No more lake balls (<Emphasis Type="Italic">Aegagropila linnaei</Emphasis> Kützing,Cladophorophyceae, Chlorophyta) in The Netherlands?

Aegagropila linnaei, a freshwater green macroalga, had been abundant in several locations in The Netherlands before the 1960s. Both the ‘lake ball’ form of this alga and dense unattached mats floating over the sediment have been described from these locations. After 1967, this species has not been recorded anymore from The Netherlands. In 2007, several historical collection sites were surveyed for extant populations of A. linnaei. All habitats have changed drastically during the last 50 years and were affected severely by eutrophication. Populations of A. linnaei seem to have become extinct in all but one location (Boven Wijde, province Overijssel), where we found very small amounts of attached filaments. The attached form had not been reported previously from The Netherlands. Environmental conditions do not seem suitable anymore to maintain extensive unattached growth forms including the enigmatic lake balls, and the species must be regarded as threatened in The Netherlands and we propose to include A. linnaei in a national red list. The decline of populations elsewhere is reviewed and discussed in this paper. In addition to morphological identification of the attached filaments, partial sequences of the nuclear large subunit rDNA were generated and compared with different growth forms and habitats from several other locations outside The Netherlands. The sequences confirm the identity of the Dutch material and indicate very little divergence both between populations in different locations and between different growth forms.     

A genetic linkage map for an apricot (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) BC<Subscript>1</Subscript> population mapping <Emphasis Type="Italic">plum pox virus</Emphasis> resistance

Plum pox virus (sharka; PPV) can cause severe crop loss in economically important Prunus species such as peach, plum, apricot, and cherry. Of these species, certain apricot cultivars (‘Stark Early Orange’, ‘Goldrich’, ‘Harlayne’) display significant levels of resistance to the disease and are the genetic substrate for studies of several xlaboratories working cooperatively to genetically characterize and mark the resistance locus or loci for marker-assisted breeding. The goals of the work presented in this communication are the characterization of the genetics of PPV resistance in ‘Stark Early Orange’ and the development of co-dominant molecular markers for marker-assisted selection (MAS) in PPV resistance breeding. We present the first genetic linkage map for an apricot backcross population of ‘Stark Early Orange’ and the susceptible cultivar ‘Vestar’ that segregates for resistance to PPV. This map is comprised of 357 loci (330 amplified fragment length polymorphisms (AFLPs), 26 simple sequence repeats (SSRs), and 1 morphological marker for PPV resistance) assigned to eight linkage groups. Twenty-two of the mapped SSRs are shared in common with genetic reference map for Prunus (T × E; Joobeur et al. 1998) and anchor our apricot map to the general Prunus map. A PPV resistance locus was mapped in linkage group 1 and four AFLP markers segregating with the PPV resistance trait, identified through bulk segregant analysis, facilitated the development of SSRs in this region. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Lalli, D.A. and Salava, J. contributed equally to this work.     

Differentiation betweenPhaeocystis pouchetii (Har.) Lagerheim andPhaeocystis globosa Scherffel

An Arctic clone ofPhaeocystis pouchetii LAGERHEIM was compared toPhaeocystis globosa SCHERFFEL isolated from the southern North Sea with regard to temperature tolerance and colony shapes. Already youngP.pouchetii colonies (<100 m) show the typical distribution of the cells in groups, separated from each other by wide zones of cell-free mucilage; the maximum colony size is ca 2 mm in diameter.P.pouchetii colonies form clouds with bubble-like vesicles, spherical colony-shapes are seldom found.P.globosa colonies are spherical up to a size of 2 mm; the cells are distributed homogeneously over the periphery of the colonies. A pouchetii-like distribution of cells never occurs either in the spherical young colonies or in the pear-shaped old colonies (size up to 8 mm). A development from the colony shape of the globosa-type to the pouchetii-type or vice versa was never found. Therefore the colony shape has to be considered a constant distinctive character. Single cells ofP.pouchetii andP.globosa cannot be separated from each other by using the light microscope; this also holds for the flagellates and the non-motile cells.P.pouchetii grows well between 0°C and 14°C,P.globosa between 4°C and 22°C, respectively. Because of the distinctive differences in the morphology of the colonies and the differences in temperature tolerances we propose thatPhaeocystis globosa should no longer be considered conspecific withPhaeocystis pouchetii.     

