Chromosome number variability in central european members of the<Emphasis Type="Italic">Festuca ovina</Emphasis> and<Emphasis Type="Italic">F. pallens</Emphasis> groups (sect.<Emphasis Type="Italic">Festuca</Emphasis>)

Chromosome numbers for 98 plants ofF. pallens, 19 ofF. psammophila, F. belensis andF. vaginata, and 44 ofF. ovina (originating from Austria, the Czech Republic, Germany, Slovakia and Latvia) are given. In addition to theF. ovina andF. pallens groups, chromosome counts for the following taxa are also reported:F. alpestris (2n=14) reported for the first time in this work,F. amethystina subsp.amethystina (2n=28),F. brevipila (2n=42),F. cinerea (2n=28),F. rupicola subsp.rupicola (2n=42) andF. versicolor subsp.versicolor (2n=14).InF. pallens, two ploidy levels (2n=2x=14+0-1B, 2n=4x=28+0-1B) as well as two natural triploid plants (2n=21+0-1B), were found. In addition to the fourF. pallens types that have been distinguished in Austria, one new tetraploid type (F. pallens “scabrifolia”) from the Czech Republic and Germany is reported and its taxonomy is discussed. The distributions of the Oberösterreich-Niederösterreich and Pannonisches-HügellandF. pallens types outside of Austria are documented.Only the diploid chromosome number (2n=14) was found inF. psammophila andF. vaginata. Chromosome numbers forF. psammophila subsp.muellerstollii andF. belensis (both 2n=14) were determined here for the first time. Two ploidy levels, 2n=14+0-5B corresponding toF. ovina subsp.ovina and 2n=28 corresponding toF. ovina subsp.guestphalica andF. cf.duernsteinensis were confirmed inF. ovina. Differences in chromosome structure (simple and multiple secondary constrictions) betweenF. pallens as opposed toF. psammophila andF. vaginata are discussed. A complete survey of published chromosome counts for Central European species from theF. ovina andF. pallens groups is included.     

Volatile organic compounds (VOCs) drive nutrient foraging in the clonal woodland strawberry, <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Background and Aims

It was previously demonstrated that stolons of Fragaria vesca respond to patches of varying nutrient quality; however, the mechanism of patch-detection remained unknown. Here we provide support for a process by which F. vesca perceives nutrient-rich patches, consistent with nutrient foraging prior to rooting.

Methods

Volatile organic compounds (VOCs) emitted from unsterilized and sterilized field substrates were collected and analyzed by stir-bar headspace extraction gas chromatography-mass spectrometry using a method modified for soil and litter systems. Selected compounds were chosen to represent unsterilized and sterilized field substrates. These synthetic volatile compound mixtures were then applied to neutral substrate to test the ability of F. vesca to choose between unsterilized versus sterilized substrates.

Results

Primary stolons exhibited chemotropism towards unsterilized (natural) substrates and grew away from the sterilized volatile substrates when the alternate choice was a negative control. We conclude that the presence of carboxylic acids tends to stimulate stolon elongation and chemotropism while aldehydes, ketones and monoterpenes tend to suppress it.

Conclusions

We provide evidence that developing stolons of F. vesca forage for nutrient-rich patches via volatile cues similar to those emitted from the soil through microflora activity.

     

Identification and expression analysis of cytokinin response regulators in <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Cytokinin response regulators (RRs) are important components of the two component signal systems, which are involved in the regulation of plant growth and development, and in the response to abiotic stress. In this study, 18 cytokinin RR genes were identified in Fragaria vesca through the genome-wide search. They were further classified into three types: type-A (FvRR1–7), type-B (FvRR8–14) and type-C (FvRR15–18) according to the domain architecture and the phylogeny. Phylogenetic analysis demonstrated that most cytokinin response regulators of F. vesca and Arabidopsis formed clear orthologous pairs. Expression patterns of the cytokinin FvRR genes in various tissues and organs at reproductive stages were detected in this study. Additionally, gene expression response patterns to ABA and abiotic stresses including high temperature and osmotic stress were investigated. The results showed that different types of cytokinin FvRRs have different expression patterns, suggesting the functional differentiation of cytokinin FvRRs during the evolution. This systematic study provides insights into possible functions of the cytokinin FvRR genes and a basis for further functional analysis.     

