HT conditions. Under HT, most flowers (53±8%) developed into parthenocarpic fruit, and the remainder (43±7%) stayed on the plant as undeveloped flowers. A slow transition of undeveloped flowers to parthenocarpic fruit was also observed under HT. Factors determining whether flowers abort, develop parthenocarpically, remain on the plant without developing further, or develop into seeded fruit were discussed in relation to carbohydrate availability and the presence of seeded fruit on the vine.

Foliar resistance to early blight disease of tomato, caused by the necrotrophic fungus Alternaria solani , is inherited in a complex quantitative manner. Our previous studies revealed that three moderately-resistant tomato breeding lines with different sources of early blight resistance, all possessed higher constitutive and more rapid accumulation of PR proteins, including specific antifungal isozymes of chitinase and β-1,3-glucanase than susceptible genotypes. In the present study, additional early blight resistant tomato breeding lines and susceptible genotypes were investigated for their constitutive levels of PR proteins. All resistant lines possessed higher constitutive levels of chitinase and β-1,3-glucanase than susceptible genotypes supporting earlier reported findings. Constitutive and pathogen-induced expression of PR genes during early stages of the interaction was found to be much higher in the highly resistant breeding line NC 24-E than a susceptible line. In vitro elicitor release experiments were performed with purified A. solani cell walls treated with constitutive total enzyme preparations isolated from resistant and susceptible plants. Enzyme preparations from resistant and susceptible genotypes differed in their ability to produce hypersensitive response (HR) elicitors from fungal cell walls: the enzyme preparations from resistant breeding lines released HR elicitors, while enzyme preparations from susceptible lines did not. Additionally, experiments with a partially purified preparation of basic tomato chitinases demonstrated that these enzymes were able to release HR elicitors from germinating spores of A. solani , but not mature, intact cell walls. The possibility that constitutively produced hydrolytic enzymes may act as an elicitor-releasing mechanism in resistance to early blight of tomato is discussed.

Amount of vascular development (veininess) is an important quality factor for processing wholepack tomatoes. The influences of nutrient and soil moisture stress on the amount of vascular development in `Chico III', `Dorchester', and `Roma' tomato fruit were studied. Fruit subjected to nutrient stress showed the highest amount of veininess. Fruit exposed to moisture stress after initial fruit set did not differ from controls in amount of veininess. Amount of vascularization did not differ among cultivars. A method for quantifying veininess was developed and compared with a traditional subjective rating scale. There was a high correlation (r2 = 0.77) between the subjective rating and quantitative measurement of veininess.

The effects of selection on genome variation were investigated and visualized in tomato using a high-density single nucleotide polymorphism (SNP) array. 7,720 SNPs were genotyped on a collection of 426 tomato accessions (410 inbreds and 16 hybrids) and over 97% of the markers were polymorphic in the entire collection. Principal component analysis (PCA) and pairwise estimates of F(st) supported that the inbred accessions represented seven sub-populations including processing, large-fruited fresh market, large-fruited vintage, cultivated cherry, landrace, wild cherry, and S. pimpinellifolium. Further divisions were found within both the contemporary processing and fresh market sub-populations. These sub-populations showed higher levels of genetic diversity relative to the vintage sub-population. The array provided a large number of polymorphic SNP markers across each sub-population, ranging from 3,159 in the vintage accessions to 6,234 in the cultivated cherry accessions. Visualization of minor allele frequency revealed regions of the genome that distinguished three representative sub-populations of cultivated tomato (processing, fresh market, and vintage), particularly on chromosomes 2, 4, 5, 6, and 11. The PCA loadings and F(st) outlier analysis between these three sub-populations identified a large number of candidate loci under positive selection on chromosomes 4, 5, and 11. The extent of linkage disequilibrium (LD) was examined within each chromosome for these sub-populations. LD decay varied between chromosomes and sub-populations, with large differences reflective of breeding history. For example, on chromosome 11, decay occurred over 0.8 cM for processing accessions and over 19.7 cM for fresh market accessions. The observed SNP variation and LD decay suggest that different patterns of genetic variation in cultivated tomato are due to introgression from wild species and selection for market specialization.