A comparison of the morpho-cytology and chemical composition of the two forms of the cyanobacterium, <Emphasis Type="Italic">Nostoc commune</Emphasis> Vauch., from the Philippines and Japan

Nostoc commune Vauch. is one of the few freshwater cyanobacteria that has been used as human food. But its commercial production has been elusive. This prompted us to investigate further on the chemical composition and morpho-cytological characteristics of the discoid and spherical forms of the alga from the Philippines and Japan. Light microscopy of the two forms revealed that they consisted of irregularly coiled, unbranched, heterocystous filaments. Transmission electron microscopy showed that a trichome was enclosed by a 14 μm  thick mucilaginous sheath (extracellular polysaccharide, EPS). A colonial sheath enveloped a spherical colony that was made up of a blue-green outer core that enclosed an inner, whitish, fleshy core, while the discoid form was a deflated or desiccated form of the spherical form. Cytologically, the outer core of the spherical colony (PS) had significantly (p < 0.01) shorter filaments and higher heterocyst frequency than the discoid colony while the discoid type had greater number of detached heterocysts than the other type. Chemical analyses revealed that the cyanobacterium had 34–45% oxalate-oxalic acid soluble substances (OOSS), a dietary fiber that was found to be in higher concentration among the discoid forms than the spherical forms. The major components of OOSS were identified as glucuronic and galacturonic acids that may play a role in modulating water flow in the glycans of the mucilaginous sheath. There were 17 amino acids identified. Philippine spherical (PS) colonies yielded generally higher concentration for each of these amino acids than the discoid types (PD and JD) except for phenylalanine, aspartic acid, and proline. There were six soluble proteins identified in the samples with the following molecular weights in kDa: 73, 55, 39, 36, 29, and 14.4. A protein band of 55 kDa was common to all types of colonies while 73 kDa was identified in the spherical form (PS) and faintly in the discoid form (JD). The protein bands of 39, 36, 29, and 14.4 kDa were found distinctly among the discoid forms (desiccated types) regardless of origin but absent in the spherical forms. In vitro protein digestion was improved, by as much as 30%, when the pigments were extracted. However, the presence of phenolic compounds could also affect protein digestion. Morpho-cytological studies and chemical analyses showed that N. commune of the same colony form generally had the same characteristics regardless of their origin. Although the common traits were more obviously observed among the discoid colonies. However, protein, crude lipid, and chlorophyll a concentrations were found to be more dependent on the age and culture condition of the cyanobacterium than on colony form or origin. Presented at the 6th Meeting of the Asia Pacific Society of Applied Phycology, Manila, Philippines.     

Genetic diversity amongst landraces of a dioecious vegetatively propagated plant,betelvine (<Emphasis Type="Italic">Piper betle</Emphasis> L.)

Betelvine (Piper betle L., family Piperaceae) is an important, traditional and widely cultivated crop of India. The cultivators and consumers recognize more than 100 cultivars (landraces) based on regional and organoleptic considerations, while in terms of phytochemical constituents only five groups have been identified for all the landraces. Since betelvine is an obligate vegetatively propagated species, genomic changes, if any, may have become ‘fixed’ in the landraces. We carried out random amplified polymorphic DNA (RAPD) analysis in several landraces considered in four groups, namely, ‘Kapoori’, ‘Bangla’, ‘Sanchi’ and ‘Others’ in order to ascertain their genetic diversity. On the basis of the data from eleven RAPD primers, we distinguished genetic variation within and among the four groups of landraces. The results indicate the’Kapoori’ group is the most diverse. The neighbour joining (NJ) tree after a bootstrap (500 replicate) test of robustness clearly shows the four groups to be well separated. Interestingly, all known male or female betelvine landraces have separated in the NJ tree indicating an apparent gender-based distinction among the betelvines.     

