Effects of X-ray irradiation on male sperm transfer ability and fertility in the sweetpotato weevils <Emphasis Type="Italic">Euscepes postfasciatus</Emphasis> (Coleoptera: Curculionidae) and <Emphasis Type="Italic">Cylas formicarius</Emphasis> (Coleoptera: Brentidae)

Gamma radiation from isotopic sources has been used in sterile insect technique (SIT) programs worldwide, but it might be difficult to continue using these sources in future SIT programs because of social issues. Therefore, an alternative sterilization source to gamma rays, such as X-rays, needs to be developed. The physical properties of radiation are different between gamma rays and X-rays: for example, X-rays have a shorter penetration depth than gamma rays. Therefore, X-rays may not fully confer male sterility, depending on the target pest insects. The present study investigated whether the West-Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) and the sweetpotato weevil Cylas formicarius (Fabricius) are sterilized by X-rays generated in a low-energy X-ray irradiator, without deterioration of male mating ability, at the doses currently used in the eradication programs for E. postfasciatus (150 Gy) and C. formicarius (200 Gy) using gamma rays at Okinawa, Japan. The results demonstrated that it is possible to use X-rays in future SIT programs for E. postfasciatus and C. formicarius, because X-ray irradiated males were almost completely sterilized without deterioration of their mating ability.     

<Emphasis Type="Italic">Piriformospora indica</Emphasis>-mediated salinity tolerance in <Emphasis Type="Italic">Aloe vera</Emphasis> plantlets

Piriformospora indica, a root endophytic fungus, has been reported to promote growth of many plants under normal condition and allow the plants to survive under stress conditions. However, its impact on an important medicinal plant Aloe vera L. has not been well studied. Therefore, this study was undertaken to investigate the effect of P. indica on salinity stress tolerance of A. vera plant. P. indica inoculated and non-inoculated A. vera plantlets were subjected to four levels of salinity treatment- 0, 100, 200 and 300 mM NaCl. The salinity stress decreased the ability of the fungus to colonize roots of A. vera but the interaction of A. vera with P. indica resulted in an overall increase in plant biomass and greater shoot and root length as well as number of shoots and roots. The photosynthetic pigment (Chl a, Chl b and total Chl) and gel content were significantly higher for the fungus inoculated A. vera plantlets, at respective salinity concentrations. Furthermore, the inoculated plantlets had higher phenol, flavonoid, flavonol, aloin contents and radical scavenging activity at all salinity concentrations. The higher phenolic and flavonoid content may help the plants ameliorate oxidative stress resulting from high salinity.     

Development and reproduction of <Emphasis Type="Italic">Amblyseius largoensis</Emphasis> (Acari: Phytoseiidae) feeding on pollen, <Emphasis Type="Italic">Raoiella indica</Emphasis> (Acari: Tenuipalpidae), and other microarthropods inhabiting coconuts in Florida,USA

The red palm mite, Raoiella indica (Acari: Tenuipalpidae), is an important pest of palms (Arecaceae) and other species within the Zingiberaceae, Musaceae and Strelitziaceae families. Raoiella indica was discovered in the USA (Palm Beach and Broward counties, Florida) late in 2007, and it subsequently spread to other Florida counties. The predatory mite Amblyseius largoensis (Acari: Phytoseiidae) has been found associated with R. indica in Florida. In order to verify whether A. largoensis can develop and reproduce when feeding exclusively on R. indica, the biology of this predator was evaluated on various food sources, including R. indica. Five diets [R. indica, Tetranychus gloveri¸ Aonidiella orientalis, Nipaecocus nipae, oak (Quercus virginiana) pollen] and a no-food control were tested to determine the predators’ development, survivorship, oviposition rate, sex ratio and longevity at 26.5 ± 1°C, 70 ± 5% RH and a 12:12 L:D photophase. Amblyseius largoensis was able to complete its life cycle and reproduce when fed exclusively on R. indica. The development of immature stages of A. largoensis was faster and fecundity and survivorship were higher when fed on R. indica or T. gloveri compared to the other food sources. The intrinsic rate of natural increase of A. largoensis was significantly higher when fed on R. indica than on other diets. These results suggest that, despite earlier assessments, A. largoensis can play a role in controlling R. indica.     

