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Abstract With over 25,000 species, orchids are among families with remarkable high rate of diversification. Since Darwin's time, major advances attributed the exceptional diversity of orchids to plant–pollinator interactions. However, unraveling the processes and factors that determine the phenotypic and genotypic variation of natural orchid populations remains a challenge. Here, we assessed genetic population structure and floral differentiation in recently diverged leafless Vanilla species in a world biodiversity hotspot, Madagascar, using seven microsatellite loci and 26 morphometric variables. Additionally, analyses were performed to test for the occurrence of any patterns of isolation by distance, isolation by environment, and isolation by adaptation and to detect possible physical barriers that might have caused genetic discontinuities between populations. Positive inbreeding coefficients detected in 22 populations were probably due to the presence of null alleles, geitonogamy and/or some admixture (sympatric species). In contrast, the only high‐altitude population showed an important rate of clonality leading to heterozygote excess. Genetic diversity was maximum in western populations, suggesting a postglacial colonization to the north and south. Clustering analyses identified seven genetic groups characterized by specific floral traits that matched five botanical descriptions in the literature. A contribution of montane refugia and river barriers on population differentiation was detected. We also detected combined effects of IBD/IBE and IBE/IBA on genetic differentiation and suggested this pattern is more likely determined by ecological isolation, although pollinator‐mediated divergent selection could not be ruled out for some of the species. Overall, this study provides further insights on speciation in orchids, a group for which Madagascar shows one of the world's highest level of endemism and confirms the importance of the peculiar biogeography of the island in shaping species differentiation.

With over 25,000 species, orchids are among families with remarkable high rate of diversification. Since Darwin's time, major advances attributed the exceptional diversity of orchids to plant–pollinator interactions. However, unraveling the processes and factors that determine the phenotypic and genotypic variation of natural orchid populations remains a challenge. Here, we assessed genetic population structure and floral differentiation in recently diverged leafless Vanilla species in a world biodiversity hotspot, Madagascar, using seven microsatellite loci and 26 morphometric variables. Additionally, analyses were performed to test for the occurrence of any patterns of isolation by distance, isolation by environment, and isolation by adaptation and to detect possible physical barriers that might have caused genetic discontinuities between populations. Positive inbreeding coefficients detected in 22 populations were probably due to the presence of null alleles, geitonogamy and/or some admixture (sympatric species). In contrast, the only high‐altitude population showed an important rate of clonality leading to heterozygote excess. Genetic diversity was maximum in western populations, suggesting a postglacial colonization to the north and south. Clustering analyses identified seven genetic groups characterized by specific floral traits that matched five botanical descriptions in the literature. A contribution of montane refugia and river barriers on population differentiation was detected. We also detected combined effects of IBD/IBE and IBE/IBA on genetic differentiation and suggested this pattern is more likely determined by ecological isolation, although pollinator‐mediated divergent selection could not be ruled out for some of the species. Overall, this study provides further insights on speciation in orchids, a group for which Madagascar shows one of the world's highest level of endemism and confirms the importance of the peculiar biogeography of the island in shaping species differentiation. [ABSTRACT FROM AUTHOR]

This study investiges the rooting ability and the growth performance of lower and upper shoot positions and type of the cuttings, i.e. soft and hard wood and leafy and non leafy, of Tecoma stans (L.) Kunth. The cuttings were collected from 4-year old plants growing in the Chauras Campus of H.N.B. Garhwal University Srinagar Garhwal, Uttarakhand, India. The rooting ability of cuttings was studied under the treatments of indole-3-butyric acid (IBA) and Indole 3-acidic acid (IAA) under 0.0%, 0.3%, 0.4%, 0.5% concentration in both hormones. The rooting response was significantly (p < 0.05) better in 0.4% IBA compared to other treatments and control (0% IBA and IAA). The ratio of number of roots to rooted cuttings and length of root to rooted cuttings in the different treatments showed significant differences (p < 0.05). The rooted cuttings were further transferred, into the polythene bags and shifted to open nursery conditions. Under such conditions, the rooted cuttings treated with 0.4% and 0.5% IBA demonstrated the highest (90% to 100%) survival capacity in the lower portion soft wood and leafy stem cuttings. Plantable plant and plant height was greater in the 0.4% IBA concentration treatment. The results of the study suggest that rooting of soft wood stem cuttings having lower position and leaves could be an effective mean of regenerating to T. stans. Furthermore, the application of 0.4% IBA concentration treatment is appropriate for rooting of juvenile leafy stem cuttings in a mist chamber.

