Differences in response to simulated herbivory between <Emphasis Type="Italic">Quercus crispula</Emphasis> and <Emphasis Type="Italic">Quercus dentata</Emphasis>

To evaluate the responses of Quercus crispula and Quercus dentata to herbivory, their leaves were subjected to simulated herbivory in early spring and examined for the subsequent changes in leaf traits and attacks by chewing herbivores in mid summer. In Quercus crispula, nitrogen content per area was higher in artificially damaged leaves than in control leaves. This species is assumed to increase the photosynthetic rate per area by increasing nitrogen content per area to compensate leaf area loss. In Quercus dentata, nitrogen content per area did not differ between artificially damaged and control leaves, while nitrogen content per mass was slightly lower in artificially damaged leaves. The difference in their responses can be attributable to the difference in the architecture of their leaves and/or the severeness of herbivory. The development of leaf area from early spring to mid summer was larger in artificially damaged leaves than in control leaves in both species, suggesting the compensatory response to leaf area loss. Leaf dry mass per unit area was also larger in artificially damaged leaves in both species, but the adaptive significance of this change is not clear. In spite of such changes in leaf traits, no difference was detected in the degree of damage by chewing herbivores between artificially damaged and controlled leaves in both species.     

Interactions of root and leaf herbivores on purple loosestrife (<Emphasis Type="Italic">Lythrum salicaria</Emphasis>)

Interspecific interactions of herbivores sharing a host plant may be important in structuring herbivore communities. We investigated host plant-mediated interactions of root (Hylobius transversovittatus) and leaf herbivores (Galerucella calmariensis), released to control purple loosestrife (Lythrum salicaria) in North America, in field and potted plant experiments. In the potted plant experiments, leaf herbivory by G. calmariensis reduced H. transversovittatus larval survival (but not larval development) but did not affect oviposition preference. Root herbivory by H. transversovittatus did not affect either G. calmariensis fitness or oviposition preference. In field cage experiments, we found no evidence of interspecific competition between root and leaf herbivores over a 4-year period. Our data suggest that large populations of leaf beetles can negatively affect root-feeding larvae when high intensity of leaf damage results in partial or complete death of belowground tissue. Such events may be rare occurrences (or affected by experimental venue) since field data differed from data obtained from potted plant experiments, particularly at high leaf beetle densities. Interspecific interactions between G. calmariensis and H. transversovittatus are possible and may negatively affect either species, but this is unlikely to occur unless heavy feeding damage results in partial or complete plant death.     

Effects of simulated herbivory on photosynthesis and N resorption efficiency in <Emphasis Type="Italic">Quercus</Emphasis><Emphasis Type="Italic">pyrenaica</Emphasis> Willd. saplings

We examined the effects of simulated folivory by caterpillars on photosynthetic parameters and nitrogen (N) resorption efficiency in Quercus pyrenaica saplings. We analyzed the differences between intact leaves in control plants, punched leaves in damaged plants, and intact leaves in damaged plants. We then established two levels of simulated folivory: low (≈13% of the leaf area of one main branch removed per plant) and high (≈26% of the leaf area of one main branch removed per plant) treatments. No differences were found in net assimilation rate and conductance between either leaf type or treatment during the most favourable period for photosynthesis. However, the N content was lower in punched than in intact leaves, and as a result PNUE was higher in damaged leaves from treated trees. In leaf-litter samples, N mass was significantly higher in punched than in intact leaves in treated plants, and LMA was significantly higher in damaged than in intact leaves of both the treated and control plants. Consequently, N resorption efficiency was around 15% lower in damaged leaves as compared with intact leaves from treated and control plants. Mechanical injury to leaves not only triggered no compensatory photosynthetic response to compensate a lower carbon uptake due to leaf area loss, but also affected the resorption process that characterizes leaf senescence.     

