Female Shoots Research Articles

CANNABIS AND MALE FERTILITY : A SYSTEMATIC REVIEW

Cannabis is a class of psychoactive substances derived from Cannabis sativa or Cannabis indica that can induce euphoria in the user. Cannabinoids are the term used to refer to the active component of cannabis, which contains 400 active compounds. DSM criterion 5 characterizes cannabis use disorder. Cannabis is the most commonly used illicit substance worldwide. The annual prevalence of cannabis abuse ranges from 2.9% to 4.3% of the global population aged 15 to 64. Cannabis sativa, Cannabis indica, and Cannabis ruderalis are the three varieties of cannabis. These three cannabis varieties contain varying amounts of tetrahydrocannabinol (THC). The THC content of Charas and hashish ranges between 7% and 14%. Cannabis and Sinsemilla are found in female shoots with an average THC concentration of 4-5% (rarely >7%). Low-grade Bhang preparations are derived from the 1% THC-containing residue of desiccated plants. Hashish oil, a concentrated liquid extracted from hashish distilleries, contains between 15 and 70 percent THC. Semen parameters provide the strongest evidence of cannabis-induced alterations in male fertility. Cannabis reduces sperm count and concentration, induces abnormalities in sperm morphology, reduces sperm motility and viability, and inhibits capacitation and fertilizing capacity, according to research.

Volatiles as Attractants of Mahogany Shoot Borer, Hypsipyla grandella Zeller (Lepidoptera: Pyralidae)

The mahogany shoot borer, Hypsipyla grandella Zeller (Lepidoptera: Pyralidae), is one of the most economically important pests in all American tropical forests because it prevents the establishment of monoculture plantations of the family Meliaceae, such as Spanish cedar, Cedrela odorata L. Various studies have focussed on the bioecological aspects and the chemical and silvicultural control of this pest. However, relatively little is known about the biological interactions between this insect and its host plant. In this study, the shoot borer's behavior and attraction response to cedar host plants was evaluated in field cages. We also identified the volatiles emitted by healthy C. odorata plants that were attractive to H. grandella adults. The attraction to headspace volatiles from cedar plants and a synthetic blend were evaluated in a Y-glass tube olfactometer. We observed that virgin and mated females exhibited low activity at night, frequent movement of the antennae, sporadic flight activity, and short (< 10s) and long (> 30s) wing-fanning. Virgin females assumed a calling position, whereas mated females exhibited three periods of oviposition. The results showed that all evaluated categories - virgin females, virgin males, and mated females - were attracted to cedar plants. We identified the following volatile compounds: α-pinene, (E)-β-ocimene, 2-ethyl-1-hexanol, limonene, nonanal, (E)-4,8-dimethyl-1,3,7-nonatriene, α-copaene, β-caryophyllene, and germacrene D. A synthetic blend significantly attracted virgin male and mated female shoot borers. Our results suggested that C. odorata volatiles compounds are responsible for the attraction of H. grandella.

Consequences of the Reproductive Effort of Dioecious Taxus baccata L. Females in a Generative Bud Removal Experiment-Important Role of Nitrogen in Female Reproduction.

Dioecious species differ in the pattern and intensity of male and female reproductive investments. We aimed to determine whether female shoots deprived of generative buds show biochemical features, indicating their less-pronounced reproductive effort. For this purpose, the same branches of mature Taxus baccata females were deprived of generative organs. In the second and third years of the experiment, measurements were made in every season from the control and bud-removed shoots of females and control males. Bud removal caused an increase in nitrogen concentration almost to the level detected in the needles of male specimens, but only in current-year needles. Moreover, differences between male and control female shoots were present in the C:N ratio and increment biomass, but they disappeared when bud removal was applied to females. Additionally, between-sex differences were observed for content of phenolic compounds, carbon and starch, and SLA, independent of the female shoot reproductive effort. The study revealed that nitrogen uptake in seeds and arils may explain the lower nitrogen level and consequently the lower growth rate of females compared to males. At the same time, reproduction did not disturb carbon level in adjacent tissues, and two hypotheses explaining this phenomenon have been put forward.

