雌、雄株和金叶银杏光合生理及黄酮成分年动态变化研究

【目的】为了解黄酮类化合物在银杏叶片中的合成代谢规律,确定银杏合适采摘期,以及选育优良的银杏品种,探讨了雌、雄株和金叶(芽变品种)银杏叶片光合生理与黄酮含量的周年变化及相关性。【方法】以银杏种质资源圃的雌株、雄株及嫁接的金叶银杏为材料,对4—11月银杏的光合色素、叶绿素荧光参数、黄酮成分及含量间的变化进行了研究。【结果】在整个叶片生长周年动态变化中,雄株银杏的含水量低于雌株和金叶银杏,特别是在6—9月夏季高温时期的差异更显著;雌株银杏的含水量、相对叶面积、叶绿素含量都大于雄株与金叶银杏,特别是在5—8月,但雄株与金叶银杏的相对叶面积增加速度较快;雌株银杏的光化学淬灭系数(qP)及非光化学淬灭系数(NPQ)高于雄株和金叶银杏,雌株具有更强的抗氧化能力。银杏叶中黄酮苷含量及总黄酮含量的高点分别出现在4—5月和9月,各银杏叶总黄酮的含量依次为金叶银杏>雄株>雌株;雄株的叶绿素、类胡萝卜素与槲皮素之间,雌株的叶绿素a、类胡萝卜素与总黄酮之间都存在极显著正相关。金叶银杏叶色在4—6月为金黄色,其叶绿素含量均比雄株、雌株银杏低,7月转绿后与雌株和雄株差异不大,其光合、黄酮代谢的变化更接近于雄株,且其黄酮合成的能力高于雄株及雌株。【结论】银杏叶的最佳采收期在9月,雄株和金叶银杏更适用于叶用林的培育,雌株的抗逆性高于雄株与金叶银杏,金叶银杏既有观赏价值,又有优良的经济性状,因而具有良好的开发利用前景。

Preliminary Study on Water Physiological Characters of Male and Female Ginkgo biloba L.

[Objective] The experiment aimed to study the difference of water physiology of male and female Ginkgo biloba L. for discussing the strategy of water utilization as well as the important role of this difference during evolution process. [Method] The stem sap flow, stomatal conductance(Gs), transpiration rate(Tr) and water use efficiency (WUE) of male and female Ginkgo biloba L. were comparatively studied. [Result] The day-night processes of flow on male and female Ginkgo biloba L. were similar. The flow on male and female Ginkgo biloba L. in day were almost same while the flow at night on male Ginkgo biloba L. was bigger than that on female Ginkgo biloba L. The Tr and Gs of male and female Ginkgo biloba L. were high in morning and at night but low at noon ,while Tr and Gs of female Ginkgo biloba L. in morning and at night were higher than these of male Ginkgo biloba L. at the same time point. However, these indexes of female plant were lower than these of male plant from 11:00 to 14:00. WUE changing trends of male and female Ginkgo biloba L. were similar, while average water utilization rate of female Ginkgo biloba L. was slightly lower than that of male Ginkgo biloba L. [Conclusion] Compared with other companion plants, water physiology of male and female Ginkgo biloba L. had strong homoplasy. The phenomenon might be a survival strategy of dioecious plants under long term evolutionary pressure.

Zoospore-derived monoecious gametophytes in Undaria pinnatifida(Phaeophyceae)