Characterization and expression analysis of cytokinin biosynthesis genes in <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Strawberry is one of the most economically important fruit crops in the world. Cytokinins (CKs) play a critical role in plant growth and development, as well as the stress response, and the level of CKs in plants is regulated by synthesis and degradation pathways. The key synthetic enzymes of CKs are isopentenyl transferases (IPTs) and LONELY GUYS (LOGs). We surveyed the strawberry genome and identified seven FvIPT genes and nine FvLOG genes. We analyzed gene structures, conserved domains, and their phylogenetic relationships with rice and Arabidopsis. The isoelectric points and glycosylation sites of the proteins were predicted. We also analyzed tissue- or organ-specific expression patterns of the FvIPT and FvLOG genes. The FvIPT and FvLOG genes showed different expression profiles in different organs. Most FvIPT and FvLOG genes were down-regulated in response to osmotic stress, high-temperature treatment, and exogenous abscisic acid (ABA) application, suggesting possible roles of these genes in the plants’ resistance to abiotic stresses. In addition, we found that the results of bioinformatics analyses to identify cis-regulatory elements may not be consistent with experimental expression data; thus, computer-predicted putative cis-elements need to be confirmed by experiments. Our systematic analyses of the FvIPT and FvLOG families provide a foundation for characterizing the function of these genes in the regulation of growth, development, and stress tolerance in Fragaria vesca, as well as a reference for improving stress tolerance by manipulating CK content.     

Development of a powder formulation based on <Emphasis Type="Italic">Bacillus</Emphasis><Emphasis Type="Italic">cereus</Emphasis> sensu lato strain B25 spores for biological control of <Emphasis Type="Italic">Fusarium verticillioides</Emphasis> in maize plants

Maize is an economically important crop in northern Mexico. Different fungi cause ear and root rot in maize, including Fusarium verticillioides (Sacc.) Nirenberg. Crop management of this pathogen with chemical fungicides has been difficult. By contrast, the recent use of novel biocontrol strategies, such as seed bacterization with Bacillus cereus sensu lato strain B25, has been effective in field trials. These approaches are not without their problems, since insufficient formulation technology, between other factors, can limit success of biocontrol agents. In response to these drawbacks, we have developed a powder formulation based on Bacillus B25 spores and evaluated some of its characteristics, including shelf life and efficacy against F. verticillioides, in vitro and in maize plants. A talc-based powder formulation containing 1 × 10⁹ c.f.u. g^?1 was obtained and evaluated for seed adherence ability, seed germination effect, shelf life and antagonism against F. verticillioides in in vitro and in planta assays. Seed adherence of viable bacterial spores ranged from 1.0 to 1.41 × 10⁷ c.f.u. g^?1. Bacteria did not display negative effects on seed germination. Spore viability for the powder formulation slowly decreased over time, and was 53 % after 360 days of storage at room temperature. This formulation was capable of controlling F. verticillioides in greenhouse assays, as well as eight other maize phytopathogenic fungi in vitro. The results suggest that a talc-based powder formulation of Bacillus B25 spores may be sufficient to produce inoculum for biocontrol of maize ear and root rots caused by F. verticillioides.     

Molecular analyses of <Emphasis Type="Italic">Ficus erecta</Emphasis> and its allies within the subsection <Emphasis Type="Italic">Frutescentiae</Emphasis> (Moraceae)