Ecological variability of seed production quality of Siberian stone pine (Pinus sibirica Du Tour) along the latitudinal gradient in the West Siberian Plain

The range of Siberian stone pine (Pinus sibirica Du Tour) in the flat part of Western Siberia occupies a wide strip from the forest-steppe zone in the south to the Arctic Circle in the north, therefore, the ecological amplitude of its growth covers conditions with different heat and moisture conditions. Optimal for this species is the moderately cold and humid climate of the middle taiga. In the north of the area, growth and reproduction are limited by a cold and short growing season, in the south of the area, by insufficient soil moisture. The relevance of studying the quality of sexual reproduction in the north and south of the area is due to the observed climatic changes, since the quality of the seeds determines the potential for adaptation and advancement of the species to new frontiers. This work analyzes the ecological variability of crop quality in three populations: (1) the border of the northern taiga subzone with the forest-tundra, (2) the middle taiga subzone, (3) the border of the southern taiga subzone with the forest-steppe. Analysis of the 22-year dynamics of the formation and maturation of cones on female shoots showed that in the southern population, with good quality of cones and seeds and a high average long-term level of cone formation, there is a tendency to reduce their maturation. The number of years with high seed production has decreased. In the northern population, the quality of cones was worse due to a decrease in the proportion of fertile scales, developed and filled seeds. The seeds had a normal weight but a short embryo. The frequency of high seed production is once every ten years. With a lower average number of initiated and matured cones on the shoot, their inter-annual dynamics demonstrates a steady upward trend.

A new species of Stolonivector (Lophocoleaceae: Hepaticophyta) from New Zealand

ABSTRACT A new species of Stolonivector (Lophocoleaceae) has been found from two separate sites in southern New Zealand. Stolonivector echioides has been assigned to this genus because it is has all the features of Stolonivector, namely the presence of stolons, a lack of secondary pigmentation, both lateral- and ventral-intercalary branching types, leafy branches that often become flagelliform, highly variable leaf apices on female shoots that are usually bifid towards the base of the stem becoming more shallowly bifid, retuse or entire towards the apex of the stem, and underleaves with apices that vary in the degree of division along the same stem ranging from undivided to deeply bifid. The most distinctive character that distinguishes this species from others in the genus is the spinose surface of leaves and perianths. This new addition brings the total number of New Zealand Stolonivector species to six, four of which are endemic.

Changes in growth and soil microbial communities in reciprocal grafting clones between Populus deltoides males and females exposed to water deficit conditions

Our findings highlight that male-rooted clones (M/M and F/M) of Populus deltoides are more water-deficit tolerant than female-rooted clones (F/F and M/F), as shown by a smaller decrease in total biomass and net photosynthetic rate in the male-rooted clones. It has been reported that graft clones (female scion and male rootstock) in poplars may be an option to mitigate the effects of water deficit on plants. However, the extent to which grafting mitigates the effect of soil water deficit on soil microorganisms remains poorly understood. The research was designed to investigate the effects of soil water deficit on plant growth, soil microbial communities, and soil enzymatic activities of the reciprocal graft clones of P. deltoides. Four different graft clones (female shoot scion and female rootstock, F/F; male shoot scion and female rootstock, M/F; male shoot scion and male rootstock scion, M/M; and female shoot scion and male rootstock, F/M) in P. deltoides were used. Two watering regimes, irrigation and soil water deficit (i.e., non-irrigation conditions, natural levels of precipitation) were included in the experiments. The microbial community structure was quantified using phospholipid fatty acid. Under water deficit, the decreases in total biomass, net photosynthetic rates, and leaf nitrogen content were more evident in M/M and F/M than in F/F and M/F. Bacterial phospholipid fatty acids (PLFAs) and actinomycetal PLFAs remained unaffected in the four graft clones. In contrast, during soil water deficit, fungal PLFAs were higher in M/M and F/M soil coincided with higher extracellular activities of β-1,4-N-acetyl-glucosaminidase and leucine aminopeptidase. Male-rooted clones (M/M and F/M) are more tolerant to water deficit than female-rooted clones (F/F and M/F). It is possible that the better performance of M/M and F/M, when exposed to water deficit, is associated mainly with higher fine root activity, greater specific root length and root/shoot ratio as well as increased fungal PLFAs.