An Experimental Test of Trade-Offs Associated with the Adaptation to Alternate Host Plants in the Introduced Herbivorous Beetle, <Emphasis Type="Italic">Ophraella communa</Emphasis>

The adaptation to alternate host plants of introduced herbivorous insects can be vital to agriculture due to the emergence of crop pests. Historically, it is assumed that there are trade-offs associated with the adaptation to new host plants; a generalist genotype that adapts to an alternate host is expected to have a relatively lower fitness on the ancestral host than a specialist genotype (physiological cost) or a relatively lower host-searching ability for the ancestral host plant (behavioral cost). In this study, we tested the costs of adaptation to a new host plant in the introduced herbivorous insect, Ophraella communa LeSage (Coleoptera: Chrysomelidae). In its native range (United States), O. communa feeds mostly on Ambrosia artemisiifolia L. (Asterales: Asteraceae) and cannot utilize the related species, Ambrosia trifida L. (Asterales: Asteraceae), as a host plant. On the other hand, the introduced O. communa population in Japan utilizes A. trifida extensively, and is adapting to it, both physiologically and behaviorally. We compared larval performance on the ancestral and alternate plants and adult host-searching ability between the native and introduced beetle populations. The introduced O. communa showed higher larval survival and adult feeding preference for the alternate host plant A. trifida than did the native O. communa, indicating that the introduced O. communa has rapidly adapted to the alternate host plant. However, there are no differences in either larval performance on the ancestral host A. artemisiifolia or host-searching accuracy between the native and introduced O. communa.     

<Emphasis Type="Italic">Melampsora pakistanica</Emphasis> sp. nov., a new rust fungus on <Emphasis Type="Italic">Euphorbia helioscopia</Emphasis> (Sun spurge) from Pakistan

A rust fungus was found on the leaves of Euphorbia helioscopia during a field study in Pakistan. Previously, Melampsora euphorbiae, M. euphorbiae-gerardianae and M. helioscopiae have been reported on E. helioscopia, the first two of which are also known from Pakistan. Morphological observations of the newly collected rust samples detected some differences from the previously described Melampsora species on E. helioscopia. The molecular analysis of the ITS and LSU sequences also detected that the rust is different from the previously reported rusts described from E. helioscopia. Based on both morphological comparisons and sequence analysis, the rust is described here as M. pakistanica sp. nov. This species could have potential as a bio-control agent against its host plant—E. helioscopia—which is a weed of wheat fields in Pakistan and elsewhere in the world.     

Association analysis of alcohol metabolizing enzymes <Emphasis Type="Italic">ADH1B,ADH7, CYP2E1</Emphasis> gene polymorphism with risk for coronary atherosclerosis

The allele and genotype distribution of two alcohol dehydrogenase genes ADH1B (exon 3 polymorphism A/G (47His)), ADH7 (intron 5 polymorphism G/C) and cytochrome P450 2E1 gene (CYP2E1; 5′-flanking region G/C and intron 6 T/A polymorphisms) were examined in Russian (Tomsk, n = 125) healthy population and in coronary atherosclerosis patients (CA, n = 92). The genotype frequencies followed the Hardy-Weinberg equilibrium and the alleles were in linkage equilibrium or gametic equilibrium in the control sample. Only two CYP2E1 gene polymorphisms were in linkage disequilibrium. The frequencies of the derived alleles at ADH1B ^* G (+MslI) allele, CYP2E1 ^* C2 (+PstI) allele and CYP2E1 ^* C (-DraI) allele were 8.48 ± 1.86, 1.20 ± 0.69, and 10.00 ± 1.90%, respectively. The ADH7 gene polymorphism showed a high level of heterozygosity; the frequency of the ADH7 ^* C (-StyI) allele was 44.58 ± 3.21%. A significantly higher frequency of CYP2E1 PstI C2 allele has been revealed in the CA group (P = 0.043; OR = 4.23; 95% CI 1.03–20.01). The tendency to significant effect of A1A2 genotype in ADH1B MslI polymorphism was observed for systolic blood pressure in the control group (P = 0.068). The statistically significant two-way interaction effects of ADH7 StyI and CYP2E1 DraI on diastolic blood pressure (P = 0.029) and on the serum high density lipoprotein level (P = 0.042) were also revealed. Association of A1A2 genotype in ADH1B MslI polymorphism with reduced amount in a serum of a very low density lipoprotein level (P = 0.045) have also been shown. This may result from multifunctional activity of alcohol metabolizing enzymes and their involvement in many metabolic and free radical reactions in the body.     

