Horticultural Types Research Articles

Horticultural Activity Type, Psychological Well-Being, and Fruit and Vegetable Intake.

The purpose of this study was to explore the effect of the frequency of participation in horticultural activity types on psychological well-being and fruit and vegetable intake. The study sought to understand the mediating effect of psychological well-being between the frequency of types of horticultural activities and the frequency of fruit and vegetable intake. Convenience sampling was used to collect 400 valid data through a self-administered questionnaire that inquired about the frequency of four horticultural activity types (indoor plant activities, outdoor plant activities, arts/crafts activities, and excursions), the measure of psychological well-being, and the frequency of fruit and vegetable intake. The results showed that a higher frequency of indoor and outdoor plant activity positively affected psychological well-being. Psychological well-being played a partial mediation role between indoor plant activity and vegetable and fruit intake and a full mediation role between outdoor plant activity and vegetable and fruit intake. The plant-related arts/crafts activities and excursions were not associated with psychological well-being or vegetable and fruit intake.

Dissection of the domestication-shaped genetic architecture of lettuce primary metabolism.

Lettuce (Lactuca sativa L.) is an important vegetable crop species worldwide. The primary metabolism of this species is essential for its growth, development and reproduction as well as providing a considerable direct source of energy and nutrition for humans. Here, through investigating 77 primary metabolites in 189 accessions including all major horticultural types and wild lettuce L. serriola we showed that the metabolites in L. serriola were different from those in cultivated lettuce. The findings were consistent with the demographic model of lettuce and supported a single domestication event for this species. Selection signals among these metabolic traits were detected. Specifically, galactinol, malate, quinate and threonate were significantly affected by the domestication process and cultivar differentiation of lettuce. Galactinol and raffinose might have been selected during stem lettuce cultivation as an adaption to the local environments in China. Furthermore, we identified 154 loci significantly associated with the level of 51 primary metabolites. Three genes (LG8749721, LG8763094 and LG5482522) responsible for the levels of galactinol, raffinose, quinate and chlorogenic acid were further dissected, which may have been the target of domestication and/or affected by local adaptation. Additionally, our findings strongly suggest that human selection resulted in reduced quinate and chlorogenic acid levels in cultivated lettuce. Our study thus provides beneficial genetic resources for lettuce quality improvement and sheds light on the domestication and evolution of this important leafy green.

Pendapatan dan kelayakan usahatani cabai rawit

Indonesia is an agrarian country, one of which produces a chili commodity that can support the economy in this country. Chili is one type of horticulture that cannot be left by the community in everyday life. Besides that, chili farming has very good prospects. The purpose of this study was to determine the revenue, income obtained by farmers in one planting season, and the feasibility of chili farming in one season. The results obtained by the total income obtained by farmers in chili farming with an average income of Rp.35,124,800.-The total income earned by farmers in chili farming with an average income earned is Rp.25,204,800,- Chilli Farming in the Village of Kaligambir is worth the effort by looking at the R/C ratio of 2.54, which means that each expenditure of Rp.100.- will receive Rp.254.

RNA sequencing provides insights into the evolution of lettuce and the regulation of flavonoid biosynthesis

Different horticultural types of lettuce exhibit tremendous morphological variation. However, the molecular basis for domestication and divergence among the different horticultural types of lettuce remains unknown. Here, we report the RNA sequencing of 240 lettuce accessions sampled from the major horticultural types and wild relatives, generating 1.1 million single-nucleotide polymorphisms (SNPs). Demographic modeling indicates that there was a single domestication event for lettuce. We identify a list of regions as putative selective sweeps that occurred during domestication and divergence, respectively. Genome-wide association studies (GWAS) identify 5311 expression quantitative trait loci (eQTL) regulating the expression of 4105 genes, including nine eQTLs regulating genes associated with flavonoid biosynthesis. GWAS for leaf color detects six candidate loci responsible for the variation of anthocyanins in lettuce leaves. Our study provides a comprehensive understanding of the domestication and the accumulation of anthocyanins in lettuce, and will facilitate the breeding of cultivars with improved nutritional value.