Структура разнообразия по вегетативной и генеративной структуре кроны кедра сибирского на плантации с разреженной посадкой

Studies of the diversity of economically valuable traits in forest tree species are of great interest not only for forest selection and practical silviculture, but also important as a general biological problem. Among the objects of attention of breeders, a special place is occupied by cone-bearing species such as Siberian stone pine. Its cultivation through the forest tree plantations for wood and for cone-bearing will allow in the future to reduce the damage for natural ecosystems significantly. The purpose of this work was to analyze the structure of diversity in growth and generative development of the Siberian stone pine crown on a specially created plantation, where a low level of natural selection makes it possible to more efficiently select for early reproduction, growth and seed productivity. This plantation is located in the south of the area (Western Siberia, south of Tomsk region). It was created from stone pine seeds of the local population, that were sown in 1977 as forest crops with standard density (0,75 х 3 м). At the age of 10, they were planted out at a distance of 8 x 8 m. The vegetative and generative development of 89 trees aged 40 years was analyzed. We used a retrospective method that allows reconstructing of the tree organogenesis and growth on the scars on the bark of the shoots. The start of sexual reproduction has been reconstructed; a comparative characteristic of the vegetative and generative development of the tree crown has been carried out. The results show that, in general, the initial idea of the dependence of the efficiency of selection on the conditions in which the trees were formed is confirmed. In the natural dense stands, many of the leader trees in cone-bearing, which we found in our study, could fall behind due to slow growth and did not live to reproductive age. On the plantation where sparse tree planting was applied, they survived and became the leaders in cone-bearing. Early start of reproduction, even under conditions of sparse tree planting, is positively correlated with the growth rate in the pre-generative period of ontogenesis (r = + 0.65). The level of variations in the generative development of trees was much higher than in the vegetative one. The abundance of male shoots in the crown and the relative length of the male generative zone of crown were determined primarily by the height of the trees. On the contrary, the active growth of the tree in height did not have a noticeable influence on the development of the female shoots and the female generative zone of crown. Contrasting differences in the traits of male and female crown development with growth traits are very interesting result, in our opinion. Tall trees with a narrow crown are most promising for pollen productivity breeding, since they have a longer male generative zone and because of this they have more male shoots in the crown. Trees with a broad crown are promising for seed production breeding. Although seed productivity is not in all cases a direct function of the size of the crown, but depends on the specific genotype of the tree. This is confirmed by the fact that in each group (high, medium and low trees) there are individuals of high-cone-bearing and low-cone-bearing, which is promising for seed production breeding in groups of different growth levels. Using the calculated relative traits «1 m2 of the area of the horizontal projection of the crown onto the ground surface» made it possible to select the best trees for seed production (combining the minimum size of the crown with the number of cones per unit area of the crown) and growth (combining greater height and narrow crown).For citation: Velisevich S.N., Popov A.V. Pattern of diversity in the vegetative and generative crown structure of the siberian stone pine on a seed orchard with sparse tree planting. Lesnoy Zhurnal [Forestry Journal], 2019, no. 5, pp. 35–47. DOI: 10.17238/issn0536-1036.2019.5.35Funding: This work is supported by the Russian Science Foundation under grant no. 18-16-00058. The article is published within the framework of implementation of the scientific journals development program in 2019, based on proceedings of XIX International conference of the young scholars “Forests of Euro-Asia – The Southern Ural” (August 25-30, 2019. Chelyabinsk).