Nutritional suitability and ecological relevance of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> and <Emphasis Type="Italic">Brassica oleracea</Emphasis> as foodplants for the cabbage butterfly, <Emphasis Type="Italic">Pieris rapae</Emphasis>

The thale cress, Arabidopsis thaliana, is considered to be an important model species in studying a suite of evolutionary processes. However, the species has been criticized on the basis of its comparatively small size at maturity (and consequent limitations in the amount of available biomass for herbivores) and on the duration and timing of its life cycle in nature. In the laboratory, we studied interactions between A. thaliana and the cabbage butterfly, Pieris rapae, in order to determine if plants are able to support the complete development of the herbivore. Plants were grown in pots from seedlings in densities of one, two, or four per pot. In each treatment, one, two, or five newly hatched larvae of P. rapae were placed on fully developed rosettes of A. thaliana. In a separate experiment, the same densities of P. rapae larvae were reared from hatching on single mature cabbage (Brassica oleracea) plants. Pupal fresh mass and survival of P. rapae declined with larval density when reared on A. thaliana but not on B. oleracea. However, irrespective of larval density and plant number, some P. rapae were always able to complete development on A. thaliana plants. A comparison of the dry mass of plants in different treatments with controls (= no larvae) revealed that A. thaliana partially compensated for plant damage when larval densities of P. rapae were low. By contrast, single cress plants with 5 larvae generally suffered extensive damage, whereas damage to B. oleracea plants was negligible. Rosettes of plants that were monitored in spring, when A. thaliana naturally grows, were not attacked by any insect herbivores, but there was often extensive damage from pulmonates (slugs and snails). Heavily damaged plants flowered less successfully than lightly damaged plants. Small numbers of generalist plant-parasitic nematodes were also recovered in roots and root soil. By contrast, plants monitored in a sewn summer plot were heavily attacked by insect herbivores, primarily flea beetles (Phyllotreta spp.). These results reveal that, in natural populations of A. thaliana, there is a strong phenological mismatch between the plant and most of its potential specialist insect herbivores (and their natural enemies). However, as the plant is clearly susceptible to attack from non-insect generalist invertebrate herbivores early in the season, these may be much more suitable for studies on direct defense strategies in A. thaliana.     

<Emphasis Type="Italic">Codium fragile</Emphasis>: rhizomatous growth in the<Emphasis Type="Italic"> Zostera</Emphasis> thief of eastern Canada

A rhizomatous growth form of Codium fragile is described for the first time. Plants were collected in the Gulf of St. Lawrence in estuaries dominated by Zostera marina. Rhizomatous plants developed from propagules of whole plants that settled horizontally. Horizontal axes of C. fragile were up to 1 m long in plants collected in situ. Plants developed several to dozens of erect axes at right angle to the base. Horizontal growth of up to 0.2 m was found in field experiments where fragments were tied to plastic mesh and left in situ for 4 months. The unconsolidated filaments at the base of C. fragile often wrapped around the rhizomes of Z. marina and up to five separate attachment sites to eelgrass were found in single plants of C. fragile. In four estuaries, 57–100% of Codium plants with identifiable substratum were attached to shoots and rhizomes of Z. marina. The rhizomatous growth form was found in plants identified as C. fragile ssp. tomentosoides (Nova Scotia and Prince Edward Island) and C. fragile ssp. atlanticum (Prince Edward Island), suggesting that this is a phenotypic response to growth in soft bottom environments.Communicated by K Lüning     

Florivory affects pollinator visitation and female fitness in <Emphasis Type="Italic">Nemophila menziesii</Emphasis>

While herbivory has traditionally been studied as damage to leaves, florivory – herbivory to flowers prior to seed set – can also have large effects on plant fitness. Florivory can decrease fitness directly, either through the destruction of gametes or through alterations to plant physiology during fruit set, and can also change the appearance of a flower, deterring pollinators and reducing seed set. In order to distinguish between these hypotheses, it is necessary to both damage flowers and add pollen in excess to study the effects of damage on pollen limitation. Very few studies have used this technique over the lifetime of a plant. Here I describe a series of experiments showing the effects of natural and artificial damage on reproductive success in the annual plant Nemophila menziesii (Hydrophyllaceae, sensu lato). I show that natural and artificial petal damage decreased radial symmetry relative to controls and that both types of damage deterred pollinator activity. Both naturally damaged flowers and artificially damaged flowers in the field set fewer fruit or seed relative to undamaged control flowers. Finally, in an experiment crossing artificial petal damage with pollen addition, petal damage alone over the lifetime of this plant decreased female fitness, but only after a threshold of damage was reached. The fitness effect appeared to be direct because there was no detectable effect of pollen addition on the relationship between florivory and fitness. This result implies that both damaged and undamaged plants show similar amounts of pollen limitation and suggests that pollinator-mediated effects contributed little to the negative effects of florivory on female fitness. Florivores may thus be an under-appreciated agent of selection in certain plants, although more experimental manipulation of florivory is needed to determine if it is important over a range of taxa.     