The annual life cycle of the brown seaweed Undariapinnatifida （Harvey） Suringer comprises a macroscopic diploid sporophyte stage and a microscopic haploid gametophyte stage. In 2011, an unusual zoospore-derived monoecious gametophyte isolate （designated as line 10-5-3） of U. pinnatifida was observed. To understand this phenomenon, a comprehensive screening of eighty-two previously identified male gametophyte cultures, isolated from three randomly selected cultivars （lines 10, 7, and 5） was performed. Thirty-six of the isolates developed both antheridia and oogonia on the same filamentous fragment in a standard gametogenesis test （SGT： 18℃, 60 umol photons/（m2.s））. Selfing of the monoecious gametophyte or crossing it with a normal male gametophyte both gave rise to morphologically normal sporophytic offspring. However, crossing resulted in a much higher fertilization rate （89.7%）. The hybrid and selfed sporophytic offspring were grown to maturity in flow tanks at an ambient temperature of 10-18℃ over a period of 69 days. Active zoospores were released from both types of mature sporophylls. The majority of these developed into male gametophytes, while 15%-20% developed into the observed monoecious structures on the same filament. Using PCR amplification it was found that all the monoecious gametophyte isolates and the sporophytic offspring resulting from the selfing and crossing lacked the femalelinked microsatellite sequence （a part of the locus Up-AC-2A8, GenBank accession No. AY738602.1）, indicating their male nature. U.pinnatifida is an invasive species in some regions and the implications of the above findings for this species in nature are briefly discussed.

Phylogeography of Batrachospermum arcuatum in North China based on ITS sequence data

Batrachospermum arcuatum Kylin is typically dioecious,although some monoecious specimens have been collected from four locations in North China.In this study,B.arcuatum populations,including monoecious and dioecious thalli,were collected from seven stream segments.The nuclear DNA internal transcribed spacer(ITS)region was sequenced for the seven populations,and a phylogenetic tree was constructed using Bayesian inference to assess intraspecifi c relationships.A haplotype network was also created.The ITS region in B.arcuatum from North China comprised 822–853 bp,with 10 haplotypes detected from the seven locations.The results of this study support the inclusion of monoecious individuals in the species B.arcuatum.

Sex-specific strategies of resource utilization and determining mechanisms of Hippophae rhamnoides in response to community succession

The dioecious plant,Hippophae rhamnoides,is a pioneer species in community succession on the Qinghai-Tibet Plateau(QTP),plays great roles in various ecosystem services.However,the males and females of the species differ both in their morphology and physiology,resulting in a change in the ratio of male to female plants depending on the environment.To further explore the functional traits critical to this sex-based distinctive response in the alpine grassland,we have surveyed the sex ratios,measured their photosynthetic parameters,height,leaf area and biomass allocation.The results showed that(i)The males had higher Pn,light saturation point,apparent quantum efficiency,A_(max) and lower water-use efficiency(WUE),which exhibited higher utilization efficiency or tolerance to strong light,while the females indicated higher utilization efficiency for low light and water.And it showed sex-specific biomass allocation patterns.(ii)H.rhamnoides populations across the successional stages all showed a male-biased sexual allocation,which was closely related to sex-specific WUE,Pn,root biomass/total biomass and root-crown ratio.(iii)The leaf traits of H.rhamnoides changed from higher N_(area),P_(area) and leaf mass per area in the early and late to lower in the middle,which meant they moved their growth strategy from resource rapid acquisition to conservation as the succession progressed.(iv)The increasing soil total phosphorus mostly contributed to regulating the sex bias of populations and variations of traits during the succession.The results are vital for the management of grassland degradation and restoration due to shrub encroachment on the QTP.

Sexual differences and sex ratios of dioecious plants under stressful environments

Dioecious plants exhibit sexual dimorphism in both sexual features(reproductive organs)and secondary sex characteristics(vegetative traits).Sexual differences in secondary traits,including morphological,physiological and ecological characters,have been commonly associated with trade-offs between the cost of reproduction and other plant functions.Such trade-offs may be modified by environmental stressors,although there is evidence that sexually dimorphic responses to stress do not always exist in all plant species.When sexual dimorphism exists,sexually different responses appear to depend on the species and stress types.Yet,further studies on dioecious plant species are needed to allow the generalization of stress effects on males and females.Additionally,sexual dimorphism may influence the frequency and distribution of the sexes along environmental gradients,likely causing niche differentiation and spatial segregation of sexes.At the present,the causes and mechanisms governing sex ratio biases are poorly understood.This review aims to discuss sex-specific responses and sex ratio biases occurring under adverse conditions,which will advance our knowledge of sexually dimorphic responses to environmental stressors.

