Gender-related differences in adaptability to drought stress in the dioecious tree <Emphasis Type="Italic">Ginkgo biloba</Emphasis>

Ginkgo (Ginkgo biloba) as a precious relict plant is cultivated around the world, and it is also a typical dioecious tree. Drought is a major environmental stress that limits the growth and development of ginkgo. Although many studies have examined the impact of drought on ginkgo, few have investigated gender-related under drought treatment in the species. In our research, we examined comparative morphology, physiology and the ultrastructure of mesophyll cell in male and female ginkgoes to determine which gender shows superior adaptability to drought stress. Two-year-old cutting-propagated male and female ginkgoes suffered to drought treatment. The experiments showed that drought significantly limited growth and development, disrupted photosynthesis, and destoried the antioxidant protection system in both male and female ginkgoes. When the gender differences in the species were compared, females showed better growth, activities of SOD and POD, concentrations of chl t, chl a/b ratio and proline, P _n, C _i, g _s, qP and NPQ under drought, but lower concentrations of H₂O₂ and O₂ ^?, and relative electrolyte leakage. In the aspect of cell ultrastructure, female plants showed a slower rate of cell breakdown and chloroplast decomposition under drought stress than males. The results indicate that female plants of ginkgo show superior growth performance and self-protective mechanisms and higher photosynthetic capacity than male plants under drought stress. Thus, we conclude that female individuals of ginkgo possess better adaptability to drought stress than male individuals.     

Pea plant volatiles guide host location behaviour in the pea moth

Identification of plant volatiles that attract mated insect females for oviposition can provide important information about plant–insect relationships that can be used to develop pest control strategies involving manipulation of the female host search. Our study represents a first step towards identifying volatiles that affect the host location behaviour of the pea moth Cydia nigricana. The behaviours of virgin and mated males and females were analysed in cage experiments testing a two-choice situation at close range and in wind tunnel experiments evaluating upwind orientation over a distance. In both experimental setups, flowering pea plants constituted the most attractive phenological stage for mated females, with 58 % landing on such plants in the wind tunnel. Testing headspace extracts of different phenological stages of pea and of detached pea buds and flowers in the wind tunnel, mated females showed the highest landing responses to volatiles during flower development (budding 42 % and flowering 56 %) and from detached buds (46 %) and flowers (66 %). Volatile compounds collected from the various phenological stages of pea were analysed by gas chromatography–mass spectrometry, and the antennal responses to these headspace collections were evaluated by gas chromatography–electroantennography. Ten antennally active compounds were identified, nine of which were present in the headspace extracts of the whole pea plants at all tested phenological stages and in detached buds and flowers. Overall, our results demonstrate a clear link between host plant phenology, the corresponding plant odour, and the behaviour of mated C. nigricana females.     

胡杨茎叶化学计量和异速生长关系特征随发育阶段变化的性别差异

胡杨(Populus euphratica Oliv.)是荒漠河岸林防风固沙和水土保持的雌雄异株树种。该研究以不同径阶(8、12、16、20 cm)的胡杨雌雄株为研究对象,通过当年生茎、叶化学计量元素(C、N、P、K)含量及生长关系分析,探讨不同器官化学计量随发育阶段的变化及异速生长关系的性别差异。结果表明：(1)胡杨雌雄株叶片C含量表现为大径阶(20 cm)显著高于小径阶(8 cm),而其叶片N含量随着径阶的增加显著增加;雌雄株茎、叶化学计量随着径阶的增加总体上呈增加趋势,且C、N含量均与径阶呈显著正相关关系;随着径阶的增加,雌株叶片P含量呈下降趋势,与径阶呈显著负相关关系,而雌雄株茎的P、K含量呈上升趋势,且与径阶呈显著正相关关系。(2)雌株各径阶叶片的N含量及8、12、20 cm径阶的叶片P含量均显著大于相应雄株,8、16、20 cm径阶当年生茎C含量以及20 cm径阶茎N、P含量均显著高于相应雄株。(3)雌株叶片C与N在20 cm径阶的斜率指数最大,而雄株在12 cm径阶斜率指数最大,雌雄株在各发育阶段N与P的变化较稳定;在相同C含量时,雄株茎能获得更多的N含量,雌株茎在相同N的情况下能获得更多P元素。研究发现,胡杨雌雄株间茎、叶化学计量元素含量和异速生长关系特征在不同发育阶段存在着明显性别差异,成熟雌株叶片需要更多的化学计量特征含量来满足生殖需求,总体反映了自身生长及环境适应的养分分配策略。     