Classification of rice germplasm: III. High-resolution fingerprinting of cytoplasmic genetic male-sterile (CMS) lines with AFLP

 The cytoplasmic genetic male-sterile (CMS) lines developed at the International Rice Research Institute are valuable in producing tropical rice hybrids. Efficient use of CMS lines in hybrid rice production will depend on their level of genetic diversity. Aside from morphological characterization, molecular analysis based on DNA markers can provide information on the genetic diversity of the germplasm. The Amplified Fragment Length Polymorphism (AFLP) technique was used to fingerprint 71 CMS lines and four rice cultivars, ‘IR64’, ‘Azucena’, ‘IR74’, and ‘FR13A’. Eleven primer pair combinations specific to the enzymes PstI and MseI were used to generate 530 AFLP markers, 176 of which were polymorphic. Each CMS line revealed a distinct fingerprint. The AFLP marker-based dendrogram depicted genetic variation among the CMS lines. The CMS lines developed in japonica background grouped with ‘Azucena’, a japonica cultivar. None of the CMS lines clustered with ‘FR13A’, a flood-tolerant traditional indica variety. ‘IR64’ was found to be distinct from the other indica CMS lines and clustered with lines developed in its background. The grouping of CMS lines into a few groups is useful for breeders in selecting genetically diverse CMS lines for hybrid rice production and in avoiding test crossing every CMS line empirically. This study demonstrated that AFLP is a powerful and reliable tool in determining the genetic relationships and in producing distinct fingerprints of rice cultivars. Received: 20 December 1996 / Accepted: 9 October 1997     

Experimental Conversion of Colony Social Organization in Fire Ants (<Emphasis Type="Italic">Solenopsis invicta</Emphasis>): Worker Genotype Manipulation in the Absence of Queen Effects

Colony social organization in the fire ant Solenopsis invicta appears to be under strong genetic control. In the invasive USA range, polygyny (multiple queens per colony) is marked by the presence of the Gp-9 ^b allele in most of a colony’s workers, whereas monogyny (single queen per colony) is associated with the exclusive occurrence of the Gp-9 ^B allele. Ross and Keller, Behav Ecol Sociobiol 51:287–295 (2002) experimentally manipulated social organization by cross-fostering queens into colonies of the alternate form, thereby changing adult worker Gp-9 genotype frequencies over time. Although these authors showed that social behavior switched predictably when the frequency of b-bearing adult workers crossed a threshold of 5–10%, the possibility that queen effects caused the conversions could not be excluded entirely. We addressed this problem by fostering polygyne brood into queenright monogyne colonies. All such treatment colonies switched social organization to become polygyne, coincident with their proportions of b-bearing workers exceeding 12%. Our results support the conclusion that polygyny in S. invicta is induced by a minimum frequency of colony workers carrying the b allele, and further confirm that its expression is independent of queen genotype or history, worker genotypes at genes not linked to Gp-9, and colony genetic diversity.     

Towards a legal framework for systematic conservation: identification and development of allele-specific PCR markers for conspecific varieties of an endangered perennial herb <Emphasis Type="Italic">Primula kisoana</Emphasis> Miquel based on sequence variation of chloroplast DNA

Primula kisoana var. kisoana (Primulaceae) is a narrow endemic found only in extremely restricted areas of central Honshu Island, Japan. Although the species is included as ‘Critically Endangered (CR)’ in the latest Japanese Red List, it is not covered by legislation such as the ‘Law for the Conservation of Endangered Species of Wild Fauna and Flora, Japan’. This poor conservation status is due, largely, to the presence of another conspecific variety, var. shikokiana, which is regarded as less threatened than var. kisoana. In this study, we investigated the genetic dissimilarity between the two varieties by examining sequence variation in three noncoding regions of chloroplast DNA. Ten distinct haplotypes were detected, none of which were distributed across populations and varieties. The genetic differentiation between the two varieties revealed by an AMOVA and a minimum spanning network suggests that var. kisoana and var. shikokiana should be conserved and managed as separate units. Using the allele-specific PCR method, four primer pairs were developed at the point mutations and insertion/deletion loci that exhibited only inter-variety variation. These markers will facilitate reliable identification of var. kisoana, assisting in the implementation of restoration programs including the introduction of seedlings and construction of a legal framework for conservation.     

Do Japanese Queenless Ants Pristomyrmex punctatus (F. Smith) Exhibit Genotype-based Kin Recognition During Colony Formation?