Characterization and Distribution of Flavonoids from Flowers in Different Horticultural Types of Begonia

Background: The begonias are ornamental plants known by the varied forms and colors of their flowers, as well as their decorative foliage. Objective: This study attempts to characterize the flavonoids isolated from flower extracts of different horticultural cultivars of the genus Begonia. Material and methods: The compounds of the ethyl acetate and aqueous extracts were separated by chromatographic methods and identified by UV spectra and chemical techniques. Results: The analysis allowed the characterization of flavonoids belonging to flavonol types in the free aglycones and glycoside forms of kaempferol and quercetin. On the other hand, fingerprinting analysis and quantification of major flavonoids of 184 cultivars were performed by high-performance liquid chromatography (HPLC). Among twenty five (25) components which were detected and separated: ten were corresponding to quercetin 3-Oglucosyl- rhamnoside (Rt=23.5), quercetin 3-O-glucoside (Rt=25), kaempferol 3-O-glucosylrhamnoside and its acylated derivative (Rt=32), kaempferol 3-O-glucoside (Rt=33), quercetin 3-O-p.coumaroyl-diglucoside (Rt=37), quercetin 3-O-P.coumaroyl-glucoside (Rt=40.5), quercetin (Rt=41.5), kaempferol and its acylated derivative (Rt=47). Only non-acylated glycosides of quercetin and kaempferol contributed to chemical variations among different cultivars based on the results of PCA. Conclusion: The genus Begonia is very heterogeneous and it is possible to distinguish several chemotypes whose differences rely on the complementarities between the metabolic pathways involved in the biosynthesis of glycosides of quercetin and kaempferol.

Effects of Agro ecosystem Land Use Types on the Diversity, Abundance and Ecosystem Functions of Insect Pollinators

Land degradation in agricultural farms is mainly manifested through loss of ecosystem services such as pollination. In Kenya, farmers knowledge of pollination is limited, many farmers lump pollinators together with insect pests and do not explicitly manage to conserve them, although pollinators may contribute substantially to yields at no cost to the farmer. Insect pollinators of crops and wild plants are threatened worldwide by pesticide use and the spread of disease and parasites. This research is multidisciplinary in approach, in this research niche theory and ecosystem functions concepts to determine the status of insect pollinators in agro-ecosystems of Mua Hills location were used. The aim of this research was to determine the diversity and abundance of pollinator insects for their role in ecosystem function (pollination) and increase of passion fruit yield. The diversity and abundance of insect pollinators was found to be least in horticultural land use type and this was attributed to the use of agro-chemicals. This research is an issue of environmental management because it focuses on natural patch land use type for sustainable use of agro-ecosystems to avoid decline of pollinators. It advocates for conservation of the environment and management of carpenter bee (Xylocopa spp) because it is an efficient pollinator of passion fruit thus makes farming more profitable through higher yield of the crop. The findings from this research are aimed to help the subsistence farmers achieve good produce in passion fruit farming. The study promotes the conservation of insect biodiversity within the existing land use types to improve pollination of horticultural crops.

Thermophilic fungi in air samples in surroundings of compost piles of municipal, agricultural and horticultural origin

In this study, the effect of the thermophilic fungi of composts was analysed on the fungal composition of the air above. Air samples were collected with an Andersen air sampler at 1.5 m height in three large industrial composting facilities treating different waste types. Repetition was collected on three calm and rain-free days of three consecutive weeks in October 2011, in January, April and July 2012; five plates were exposed successively per sampling day. Compost samples were also collected (averaging 1 kg/compost piles). Air and compost samples were cultured at 50 °C. The thermophilic fungal composition of the air near the compost piles of different waste types differed significantly (p < 0.05) from that of the control site above a grassland ecosystem at each sampling time. Seasonal differences could be detected regarding the total number of thermophilic fungi in the air near the agricultural and horticultural compost types, but smaller differences were found near the municipal compost type. A total of 13 and 11 fungal species were detected in the compost and air samples where the dominant species were Thermomyces lanuginosus and Rasamsonia emersonii, respectively. The concentration of airborne thermophilic fungi was higher near the horticultural compost type and lower near the municipal compost. The results suggest that the differences between the incidences of some species in composts and associated aerosols refer to spore ontogeny and biological mechanisms of spore liberation.