Gender-specific costs of reproduction on vegetative growth and physiological performance in the dioecious shrub Corema album

Background and Aims

Reproductive costs imply trade-offs in resource distribution at the physiological level, expressed as changes in future growth and/or reproduction. In dioecious species, females generally endure higher reproductive effort, although this is not necessarily expressed through higher somatic costs, as compensatory mechanisms may foster resource uptake during reproduction.

Methods

To assess effects of reproductive allocation on vegetative growth and physiological response in terms of costs and compensation mechanisms, a manipulative experiment of inflorescence bud removal was carried out in the sexually dimorphic species Corema album. Over two consecutive growing seasons, vegetative growth patterns, water status and photochemical efficiency were measured to evaluate gender-related differences.

Key Results

Suppression of reproductive allocation resulted in a direct reduction in somatic costs of reproduction, expressed through changes in growth variables and plant physiological status. Inflorescence bud removal was related to an increase in shoot elongation and water potential in male and female plants. The response to inflorescence bud removal showed gender-related differences that were related to the moment of maximum reproductive effort in each sexual form: flowering in males and fruiting in females. Delayed costs of reproduction were found in both water status and growth variables, showing gender-related differences in resource storage and use.

Conclusions

Results are consistent with the existence of a trade-off between reproductive and vegetative biomass, indicating that reproduction and growth depend on the same resource pool. Gender-related morphological and physiological differences arise as a response to different reproductive resource requirements. Delayed somatic costs provide evidence of gender-related differences in resource allocation and storage. Adaptive differences between genders in C. album may arise through the development of mechanisms which compensate for the cost of reproduction.     

Development of Prevotella intermedia-specific PCR primers based on the nucleotide sequences of a DNA probe Pig27

The aim of this study was to develop Prevotella intermedia-specific PCR primers based on the P. intermedia-specific DNA probe. The P. intermedia-specific DNA probe was screened by inverted dot blot hybridization and confirmed by Southern blot hybridization. The nucleotide sequences of the species-specific DNA probes were determined using a chain termination method. Southern blot analysis showed that the DNA probe, Pig27, detected only the genomic DNA of P. intermedia strains. PCR showed that the PCR primers, Pin-F1/Pin-R1, had species-specificity for P. intermedia. The detection limits of the PCR primer sets were 0.4 pg of the purified genomic DNA of P. intermedia ATCC 49046. These results suggest that the PCR primers, Pin-F1/Pin-R1, could be useful in the detection of P. intermedia as well as in the development of a PCR kit in epidemiological studies related to periodontal diseases.     

Different arbuscular mycorrhizal interactions in male and female plants of wild Carica papaya L.

The different resource demands on male and female plants of dioecious species can lead to secondary sexual dimorphisms. Male and female plants might also interact differently with antagonists and mutualists. We used a repeated measures natural experiment in five subpopulations to investigate secondary sexual dimorphism in Carica papaya including interactions with arbuscular mycorrhizal fungi. Male and female plants did not differ in size or growth rate, but male plants flowered earlier than female plants. We observed different patterns of root colonization by arbuscular mycorrhizal fungi in male and female plants of C. papaya. These differences between the sexes preceded the flowering of most female plants. Female plants were sensitive to changes in soil fertility and adjusted the extent of their root colonization by arbuscular mycorrhizal fungi accordingly. Overall, the different resource demands on male and female plants seem to modulate the interactions of C. papaya with arbuscular mycorrhizal fungi.     