The queenless ant, Pristomyrmex punctatus (F. Smith) reproduces parthenogenetically. Workers lay unfertilized eggs, which develop into female workers. This mode of reproduction generates hereditary clones, though a colony is not necessarily constructed from single clonal line. In a previous study, where a colony was separated into two subcolonies, it was found that genetically monomorphic colonies tended to reassemble but genetically polymorphic colonies did not. Here, we used multiple clonal colonies to investigate whether P. punctatus could recognize “individual” relatedness and assemble with subcolony members of the same clonal type. Results show individuals did not assemble with individuals of the same clonal type in each subcolony. This suggests they cannot recognize individual relatedness.     

QTL mapping of aroma compounds analysed by headspace solid-phase microextraction gas chromatography in the apple progeny ‘Discovery’ × ‘Prima’

Improving fruit quality of apple varieties is an important but complex breeding goal. Flavour is among the key factors of apple fruit quality but in spite of the analytical and biochemical knowledge about volatiles little is known about the genetic and molecular bases of apple aroma. The aim of this study was to use a saturated molecular linkage map of apple to identify QTLs for aroma compounds such as alcohols, esters and terpenes, but also for a number of unidentified volatile compounds (non-targeted analysis approach). Two parental genetic maps were constructed for the apple cultivars ‘Discovery’ and ‘Prima’ by using mainly AFLP and SSR markers. ‘Discovery’ and ‘Prima’ showed very different volatile patterns, and ‘Discovery’ mostly had the higher volatile concentrations in comparison with the Vf-scab resistant ‘Prima’ which has its origin in the small-fruited apple species Malus floribunda. About 50 putative QTLs for a total of 27 different apple fruit volatiles were detected through interval mapping by using genotypic data of 150 F₁ individuals of the mapping population ‘C3’ together with phenotypic data obtained by head-space solid phase microextraction gas chromatography. QTLs for volatile compounds putatively involved in apple aroma were found on 12 out of the 17 apple chromosomes, but they were not evenly dispersed. QTLs were mainly clustered on linkage groups LG 2, 3 and 9. In a first attempt, a LOX (lipoxygenase) candidate gene, putatively involved in volatile metabolism, was mapped on LG 9, genetically associated with a cluster of QTLs for ester-type volatiles. Implications for aroma breeding in apple are discussed.     

Aggressive and Docile Colony Defence Patterns in Apis mellifera. A Retreater–Releaser Concept

Colony defence in Apis mellifera involves a variety of traits ranging from ‘aggressive’ (e.g. entrance guarding, recruitment of flying guards) to ‘docile’ (e.g. retreating into the nest) expression. We tested 11 colonies of three subspecies (capensis, scutellata, carnica) regarding their defensiveness. Each colony was selected as reportedly ‘aggressive’, ‘intermediate’ or ‘docile’ and consisted of about 10,000 bees. We applied three stimulation regimes (mechanical disturbance, exposure to alarm pheromones, and the combination of both) and measured their behaviours by tracking the rates of outflying bees at the entrance sites of the test hives. We provided evidence that for mechanical disturbances the test colonies resolved into two response types, if the ‘immediate’ defence response, assessed in the first minute of stimulation, was taken as a function of foraging: ‘releaser’ colonies allocated flying guards, ‘retreater’ colonies reduced the outside-hive activities. This division was observed irrespective of the subspecies membership and maintained in even roughly changing environmental conditions. However, if pheromone and mechanical stimulation were combined, the variety of colony defensiveness restricted to two further types irrespective of the subspecies membership: six of nine colonies degraded their rate of flying defenders with increasing foraging level, three of the colonies extended their ‘aggressiveness’ by increasing the defender rate with the foraging level. Such ‘super-aggressive’ colonies obviously are able to allocate two separate recruitment pools for foragers and flying defenders.     

Experimentally induced helper dispersal in colonially breeding cooperative cichlids