Parallel Evolution Under Domestication and Phenotypic Differentiation of the Cultivated Subspecies of <Emphasis Type="Italic">Cucurbita pepo</Emphasis> (Cucurbitaceae)

Parallel Evolution under Domestication and Phenotypic Differentiation of the Cultivated Subspecies of Cucurbita pepo (Cucurbitaceae). Cucurbita pepo (pumpkin, squash, gourd, Cucurbitaceae) is an ancient North American domesticate of considerable economic importance. Based on molecular genetic polymorphisms, two cultivated lineages of this species, each consisting of very many edible–fruited cultigens, have been recognized, C. pepo subsp. pepo and C. pepo subsp. texana. However, the phenotypic commonalities and differences between these two subspecies have not as yet been systematically collected and organized. Among the evolutionary developments common to the two subspecies are the increased size of the plant parts, less plant branching, and premature loss of chlorophyll in the exocarp of the fruits. In both subspecies, bush growth habit, conferred by allele Bu, is common to the cultigens grown for consumption of the immature fruits, as is the deviation from the 1:1 ratio of fruit length to fruit width. A major characteristic differentiating between the edible–fruited cultigens of the respective subspecies are the longitudinal protrusions, in subsp. pepo, versus depressions, in subsp. texana, of the fruit surface corresponding with the subsurface primary carpellary vein tracts. Subsp. pepo also has larger fruits and larger and longer seeds. In addition, some alleles affecting stem color, leaf mottling, multiple flower bud production, and fruit characteristics are frequently occurring to nearly fixed in one subspecies but are rare to less common in the other.     

Parasitism <Emphasis Type="Italic">versus</Emphasis> mutualism in the ant-garden parabiosis between <Emphasis Type="Italic">Camponotus femoratus</Emphasis> and <Emphasis Type="Italic">Crematogaster levior</Emphasis>

Ant-gardens represent a special type of association between ants and epiphytes. Frequently, two ant species can share the same nest in a phenomenon known as ‘parabiosis’, but the exact nature (i.e., mutualistic or parasitic) of this interaction is the subject of debate. We thus attempted to clarify the mutual costs and benefits for each partner (ants and plants) in the Crematogaster levior/Camponotus femoratus ant-garden parabiosis. The ants’ response to experimental foliar damage to the epiphytes and to the host tree as well as their behavior and interactions during prey capture were investigated to see if the purported parasitic status of Cr. levior could be demonstrated in either the ant-ant or in the ant-plant interactions. The results show that both species take part in protecting the epiphytes, refuting the role of Cr. levior as a parasite of the ant-garden mutualism. During capture of large prey Ca. femoratus took advantage from the ability of Cr. levior to discover prey; by following Cr. levior trails Ca. femoratus workers discover the prey in turn and usurp them during agonistic interactions. Nevertheless, the trade-off between the costs and benefits of this association seems then to be favorable to both species because it is known that Cr. levior benefits from Ca. femoratus building the common carton nests and furnishing protection from vertebrates. Consequently, parabiosis can then be defined as the only mutualistic association existing between ant species, at least in ant-gardens. Received 31 August 2006 ; revised 8 December 2006 ; accepted 12 December 2006     

Effect of cultural methods on leaf spot (<Emphasis Type="Italic">Mycosphaerella fragariae</Emphasis>) and gray mold (<Emphasis Type="Italic">Botrytis cinerea</Emphasis>) damage in strawberries

Damage of leaf spot, caused by Mycosphaerella fragariae and gray mold also called Botrytis fruit rot, caused by Botrytis cinerea, average fruit weight and yield were evaluated with regard to cultural methods over 2years. Leaf spot damage decreased significantly by around 90% due to leaf sanitation (removal of dead and leaf spot infected leaves in early spring) and by 50% due to plantation in a one-row-system instead of a two-row-system. When all leaves including the healthy green ones were removed in early spring, average fruit weight decreased significantly by 10%. Fruit sanitation – the third treatment – did not influence any of the measured parameters. Neither leaf sanitation nor fruit sanitation (removal of damaged fruits during harvest) reduced B. cinerea damage significant. Only the combination of a one-row-system, leaf sanitation and fruit sanitation almost halved (not significantly) B. cinerea damage in the first crop year compared to a two-row-system without leaf and fruit sanitation. B. cinerea damage correlated significantly and positively with the biomass of plants by R²= 0.47. According to this study and the cited literature it is suggested for humid Central European conditions to apply a one-row-system combined with leaf sanitation in early spring and fruit sanitation during harvest if fruit density is high, to reduce the risk of damages in larger dimension caused by M. fragariae and B. cinerea.     