The pantropical genus Vanilla is a member of the Orchidaceae family, one of the largest and most diverse families of angiosperms in the world. It originated in America and differentiated in America, Africa, and Asia. About 132 species of Vanilla have now been accepted since the discovery of the genus. Within the Vanilla genus, leaflessness has appeared at least three independent times, in Africa, Asia, and America as an adaptation to drought conditions. The South-West Indian Ocean (SWIO) region, a biodiversity hotspot for orchids, is home to seven leafless species. Chloroplast markers failed to differentiate species within this recent SWIO clade. Morphological traits used for description are very similar between species and do not provide reliable identification. Moreover, some of the species have overlapping flowering periods and geographic distribution in Madagascar, increasing the probability of finding some sympatric species and, therefore, hybrids. Leafless Vanilla species from the SWIO islands are thus an excellent model for understanding the evolution of orchids. For their conservation, and to confirm the identity of these leafless species, an integrated approach with classical taxonomy using a large number of samples, intense fieldwork on biology and ecology, and molecular studies using variable markers is necessary.

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Background and Aims The endangered leafless ghost orchid, Dendrophylax lindenii, one of the most renowned orchids in the world, is difficult to grow under artificial conditions. Published information on asymbiotic and symbiotic (co-culture with a mycobiont) seed germination, seedling anatomy and developmental morphology of this leafless orchid is completely lacking. This information is critical for the development of efficient procedures for ghost orchid production for successful reintroduction.Methods Ghost orchid seedling early development stages were morphologically and anatomically defined to compare germination, embryo and protocorm maturation and seedling development during asymbiotic and symbiotic culture with one of two mycorrhizal strains (Dlin-379 and Dlin-394) isolated from ghost orchid roots in situ.Key Results Seeds symbiotically germinated at higher rates when cultured with fungal strain Dlin-394 than with strain Dlin-379 or asymbiotically on P723 medium during a 10-week culture period. Fungal pelotons were observed in protocorm cells co-cultured with strain Dlin-394 but not Dlin-379. Some 2-year-old seedlings produced multinode inflorescences in vitro. Production of keikis from inflorescence nodes indicated the capacity for clonal production in the ghost orchid.Conclusions Ghost orchid embryo and seedling development were characterized into seven stages. Fungal strain Dlin-394 was confirmed as a possible ghost orchid germination mycobiont, which significantly promoted seed germination and seedling development. Internal transcribed spacer sequencing data confirmed that Dlin-394 belongs within the genus Ceratobasidium. These results offer the opportunity to examine the benefits of using a mycobiont to enhance in vitro germination and possibly ex vitro acclimatization and sustainability following outplanting. [ABSTRACT FROM AUTHOR]

Hair-like structures are shared by most living organisms. The hairs on plant surfaces, commonly referred to as trichomes, form diverse types to sense and protect against various stresses. However, it is unclear how trichomes differentiate into highly variable forms. Here, we show that a homeodomain leucine zipper (HD-ZIP) transcription factor named Woolly controls the fates of distinct trichomes in tomato via a dosage-dependent mechanism. The autocatalytic reinforcement of Woolly is counteracted by an autoregulatory negative feedback loop, creating a circuit with a high or low Woolly level. This biases the transcriptional activation of separate antagonistic cascades that lead to different trichome types. Our results identify the developmental switch of trichome formation and provide mechanistic insights into the progressive fate specification in plants, as well as a path to enhancing plant stress resistance and the production of beneficial chemicals. [Display omitted] • Woolly governs trichome differentiation in a concentration-dependent mode • Woolly levels result from opposing actions between self-activation and negative feedback • SlWox3b/MX1 and LFS promote the fate of digitate and peltate trichomes, respectively • High Woolly levels preferentially activate SlWox3b/MX1, which can repress LFS expression In plants, hair-like structures known as trichomes， form different types with diverse shapes and functions for protection but the mechanism of trichome differentiation remains unclear. Wu et al. demonstrate that a HD-ZIP transcription factor can establish the cell fate landscape of tomato trichomes in a dose-dependent manner. [ABSTRACT FROM AUTHOR]