Compact-growth-habit (CGH) tomatoes (Lycopersicon esculentum Mill.) do not require the pruning, staking, and tying required for many fresh-market tomato cultivars. In 1990, 5-week-old transplants of the CGH tomato breeding line NC 13G-1 were grown in single rows with in-row spacings of 31, 46, 61, and 76 cm and in double rows with in-row spacings of 31 and 46 cm. NC 13G-1 produced high early and total season marketable yields when grown in either double-row treatment compared to any single-row treatment. In 1991 and 1992, 4- and 5-week-old NC 13G-1 transplants were produced in five root cell volumes (8.6, 13.6, 27.0, 37.1, and 80.0 cm3), transplanted into double rows with an in-row spacing of 46 cm, and evaluated for yield. Five-week-old transplants produced in 37.1- and 80-cm3 cells flowered sooner after transplanting and produced higher early season yields than 4-week-old transplants produced in the three smaller cells. Midseason yields increased quadratically and late-season yields decreased quadratically as root cell volume increased. Total season marketable yields did not differ among treatments. In 1991, production costs were influenced by root cell volume, but not in 1992. In 1992, net returns for the four smallest cell volumes were similar, and lower than for transplants grown in the largest cell volume. In both years, highest net returns were achieved with transplants produced in 37.1-cm3 cells. Considering the estimated 1992 net returns of $17,000/ha, production of CGH tomatoes may provide an alternative for staked-tomato growers concerned with labor availability and production costs, even though marketable yield from NC 13G-1 was lower than with a conventional cultivar under the standard system.

Pointed blossom-end morphology may be used to reduce blossom-end scar size in large-fruited, fresh-market tomatoes (Lycopersicon esculentum Mill.). The usefulness of this characteristic has been limited due to persistence of pointedness on mature fruit, resulting in postharvest bruising, and to close association of pointedness with leaf curl, which may increase foliar disease problems. The inheritance of pointedness in three breeding lines (NC 140, Fla 890559-24, and Fla 894413-1) and four accessions with previously described blossom-end morphology genes [LA 2-5 with persistent style (pst), LA 986 with beaky (bk), LA 1787 with beaky-2 (Bk-2), and LA 2353 with nipple tip (n)] was investigated. In F1 s and F2s of crosses with wild types, some pointedness was observed in heterozygotes, but the level of expression was generally close to wild type expression, except for LA 986. Consequently, Bk-2 in LA 1787 was renamed bk-2. F1 complementation tests were difficult to interpret. Wild types segregated in F2s of all complementation crosses, except for LA 986 × LA 2-5, a result indicating the presence of the same gene in these two accessions. Three new nipple-tip genes were named; n-2 in NC 140, n-3 in Fla 890559-24, and n-4 in Fla 894413-1. None of the seven accessions tested had significant leaf curl. Early identification of mutant plants by the shape of the stylar base in flowers at anthesis was reliable only for bk. Various blossom-end morphology genes may be backcrossed into otherwise desirable breeding lines, and complementing parents may be intercrossed to obtain optimal smoothness in the hybrid without undesirable pointed mature hybrid fruit.