A battle of the sexes? Sex ratio and performance at small scales in dioecious Mercurialis perennis

Mercurialis perennis is a dioecious clonal woodland herb. Its male-biased shoot sex ratio may result from differential selection (with skewed genet sex ratio) and/or differential performance (fairly even genet sex ratio but skewed shoot sex ratio since male clones grow more vigorously or have a higher flowering propensity). To test both scenarios, a total of 1024 shoots were mapped and excavated in five 1 m2 plots in an old-growth forest in northeastern Germany. SSR genotyping revealed a less skewed intrinsic male:female shoot sex ratio (1.6) and a nearly even genet sex ratio. The sexes showed intermingling rather than sexual niche segregation. Most of the 36 genets found split into numerous independent units (merigenets). A slight sexual size dimorphism (SSD) was found: male clones possess on average more shoots, have longer stolons and a higher proportion of flowering shoots. Analyses of resource allocation patterns showed 1.5–2.8 times higher costs for sexual reproduction (dry mass, nitrogen) for females. Males invest surplus resources into leaves and stolons, accentuating the SSD; although for genets the difference may be smaller due to the higher flowering rate of males (53% vs. 34%). Photosynthetic performance, deduced from rapid light curves measured with a portable fluorometer, was similar for both sexes, especially in spring; the main challenge being the transformation from light to shade plant with tree foliation. Our data indicate that differential performance accounts for the male bias in shoot sex ratio; competition between sexes is unlikely given the strongly intermingled clones.

Status, conservation and ecology of Pallavicinia lyellii (Hook.) Carruth. in a key region of England

ABSTRACTIntroduction. Pallavicinia lyellii is recognised as being of principal importance for conservation in England and is threatened with extinction in Europe. The aims of this study were to investigate the current status, conservation and ecology of the species in S Hampshire, a key region for the plant.Methods. All recent and historic locations for Pallavicinia lyellii in S Hampshire were searched and information collected on distribution, abundance and ecology.Results. Pallavicinia lyellii was re-found at three sites. It is almost certainly extinct at two sites and may have been lost from a third. Whilst few colonies were sterile, most comprised a single sex. Colonies with both male and female plants were confined to Cadnam Bog, which supported 49 (91%) of the colonies found. Overall, female shoots occurred at 41 (76%) colonies and males at 26 (48%), producing a female sex bias (1.6:1). All colonies occur in boggy woodland, mostly on the sides of low mounds of damp, acidic, peaty soil developed, due to poaching by ponies and cattle, at the base of trees, usually I. aquifolium. The community mainly comprises a species-poor mix of acidophilous mosses and liverworts, most frequently Mnium hornum, Pseudotaxiphyllum elegans and Leucobryum juniperoideum.Conclusions. Cadnam Bog appears to support the largest sexually reproducing population of Pallavicinia lyellii in England. The site is specially protected, actively managed with consideration to P. lyellii and seemingly in favourable condition for the plant. Research is needed to quantify canopy shade favoured by the plant and assess implications for woodland management. Future monitoring should include re-survey of populations every 3 yr.

Sex ratio and sex expression in an urban population of the silver moss, Bryum argenteum Hedw.

ABSTRACTIntroduction. A well-supported pattern among dioicous bryophytes is male rarity. However, few assessments of bryophyte sex ratios have been made across environmental gradients to assess the role of environment in shaping population sex ratios.Methods. We systematically surveyed 200 shoots from a 20 m2 urban population of Bryum argenteum, and regenerated each shoot apex until sex expression occurred (up to 315 days).Key results. Female shoots outnumbered male shoots 132 to 68, giving a sex ratio of 1.94♀: 1♂. The female bias was found in two transects in higher light environments but not in the third transect, which had a lower light level and an equal sex ratio. Female shoots took longer than male shoots to reach gametangial induction (122 vs. 60 days) and longer to produce 5 inflorescences (120 vs. 80 days). Male shoots produced an average of 10× the total number of inflorescences compared to female shoots (34 vs. 3.5 inflorescences). Despite producing more inflorescences, male plants also produced more regenerant shoots, thus contradicting the prediction that a higher prefertilisation reproductive effort in males trades off with vegetative proliferation. Female plants harboured significantly more associated microbes than male plants.Conclusions. Our results support the role of light in influencing sex ratios in this species, suggest that trade-offs between reproduction and vegetative growth may not be strong for males, and indicate a potential role of a sex-specific microbiome in influencing sex ratios.