Genetic diversity of 129 spring orchid (Cymbidium goeringii) cultivars and its relationship to horticultural types as assessed by EST-SSR markers

Spring orchid (Cymbidium goeringii), a valuable and endangered species in China, plays an important role as a potted flower. The genetic diversity of 129 spring orchid cultivars was evaluated with 13 selected EST-SSR markers and 120 alleles were identified, of which 111 alleles were polymorphic. The plum petal type, with 43 cultivars, contributed 102 polymorphic alleles out of the 111, while the colored flower type, with 3 cultivars, had 38 polymorphic alleles. Cluster analysis showed that these 129 spring orchid cultivars could be sorted into two groups, or three subgroups (A1, A2, B), based on the allelic data, and with all cultivars from three currently recognized variants intermingled with some cultivars from C. goeringii in the same subgroup, indicating that they should not be regarded as variants. Through principal coordinate analysis, only a weak correlation between DNA fingerprints and the horticultural types of the spring orchid was observed. However, common alleles existed in cultivars from the same horticultural type, for example, 15 common alleles were found in the 3 cultivars of the colored flower type, and the CY2-J allele existed in the 43 cultivars of the plum petal type. All these cultivars, except for Longzi and Lao Longzi, could be distinguished from each other using these EST-SSR markers. Moreover, a set of 102 out of the 129 cultivars had their own specific alleles, and therefore, with a single EST-SSR marker, each of these cultivars can be distinguished from all other cultivars. These findings can be valuable for taxonomy improvement as well as resource conservation and utilization, and the EST-SSR markers developed can also be a useful tool for cultivar identification which is frequently required commercially.

Use of EST-SSR markers for evaluating genetic diversity and fingerprinting celery (Apium graveolens L.) cultivars.

Celery (Apium graveolens L.) is one of the most economically important vegetables worldwide, but genetic and genomic resources supporting celery molecular breeding are quite limited, thus few studies on celery have been conducted so far. In this study we made use of simple sequence repeat (SSR) markers generated from previous celery transcriptome sequencing and attempted to detect the genetic diversity and relationships of commonly used celery accessions and explore the efficiency of the primers used for cultivars identification. Analysis of molecular variance (AMOVA) of Apium graveolens L. var. dulce showed that approximately 43% of genetic diversity was within accessions, 45% among accessions, and 22% among horticultural types. The neighbor-joining tree generated by unweighted pair group method with arithmetic mean (UPGMA), and population structure analysis, as well as principal components analysis (PCA), separated the cultivars into clusters corresponding to the geographical areas where they originated. Genetic distance analysis suggested that genetic variation within Apium graveolens was quite limited. Genotypic diversity showed any combinations of 55 genic SSRs were able to distinguish the genotypes of all 30 accessions.

Differential Susceptibility of Nine Cucurbit Species to the Foliar Blight and Crown Canker Phases of Gummy Stem Blight.

Eighteen cucurbit cultivars representing five genera, nine species, and 17 horticultural types were inoculated with Didymella bryoniae in field plots in Charleston, SC, in autumn 2008, autumn 2009, and spring 2011 to determine susceptibility to gummy stem blight. In each year, gummy stem blight cankers occurred more frequently on crowns or main stems of 'Athena' muskmelon (Cucumis melo) and 'Green Striped Cushaw' squash (Cucurbita argyrosperma) than on all other cultivars except 'Rocio' honeydew (Cucumis melo) in 2009, and bottle gourd (Lagenaria siceraria) and Ojakkyo citron (Citrullus lanatus var. citroides) in 2011. Cucurbita moschata was highly resistant to stem cankers. Severity of gummy stem blight on foliage was moderate to severe in autumn 2009, mild to severe in autumn 2008, and very mild in spring 2011 (due to unusually dry weather). Watermelon (Citrullus lanatus var. lanatus) and melon were the most susceptible to foliar blight in 2008 and 2009. In all 3 years, 'Cheese' and 'Bugle' squash (both Cucurbita moschata), and 'Judgment III' and 'Lioness' summer squash (C. pepo) were among the cultivars with the least diseased leaf area. C. moschata, C. pepo, C. maxima, and Luffa cylindrica (smooth loofah) were significantly less susceptible to foliar blight than Cucumis melo and three Citrullus lanatus cultivars in 2008 and 2009. This study also is the first documentation of susceptibility of Cucurbita argyrosperma to gummy stem blight.