The heritability of shortened fruit maturation (SFM) period in Cornell 871213-1, an inbred cherry tomato (Lycopersicon esculentum var. cerasiforme (Dunal.) A. Gray) line, was estimated from a greenhouse experiment. Cornell 871213-1 was crossed with the cherry tomato line NC 21C-1. Mean fruit maturation period (FMP) (days from anthesis to the breaker stage of fruit color) was 40.8 days for NC 21C-1 and 32.0 days for Cornell 871213-1. Parental, F1, F2, and backcross generations all differed in mean FMP and yielded, estimates of broad- and narrow-sense SFM heritabilities of 72% and 40%, respectively, on a single-plant basis. A test for midparent heterosis showed significance. Genetic control of SFM was quantitative in nature and highly dominant. A field study of an F 2 population developed from the cross Cornell 871213-1 × NC 84173, the latter a large-fruited tomato line (Lycopersicon esculentum Mill.), gave a mean FMP of 48.4 and 31.2 days for NC 84173 and Cornell 871213-1, respectively. The F 1 and F2 generations had FMP of 33.1 and 34.7 days, respectively. The parents, F 1, and F2 generations all differed in FMP. Parental, F 1, and F2 generations yielded an estimate of broad-sense SFM heritability of 64% on a single-plant basis. F 3 progenies from selected F2S were grown in a greenhouse, and F3-F2 regression analysis gave a narrow-sense SFM heritability of 39%. Parental means differed from each other and from the F 1 and F2 means for period from sowing to anthesis, fruit weight, and locule number. F 1 and F2 means did not differ for any trait and were far below the midparent values, approaching Cornell 871213-1 for each trait except for the number of days from sowing to anthesis. Significant correlations existed in the F2 generation between FMP and fruit weight (0.61) and between fruit weight and locule number (0.69). Significant correlations existed between selected F 2s and their F3 progeny for FMP (0.53), fruit weight (0.78), and days from sowing to anthesis (0.78). In the F 3 generation, a significant correlation occurred between FMP and fruit weight (0.48). F3-F2 regression and realized heritabilities were used as two estimates of narrow-sense heritability (29% and 31%, respectively) for days from sowing to anthesis. Early maturity in tomato cultivars is highly desirable since early season fruit tend to bring the highest price in the fresh market (Burdick, 1954; Honma et al., 1964; Kerr, 1955). The mechanisms controlling earliness in tomato have been exten- sively studied (Banerjee and Kaloo, 1989; Corbeil, 1964; Curr- ence, 1938; Lopez, 1960; Lyon, 1941; Powers, 1939; Powers and Lyon, 1941; Tayel et al., 1959). These researchers defined earliness in different ways but, in general, measured relative earliness (or lateness) as the number of days from sowing to the first ripe fruit. In addition, researchers have examined discreet components, or stages of earliness. The time period from sowing to anthesis has been extensively studied (Banerjee and Kaloo, 1989; Cor- beil, 1964; Currence, 1938; Lopez, 1960; Lyon, 1941; Powers, 1939; Powers and Lyon, 1941; Tayel et al., 1959). Powers and Lyon (1941) divided earliness into three stages: 1) days from sowing to ahthesis, 2) days from anthesis to first fruit set, and 3) days from first fruit set to first ripe fruit. They concluded that there was sufficient variation within these stages to consider each a unique and heritable trait. Environmental factors, especially temperature and light in- tensity, play a significant role in the expression of any com

Prostrate growth habit (PGH) in tomato (Lycopersicon esculentum Mill.) lines derived from breeding material developed at the Agriculture Canada Research Station, Beaverlodge, Alberta, was the subject of a quanti- tative inheritance study. Plants with PGH have an increased lateral branch angle, relative to upright plants, and crown-set fruit supported above the soil surface making hand harvest easier. Genetic parameters were estimated in two families (20G and 53G), each containing PGH and upright-habit parental lines, F 1, F2, and backcrosses to each parent. Field-grown plants were subjectively rated twice during the growing season. Broad-sense heritability of PGH in family 20G was estimated to be 0.65 and 0.71 for ratings of plant growth habit 6 and 9 weeks after transplanting, respectively, and 0.71 and 0.68 for those of family 53G. Narrow-sense heritability was estimated to be 0.83 and 1.05 for the two ratings in the 20G family and 0.77 and 0.78 in the 53G family. F 1 and F2 means were not different from mid-parent values. The genetic variance was entirely additive and expression was influenced by the environment. The data did not support the hypothesis that PGH was controlled by a single gene. Many genes have been described that affect plant habit and/ or branching in tomato. Among these are decumbens (dec) (Stubbe, 1959), procumbens-2 (prc-2) (Stubbe, 1960), and brachytic (br) (Barton et al., 1955). Genes causing an increase in lateral branching include erecta-2 (er-2) (Clayburg et al., 1979), globiformis (glf), and globosa-2 (glo-2) (Clayburg et al., 1966). Increased branching may be due to reduced apical dom- inance (Campbell and Nonnecke, 1974). Lateral promoter (Lp) has been described in lines derived from breeding material developed at the Agriculture Canada Research Station, Beaverlodge, Alberta (Campbell and Non- necke, 1974). The gene Lp is partially dominant and causes the formation of lateral branches at the cotyledonary node upon an early termination of the main axis. Other laterals follow in se- quence proximally, and defoliation is early (I.L. Nonnecke, personal communication). The objective of this study was to estimate the inheritance of prostrate growth habit (PGH) in fresh-market tomato breeding lines derived from Beaverlodge material. This trait has been studied and found to increase the percentage of marketable fruit