Population dynamics of the West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire): a simulation analysis

The West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) is a major pest of the sweet potato Ipomoea batatas (L.) Lam. and this weevil is a target of an eradication program using the Sterile Insect Technique in Okinawa Prefecture, Japan. Understanding the population ecology is essential in the planning of an eradication program; hence, a host‐plant infestation survey and light trap survey have been conducted to monitor the population dynamics of the weevil on Kume Island (Okinawa Prefecture), which is the target area of the trial weevil eradication project. Seasonal tendencies of weevil density were found in these field surveys, but the tendency found in the host‐plant infestation survey was not seen every year, and the effectiveness of the light trap is somewhat suspect. To confirm the reliability of the tendency observed in these field surveys, the present study attempted to explain the tendency by a seasonal temperature change using a temperature‐based model of weevil population dynamics. The seasonal changes of weevil density differed according to host plants and host‐plant fields. The seasonal changes of weevil density inside the host plant Ipomoea indica and outside the host plants in I. indica fields were consistent with those predicted by the model. However, those inside the host plant Ipomoea pes‐caprae in the host‐plant infestation survey were contrary to the predicted ones, and those observed outside host plants in I. pes‐caprae fields by the light trap survey were not in good agreement with the predicted ones. It was concluded that the seasonal change of the weevil density observed in I. indica and I. indica fields can be explained by a seasonal temperature change, but factors other than seasonal temperature change are needed to explain those in I. pes‐caprae and I. pes‐caprae fields.     

Characterisation of seven <Emphasis Type="Italic">Inocybe</Emphasis> ectomycorrhizal morphotypes from a semiarid woody steppe

Ectomycorrhizas (ECM) of Inocybe species (Inocybaceae, Basidiomycota) formed by three host plant species (Populus alba, Salix rosmarinifolia and Pinus nigra) in a semiarid woody steppe of Hungary were studied. To identify the fungal partners, we performed phylogenetic analyses of nucleotide sequences for the internal transcribed spacer region of nuclear DNA (nrDNA ITS) together with sequences gained from public databases. Seven Inocybe ectomycorrhiza morphotypes were morpho-anatomically characterised. Five morphotypes were identified (I. phaeoleuca, I. psammophila, I. semifulva, I. splendens and I. subporospora), whereas two morphotypes represented unidentified Inocybe species. Differences were discernible among the morphotypes, and they showed general anatomical characteristics of Inocybe ECM, such as the slightly organised plectenchymatic mantle (types A, B and E and the gelatinous C). The ECM of I. subporospora and I. phaeoleuca were detected from the introduced Pinus nigra. These two fungi are probably native to the area but capable of forming a novel ectomycorrhizal association with the invasive host.     

Pollinator-mediated impacts of alien invasive plants on the pollination of native plants: the role of spatial scale and distinct behaviour among pollinator guilds

Alien invasive plant species can affect pollination, reproductive success and population dynamics of co-flowering native species via shared pollinators. Consequences may range from reproductive competition to facilitation, but the ecological drivers determining the type and magnitude of such indirect interactions remain poorly understood. Here, we examine the role of the spatial scale of invader presence and spatially contingent behavioural responses of different pollinator groups as potential key drivers, using the invasive Oxalis pes-caprae and the self-incompatible native annual Diplotaxis erucoides as a model system. Three treatments were assigned to native focal plants: (1) invader present at the landscape scale (hectares) but experimentally removed at the floral neighbourhood scale (pa); (2) invader present at both scales (pp); (3) invader absent at both scales (aa). Interestingly, we found pronounced spatially contingent differences in the responses of pollinators: honeybees and bumblebees were strongly attracted into invaded sites at the landscape scale, translating into native plant visitation facilitation through honeybees, while bumblebees almost exclusively visited Oxalis. Non-corbiculate wild bees, in contrast, showed less pronounced responses in foraging behavior, primarily at the floral neighborhood scale. Average heterospecific (Oxalis) pollen deposition onto stigmas of Diplotaxis was low (<1 %), but higher in the pp than in the pa treatment. Hand-pollination of Diplotaxis with Oxalis and conspecific pollen, however, reduced seed set by more than half when compared to hand-pollination with only conspecific pollen. Seed set of Diplotaxis, finally, was increased by 14 % (reproductive facilitation) in the pp treatment, while it was reduced by 27 % (reproductive competition) in the pa treatment compared to uninvaded populations. Our study highlights the crucial role of spatial scale and pollinator guild driving indirect effects of invasive on co-flowering native plant species.     