The sexual dimorphism displayed by the roots of mulberry(Morus alba)saplings depends on the sex of the neighboring plants

Aims Dioecious plants present sexual dimorphism,but how the root traits and nutrient uptake of female and male plants in dioecious species response to the sexual identity change of the neighbor plants are poorly understood.Methods Mulberry(Morus alba L.),a dioecious plant widely distributed in China,was employed in our study.Male and female plants were grown with neighbors of the same and opposite sex for 3 months.At harvest,the root anatomy,root morphology,nutrient concentrations and biomass accumulation were measured.Important Findings When grown with the opposite sex,the males showed decreases in root xylem size,biomass of root and stem and increases in root N,P and K concentrations compared with grown with the same sex.By contrast,females showed significant increases in xylem size,fine root system(e.g.fine root length,root surface area and root volume),root carbon isotope composition(δ13C)and root N,P and K concentrations.The changes in theδ13C and N,P and K concentrations in male and female plants were associated with the changes of root traits.These results demonstrated that the sexual identity of the neighboring plants affected root anatomy and morphology of female and male mulberry plants.Meanwhile,the responses of female and male plants to the sex change of the neighboring plants showed sexual dimorphism,which influenced water-use efficiency and resource acquisition.These findings are important for understanding the population dynamics of other dioecious species in forestry and natural systems.

Intersexual differences in leaf size and shape in dioecious Adriana tomentosa

Aims Leaf size and shape as objects of natural selection can play adaptive roles,and can change with the age of leaves.They can differ between sexes in dioecious species,and in most cases,females have larger leaves.Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing.In this study,we investigated whether there were other differences between sexes in leaf size,shape and ecophysiology,and if those differences were connected with adaptations and reproductive roles in the sexes of A.tomentosa.Methods Physical and chemical features of young and old leaves originating from female and male A.tomentosa plants growing in two disjunct populations in eastern Australia were measured.We determined leaf area,perimeter length,serration,circularity,aspect ratio(AR),roundness and the ecophysiological factors:specific leaf area,dry matter content,leaf moisture,relative water content,δ^(13)C,δ^(15)N isotope compositions,carbon and nitrogen contents and C:N ratio.Leaf lobing,the degree of lamina damage and the content of photosynthetic pigments were also determined.Important Findings In both populations studied,the sex of plants significantly influenced almost all parameters connected with leaf morphology such as area,perimeter length,circularity,AR and roundness.Contrary to expectations,males from both populations had a greater leaf area that was independent of leaf age.Male leaves were more lobed with a longer perimeter,but they were less elongated and less serrated.Only small differences between female and male leaves were observed for the ecophysiological factors.The degree of leaf damage differed between sexes but also with population.Differences between sexes in leaf area and shape were not compensated by measured ecophysiological factors.However,leaf area may be compensated by other ecophysiological mechanisms related to leaf morphology,because females had greater leaf serration in comparison to males despite the smaller leaf area.

Sexual selection and hermaphroditic organisms： Testing theory

Sexual selection is widespread if not ubiquitous in hermaphroditic organisms. Although many phenomena that have been described as sexual selection in gonochores, （e.g. harem polygamy, multiple mating, elaborate courtship, even secondary sexual characters） can be found in some hermaphrodites, what is more interesting is the ways in which sexual selection in her- maphrodites may differ from dioecious taxa. In hermaphrodites, an individual＇s mating success includes its success from both sexual roles. Secondly, in many simultaneously hermaphroditic taxa there is strong evidence of sexual selection and yet the ope- rational sex ratio is 1：1, by definition. Many simultaneous hermaphrodites have elaborate courtship and genital anatomy, suggest- ing sexual selection plays an important role in reproductive success. Sperm competition and cryptic female choice mean that the number of mates acquired is not necessarily a predictor of reproductive success. Even in simultaneous hermaphrodites with re- ciprocal mating, variance in reproductive success through the male role and through the female role may differ in a population. Moreover hermaphrodites may choose to emphasize one sexual role over the other. Data suggest that the preferred role varies in hermaphrodites, which creates an opportunity to test fundamental predictions and assumptions of sexual selection theory. Hermaphrodites may vary their emphasis on one sexual role over the other either developmentally or behaviorally in response to environmental or social parameters. How they use this capability in acquiring more or higher quality mates still requires study