Molecular cloning and characterization of the <Emphasis Type="Italic">Dicer-like</Emphasis> 2 gene from <Emphasis Type="Italic">Brassica rapa</Emphasis>

Dicer-like proteins (DCLs) are involved in small RNA-mediated development and viral defense in plants. In model plants, at least four DCLs have been found and a number of studies have helped to understand their function. However, the function of the Dicer or DCLs in other plants is still unclear. Here, we report the full-length cDNA sequence of Brassica rapa ssp. chinensis DCL2 (BrDCL2) gene, which contains a 4,179 bp open reading frame (ORF) encoding a protein of 1,392 amino acids. At the 3′ end of BrDCL2, clones with three different lengths of 3′ untranslated region were found. An alternative splice variant of BrDCL2, BrDCL2sv, in which one intron was retained between exon9 and exon10, was also cloned. Because of a change in the coding sequence resulting in a premature terminal codon, BrDCL2sv was expected to translate a short peptide containing the whole DEXHc domain.     

Patterns of DNA Variation Among Three Centromere Satellite Families in <Emphasis Type="Italic">Arabidopsis halleri</Emphasis> and <Emphasis Type="Italic">A</Emphasis>. <Emphasis Type="Italic">lyrata</Emphasis>

We describe patterns of DNA variation among the three centromeric satellite families in Arabidopsis halleri and lyrata. The newly studied subspecies (A. halleri ssp. halleri and A. lyrata ssp. lyrata and petraea), like the previously studied A. halleri ssp. gemmifera and A. lyrata ssp. kawasakiana, have three different centromeric satellite families, the older pAa family (also present in A. arenosa) and two families, pAge1 and pAge2, that probably evolved more recently. Sequence variability is high in all three satellite families, and the pAa sequences do not cluster by their species of origin. Diversity in the pAge2 family is complex, and different from variation among copies of the other two families, showing clear evidence for exchange events among family members, especially in A. halleri ssp. halleri. In A. lyrata ssp. lyrata there is some evidence for recent rapid spread of pAge2 variants, suggesting selection favoring these sequences. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users. [Reviewing Editor: Dr. Brian Morton]     

The influence of a neotropical herbivore (<Emphasis Type="Italic">Lamponius portoricensis</Emphasis>) on nutrient cycling and soil processes

The role of phytophagous insects in ecosystem nutrient cycling remains poorly understood. By altering the flow of litterfall nutrients from the canopy to the forest floor, herbivores may influence key ecosystem processes. We manipulated levels of herbivory in a lower montane tropical rainforest of Puerto Rico using the common herbivore, Lamponius portoricensis (Phasmatidea), on a prevalent understory plant, Piper glabrescens (Piperaceae), and measured the effects on nutrient input to the forest floor and on rates of litter decomposition. Four treatment levels of herbivory generated a full range of leaf area removal, from plants experiencing no herbivory to plants that were completely defoliated (>4,000 cm² leaf area removed during the 76-day study duration). A significant (P<0.05) positive regression was found between all measures of herbivory (total leaf area removed, greenfall production, and frass-related inputs) and the concentration of NO ₃ ⁻ in ion exchange resin bags located in the litter layer. No significant relationship was found between any of the herbivory components and resin bag concentrations of NH ₄ ⁺ or PO ₄ ⁻ . Rates of litter decay were significantly affected by frass-related herbivore inputs. A marginally significant negative relationship was also found between the litter mass remaining at 47 days and total leaf area removed. This study demonstrated a modest, but direct relationship between herbivory and both litter decomposition and NO ₃ ⁻ transfer to the forest floor. These results suggest that insect herbivores can influence forest floor nutrient dynamics and thus merit further consideration in discussions on ecosystem nutrient dynamics.     