Temporal and spatial changes in population structure of the freshwater macroalga Nitellopsis obtusa (Desv.) J.Groves

Nitellopsis obtusa usually inhabits deep lakes, where the plants display vegetative growth and survive through the winter. In the present study we investigated a shallow lake where Nitellopsis reproduces sexually; we were interested in the effect of light conditions, temperature and water level on sexual reproduction of the species and its ability to survive lakebed drying. We estimated the distribution of all macrophyte species each July from 2009 to 2014 and correlated annual variations with fluctuations in hydrological conditions. We also sampled a variety of morphological characteristics of N. obtusa plants in nine periods throughout the 2009 and 2010 growth seasons and related them to water depth, day length and accumulated heat energy (growing degree-day) at the date of sampling. N. obtusa population was negatively impacted by decrease of water level, probably through the combined effects of competition with fast-growing pioneer species and lack of intrinsic ecological requirements. The fertility of N. obtusa could be interpreted as a response to disturbance in external conditions, leading to the production of long-lived and drought-resistant oospores. Development of male shoots prior to female shoots and their persistence throughout the season probably optimize the fertilization process. Sexual reproduction seems to be controlled by light and temperature conditions. An alternative hypothesis suggests that fertile and sterile populations belong to two distinct ecotypes.

Population structure and genetic diversity in the nannandrous moss Homalothecium lutescens: does the dwarf male system facilitate gene flow?

BackgroundNannandry is a sexual system where males (”dwarf males”) are much smaller than the conspecific females. Dwarf males occur in a wide range of unrelated organisms but the evolutionary advantages of this condition are poorly understood. The dwarf male sexual system results in differences in the mode of dispersal and establishment as well as the life span between males and females. Such differences must have profound effects on the population dynamics and genetic structures. We have studied four populations of the nannandrous moss Homalothecium lutescens in southern Sweden. We genotyped dwarf males and female shoots with the aim of describing the genetic diversity and structure of the populations.ResultsDwarf males were most related to their host shoot, then their colony (within 0.5 m2) and then the rest of the population, which suggests restricted spore dispersal. However, a few dwarf males in each population appeared to originate from other colonies and sometimes even other populations. Genetic diversity of dwarf males was generally high but showed no tendency to be consistently higher or lower than female genetic diversity within the four populations.ConclusionsAlthough most dwarf males have local origin, sporadic dispersal events occur. The ability of the dwarf males to establish in high numbers in mature colonies facilitates gene flow between populations as well as increases the potential to accumulate genetic diversity within populations.

No evidence of sexual niche partitioning in a dioecious moss with rare sexual reproduction.

Roughly half of the species of bryophytes have separate sexes (dioecious) and half are hermaphroditic (monoecious). This variation has major consequences for the ecology and evolution of the different species. In some sexually reproducing dioecious bryophytes, sex ratio has been shown to vary with environmental conditions. This study focuses on the dioecious wetland moss Drepanocladus trifarius, which rarely produces sexual branches or sporophytes and lacks apparent secondary sex characteristics, and examines whether genetic sexes exhibit different habitat preferences, i.e. whether sexual niche partitioning occurs. A total of 277 shoots of D. trifarius were randomly sampled at 214 locations and 12 environmental factors were quantified at each site. Sex was assigned to the individual shoots collected in the natural environments, regardless of their reproductive status, using a specifically designed molecular marker associated with female sex. Male and female shoots did not differ in shoot biomass, the sexes were randomly distributed with respect to each other, and environmental conditions at male and female sampling locations did not differ. Collectively, this demonstrates a lack of sexual niche segregation. Adult genetic sex ratio was female-biased, with 2·8 females for every male individual. The results show that although the sexes of D. trifarius did not differ with regard to annual growth, spatial distribution or habitat requirements, the genetic sex ratio was nevertheless significantly female-biased. This supports the notion that factors other than sex-related differences in reproductive costs and sexual dimorphism can also drive the evolution of biased sex ratios in plants.