The Role of MPK6 as Mediator of Ethylene/Jasmonic Acid Signaling in <Emphasis Type="Italic">Serendipita indica</Emphasis>-Colonized Arabidopsis Roots

Serendipita indica is an axenically cultivable fungus, which colonizes a broad range of plant species including the model plant Arabidopsis thaliana. Root colonization by this endophyte leads to enhanced plant fitness and performance and promotes resistance against different biotic and abiotic stresses. The involvement of MPK6 in this mutualistic interaction had been previously shown with an mpk6 A. thaliana mutant, which failed to respond to S. indica colonization. Here, we demonstrate that mpk6 roots are significantly less colonized by S. indica compared to wild-type roots and the foliar application of plant hormones, ethylene, or jasmonic acid, restores the colonization rate at least to the wild-type level. Further, hormone-treated mpk6 plants show typical S. indica-induced growth promotion effects. Moreover, expression levels of several genes related to plant defense and hormone signaling are significantly changed at different colonization phases. Our results demonstrate that the successful root colonization by S. indica depends on efficient suppression of plant immune responses. In A. thaliana, this process relies on intact hormone signaling in which MPK6 seems to play a pivotal role.     

Histological and cytological studies of plant infection by <Emphasis Type="Italic">Erysiphe euonymi</Emphasis>-<Emphasis Type="Italic">japonici</Emphasis>

Powdery mildew caused by Erysiphe euonymi-japonici (Eej) is an increasingly serious fungal disease on Euonymus japonicus that is an important ornamental plant. However, little is currently known about infection and pathogenesis of Eej on E. japonicus. Here, we report plant infection by Eej at the histological and cytological levels. Eej caused severe disease symptoms with white and snow-like colonies on leaf surfaces of E. japonicus. Microscopic observations were conducted continuously to define infection process of Eej on E. japonicus. Eej conidia germinated to produce appressorial germ tubes on leaf surfaces and formed irregular haustoria in plant epidermal cells at 6 h post-inoculation (hpi) and 12 hpi, respectively. After uptaking nutrients from host cells by haustoria, Eej formed numerous hyphae and extensive colonization on leaf surfaces at 96 hpi and finally produced abundant conidiophores and new conidia on leaf surfaces at 168 hpi. In addition, there was consistently a single nucleus in different Eej infection structures and haustorial development could be divided into three major stages, including formation of penetration peg, formation of haustorial neck and initial haustorium, and maturation of haustorium. These results provide useful information for further determination of Eej pathogenesis and finally controlling the disease.     

Steroid compounds from two pacific starfish of the genus <Emphasis Type="Italic">Evasterias</Emphasis>

Three new steroid glycosides (evasteriosides C, D, and E) along with six known compounds were isolated from two Pacific starfish of the genus Evasterias. Evasterioside C from E. retiferacollected from the Sea of Japan was identified as (20R, 22E)-3-O-(β-D-xylopyranosyl)-24-nor-5α-cholest-22-ene-3β,6β,15α,26-pentaol 26-sulfate sodium salt. The structures of evasteriosides D and E from E. echinosoma (collected from the Gulf of Shelichov, the Sea of Okhotsk) were established as (20R, 24S)-24-O-(β-D-glucopyranosyl)-5α-cholestane-3β,6α,8,15β,24-pentaol and (20R,24S)-3,24-di-O-(β-D-xylopyranosyl)-cholest-4-ene-3β,6β,8,15α,24-pentaol, respectively. In addition, the known compounds pycnopodiosides A and C, luridoside A, 5α-cholestane-3β,6α,8,15β,16β,26-hexaol. 5α-Cholestane-3β,6α,8,15β,24-pentaol 24-sulfate sodium saltand marthasterone sulfate sodium salt were identified in E. echinosoma. The structures of the isolated compounds were established on the basis of spectroscopic analyses, using 1D and 2D NMR techniques, mass spectrometry, and some chemical transformations.     