Characterization of directly transformed weedy <Emphasis Type="Italic">Brassica rapa</Emphasis> and introgressed <Emphasis Type="Italic">B. rapa</Emphasis> with Bt <Emphasis Type="Italic">cry1Ac</Emphasis> and <Emphasis Type="Italic">gfp</Emphasis> genes

Crop to weed transgene flow, which could result in more competitive weed populations, is an agricultural biosafety concern. Crop Brassica napus to weedy Brassica rapa hybridization has been extensively characterized to better understand the transgene flow and its consequences. In this study, weedy accessions of B. rapa were transformed with Bacillus thuringiensis (Bt) cry1Ac- and green fluorescence protein (gfp)-coding transgenes using Agrobacterium to assess ecological performance of the wild biotype relative to introgressed hybrids in which the transgenic parent was the crop. Regenerated transgenic B. rapa events were characterized by progeny analysis, Bt protein enzyme-linked immunosorbent assay (ELISA), Southern blot analysis, and GFP expression assay. GFP expression level and Bt protein concentration were significantly different between independent transgenic B. rapa events. Similar reproductive productivity was observed in comparison between transgenic B. rapa events and B. rapa × B. napus introgressed hybrids in greenhouse and field experiments. In the greenhouse, Bt transgenic plants experienced significantly less herbivory damage from the diamondback moth (Plutella xylostella). No differences were found in the field experiment under ambient, low, herbivore pressure. Directly transformed transgenic B. rapa plants should be a helpful experimental control to better understand crop genetic load in introgressed transgenic weeds.     

Impact of <Emphasis Type="Italic">cry1AC</Emphasis>-carrying <Emphasis Type="Italic">Brassica rapa</Emphasis> subsp. <Emphasis Type="Italic">pekinensis</Emphasis> on leaf bacterial community

The effects of Chinese cabbage (Brassica rapa subsp. pekinensis) carrying cry1AC derived from Bacillus thuringiensis (Bt) on leaf bacterial community were examined by analyzing the horizontal transfer of trans-gene fragments from plants to bacteria. The effect of plant pathogenic bacteria on the gene transfer was also examined using Pseudomonas syringae pathovar. maculicola. The frequency of hygromycin-resistant bacteria did not alter in Bt leaves, though slight increase was observed in Pseudomonas-infected Bt leaves with no statistical significance. The analysis of bacterial community profiles using the denaturing gradient gel electrophoresis (DGGE) fingerprinting indicated that there were slight differences between Bt and control Chinese cabbage, and also that infected tissues were dominated by P. syringae pv. maculicola. However, the cultured bacterial pools were not found to contain any transgene fragments. Thus, no direct evidence of immediate gene transfer from plant to bacteria or acquisition of hygromycin resistance could be observed. Still, long-term monitoring on the possibility of gene transfer is necessary to correctly assess the environmental effects of the Bt crop on bacteria.     

Cost of trichome production and resistance to a specialist insect herbivore in <Emphasis Type="Italic">Arabidopsis lyrata</Emphasis>

Theory predicts that trade-offs between resistance to herbivory and other traits positively affecting fitness can maintain genetic variation in resistance within plant populations. In the perennial herb Arabidopsis lyrata, trichome production is a resistance trait that exhibits both qualitative and quantitative variation. Using a paternal half-sib design, we conducted two greenhouse experiments to ask whether trichomes confer resistance to oviposition and leaf herbivory by the specialist moth Plutella xylostella, and to examine potential genetic constraints on evolution of increased resistance and trichome density. In addition, we examined whether trichome production is induced by insect herbivory. We found strong positive genetic and phenotypic correlations between leaf trichome density and resistance to leaf herbivory, demonstrating that the production of leaf trichomes increases resistance to leaf damage by P. xylostella. Also resistance to oviposition tended to increase with increasing leaf trichome density, but genetic and phenotypic correlations were not statistically significant. Trichome density and resistance to leaf herbivory were negatively correlated genetically with plant size in the absence of herbivores, but not in the presence of herbivores. There was no evidence of increased trichome production after leaf damage by P. xylostella. The results suggest that trichome production and resistance to leaf herbivory are associated with a cost and that the direction of selection on resistance and trichome density depends on the intensity of herbivory.     