The ‘benefits of philopatry’ hypothesis states that helpers in cooperatively breeding species derive higher benefits from remaining home, instead of dispersing and attempting to breed independently. We tested experimentally whether dispersal options influence dispersal propensity in the cooperatively breeding Lake Tanganyika cichlids Neolamprologus pulcher and N. savoryi. Cooperative groups of these fishes breed in densely packed colonies, surrounded by unoccupied, but apparently suitable breeding habitat. Breeding inside colonies and living in groups seems to benefit individuals, for example by early detection and deterrence of predators. We show that despite a slight preference of both species for habitat with a higher stone cover, 40% of the preferred habitat remained unoccupied. On average, the colonies contained a higher number of (1) predators of adults, juveniles and eggs, (2) shelter competitors, and (3) other species including potential food competitors, compared to the outside colony habitat. Apparently, habitat differences cannot explain why these cichlids breed in colonies. Accordingly, dispersal may not be limited by a lack of suitable breeding shelters, but by the relatively higher risk of establishing an outside- compared to a within-colony breeding territory. To test whether cichlids prefer within- to outside-colony breeding territories, we provided breeding shelters inside the colony and at the colony edge and studied helper dispersal. As expected, significantly more shelters were occupied within the colony compared to the edge. New breeding pairs with several helpers occupied these shelters. We conclude that although breeding habitat is plentiful outside the colonies, helpers delay dispersal to obtain a higher quality breeding position within the group or colony eventually, or they disperse in groups. Our results suggest that (1) group augmentation and Allee effects are generally important for dispersal decisions in cooperatively breeding cichlids, consistent with the ‘benefits of philopatry hypothesis’, and (2) habitat saturation cannot fully explain delayed dispersal in these species.     

Genetic variability and structure of natural and domesticated populations of Caribbean pine (Pinus caribaea Morelet)

 Isozyme analysis of seed samples derived from natural and managed populations of the tropical pine Pinus caribaea vars ‘bahamensis’ and ‘caribaea’ was used to assess population genetic structure in its native range and to detect changes occurring during early domestication of the species. Baseline data from natural populations of the two varieties showed that populations sampled as seed are characterized by high gene diversity (mean H_e=0.26) and a low level of inbreeding ( mean F_is=0.15). A UPGMA tree of genetic relatedness among populations indicates that the two varieties represent distinct evolutionary units. Within each variety there is significant differentiation among populations, and this is greater for the more fragmented populations of var ‘bahamensis’ (F_st=0.08) than for var ‘caribaea’ (F_st=0.02). Seed from a seed orchard population of var ‘caribaea’ established within its natural range showed no change in genetic diversity but did show a reduced inbreeding coefficient (F_is=0.09) compared with its progenitor populations, suggesting a decrease in selfing and/or biparental inbreeding. A bulked seed sample from an exotic plantation of var ‘bahamensis’ in Australia displayed a large increase in the inbreeding coefficient (F_is=0.324) compared with that found in natural populations, possibly due to elevated self-fertilization. Finally, a bulked seed sample from an exotic plantation population of var ‘caribaea’ from China showed enhanced genetic diversity, an increase in the inbreeding coefficient and more linkage disequilibrium than its presumed progenitor populations. It was also genetically divergent from them. RFLP analysis of chloroplast DNA variation in the Chinese sample suggested that seeds of the related taxa P. elliottii and P. taeda, or seeds derived from hybridization with these taxa growing in the seed production area, had been included in the seed crop during harvesting. We conclude that monitoring of appropriate genetic markers may be an effective means of identifying potentially deleterious genetic changes occurring during forest tree domestication. Received: 10 August 1998 / Accepted: 8 September 1998     

Permanent loss of wings in queens of the ant <Emphasis Type="Italic">Odontomachus coquereli</Emphasis> from Madagascar

Winged queens are the most common reproductives in ants. They are morphologically specialized for independent colony foundation, with wings for long-range dispersal and metabolic reserves to raise the first brood. However independent foundation can sometimes be selected against and replaced by fission, featuring short-range dispersal on the ground and reproductives that are dependent on the wingless workers for all non-reproductive tasks. We investigated the evolutionary consequences of this transition on the morphology of the reproductives by collecting 30 colonies of Odontomachus coquereli from Madagascar, the only species in the genus where winged queens have never been found. Data about colony demography, morphometry, allometry and ovarian dissections showed that the winged queen caste has been replaced by a wingless reproductive caste with distinct body proportions relative to the workers or to congeneric winged queens. The 17 reproductives that we measured exhibited little size variability. A single wingless reproductive was found in each colony, corresponding to ‘ergatoids’ in literature. Several facts suggest that colonies reproduce by fission, notably the relatively constant colony size (19±11 workers). The developmental origins of wingless reproductive phenotypes need investigation; little genetic change may be involved, as seen when Odontomachus larvae are parasitized by nematodes. The sole function of wingless reproductives in O. coquereli is reproduction, and they contrast with multi-purpose wingless reproductives found in other ants, where numerous intermorphs occur in each colony and contribute to sterile tasks. Received 15 December 2006; revised 26 February 2007; accepted 1 March 2007.     