An invasive plant provides refuge to native plant species in an intensely grazed ecosystem

Invasion by exotic plant species and herbivory can individually alter native plant species diversity, but their interactive effects in structuring native plant communities remain little studied. Many exotic plant species escape from their co-evolved specialized herbivores in their native range (in accordance with the enemy release hypothesis). When these invasive plants are relatively unpalatable, they may act as nurse plants by reducing herbivore damage on co-occurring native plants, thereby structuring native plant communities. However, the potential for unpalatable invasive plants to structure native plant communities has been little investigated. Here, we tested whether presence of an unpalatable exotic invader Opuntia ficus-indica was associated with the structure of native plant communities in an ecosystem with a long history of grazing by ungulate herbivores. Along 17 transects (each 1000 m long), we conducted a native vegetation survey in paired invaded and uninvaded plots. Plots that harboured O. ficus-indica had higher native plant species richness and Shannon–Wiener diversity H′ than uninvaded plots. However, mean species evenness J was similar between invaded and uninvaded plots. There was no significant correlation between native plant diversity and percentage plot cover by O. ficus-indica. Presence of O. ficus-indica was associated with a compositional change in native community assemblages between paired invaded and uninvaded plots. Although these results are only correlative, they suggest that unpalatable exotic plants may play an important ecological role as refugia for maintenance of native plant diversity in intensely grazed ecosystems.     

Tandem duplications of receptor-like kinase genes reshaped the homologous chromosome 1 regions in <Emphasis Type="Italic">Oryza sativa</Emphasis> ssp. <Emphasis Type="Italic">indica</Emphasis> and <Emphasis Type="Italic">japonica</Emphasis> and their possible ancestral genomes

Plant receptor-like kinase (Rlk) genes form a large family, each encoding a protein with a signal motif, a single transmembrane region, and a cytoplasmic kinase domain. Various gene duplications have contributed to the establishment and expansion of the family. Here, we characterized the formation and evolution of the Rlk gene family in cultivated rice and their possible progenitors. Using wheat Rlk gene sequences, we identified orthologs from the genomes of domesticated rice subspecies Oryza sativa ssp. japonica and ssp. indica and their putative progenitors O. glaberrima and O. rufipogon. The four chromosome 1 orthologous regions ranged from 103 to 281 kb comprising 181 syntenic blocks with 75 to 100% sequence identity. These regions contained 11–19 Triticum aestivum kinases (Taks) and 10–15 Lr10 receptor-like kinases (Lrks) organized in clusters and 3–12 transposable elements (TEs). Dot plot analyses showed that the 4 regions had 21–37 conserved catalytic domains, mainly in protein kinases (PKs) and tyrosine kinases (TyrKs) in coupling state. Over 50% of the sequences of glaberrima/rufipogon and japonica/indica pairs were colinear, while japonica/indica displayed a marked sequence expansion with duplicated genes and TEs. A total of 2312 single nucleotide polymorphisms (SNPs) and insertion-deletions (INDELs) were identified between japonica and indica. Duplication of the Rlk genes in O. glaberrima and O. rufipogon occurred after the grass species radiation and before the divergence of O. rufipogon from O. glaberrima; the orthologous Rlk genes from O. japonica and O. indica duplicated after O. sativa separated from O. rufipogon; paralogs, obtained through extensive duplication, happened after the separation of rice from maize. Tandem duplication was the major factor contributing to the gene copy number variation and genome size expansion.     

Characterisation of a novel quantitative trait locus, <Emphasis Type="Italic">GN4</Emphasis>-<Emphasis Type="Italic">1</Emphasis>, for grain number and yield in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Key message

A novel QTL for grain number, GN4-1, was identified and fine-mapped to an ~ 190-kb region on the long arm of rice chromosome 4.

Abstract

Rice grain yield is primarily determined by three components: number of panicles per plant, grain number per panicle and grain weight. Among these traits, grain number per panicle is the major contributor to grain yield formation and is a crucial trait for yield improvement. In this study, we identified a major quantitative trait locus (QTL) responsible for rice grain number on chromosome 4, designated GN4-1 (a QTL for Grain Number on chromosome 4), using advanced segregating populations derived from the crosses between an elite indica cultivar ‘Zhonghui 8006’ (ZH8006) and a japonica rice ‘Wuyunjing 8’ (WYJ8). GN4-1 was delimited to an ~ 190-kb region on chromosome 4. The genetic effect of GN4-1 was estimated using a pair of near-isogenic lines. The GN4-1 gene from WYJ8 promoted accumulation of cytokinins in the inflorescence and increased grain number per panicle by ~ 17%. More importantly, introduction of the WYJ8 GN4-1 gene into ZH8006 increased grain yield by ~ 14.3 and ~ 11.5% in the experimental plots in 2014 and 2015, respectively. In addition, GN4-1 promoted thickening of the culm and may enhance resistance to lodging. These results demonstrate that GN4-1 is a potentially valuable gene for improvement of yield and lodging resistance in rice breeding.