Balance between inbreeding and outcrossing in a nannandrous species, the moss Homalothecium lutescens.

Epiphytic dwarf males on the females present a possible solution to the problem of short fertilization distances in mosses. However, leptokurtic spore dispersal makes dwarf males likely to be closely related to their host shoot, with an accompanying risk of inbreeding. The capacity of a female to harbour a high number of different dwarf males suggests that there may be mechanisms in place that counteract inbreeding, such as polyandry and post-fertilization selection. We have genotyped sporophytes, female host shoots and dwarf males in four populations of the moss Homalothecium lutescens. We found no evidence of selective sporophyte abortion based on level of heterozygosity. The occurrence of entirely homozygous sporophytes together with significantly positive inbreeding coefficients in three of the populations (mean FIS between 0.48 and 0.64) suggest frequent mother-son mating events. However, 23% of all sampled sporophytes had a higher level of heterozygosity compared with the mean expected heterozygosity at the population level. Polyandry was frequent, on average 59% of the sporophytes on a female shoot were sired by distinct fathers. In conclusion, sporadic fertilizations by dwarf males originating from nonhost female shoots appear to counteract strong inbreeding.

Sexual dimorphism in floral longevity and flowering synchrony in relation to pollination and mating success in three dioecious Ilex species.

• Sexual floral dimorphism may have evolved under pollinator-mediated natural selection by which female and male functions are differently influenced. We hypothesized that mating success is differently influenced by display size between sexes, under which sexual dimorphism in flowering schedule has evolved in dioecious species.• We examined sexual dimorphism in the total number of flowers per shoot, maximum daily display size, longevity of individual flowers, and flowering synchrony (maximum proportion of open flowers) in three dioecious Ilex species (I. pedunculosa, I. serrata, and I. crenata) whose female flowers are not smaller than male flowers. We compared pollinator response to natural variation of daily display size between sexes. We also examined the effect of display size on female and male success (fruit set and pollen deposition and removal).• In the three species, male shoots produced significantly more flowers than female shoots did. Although female flowers lasted longer and opened more synchronously than male flowers, maximum daily display size was larger on male shoots than on female shoots. Fruit set was significantly pollen-limited in the field in all species. Pollen deposition and/or fruit set increased with female display size, whereas pollen removal decreased or was approximately constant with male display size in the three species.• We suggest that sexual dimorphism in floral longevity and flowering synchrony might enhance both female and male success in relation to the display size-mating success (pollinator attraction) association irrespective of flower size dimorphism.

Hormonal balance in apical meristems of Scots pine shoots as a very early symptom of flower sex differentiation

The investigations were conducted on the embryonic shoots which were taken at the stage just before the start of the elongation of the last year formed embryonic shoot; it means long time before male and female cone primordia initiation. The results point out to the existence of distinctive balance of auxins to gibberellins in apical meristems oi potentially female and male shoots for about a month before the initiation of new embryonic shoots. These results confirm our previous suggestions that femaleness and maleness in Scots pine is correlated with a high amount of auxins and gibberellins, respectively.

Sexual reproduction in the phyllodioicous bryophyte Homalothecium lutescens (Hedw.) H.Rob. in relation to habitat age, growth conditions and genetic variation