Lack of structure in the gene pool of the highly polyploid ornamental chrysanthemum

Selection of clonally propagated chrysanthemums is mostly performed on F1 hybrids using phenotypic characteristics without the use of molecular information. We applied 448 amplified fragment length polymorphism markers to a set of 81 accessions, mainly from the European gene pool, covering the different horticultural types (cut, pot and garden varieties) and originating from the most important European chrysanthemum breeders. The average pairwise genetic similarity of 0.69 was moderate to rather high. Neighbour-joining clustering resulted in no grouping of the accessions, either by their common origin or their horticultural type, or by similarities in important phenotypic characteristics. The structure of the dendrogram could not be supported by bootstrap analysis. Furthermore, network analysis using SplitsTree, principal coordinate analysis via DARwin or analysis of the population with structure did not differentiate reliable and invariable clusters. Therefore, we tested the marker saturation by plotting the mean coefficient of variation for every pairwise similarity of the bootstrap analysis against the different numbers of markers. We showed that the number of markers is sufficient for a precise estimate of genetic similarity and that the lack of bootstrap support is not due to a low genetic diversity or a lack of marker information, but most likely resulted from the breeding history of the cultivars, involving repeated backcrosses and the exchange of genotypes between breeders.

Diagnostic Guide for Gummy Stem Blight and Black Rot on Cucurbits

Gummy stem blight and black rot affect all commonly cultivated cucurbits, including melon, watermelon, cucumber, pumpkin, and squash. Symptoms may be found on all vegetative and reproductive parts of plants, although there is variation in susceptibility among species and horticultural types. Characteristic symptoms include foliar blight, crown and stem cankers, and fruit rot. The pathogen, Didymella bryoniae, can be identified from its fruiting bodies of pycnidia and pseudothecia on diseased tissue and in culture. Accepted for publication 27 August 2013. Published 24 October 2013.

Carbon, Nitrogen, and Orthophosphate Leaching from Soil under Single- and Mixed-species Landscapes

Effective landscape management practices in urban landscapes must include an awareness of nutrient removal from soil caused by leaching, and these practices should be those least damaging to freshwaters. Annual mean dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate-N, ammonium-N, soluble phosphate, and bicarbonate concentrations and fluxes were quantified in leachate from landscapes planted with different urban horticultural types. Plot vegetation consisted of either a single species or mixed species. The experiment was conducted at two sites in Texas with significantly different irrigation water chemistry. At the two sites, plant species had a significant effect on PO43--P flux, and irrigation chemistry had a significant effect on all nutrient fluxes. There was an interaction between plant species and irrigation chemistry for PO43--P flux (P &lt; 0.05) only. The relationship between bicarbonate and DOC flux at sites was stronger and significant (0.92; P &lt; 0.05) at the site irrigated with Na-HCO3 municipal tap water than at the site irrigated with Ca-HCO3 municipal tap water (R2 = 0.76, P = 0.05). Type of irrigation water chemistry may result in lower plant water uptake resulting in increased nutrients lost to leachate.

LSGermOPA, a custom OPA of 384 EST-derived SNPs for high-throughput lettuce (Lactuca sativa L.) germplasm fingerprinting

To deploy a high-throughput genotyping platform in germplasm management, we designed and tested a custom OPA (Oligo Pool All), LSGermOPA, for assessing the genetic diversity and population structure of the USDA cultivated lettuce (Lactuca sativa L.) germplasm collection using Illumina’s GoldenGate assay. This OPA contains 384 EST (expressed sequence tag)-derived SNP (single nucleotide polymorphism) markers selected from a large set of SNP markers experimentally validated and mapped by the Compositae Genome Project. Used for genotyping were DNA samples prepared from bulked leaves of five randomly-selected seedlings from each of 380 lettuce accessions. High-quality genotype data were obtained from 354 of the 384 SNPs. The reproducibility of automatic genotype calls was 99.8% as calculated from the four pairs of duplicated DNA samples in the assay. An unexpectedly high percentage of heterozygous genotypes at the polymorphic loci for most accessions indicated a high level of heterogeneity within accessions. Only 148 homogenous accessions, collectively comprising all five horticultural types, were used in subsequent analyses to demonstrate the usefulness of LSGermOPA. The results of phylogenetic relationship, population structure and genetic differentiation analyses were consistent with previous reports using other marker systems. This suggests that LSGermOPA is capable of revealing sufficient levels of polymorphism among lettuce cultivars and is appropriate for rapid assessment of genetic diversity and population structure in the lettuce germplasm collection. Challenges and strategies for effective genotyping and managing lettuce germplasm are discussed.