Ficus (Moraceae) is a keystone group in tropical and subtropical forests with remarkable diversity of species and taxonomical challenges as a consequence of fig–pollinator coevolution. Ficus subsect. Frutescentiae includes about 30 species that are predominantly shrubs or small trees with Terminalia branching. Many of these species are difficult to delimit morphologically, and the group includes a tangle of uncertain taxa and incorrectly applied names. We conducted a phylogenetic analysis with internal and external transcribed spacer data (ITS and ETS) and data from 18 polymorphic microsatellite loci to evaluate the species status of the most perplexing members of this subsection. The results confirm the monophyly of subsect. Frutescentiae, with F. pedunculosa as sister to the rest. The F. erecta complex comprises approximately 17 taxa: F. erecta, F. abelii, F. boninsimae, F. nishimurae, F. iidaiana, F. gasparriniana var. laceratifolia, F. gasparriniana var. viridescens, F. pyriformis, F. stenophylla, F. fusuiensis, F. fengkaiensis, F. sinociliata, F. tannoensis, F. vaccinioides, F. formosana, F. pandurata, and F. periptera. The last five of these were supported as good species, while the others were not well supported by the present evidence. Evidence also supported the status of the non-F. erecta complex species including. F. pedunculosa, F. ischnopoda, F. heteromorpha, and F. variolosa. Ficus filicauda and F. neriifolia are possibly conspecific. The species status of F. potingensis should be restored and it should be treated as a member of section Eriosycea. Identification of the remaining taxa (F. gasparriniana var. esquirolii, F. ruyuanensis, F. daimingshanensis, F. chapaensis, F. changii, F. trivia, and F. tuphapensis) and their relationships to the F. erecta complex were not clarified. As a whole, only ten species in this subsection are confirmed, one is excluded, one is synonymous, and the others are either unresolved or short of samples. There appears to be a consistent genetic background among these unresolved groups, which suggests that repeated hybridization (as a result of pollinator host shifts) has filled up the interspecific gaps during the fig–pollinator coevolution process.     

Seed Dispersal by Primates and Implications for the Conservation of a Biodiversity Hotspot,the Atlantic Forest of South America

Primates play a fundamental role as seed dispersers, particularly in tropical rainforests. Because defaunation and fragmentation are leading several primate species to local extinction, it is fundamental to understand the role of primates as effective seed dispersers. Here we present a systematic review of studies of seed dispersal by primates in a biodiversity hotspot, the Atlantic Forest of South America, to 1) highlight gaps in our knowledge, 2) determine species richness and proportion of seed species dispersed, and 3) test the relationship between primate body size and the size of dispersed species. Our review found 79 studies of the diet of six ecospecies (Callithrix, Leontopithecus, Callicebus, Sapajus, Alouatta, Brachyteles) but only 20 of these report information on seed dispersal, and none of these are on Callithrix or Callicebus. We found a strong bias in the distribution of species and regions, with most of the studies concentrated in southeastern Brazil. All ecospecies dispersed a large proportion of the seed species they handled (72.1–93.6%). Brachyteles dispersed the highest diversity of plants (N = 73), followed by Sapajus (N = 66), Leontopithecus (N = 49), and Alouatta (N = 26). Although we found no significant relationship between primate body size and the size of seeds dispersed, Brachyteles disperse a higher diversity of large-seeded species than smaller-bodied primates. These results suggest that the local extinction of large primate species may lead to dramatic changes in the plant community, as many large-seeded plants are inaccessible to smaller arboreal frugivores. We propose guidelines for future research on primate seed dispersal to enable the evaluation of seed dispersal effectiveness and to improve our understanding of the fundamental role of primates in this key ecosystem process.     

Reactive oxygen species (ROS) and antioxidative enzyme status in <Emphasis Type="Italic">Solanum lycopersicum</Emphasis> on priming with fluorescent <Emphasis Type="Italic">Pseudomonas</Emphasis> spp. against <Emphasis Type="Italic">Fusarium oxysporum</Emphasis>

In plants, ROS signaling and increase in activities of antioxidants are among defense responses. The present study describes the oxidative stress profiling in model host plant tomato (Solanum lycopersicum L.), during an invasion of the wilt pathogen Fusarium oxysporum f. sp. lycopersici with or without seed priming with Pseudomonas isolates M80, M96 and T109. Tomato seeds were primed with known Pseudomonas isolates M80, M96 and T109 and the forty-day- old plants were challenged with spores of F. oxysporum under greenhouse conditions. Leaf samples were collected at 0, 24, 48 72 and 96 h post fungal challenge and analysed for systemic level of oxidative stress parameters including total phenolics, proline, hydrogen peroxide, lipid peroxidation and enzymatic antioxidants. Disease incidence in the plants under greenhouse conditions was also calculated. Results revealed that priming with Pseudomonas isolates resulted in reduced oxidative stress in the host, during pathogen invasion. M80-priming showed highest antioxidative protection to the host plants during F. oxysporum invasion. The observed reduction in hydrogen peroxide and lipid peroxidation in primed plants was in agreement with the increased activities of the corresponding antioxidant enzymes. Greenhouse results showed that the highest wilt disease symptoms were with M80-priming followed by M96 and T109. The present study gives substantial evidences on the oxidative stress mitigation in response to Pseudomonas-priming on the model tomato-Fusarium interaction system.     