A comparison of growth and reproduction, under laboratory conditions, of males and females of a dioecious fig tree

The interaction between Ficus spp. (Moraceae) and their pollinating wasps (Chalcidoidae: Agaonidae) is a highly co-evolved mutualism. Approximately half of all fig species are monoecious and produce a mixture of wasps and seeds within the same fig. In functionally dioecious fig trees male and female functions are separate. Figs on male trees produce wasps and pollen, whereas figs borne on female plants produce only seeds. Dioecious fig phenology provides an excellent opportunity to investigate the effect of sexual specialization on the obligate fig?Cfig wasp interaction and the non-pollinators associated with the system. Here we describe laboratory studies of phenological variation between two sexes in terms of vegetative growth and fig production in a dioecious fig tree Ficus montana. We also describe reproductive output in terms of wasp production in males and seeds in females. Intrasexual asynchrony was observed for the plants, with synchrony between the sexes with year-round production of figs. Male plants grew more rapidly, but leaf phenology was very similar. Crop sizes and development times were the same for males and females. Seasonal effects were strong for leaf phenology and fig initiation, but had a very limited effect on fig composition. The results show that the phenological differences described for other dioecious figs do not apply to all species.     

Gender-related differences in polyamine oxidase activity in rat tissues

Summary Variations in level of polyamines and their related enzymes are frequently observed in response to some treatments which affect in a different way male and female. The possibility of a gender-related difference in the oxidation of polyamines was investigated in rats by measuring the activity of polyamine oxidase, a ubiquitous enzyme of vertebrate tissues, which transforms spermine into spermidine and spermidine into putrescine. The study was carried out on thymus, spleen, kidney and liver of young rats of both sexes, and female rats showed a lower polyamine oxidase activity than male rats in all the tissues. We also found higher values of spermidine acetylation in female than male rats in thymus and liver. Owing to these gender-related differences, a higher spermidine N-acetyltransferase/ polyamine oxidase ratio was found in female than in male rats. A second gender-related difference was a higher spermidine/spermine ratio in female than in male, the only exception being the thymus. These basal differences possibly account for the gender-related differences of polyamine metabolic enzyme activities in response to some treatments, including drugs or hormones.     

Sexual dimorphism, sex ratio and spatial distribution of male and female shrubs in the dioecious speciesPistacia lentiscus L.

The population sex ratio, spatial distribution, relative growth rate, canopy size and morphology, and nitrogen content of leaves of male and female individuals were compared in seven populations of the dioecious shrubPistacia lentiscus L. occurring in different localities of the Serra da Arrábida Natural Park, Portugal. The expected pattern of male preponderance in stressful habitats was tested. Less perturbed areas, with a well developed vegetation cover, had male-biased sex ratios, while in former agricultural areas there were no significant differences between the number of male and female plants. Our results failed to reveal any significant differences in the morphological variables between sexes except in the number of basal stems. Male plants also had a significantly higher chlorophyll content (chl a+b) than female plants. But when plants were sorted into large and small individuals, larger plants showed a significantly higher leaf area index and a significantly higher number of basal stems. There were no significant differences in the leaf nitrogen content between male and female plants from June to August, but such differences appeared (P<0.001) in September and October corresponding to the production of mature fruits. Differences in sex-ratio may be explained by different resource allocation patterns of the two sexes, which favoured male plants in the less perturbed environments. In agricultural areas farmers could also have favoured female plants in former times.     

Evaluation of gender-related differences in various oxidative stress enzymes in mice

Oxidative stress caused by redundant free radical, lipid oxygen and peroxide usually results in the pathogenesis of various diseases, which can be alleviated by cellular antioxidant enzymes. According to statistics, there are different incidence rates of some diseases depending on the gender. The present study aimed to investigate potential gender-related differences of antioxidant enzymes in mice. The activities of glutamate-cysteine ligase (GCL), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) in the kidney, brain, lung and heart of both male and female mice were determined. Our results showed that GPx and GCL activities were higher in female kidney and brain than those in male. On the other hand, the activities of SOD were higher in female brain and lung than those in male. Moreover, female kidney appeared to show higher activities of CAT than the male kidney. But the activities of GCL and GPx were higher in male heart than those in female. Taken together, our results demonstrate that there are gender-related differences in the activities of cellular antioxidant enzymes in various important organs in mice. Variations in such enzymes may be the explanation for some gender-related diseases.     