Eight staked, determinate tomato (Lycopersicon esculentum Mill.) cultivars were harvested when green (before breaker stage) or when pink (breaker stage and riper) in two replicated field studies. In general, total yield and average fruit size were reduced when fruit were harvested at the green stage. Harvest maturity had only a small effect on occurrence of most fruit defects, except fruit cracking, which was more severe for pink than for green fruit in the early season experiment. Although total yields for pink harvested fruit were higher than for green harvested fruit in the early season study, the high incidence of fruit crack in pink fruit resulted in similar yields of U.S. combination grade (U.S. no. 1 and U.S. no. 2) fruit for both treatments. Because the largest fruit often bring a premium price, harvesting fruit when pink probably will result in a higher price per kilogram than harvesting fruit when green. Fruit harvested green, however, are generally firmer, more crack resistant, and require fewer harvests than fruit harvested pink.

NC HS-1. Plant habit is determinate (sp) (Mutschler et al., 1987). The noncurled foliage is medium green and develops a canopy with moderate fruit coverage. The plants grow vigorously and typically outgrow the stake used in the short-stake, string-weave system. Fruit of NC HS-1 are deep oblate to flattened globular and are symmetrical with a small, smooth, blossom-end scar. Immature fruit are a glossy, uniform green (u) and ripen to an acceptable red exterior and interior color with medium firmness (subjective ratings). Fruit pedicels are jointed and separate easily from the fruit during harvest. NC HS-1 had high total and marketable yields when compared with standard cultivars in trials at Fletcher, N.C. under non–heat stress conditions. Fruit size was smaller than that of ‘Sun Leaper’ and ‘Solar Set’ and did not differ from ‘Flora-Dade’ (Table 1). NC HS-1 is resistant (I, I-2) to races 1 and 2 of Fusarium oxysporum f.sp. lycopersici (Sacc.) Snyd. and Hans., the incitant of fusarium wilt, and is resistant (Ve) to race 1 of Verticillium dahliae Kleb., the incitant of verticillium wilt. Fruit are highly resistant to radial and concentric cracking and to cuticle cracking (weather check). improved cultivar for summer production in piedmont and eastern North Carolina, where night temperatures often range from 21 to 25 °C. ‘Sun Leaper’ was tested as NC 92191 and in the Southern Tomato Exchange Program as STEP 744.

NC 2C ms-10,aa was developed by transferring the ms-10 nuclear male-sterile gene characteristics of the two lines. NC 2C ms10,aa has the same characteristics as previously described for NC 2C PVP (Gardner, 1993). Major plant and fruit characteristics controlled by single genes include determinate growth (sp), uniform light green color of nonripe fruit (u), and jointless pedicels (j-2). To compare NC 2C ms-10,aa with NC 2C PVP in hybrid seed production, both were pollinated with pollen of NC 1C PVP to produce hybrid seed of ‘Mountain Belle’. In replicated trials conducted during three growing seasons, the two hybrids did not differ in earlyor total-season yields. Fruit size tended to be slightly, but not significantly, smaller for the progeny of the male-sterile female parent. Observations of plant and fruit characteristics of the two hybrids in the replicated trials and in several other trial plots over a 3-year period indicated no visible differences for any character.

There is a good market for heirloom tomatoes that, according to many consumers, taste better than regular tomatoes. Unfortunately, most heirloom tomatoes have little disease resistance, tend to crack, are rough in appearance, and are not uniform in size. Randy Gardner recently developed several new indeterminate hybrid tomatoes with the goal of combining the flavor of heirloom tomatoes with the disease resistance, uniform size, and good shipping characteristics of more modern varieties. Two tests, using organic and conventional practices, were conducted in Waynesville, N.C., in which three popular heirloom varieties (German Johnson, Mr. Stripey, and Cherokee Purple) and four late blight resistant hybrids (NC 0455, NC 0571, NC 0576, and NC 05114), replicated four times, were grown using a high trellis system. The highest yields were obtained with German Johnson NC 0455, and NC 0576 in the conventional trial and German Johnson NC 0455, and NC 0571 in the organic trial. Public taste test results revealed that the experimental hybrid cluster type, NC 05114, was ranked by over 82% of the participants as good or excellent. NC 0455 was rated as good or excellent by >83% of the participants, which was better than the popular heirlooms Cherokee Purple and Mr. Stripey. This study demonstrated that the heirloom-type hybrid tomatoes could be successfully grown in organic and conventional systems in Western North Carolina and that two out of the four tested had flavor ratings similar to, or better than, the three heirloom varieties tested.