Genetic marking of glume color in <Emphasis Type="Italic">Triticum spelta</Emphasis> L. var. <Emphasis Type="Italic">caeruleum</Emphasis> using gliadins

Using gliadins as genetic markers, Triticum spelta L. var. caeruleum accessions were analyzed to identify genetic control of the dark color of glumes. The research material was F₂ and BC₁ plants from crosses between spelt accessions and white-glumed common wheat varieties. The segregation for glume color fitted the monogenic control of the trait. The electrophoretic analysis of gliadins in grains from the hybrid plants has shown that the Gli-Alj* allele in the T. spelta var. caeruleum accessions is linked to the allele for the dark (black) color of glumes at the Rg-A1 locus.     

Seed dispersal distances by ant partners reflect preferential recruitment patterns in two ant-dispersed sedges

An important feature of seed dispersal mutualism is the differentiation of dispersal-related seed traits (dispersal syndrome), which potentially contribute to partitioning of both seed dispersers and regeneration sites among sympatric plants. Yet, the selective factors underlying the diversity in dispersal syndromes are largely unknown. The differential requirements for seed dispersal distances are often proposed as a main factor in plant adaptations to disperser animals. Focusing on two sympatric ant-dispersed sedges Carex lanceolata and Carex tristachya (Cyperaceae), we tested the association of the adaptation to different dispersers with requirements for seed dispersal distances. We found that C. lanceolata was more frequently dispersed by the large ant Formica japonica (which had relatively long dispersal distances compared with other smaller ants) than by C. tristachya, and this was caused by the higher seed attractiveness of C. lanceolata to F. japonica. Pot experiments manipulating adult-to-seedling distances showed that isolation from conspecific adults only benefited C. lanceolata seedlings, and C. tristachya seedlings were not affected. These results support the importance of differential requirements for seed dispersal distances as a factor underlying the diversity in dispersal syndromes among animal-dispersed plants.     

The <Emphasis Type="Italic">APX4</Emphasis> locus regulates seed vigor and seedling growth in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

The amino acid sequence of APX4 is similar to other ascorbate peroxidases (APXs), a group of proteins that protect plants from oxidative damage by transferring electrons from ascorbate to detoxify peroxides. In this study, we characterized two apx4 mutant alleles. Translational fusions with GFP indicated APX4 localizes to chloroplasts. Both apx4 mutant alleles formed chlorotic cotyledons with significantly reduced chlorophyll a, chlorophyll b and lutein. Given the homology of APX to ROS-scavenging proteins, this result is consistent with APX4 protecting seedling photosystems from oxidation. The growth of apx4 seedlings was stunted early in seedling development. In addition, APX4 altered seed quality by affecting seed coat formation. While apx4 seed development appeared normal, the seed coat was darker and more permeable than the wild type. In addition, accelerated aging tests showed that apx4 seeds were more sensitive to environmental stress than the wild-type seeds. If APX4 affects seed pigment biosynthesis or reduction, the seed coat color and permeability phenotypes are explained. apx4 mutants had cotyledon chlorosis, increased H₂O₂ accumulation, and reduced soluble APX activity in seedlings. These results indicate that APX4 is involved in the ROS-scavenging process in chloroplasts.     