Gender-related differences in expression and function of hepatic P-glycoprotein and multidrug resistance-associated protein (Mrp2) in rats

To clarify whether gender-related differences exist in the expression and function of hepatic P-glycoprotein- and/or multidrug resistance-associated protein (Mrp2), we measured the hepatobiliary excretion of doxorubicin and their protein levels in male and female Sprague-Dawley rats. When rats received a single intravenous injection of doxorubicin (5 mg/kg), a delay in the disappearance of doxorubicin from plasma was observed in male rats. When rats received a constant-rate infusion of doxorubicin, no significant gender-related differences in the apparent biliary clearance of doxorubicin based on the steady state plasma concentrations were observed between male and female rats. However, the net biliary clearance of doxorubicin based on the liver concentration, which represents the actual function of P-glycoprotein and/or Mrp2, was higher in female rats than in male rats. These results suggest that the actual function of the hepatobiliary transport of doxorubicin is greater in female than in male rats. Western blot analysis revealed that the expression of P-glycoprotein and Mrp2 in the liver of female rats was significantly higher than in male rats, similar to results of hepatobiliary excretion experiments. The expression of hepatic cytochrome P450 (CYP) 2B1, which is involved in the metabolism of doxorubicin, was significantly higher in male than in female rats. By pretreatment with testosterone (10 mg/day for 7 days), the actual biliary clearance of doxorubicin in female rats was nearly that of male rats. The protein levels of P-glycoprotein and Mrp2 in female rats were also lowered by treatment with testosterone so as to be nearer those in male rats. These results suggest that gender-related differences exist in P-glycoprotein- and Mrp2-mediated hepatobiliary transport and that these two transporters may be regulated by sex hormones.     

Attractiveness of stages of rice panicle development to Oebalus pugnax (Hemiptera: Pentatomidae)

Greenhouse experiments were conducted during 2004 and 2005 with male and female Oebalus pugnax (F.) (Hemiptera: Pentatomidae) caged on rice plants at different stages of panicle development with the objective of determining the most attractive stage to O. pugnax. Field-collected insects were released inside cages containing potted plants and observed during morning and afternoon hours for 5 d. Results showed that attractiveness of male and female O. pugnax to plants with panicles at milk and soft dough stages was greater than plants at preheading and heading stages. Preheading plants were the least attractive to the insects, confirming field observations. Results imply that insecticide applications during the preheading stage are likely ineffective and that monitoring efforts during the milk and soft dough stages of panicle development should be intensified.     

Orientation of field populations ofBrachymeria intermedia [Hym.: Chalcididae], to host and host-habitat cues

Brachymeria intermedia (Nees), a pupal parasitoid of the gypsy moth, was caught in the field using plexiglas traps coated with Tangletrap (2). Significantly greater numbers of females were collected in traps baited with gypsy moth pupae than in traps with male or femaleB. intermedia or traps painted yellow.B. intermedia collected in traps during the first 3 weeks of native gypsy moth pupation were primarily female. A preponderance of males were caught during the fourth week. The hyperparasite,Brachymeria compsilurae (Cwfd) was also trapped in small numbers. Gypsy moth pupae were hung in interior and exterior areas of woodland sites. A greater number ofB. intermedia emerged from pupae in woodland edge sites than from pupae in interior woodland sites.     