In vitro and in vivo anti-allergic effects of ‘benifuuki’ green tea containing O-methylated catechin and ginger extract enhancement

‘Benifuuki’, a tea (Camellia Sinensis L.) cultivar in Japan, is rich in anti-allergic epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me). ‘Benifuuki’ green tea and simultaneous addition of ginger extract remarkably suppressed cytokine (TNF-α and MIP-1α) secretion from mouse bone marrow-derived mast cells after antigen stimulation and, as expected, suppressed delay-type allergy. After drinking ‘benifuuki’ green tea containing 43.5 mg of EGCG and 8.5 mg of EGCG3″Me, the AUC (area under the drug concentration time curve; min μg/ml) of EGCG was 6.72 ± 2.87 and EGCG3″Me was 8.48 ± 2.54 in healthy human volunteers. Though the dose of EGCG was 5.1 times the dose of EGCG3″Me, the AUC of EGCG3″Me was higher than that of EGCG. A double blind clinical study on subjects with Japanese cedar pollinosis was carried out. At the 11th week after starting the study, in the most severe cedar pollen scattering period, symptoms, i.e., blowing the nose and itching eyes, were significantly relieved in the ‘benifuuki’ intake group compared with the placebo group, and blowing the nose, itching eyes and nasal symptom score, and at the 11th and 13th weeks, stuffy nose, throat pain and the nasal symptom medication score were significantly relieved in the ‘benifuuki’ containing ginger extract group compared with the placebo group. These results suggested that over one consecutive month, drinking ‘benifuuki’ green tea was useful to reduce some of the symptoms from Japanese cedar pollinosis, and did not affect any normal immune response in subjects with seasonal rhinitis, and the ginger extract enhanced the effect of ‘benifuuki’ green tea.     

The nature and construction of skeletal spines inPocillopora damicornis (Linnaeus)

Extreme variability in the size, shape and spacing of skeletal spines ofPocillopora damicornis has been demonstrated both within single colonies and also between colonies from different environments. Preliminary studies indicated that the majority of spines from branch tips at the apex of the colony display a ‘fasciculate’ growth surface in contrast to partly fasciculate or ‘smooth’ growth surfaces exhibited by spines from branch tips at the base of the colony. No significant differences in the height and width of costal spines from apical and basal branch tips within a single colony were observed, although spines from colonies exposed to strong wave action tended to be significantly shorter and narrower than those from more sheltered environments. Both costal and coenosteal spines from wave-exposed colonies displayed branching and divided extremities while those from sheltered environments consisted of simple cones. Spines develop as an outgrowing of the calicoblastic ectoderm which secretes the skeleton. Growing costal and coenosteal spines are enveloped by a layer of calicoblastic ectoderm which penetrates through mesogloea, aboral gastroderm, coelenteron, oral gastroderm, mesogloea and finally oral ectoderm. Spines within the corallite are surrounded by calicoblastic ectoderm, mesogloea and aboral gastroderm only. A scheme for the growth of the spines is discussed.     

The influence of hybridization on colony structure in the ant species Temnothorax nylanderi and T. crassispinus

The parapatric sibling ant species Temnothorax nylanderi and T. crassispinus hybridize in the contact zone in the Franconian Jura, Southern Germany. Aim of our study was to investigate the impact of hybridization on colony composition and fitness. We classified colonies as either ‘pure’ or containing hybrids by determining their allozyme pattern at GPI, an enzyme that is fixed for different alleles in the two parental species, and quantified their reproductive output. Most colonies with hybrid workers had a T. crassispinus queen. Colonies with heterozygous, hybrid workers produced more young workers than colonies of the parental species but similar numbers of male and female sexuals. Female sexuals from colonies with heterozygous workers had a significantly lower weight than female sexuals from pure colonies. Only a single reproductive queen was found to be heterozygous, suggesting reduced fitness of hybrid queens. As in the parental species, hybrid colonies appear to be frequently taken over by alien queens, which obscures the genetic colony structure. Received 6 April 2006; revised 10 June 2006; accepted 15 June 2006.     