The seeds of success: release from fungal attack on seeds may influence the invasiveness of alien <Emphasis Type="Italic">Impatiens</Emphasis>

Although closely related, Impatiens glandulifera and Impatiens balfourii differ in their invasiveness in Europe; only the former is highly invasive there. Following the assumptions of the enemy release hypothesis (ERH), we tested whether these differences may be explained by the levels of seed infestation by pathogenic fungi. Using seeds collected along the Swiss-Italian border, we recorded four true pathogens of seeds: Fusarium culmorum, F. oxysporum, F. sporotrichoides, and Giberella avenacea. In Italy the seeds of I. balfourii were infected by fungal pathogens more often than those of I. glandulifera, while in Switzerland both species were under the same level of pressure. However, the overall differences in pathogen abundance were consistent with the ERH: seeds of the more invasive species were attacked less. This could be a result of differences between the communities of fungal pathogens attacking the seeds of both species in each country. The number of colonies of secondary pathogens (Cladosporium cladosporioides, Alternaria alternata) correlated negatively with the number of colonies of true pathogens; we suggest that the secondary pathogens may have prevented the occurrence of the true pathogens. The reason for the between-country differences in the fungal pathogen communities is unclear. A possible explanation is that Italy and Switzerland differ in their road and green-area maintenance work schemes, which may have influenced pathogen pressure on seeds. This study is one of the few that offers results indicating that release from enemies may be crucial to the invasion success of plants as early as the seed stage.     

The <Emphasis Type="Italic">Drosophila bipectinata</Emphasis> species complex: phylogenetic relationship among different members based on chromosomal variations

Making interspecific hybridizations, where possible remains an unparalleled option for studying the intricacies of speciation. In the Drosophila bipectinata species complex comprising of four species, namely D. bipectinata, D. parabipectinata, D. malerkotliana and D. pseudoananassae, interspecific hybrids can be obtained in the laboratory, thus bequeathing an ideal opportunity for studying speciation and phylogeny. With the view of investigating the degree of divergence between each species pair, we planned to study the polytene chromosomes of the F ₁ hybrids, as it would mirror the level of compatibility between the genomes of the parental species. Two sets of crosses were made, one involving homozygous strains of all four species from India and the other including homozygous strains from different places across the globe. Polytene chromosomes of F ₁ larvae from both sets of crosses had similar configurations. In F ₁ larvae from crosses involving D. bipectinata, D. parabipectinata and D. malerkotliana, complex configurations (depicting overlapping inversions) could be detected in different arms. However, they were fairly synapsed, indicating that the differences are only at the level of gene arrangements. The polytene chromosomes of larvae obtained by crossing D. pseudoananassae with the other three species were very thin with gross asynapsis in all the arms, demonstrating that the genome of D. pseudoananassae is widely diverged from rest of the species. The overlapping inversions (reflected in complex configuration), are inferred in the light of earlier chromosomal studies performed in this complex.     

Gene actions for yield and its attributes and their implications in the inheritance pattern over three generations in opium poppy (<Emphasis Type="Italic">Papaver somniferum</Emphasis> L.)

The gene actions for yield and its attributes and their inheritance pattern based on five parameter model have been explored in four single crosses (NBIHT-5 × NBIHT-6, NBIHT-5 × NBMHT-1, NBMHT-1 × NBIHT-6 and NBMHT-2 × NBMHT-1) obtained using thebaine rich pure lines of opium poppy (Papaver somniferum L.) for three consecutive generations. All the traits showed nonallelic mode of interaction, however, dominance effect (h) was more pronounced for all the traits except thebaine and papaverine. The dominance × dominance (l) effects were predominant over additive × additive (i) for all traits in all the four crosses except for papaverine. The seed and opium yield, and its contributing traits inherited quantitatively. The fixable gene effects (d) and (i) were lower in magnitude than nonfixable (h) and (l) gene effects. The estimates of heterosis were also higher in comparison to the respective parents which suggested preponderance of dominance gene action for controlling most of the traits. The phenotypic coefficient of variation was marginally higher than those of genotypic coefficient of variation for all the traits. The traits thebaine, narcotine, morphine and opium yield had high heritability coupled with high genetic advance. The leaf number, branches per plant and stem diameter showed positive correlation with opium and seed yields. The selection of plants having large number of leaves, branches and capsules with bigger size would be advantageous to enhance the yield potential.     