Resource-related variables drive individual variation in flowering phenology and mediate population-level flowering responses to climate in an asynchronously reproducing palm

Many tropical plant species show wide intra-population variation in reproductive timing, resulting in the protracted presence of flowering and fruiting individuals. Various eco-evolutionary drivers have been proposed as ultimate causes for asynchronous phenology, yet little is known about the proximate factors that control reproductive onset among individuals or that influence the proportion of trees producing new inflorescences within a population. We employed a nine-year phenological record from 178 individuals of the hyperdominant, asynchronously flowering canopy palm, Oenocarpus bataua (Arecaceae)¸ to assess whether resource-related variables influence individual- and population-level flowering phenology. Among individuals, access to sunlight increased rates of inflorescence production, while the presence of resource sinks related to current investment in reproduction—developing infructescences—reduced the probability of producing new inflorescences. At the population level, climate anomalies induced by El Niño Southern Oscillation (ENSO) affected the proportion of the population producing inflorescences through time. Moreover, the effects of ENSO anomalies on flowering patterns depended on the prevalence of developing infructescences in the population, with stronger effects in periods of low developing-infructescence frequency. Taken together, these results suggest that resource-related variables can drive phenological differences among individuals and mediate population-level responses to larger-scale variables, such as climate anomalies. Consequently, a greater focus on the role of resource levels as endogenous cues for reproduction might help explain the frequent aseasonal phenological patterns observed among tropical plants, particularly those showing high intra-population asynchrony.     

Nutrient deficiency promotes male-biased apparent sex ratios at the ramet level in the dioecious plant <Emphasis Type="Italic">Myrica gale</Emphasis> var. <Emphasis Type="Italic">tomentosa</Emphasis> in oligotrophic environments in bogs

In populations of dioecious plants, the differences in the cost of reproduction between male and female plants can promote a male-biased sex ratio. In this study, we examine the macronutrient levels in tissues of the dioecious wetland shrub Myrica gale to identify the cost of reproduction for male and female plants and to examine the effect of nutrients on the apparent sex ratio at the ramet level. We examined plants across 12 populations of M. gale inhabiting bogs and fens in Japan. For each population, we used line transects to estimate the apparent sex ratio and measured the concentrations of nitrogen (N), phosphorus (P), and potassium (K) in the leaves sampled from male and female plants and in the fruits from female plants. For five of the populations, we calculated the flowering frequency, mortality, and the recruitment rate (as the rate of clonal propagation). We found that the proportion of females was positively affected, and the male bias of sex ratios reduced, by increases in P concentration in leaves sampled from female plants. Neither mortality nor recruitment was affected by sex or by the nutrient concentration (P, K). The flowering frequency was not affected by sex or by K concentration, but decreased with decreases in the P concentration measured in leaves. This study confirmed that reproduction in M. gale is P-limited. We found no distinct differences in the flowering frequency, mortality, or recruitment rate between the male and female plants.     

Using a phenological network to assess weather influences on first appearance of butterflies in the Netherlands

Phenological responses of butterflies to temperature have been demonstrated in several European countries by using data from standardized butterfly monitoring schemes. Recently, phenological networks have enabled volunteers to record phenological observations at project websites. In this study, the quality of the first appearance data of butterflies from the Dutch phenological network ‘De Natuurkalender’ was examined and these data were then used to analyze trends in butterfly appearance between 2001 and 2013, the effects of climatic factors on appearance of butterflies as well as the phenological interaction of one butterfly species, Anthocharis cardamines, and its two major host plants. Although phenological networks are relatively unstructured, this study shows that data from De Natuurkalender were highly comparable to more standardized data collected by the Dutch Butterfly Monitoring Scheme. No trend in first appearance of any butterfly species was found during the time period 2001–2013. The first appearance dates of most butterflies showed, however, a clear relationship with spring temperature. Higher temperatures, especially in March and April, advanced the first appearance of butterflies. Therefore, with climatic warming in the future, earlier appearance of butterflies is expected. Although climate warming is a potential threat for phenological mismatches between different trophic levels, this study shows a similar temperature response of A. cardamines and its main host plants in the Netherlands. However, as only few phenological interactions between species are examined, further research including rarer monophagous butterfly species and their host plants is needed.     

Characteristic differences in metabolite profile in male and female plants of dioecious <Emphasis Type="Italic">Piper betle</Emphasis> L.