Mapping a dominant negative mutation for triforine sensitivity in lettuce and its use as a selectable marker for detecting hybrids

Some lettuce cultivars are highly sensitive to triforine, an inhibitor of sterol biosynthesis found in some commercial systemic fungicides. First symptoms of a sensitive reaction are usually observed within 24–48 h after treatment and include severe wilting, necrosis and rapid plant death. We mapped a single dominant gene (Tr) that confers sensitivity of lettuce to triforine to linkage group 1 of the integrated genetic map of lettuce. The occurrence of sensitivity is not uniform across horticultural types of lettuce. While over 80% of green-romaine lettuce cultivars tested were sensitive, most cultivars of all other lettuce types were insensitive to triforine. All accessions of wild Lactuca spp. were insensitive to triforine. Allelism tests using F1 and F2 progeny revealed that sensitive cultivars of all horticultural types likely carry the same Tr gene. The dominant allele for sensitivity found in cultivated lettuce probably had a monophyletic origin. The reaction to triforine can be used as a marker for detecting hybrids originating from a cross between phenotypically similar parents with different responses to triforine treatment. It also provides an indication of genotypes for which applications of triforine-containing fungicides are inappropriate.

DEVELOPMENT OF MOLECULAR MARKERS FOR MARKER-ASSISTED SELECTION OF DIEBACK DISEASE RESISTANCE IN LETTUCE (LACTUCA SATIVA)

Lettuce dieback disease is widespread in commercially grown romaine and leaf-type lettuces, but not in iceberg-type cultivars. The disease is caused by two closely related Tombusviruses: Tomato bushy stunt virus (TBSV) and Lettuce necrotic stunt virus (LNSV). A single dominant gene (Tvr1) on chromosomal linkage group 2 has been found to be responsible for the resistance observed in modern iceberg lettuces. A population of 192 F 8 recombinant inbred lines (RILs) developed from crosses between the susceptible romaine cultivar 'Valmaine' and the resistant iceberg cultivars 'Salinas 88' and 'Salinas' was used to pinpoint the position of the resistance gene with EST-based molecular markers. Nine markers closely linked to the Tvrl gene were subsequently tested for association with resistance in a set of 68 accessions from all horticultural types of lettuce. Sequencing of the marker that matched precisely with resistance revealed the presence of three haplotypes in L. sativa, two of them associated with resistance. High-resolution DNA melting analysis, which allows detection of all three haplotypes in a single analysis, was successfully applied to study the marker-trait association. Results confirmed the usefulness of the marker for marker-assisted selection in all types of cultivated lettuce.

Variation in susceptibility of lettuce cultivars to fusarium wilt caused by Fusarium oxysporum f.sp. lactucae

Lettuce cultivars adapted to Californian growing conditions were screened for resistance to fusarium wilt caused by Fusarium oxysporum f.sp. lactucae in order to determine if differences in susceptibility among currently grown cultivars might contribute to management of this disease. Based on a preliminary evaluation of 46 cultivars, eight that were among the most resistant of their horticultural type (iceberg, romaine or leaf) were selected for further testing. The relative susceptibility of these cultivars was assessed by: (i) root‐dip inoculation, (ii) sowing seeds into infested potting mix and (iii) transplanting seedlings into an infested field. Evaluations of disease severity showed that both methods (i) and (ii) produced cultivar rankings that were significantly correlated with rankings from field trials [method (iii)]. Two romaine and two leaf cultivars were highly resistant to fusarium wilt (mean disease severity rating of ≤1·3 on a 1–4 scale) under all test conditions. Other romaine and leaf cultivars, however, were highly susceptible in root–dip tests, so there was no consistent association between cultivar type and susceptibility to fusarium wilt. Likewise, there was considerable variation in susceptibility to wilt among iceberg cultivars, but all were significantly more susceptible than the most resistant romaine and leaf cultivars.

Effects of soil texture and land use interactions on organic carbon in soils in North China cities' urban fringe