The lentil ( Lens culinaris Medik.) is a self-pollinated seed legume with cleistogamous flowers. A spontaneous open flower semi leaf-less mutant, was observed from segregating generation (F) of a cross IPL 313 × RKL 1001 in which reproductive organs were not enclosed by the keel petals and thus remained exposed. Leaves on this mutant plant was very less and random with 1-3 pairs of leaf lets whereas in normal plant leaves are present at every reproductive node with 5-7 pairs of leaf lets. A very large number of open flowers (>90 %) remained sterile in mutant plant and their progenies, though its pollen fertility was as high as the standard cultivars. The progenies of the mutant open flower plant were segregates in three morphological different plant types as (1) open flower leaf-less plants, (2) open flower semi leaf-less plants and (3) normal plants having cleistogamous (closed) flowers and normal bearing leaves. The open flower leafless plant were low yielder whereas open flower semi leafless progenies have good yield potential and are important source of rare novel mutant alleles for important economic traits like multiple peduncles per reproductive node, more number of flowers/pods per peduncle and long reproductive phase. The open flower trait offers opportunity for exploring hybrid technology in the lentil and mutant alleles can play a crucial role in understanding the genetics of the target trait and for improvement of lentils. [ABSTRACT FROM AUTHOR]

Application of models for estimating rainfall partitioning in deciduous forests may be considered time consuming and laborious given the need for two different parameter sets to describe leafed and leafless periods. This paper reports how rainfall partitioning modelling was done for a downy oak forest plot (Eastern Pyrenees Mountains, NE Spain) using sparse Rutter and Gash interception loss models and their suitability for such studies. Moreover, variability in model sensitivity is evaluated, and an attempt to simplify their application is also presented. The estimation error for interception loss in the leafed period was −26.3% and −4.2% with the Rutter model and the Gash model applied with Penman-Monteith-based evaporation rate, respectively. The estimate for the leafless period was less accurate in both models, suggesting that modelling in the leafless period is more susceptible to error. Nevertheless, with the Gash model, the result was well below the expected measurement error. Models proved to be highly sensitive to change in canopy cover in all periods tested. The Rutter model was especially sensitive to zero plane displacement changes in the leafed period, while the Gash model showed high linear sensitivity to evaporation rate. In addition, a decrease in rainfall rate affects the estimation of interception loss more than an increase in it. Regardless of its high sensitivity to these parameters, the Gash model yielded a good estimate of rainfall partitioning for the total period, when only one set of parameters was used, although event-based error compensation occurred, and some periods were over or underestimated. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background and Aims: The endangered leafless ghost orchid, Dendrophylax lindenii, one of the most renowned orchids in the world, is difficult to grow under artificial conditions. Published information on asymbiotic and symbiotic (co-culture with a mycobiont) seed germination, seedling anatomy and developmental morphology of this leafless orchid is completely lacking. This information is critical for the development of efficient procedures for ghost orchid production for successful reintroduction., Methods: Ghost orchid seedling early development stages were morphologically and anatomically defined to compare germination, embryo and protocorm maturation and seedling development during asymbiotic and symbiotic culture with one of two mycorrhizal strains (Dlin-379 and Dlin-394) isolated from ghost orchid roots in situ KEY RESULTS: Seeds symbiotically germinated at higher rates when cultured with fungal strain Dlin-394 than with strain Dlin-379 or asymbiotically on P723 medium during a 10-week culture period. Fungal pelotons were observed in protocorm cells co-cultured with strain Dlin-394 but not Dlin-379. Some 2-year-old seedlings produced multinode inflorescences in vitro Production of keikis from inflorescence nodes indicated the capacity for clonal production in the ghost orchid., Conclusions: Ghost orchid embryo and seedling development were characterized into seven stages. Fungal strain Dlin-394 was confirmed as a possible ghost orchid germination mycobiont, which significantly promoted seed germination and seedling development. Internal transcribed spacer sequencing data confirmed that Dlin-394 belongs within the genus Ceratobasidium These results offer the opportunity to examine the benefits of using a mycobiont to enhance in vitro germination and possibly ex vitro acclimatization and sustainability following outplanting., (© The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company.)