Sporophyte production and female fertility were investigated in seventeen calcareous grassland demes of the moss Homalothecium lutescens (Hedw.) H.Rob. on the Baltic island of Öland, with the aim of understanding the relationships between sexual reproduction, habitat age, genetic variation and factors related to growth conditions. The overall proportion of fertile female shoots (with perichaetia) was 35%. Fertility status at the level of individual shoots was positively associated with shoot length and density, while within deme fertility was positively associated with bush cover. There was no association between female fertility and habitat age, genetic diversity (HS) or allelic richness. Out of 1344 investigated shoots, only two were normal-sized fertile males. Dwarf males were also extremely rare, and found almost exclusively on shoots with sporophytes. Few sporophytes were observed (in the two demes with highest fertility and bush cover). No relationship between genetic variation and the frequency of sporophytes and males was found. The lack of a relationship between sexual reproduction and genetic variation suggests that sexual reproduction may not occur in the same grassland fragments as the recruitment of new clones (from spores or vegetative fragments). The majority of the dry, open grassland habitats, where H. lutescens is typically found in the study area, appear to be suboptimal for both dwarf males and fertilization. Sexual reproduction is more likely to occur in shaded (although grazed) grassland patches, where moisture levels are likely to be higher and the moss colonies are generally more vigorous.

Sex ratio, sex-specific pattern in vegetative growth and gemma production in an aquatic liverwort,Scapania undulata(Marchantiophyta: Scapaniaceae)

Scapania undulata is an aquatic dioicous liverwort growing in shallow streams in boreal to subtropical zones. We studied the expressed sex ratio, sex-specific differences in shoot architecture and possible trade-off between sexual and asexual reproduction in ten populations of S. undulata by surveying 100 plots in ten streams in southern Finland. The expressed sex ratio was male biased, in contrast with the sex ratio in most dioicous bryophytes. It was also highly variable between the streams, but individual plots frequently comprised shoots from only one sex. The overproduction of males might be a strategy to overcome sperm dilution and ensure fertilization over longer distances in water. No size differences between females and males were detected, but they differed in branching patterns. Evidence for a higher cost of sexual reproduction in females than males can be seen from the following: the male-biased sex ratio; low number of sex-expressing female shoots in female-only plots; no co-occurrence of gemmae and female sex organs on a single branch, and no more than one sexual branch per female shoot. In contrast, high gemma production of male and female sex-expressing shoots indicates a minimal trade-off between sexual and asexual reproduction.

An experimental demonstration of rhizautoicy, self-incompatibility, and reproductive investment inAloina bifrons(Pottiaceae)

Abstract Shoots of Aloina bifrons were regenerated from four herbarium specimens collected from theAmerican southwest, ranging in age from 4 to 12 years old, subcultured to remove field effects, and grown in Petri dishes on native sand for 238 days (70–90 days after gametangial maturation). Rhizautoicy was demonstrated in three of the four genotypes. Plants were protandrous in gametangial development and in time to maturation, although overlap occurred where both sexes were producing mature gametes. Roughly twice as many perigonia were produced than perichaetia. Female shoots were larger than male shoots, yet devoted much less than male shoots to prefertilization reproductive investment. Adjusted to culture area, investment into reproduction on a prefertilization basis was about ten times greater for male function than for female function. Self-fertilization within a single clonal line was accomplished, but sporophytes did not develop beyond the embryonic phenophase. The clonal lines used appear to be sel...

Reciprocal grafting separates the roles of the root and shoot in sex‐related drought responses in Populus cathayana males and females

Drought stress responses and sensitivity of dioecious plants, such as Populus cathayana Rehd., are determined by different mechanisms in each sex. In general, males tend to be more resistant while females are more sensitive. Here, we used reciprocal grafting between males and females to determine the relative importance of roots and shoots when plants are exposed to drought stress. Total dry matter accumulation (DMA), photosynthetic capacity, long-term water-use efficiency (Δ), water potential and ultrastructure of mesophyll cells were evaluated to determine the different roles of root and shoot in sex-related drought responses. Plants with male roots were found to be more resistant and less sensitive to water stress than those with female roots under drought conditions. On the contrary, plants with female shoots grew better than those with male shoots under well-watered conditions. These results indicated that the sensitivity of males and females to water stress is primarily influenced by root processes, while under well-watered conditions sexual differences in growth are primarily driven by shoot processes. Furthermore, grafting female shoot scion onto male rootstock was proved to be an effective mean to improve resistance to water stress in P. cathayana females.