Limited information exists on the linkages between soil texture and land use on C storage efficiency. Organic C concentration in soils at the rural–urban interface was measured in 1982, 2000, and 2006 to determine controlling factors and optimal land use type to enhance soil organic C (SOC) storage in benchmark soil textural classes in the North China Plain's Daxing district. Soil texture was the key to attaining elevated SOC concentrations in different land use types under different management intensities. From 1982 to 2006, the order of increasing SOC concentrations across land use types was fine sand (FS) < sand loam (SL) < light loam (LL) < middle loam (ML), indicating that soil with larger proportions of fine particles has larger storage capacities and rates of SOC accumulation. Since 1982, increased use of inorganic fertilizers, intensive cropping and increased crop yields, and the practice of returning crop residues to the soil have been beneficial to C storage in agricultural soils across the district. Diversification of land uses was extensive since 2000, but only the continuous wheat–maize (WM1982–WM2000–WM2006) system has maintained elevated SOC concentrations across the range of soil texture classes ranging from FS to ML. Differential declines in SOC concentrations were observed in most other land uses that included vegetables, watermelon, fruits, and other cash crops. Conversion of a WM land use type to horticultural land use types was more detrimental to FS soils than to finer-textured SL or LL soils, particularly with the continuous use of low-biomass producing land use types in urban fringe areas in the North China Plain.

Association mapping and marker-assisted selection of the lettuce dieback resistance gene Tvr1.

BackgroundLettuce (Lactuca saliva L.) is susceptible to dieback, a soilborne disease caused by two viruses from the family Tombusviridae. Susceptibility to dieback is widespread in romaine and leaf-type lettuce, while modern iceberg cultivars are resistant to this disease. Resistance in iceberg cultivars is conferred by Tvr1 - a single, dominant gene that provides durable resistance. This study describes fine mapping of the resistance gene, analysis of nucleotide polymorphism and linkage disequilibrium in the Tvr1 region, and development of molecular markers for marker-assisted selection.ResultsA combination of classical linkage mapping and association mapping allowed us to pinpoint the location of the Tvr1 resistance gene on chromosomal linkage group 2. Nine molecular markers, based on expressed sequence tags (EST), were closely linked to Tvr1 in the mapping population, developed from crosses between resistant (Salinas and Salinas 88) and susceptible (Valmaine) cultivars. Sequencing of these markers from a set of 68 cultivars revealed a relatively high level of nucleotide polymorphism (θ = 6.7 × 10-3) and extensive linkage disequilibrium (r2 = 0.124 at 8 cM) in this region. However, the extent of linkage disequilibrium was affected by population structure and the values were substantially larger when the analysis was performed only for romaine (r2 = 0.247) and crisphead (r2 = 0.345) accessions. The association mapping approach revealed that one of the nine markers (Cntg10192) in the Tvr1 region matched exactly with resistant and susceptible phenotypes when tested on a set of 200 L. sativa accessions from all horticultural types of lettuce. The marker-trait association was also confirmed on two accessions of Lactuca serriola - a wild relative of cultivated lettuce. The combination of three single-nucleotide polymorphisms (SNPs) at the Cntg10192 marker identified four haplotypes. Three of the haplotypes were associated with resistance and one of them was always associated with susceptibility to the disease.ConclusionWe have successfully applied high-resolution DNA melting (HRM) analysis to distinguish all four haplotypes of the Cntg10192 marker in a single analysis. Marker-assisted selection for dieback resistance with HRM is now an integral part of our breeding program that is focused on the development of improved lettuce cultivars.

Development of EST-SSR markers for the study of population structure in lettuce (Lactuca sativa L.).

A set of 61 simple sequence repeat (SSR) markers was developed from the 19,523 Lactuca sativa and Lactuca serriola unigenes. Approximately 4.5% of the unigenes contained a perfect SSR at least 20 bp long, corresponding to roughly 1 perfect SSR per 14.7 kb. Marker polymorphism was tested on a set comprising 96 accessions representing all major horticultural types and 3 wild species (L. serriola, Lactuca saligna, and Lactuca virosa). Both the average marker heterozygosity (UHe = 0.32) and the number of different alleles per locus (Na = 3.56) were significantly reduced in expressed sequence tag (EST)-SSRs as compared with anonymous SSRs (UHe = 0.59, Na = 5.53). Marker transfer rate to the wild species corresponded to the decreasing sexual compatibility with L. sativa and was higher for EST-SSRs (100% L. serriola, 87% L. saligna, and 75% L. virosa) than for anonymous SSRs (93%, 66%, and 42%, respectively). Assessment of population structure among 90 L. sativa cultivars with SSRs was in good agreement with classification into the horticultural types. The average marker heterozygosity was smallest in iceberg (0.097), Latin (0.140), and romaine-type (0.151) cultivars while highest in leaf (green leaf 0.208 and red leaf 0.240) lettuces. The level of marker heterozygosity is in accord with morphological variability observed in different horticultural types.