AFLP analysis of nephthytis (Syngonium podophyllum Schott) selected from somaclonal variants

This study analyzed genetic differences of 19 cultivars selected from somaclonal variants of Syngonium podophyllum Schott along with their parents as well as seven additional Syngonium species and six other aroids using amplified fragment length polymorphism (AFLP) markers generated by 12 primer sets. Among the 19 somaclonal cultivars, ‘Pink Allusion’ was selected from ‘White Butterfly’. Tissue culture of ‘Pink Allusion’ through organogenesis resulted in the development of 13 additional cultivars. Self-pollination of ‘Pink Allusion’ obtained a cultivar, ‘Regina Red Allusion’, and tissue culture propagation of ‘Regina Red Allusion’ led to the release of five other cultivars. The 12 primer sets generated a total of 1,583 scorable fragments from all accessions, of which 1,284 were polymorphic (81.9%). The percentages of polymorphic fragments within ‘White Butterfly’ and ‘Regina Red Allusion’ groups, however, were only 1.2% and 0.4%, respectively. Jaccard's similarity coefficients among somaclonal cultivars derived from ‘White Butterfly’ and ‘Regina Red Allusion’, on average, were 0.98 and 0.99, respectively. Seven out of the 15 cultivars from the ‘White Butterfly’ group and three out of six from the ‘Regina Red Allusion’ group were clearly distinguished by AFLP analysis as unique fragments were associated with respective cultivars. The unsuccessful attempt to distinguish the remaining eight cultivars from the ‘White Butterfly’ group and three from the ‘Regina Red Allusion’ group was not attributed to experimental errors or the number of primer sets used; rather it is hypothesized to be caused by DNA methylation and/or some rare mutations. This study also calls for increased genetic diversity of cultivated Syngonium as they are largely derived from somaclonal variants.     

Variation in the life history pattern of Tetranychus urticae (Acari: Tetranychidae) after selection for dispersal

The spider mite Tetranychus urticae shows variation in its dispersal capacity (i.e., the leaf quality at which a female decides to disperse). We were able to artificially select mites that had either a high or a low dispersal capacity, indicating that this trait was genetically controlled. We then compared correlated responses to this selection. Mites with a genetically high dispersal capacity (‘HD’ strains) had a higher diapause incidence and a lower performance compared to mites with a low dispersal capacity (‘LD’ strains). A possible effect of random genetic drift during the selection was negligible. Our results suggest that differential dispersal capacity is associated with contrasting life history patterns as a result of natural selection. This revised version was published online in July 2006 with corrections to the Cover Date.     

Response of antioxidant activity to excess copper in two cultivars of <Emphasis Type="Italic">Brassica campestris</Emphasis> ssp. <Emphasis Type="Italic">chinensis</Emphasis> Makino

Changes in ascorbic acid content and antioxidant enzyme activities were investigated in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) leaves of ‘Wutacai’ and ‘Erqing’ exposed to excess copper (Cu). Cu treatment reduced the fresh weight of shoot and root by 57% and 46% in ‘Wutacai’, and 60 and 54% in ‘Erqing’, respectively. The accumulation of copper in leaves was higher in ‘Wutacai’ than that in ‘Erqing’. Compared to the control, ascorbic acid (AsA) contents were significantly decreased after copper treatment in both cultivars, while they were higher in ‘Wutacai’ than in ‘Erqing’, which may explain the higher copper-tolerance of ‘Wutacai’ with higher copper accumulation. The higher AsA contents of ‘Wutacai’ resulted from their lower activities of degrading enzymes, such as ascorbate oxydase (AAO) and ascorbate peroxidase (APX), as well as the increasing activity of dehydroascorbate reductase (DHAR) after copper treatment compared with ‘Erqing’. Copper stimulated superoxide dismutase (SOD) activity in both cultivars, but for catalase (CAT), there was little difference between both cultivars. Peroxidases (POD) activity was decreased after copper treatment in ‘Erqing’, while in ‘Wutacai’, it was significantly increased at 14 days, and POD activity was higher in ‘Wutacai’ than that in ‘Erqing’ at 21 and 28 days. Therefore, the induced increasing activity of POD in ‘Wutacai’ also played an important role in its copper tolerance.