Mapping of genetic locus for leaf trichome in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

Key message

The genetic locus for leaf trichome was identified via marker-based mapping and SNP microarray assay, and a functional marker was developed to facilitate the breeding for hairiness in Brassica oleracea.

Abstract

Plant trichomes are involved in various functions particularly in protecting plants against some biotic and abiotic damages. In the present study, an F2 segregating population was developed from the cross between a glabrous cultivated B. oleracea (CC, 2n = 18) and a hairy wild relative, B. incana (CC, 2n = 18). A 1:3 segregation pattern between glabrous and hairy plants was detected among 1063 F2 genotypes, and the locus for hairiness was mapped in a 4.3-cM genetic region using 267 SSR markers among 149 F2 genotypes, corresponding to a 17.6-Mb genomic region on chromosome C01. To narrow the genetic region for hairiness, the Brassica 60 K SNP Bead Chip Arrays were applied to genotype 64 glabrous and 30 hairy F2 plants, resulting in a 1.04-Mb single peak region located in the 17.6-Mb interval. A candidate gene, BoTRY, was identified by qRT-PCR which revealed significant higher expression in glabrous F2 genotypes as compared with that in hairy plants. A cleaved amplified polymorphic site marker was successfully developed to distinguish the sequence variations of BoTRY between hairy and glabrous plants. Our study will be helpful for molecular breeding for hairiness in B. oleracea.

     

Expansion and evolutionary patterns of GDSL-type esterases/lipases in Rosaceae genomes

GDSL-type esterase/lipase (GELP) is mainly characterized by a conserved GDSL domain at N terminus, and is widely found in all living species, both prokaryotes and eukaryotes. GELP gene family consists of a wide range of members playing important roles in plant physiological processes, such as development, stress responses, and functional divergences. In our study, 597 GELP genes were identified from six Rosaceae genomes (i.e., Fragaria vesca, Prunus persica, Prunus avium, Prunus mume, Pyrus bretschneideri, and Malus domestica) by a comprehensive analysis. All GELP genes were further divided into ten subfamilies based on phylogenetic tree analysis. Subfamily D and subfamily E are the two largest subfamilies. Microcollinearity analysis suggested that WGD/segmental events contribute to the expansion of the GELP gene family in M. domestica and P. bretschneideri compared to F. vesca, P. persica, P. avium, and P. mume. Some PbGELPs were expressed during the fruit development of P. bretschneideri and pollen tubes, indicating their activity in these tissues. The expression divergence of PbGELP duplication gene pairs suggests that many mutations were allowed during evolution, although the structure of GELP genes was highly conserved. The current study results provided the feasibility to understand the expansion and evolution patterns of GELP in Rosaceae genomes, and highlight the function during P. bretschneideri fruits and pollen tubes development.     

Generation of genetically stable transformants by <Emphasis Type="Italic">Agrobacterium</Emphasis> using tomato floral buds

Tomato (Solanum lycopersicum) is a model crop plant for the study of fruit ripening and disease resistance. Here we present a systemic study on in planta transformation of tomato with Agrobacterium tumefaciens strain LBA4404 harboring pCAMBIA1303 binary vector bearing HPTII as a plant selectable marker and mGFP/GUS fusion as the reporter gene. We attempted the transformation of tomato at different developmental stages viz. during seed germination, seedling growth, and floral bud development. The imbibition of seeds with Agrobacterium suspension led to seed mortality. The vacuum infiltration of seedlings with Agrobacterium suspension led to sterility in surviving plants. Successful transformation could be achieved either by dipping of developing floral buds in the Agrobacterium suspension or by injecting Agrobacterium into the floral buds. Most floral buds subjected to dip as well as to injection either aborted or had arrested development. The pollination of surviving floral buds with pollen from wild-type plants yielded fruits bearing seeds. A transformation efficiency of 0.25–0.50% was obtained on floral dips/floral injections. Transgenic plants were selected by screening seedlings for hygromycin resistance. The presence of the transgene in genomic DNA was confirmed by Southern blot analysis and expression of the reporter gene up to the T₄ generation. The amenability of tomato for in planta transformation simplifies the generation of transgenic tomato plants obviating intervening tissue culture.