The influence of flat cell volume (cavity containing growing medium) on transplant growth and development of NC 13G-1, a compact-growth-habit, fresh-market tomato (Lycopersicon esculentum Mill.) breeding line, was compared to that of a normal growth habit line, NC 8288. Transplants of each line were produced in four cell volumes (3.3, 27, 37.1, and 80cm3) for 5 weeks, evaluated and then transplanted to larger containers, and grown until anthesis. During the first 5 weeks after seeding, plant dry weight did not differ between the lines; however, plant height of NC 13G-1 was ≈60% of the height of NC 8288. For both lines, number of days from sowing to anthesis decreased as root cell volumes increased. For space-efficient production of large quantities of compact-growth-habit tomato transplants, flats with root cell volumes as small as 27 and 37 cm3 can be used without greatly delaying anthesis.

‘Mountain Delight’ is the F1 hybrid resulting from the cross of ‘Piedmont’ (Gardner, 1985) x NC 8288. Both parents were developed in the North Carolina fresh-market tomato breeding program. ‘Mountain Delight’ was evaluated in trials as NC 84100 and in the 1987 Southern Tomato Exchange Program (STEP) as STEP 693. NC 8288 is an F, selection from the cross of ‘Piedmont’ × ‘Florida 1B’ (Augustine et al., 1981). NC 8288 was evaluated in the STEP trials in 1985, 1986, and 1987 as STEP 689.

Two inbred lines of fresh-market tomato (Lycopersicon esculentum Mill.), NC 20G-1 and NC 53G-1, both exhibiting prostrate growth habit (PGH), were crossed with the upright growth habit cultivar Piedmont and advanced to the F2 generation. Plants of each F2 population were grown without plant support on black plastic and subjectively rated in field plots for PGH. Extreme upright and prostrate plants were chosen from each F2 population for harvest. Mean comparisons between plants of extreme upright and prostrate habit showed increased total and marketable yields from plants with a prostrate habit. Decay and groundscarring of fruit were less in prostrate than in normally upright plants; the percentage of misshapen fruit was similar in both. The PGH character may be useful in increasing total and marketable yield of ground-culture tomatoes.

Experiments were conducted in 1989 to determine the heritability of shortened fruit maturation (SFM) period in 871213-1, an inbred cherry tomato line (Lycopersicon esculentum var. cerasiforme (Dunal.) A. Gray), and to determine the relationship between this trait and fruit size. In the first study, a cross was made between 871213-1 and NC 21C-1, an inbred cherry line. NC 21C-1 had a mean maturation period of 40.8 days compared to 32.0 days for 871213-1. A mean maturation period for the F1 hybrid of 32.9 days and 32.2 days was found using 871213-1 as the female and male parent, respectively. Analysis of the data from parental, F1, F2 and backcross generations yielded estimates of broad-sense and narrow-sense heritabilities for SFM as 0.72 and 0.56, respectively. Further analysis indicated that genetic control of SFM was quantitative in nature and highly dominant. A test for epistatic interaction showed significance. In the second study, an F2 population from the cross 871213-1 x NC 309-1, a large-fruited tomato line (Lycopersicon esculentum Mill.), was evaluated to determine if any correlations existed between fruit size and SFM. Two fruit characteristics, locule number and fruit weight, were used as estimates of fruit size. Correlations between SFM and these two characteristics were +0.28 and +0.61, respectively. Broad-sense heritability of SFM was estimated as 0.64.