Increased competitive ability and herbivory tolerance in the invasive plant <Emphasis Type="Italic">Sapium sebiferum</Emphasis>

The evolution of increased competitive ability (EICA) hypothesis predicts that release from natural enemies in the introduced range favors exotic plants evolving to have greater competitive ability and lower herbivore resistance than conspecifics from the native range. We tested the EICA hypothesis in a common garden experiment with Sapium sebiferum in which seedlings from native (China) and invasive (USA) populations were grown in all pairwise combinations in the native range (China) in the presence of herbivores. When paired seedlings were from the same continent, shoot mass and leaf damage per seedling were significantly greater for plants from invasive populations than those from native populations. Despite more damage from herbivores, plants from invasive populations still outperformed those from native populations when they were grown together. Increased competitive ability and higher herbivory damage of invasive populations relative to native populations of S. sebiferum support the EICA hypothesis. Regression of biomass against percent leaf damage showed that plants from invasive populations tolerated herbivory more effectively than those from native populations. The results of this study suggest that S. sebiferum has become a faster-growing, less herbivore-resistant, and more herbivore-tolerant plant in the introduced range. This implies that increased competitive ability of exotic plants may be associated with evolutionary changes in both resistance and tolerance to herbivory in the introduced range. Understanding these evolutionary changes has important implications for biological control strategies targeted at problematic invaders.     

Biological control of <Emphasis Type="Italic">Lantana camara</Emphasis> in South Africa: targeting a different niche with a root-feeding agent, <Emphasis Type="Italic">Longitarsus</Emphasis> sp.

The root-feeding flea beetle, Longitarsus sp. (Coleoptera: Chrysomelidae: Alticinae), was studied as a potential biological control agent for Lantana camara L. (Verbenaceae) in South Africa. Host range tests were carried out on 52 plant species in 11 families. Although 11 plant species, all in the family Verbenaceae, supported complete development of Longitarsus sp. during no-choice tests, the beetles showed very strong preferences for L. camara during paired-choice and multi-choice tests. The results confirm that the beetles have a narrow host range, and that under natural conditions they are highly unlikely to utilise plants other than L. camara. In the unlikely event that some of the Lippia spp. are attacked in the field, they are not expected to sustain populations of the flea beetle over time. Attributes that should enhance the biocontrol potential of Longitarsus sp. include: the adults are long-lived and highly mobile; and, the larvae cause extensive direct damage to the roots of L. camara, which could in turn expose the plants to soil-born pathogens. All indications are that Longitarsus sp. could make a substantial contribution to the biological control of L. camara in many countries around the world because the beetles pose no threat to non-target plant species and they damage a part of the plant (i.e. roots) not yet affected by any other agent species.     

A consensus map for <Emphasis Type="Italic">Cucurbita pepo</Emphasis>

Using random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), simple sequence repeats (SSR), and morphological traits, the first genetic maps for Cucurbita pepo (2n=2x=40) were constructed and compared. The two mapping populations consisted of 92 F₂ individuals each. One map was developed from a cross between an oil-seed pumpkin breeding line and a zucchini accession, into which genes for resistance to Zucchini Yellow Mosaic Virus (ZYMV) from a related species, C. moschata, had been introgressed. The other map was developed from a cross between an oil-seed pumpkin and a crookneck variety. A total of 332 and 323 markers were mapped in the two populations. Markers were distributed in each map over 21 linkage groups and covered an average of 2,200 cM of the C. pepo genome. The two maps had 62 loci in common, which enabled identification of 14 homologous linkage groups. Polyacrylamide gel analyses allowed detection of a high number of markers suitable for mapping, 10% of which were co-dominant RAPD loci. In the Pumpkin-Zucchini population, bulked segregant analysis (BSA) identified seven markers less than 7 cM distant from the locus n, affecting lignification of the seed coat. One of these markers, linked to the recessive hull-less allele (AW11-420), was also found in the Pumpkin-Crookneck population, 4 cM from n. In the Pumpkin-Zucchini population, 24 RAPD markers, previously introduced into C. pepo from C. moschata, were mapped in two linkage groups (13 and 11 markers in LGpz1 and LGpz2, respectively), together with two sequence characterized amplified region (SCAR) markers linked to genes for resistance to ZYMV.