Piper betle is a dioecious pan-Asiatic plant having cultural and medicinal uses. It belongs to the family Piperaceae and is a native of the tropics although it is also cultivated in subtropical areas. Flowering in P. betle occurs only in tropical regions. Due to lack of inductive floral cycles the plant remains in its vegetative state in the subtropics. Therefore, due to lack of flowering, gender distinction cannot be made the in the subtropics. Gender distinction in P. betle in vegetative state can be made using Direct Analysis in Real Time Mass Spectroscopy (DARTMS), a robust high-throughput method. DARTMS analysis of leaf samples of two male and six female plants showed characteristic differences in the spectra between male and female plants. Semi-quantitative differences in some of the identified peaks in male and female landraces showed gender-based differences in metabolites. Cluster analysis using the peaks at m/z 151, 193, 235 and 252 showed two distinct clusters of male and female landraces. It appears that male and female plants besides having flowers of different sexes also have characteristic differences in the metabolites representing two metabolic types.     

Sexual difference in juvenile-hormone titer in workers leads to sex-biased soldier differentiation in termites

In termites, the soldier caste, with its specialized defensive morphology, is one of the most important characteristics for sociality. Most of the basal termite species have both male and female soldiers, and the soldier sex ratio is almost equal or only slightly biased. However, in the apical lineages (especially family Termitidae), there are many species that have soldiers with strongly biased sex ratio. Generally in termites, since high juvenile hormone (JH) titer is required for soldier differentiation from a worker via a presoldier stage, it was hypothesized that the biased soldier-sex ratio was caused by differences in JH sensitivity and/or JH titer between male and female workers. Therefore, we focused on the presoldier differentiation and the worker JH titer in species with only male soldiers (Nasutitermes takasagoensis) and with both male and female soldiers (Reticulitermes speratus) in natural conditions. In the former species, there are four types of workers; male minor, male medium, female medium and female major workers, and presoldiers differentiate from male minor workers. First, we tried to artificially induce presoldiers from male and female workers. In N. takasagoensis, the presoldier differentiation rate and mortality was significantly higher in male minor workers. Morphological analyses showed that both male and female induced presoldiers possessed normal soldier-specific morphologies. It was suggested that female workers, from which soldiers do not differentiate under natural conditions, also maintained the physiological and developmental potential for soldier differentiation. In R. speratus, however, no differences were observed in solder differentiation rate and mortality between male and female workers. Second, the JH titers of each sex/type of workers were quantified by high performance liquid chromatography–mass spectrometry in two different seasons (April and December). The results showed that, in N. takasagoensis, JH titer in male minor workers was consistently higher than those in other worker types. In R. speratus, in contrast, there were no significant differences in JH titers between male and female workers. These results suggested that, in N. takasagoensis, male minor workers maintain JH titers at a high level throughout a year, and this may cause the male-biased presoldier differentiation.     

Epigenetic control of sexual phenotype in a dioecious plant,Melandrium album

Melandrium album (syn.Silene latifolia) is a model dioecious species in which theY chromosome, present only in heterogametic males, plays both a male-determining and a strict female-suppressing role. We showed that treatment with 5-azacytidine (5-azaC) induces a sex change to androhermaphroditism (andromonoecy) in about 21% of male plants, while no apparent phenotypic effect was observed in females. All of these bisexual androhermaphrodites (with the standard male 24,AA +XY karyotype) were mosaics possessing both male and hermaphrodite flowers and, moreover, the hermaphrodite flowers displayed various degrees of gynoecium development and seed setting. Southern hybridization analysis with a repetitive DNA probe showed that the 5-azacytidine-treated plants were significantly hypomethylated in CG doublets, but only to a minor degree in CNG triplets. The bisexual trait was transmitted to two successive generations, but only when androhermaphrodite plants were used as pollen donors. The sex reversal was inherited with incomplete penetrance and varying expressivity. Based on the uniparental inheritance pattern of androhermaphroditism we conclude that it originated either by 5-azaC induced inhibition ofY-linked female-suppressing genes or by a heritable activation of autosomal female-determining/promoting genes which can be reversed, on passage through female meiosis, by a genomic imprinting mechanism. The data presented indicate that female sex suppression inM. album XY males is dependent on methylation of specific DNA sequences and can be heritably modified by hypomethylating drugs.