Seedling progenies from controlled crosses involving Malus sp. clones were tested for resistance to Erwinia amylovora (Burrill) Winslow et al. by shoot tip inoculation. In progenies from crosses between fire blight-susceptible M. pumila selections, over 90% of the seedlings were killed. In most progenies from crosses between resistant and susceptible selections, regardless of species source, few resistant seedlings occurred. Progenies from crosses between resistant parents generally had the most resistant seedlings, but segregated some highly susceptible offspring. Distribution patterns suggested quantitative control of resistance, with resistant parents heterozygous for resistance genes. In progenies from crosses of the highly resistant M. × robusta No. 5 (R5) and M. × sublobata PI 286613 (613) with susceptible parents, about 1/8 of the seedlings exhibited the fire blight reaction of the highly resistant parent. All progenies of 613 and R5, including those obtained by selfing and by crossing the two with each other, segregated some susceptible offspring. In a replicated nursery test involving seedlings of a 613 progeny, various fire blight resistance classes in the population were distinguished statistically. Resistance in 613 and R5 was interpreted as oligogenic (conditioned by few genes), with dominant, additive genes carried in the heterozygous condition.

Reactions of 122 apple clones, representing 26 pure and hybrid species of Malus, to Erwinia amylovora (Burrill) Winslow et al. were evaluated in the greenhouse, orchard, and field nursery. Vigorously growing shoots, 7 to 9 weeks old, were tip inoculated by injecting a 24-hour broth culture of a highly pathogenic isolate of E. amylovora. Lesion development, measured 5 to 7 weeks after inoculation, was expressed as a percentage of the current season’s shoot length killed by fire blight. Inter- and intraspecific variation in resistance, similar to that reported for Pyrus, was observed. The highest level of resistance, typified by a small necrotic lesion 2-3 mm in diameter around the inoculation point, occurred in small-fruited selections derived from Asiatic species. Few selections of the cultivated apple, Malus pumila Mill., were resistant. Fire blight ratings were assigned the clones based on their potentials as parents for breeding apple rootstocks.

Early blight resistance was estimated in field plots for parents and F1, F2, and backcross progenies of crosses with NC EBR-1, a line derived from Lycopersicon hirsutum P.I. 126445. Areas under the disease progress curve (AUDPC) showed that resistance from NC EBR-1 was heritable and quantitative in nature. generation means in two families were intermediate to those of NC EBR-1 and susceptible parents. The distribution of AUDPC means for the different generations in both families indicated the presence of epistasis or gene linkage. Lack of fitness tests for curve-linearity confirmed this in one family. A, B, and C scaling tests showed similar results. A joint three-factor model and subsequently a six-factor model displayed the presence of epistasis in both families. Ignoring epistatic effects, narrow-sense heritability (h2) was 0.49 in one family and 0.40 in the other. By regressing F3 progeny AUDPC means on selected F2 plant values, h2 was 0.25 and 0.17, respectively.

Eight stamenless tomato mutants (Lycopersicon esculentum Mill.) were intercrossed in a half-diallel design to determine allelic relationships. Two allelic series were represented among the mutants. One series included sl, sl2, sl5, cs, and fl. The 2nd series included bn, sl?, and pms. No allelic interactions occurred between members of the 2 series. Fruit and seed set resulting from cross-pollinations varied greatly among the mutants. The stamenless types, with the exception of sl2, do not appear to be promising for use in producing hybrid tomato seed because of poor fruit and seed set.

Early blight, incited by Alternaria solani (Ellis and Martin) Jones and Grout, is a severe foliar disease of tomatoes in western North Carolina. Resistance breeding, initiated in 1976 at the Mountain Horticultural Crops Research and Extension Center, Fletcher, N.C. has resulted in the development of NC EBR-1 and NC EBR-2. Both lines exhibit a moderate level of foliar resistance to early blight.

A mutant of the tomato (Lycopersicon esculentum Mill. cv. Flora-Dade) was characterized by straight pedicels oriented in an upright position. A genetic study indicated the mutant character was controlled by a single recessive gene, which has been tentatively designated as up-right pedicel (up). The up locus is linked to the jointless pedicel (j-2) character of ‘Flora-Dade’, with a crossover distance of 8.5 units.

NC50-7, ‘Cherokee’ and ‘Mountain Pride’ are mid-season, determinate (sp gene) tomatoes (Lycopersicon esculentum Mill.) developed at the Mountain Horticultural Crops Research Station, Fletcher, N.C. ‘Cherokee’ and ‘Mountain Pride’ are adapted to vine-ripe harvest for local market and shipping. NC507 is useful as a parent in breeding for firmness and crack resistance and, in addition, is the male parent of the F1 hybrid ‘Mountain Pride’.