The decline in interest in plants in biological education is an established phenomenon. Compared to animals, plants are under-represented in biology textbooks and other media. Biology teachers often avoid using plant examples in class due to their own lack of knowledge or interest, perpetuating the cycle. With botanical topics often relegated to single modules or lecture sets and limited opportunities for fieldwork, learning of species identification has inevitably suffered.
Species identification is a fundamental requirement for learning and understanding biodiversity, but it also plays a role in fostering concern for its preservation. Plant identification draws people’s attention to the wide variation in plant form, texture, colour, etc., increasing their interest in plants and their appreciation of biodiversity. Given the rapid rate of decline of plant species and consequences for wider ecosystems, there may be a greater need than ever to find ways to promote identification skills not only in the classroom but among the general public.
Most beginners are introduced to plant diversity through identification keys, which develop differentiation skills but not species memorisation. A paper in the Journal of Biological Education proposes that mnemonics, memorable ‘name clues’ linking a species name with morphological characters, are a complementary learning tool for promoting species memorisation.
In the first of two experiments, 64 adults in a group-learning environment were taught species identification using mnemonics, an educational card game and a text-based dichotomous key. In the second experiment, 43 adults in a self-directed learning environment were taught species identification using mnemonics and a pictorial dichotomous key. In both experiments, mnemonics produced the highest retention rates of species identification based on vegetative characters. The educational value of these findings is discussed for vegetative plant identification and broader applications. Participants in this study also enjoyed mnemonics more than a keying-out activity, suggesting that they could help to stimulate interest in botany.
Bethan C. Stagg and Maria E. Donkina. Mnemonics are an Effective Tool for Adult Beginners Learning Plant Identification. Journal of Biological Education 27 Feb 2015 doi: 10.1080/00219266.2014.1000360
In conifers, mature somatic embryos and zygotic embryos appear to resemble one another physiologically and morphologically. However, phenotypes of cloned conifer embryos can be strongly influenced by a number of in vitro factors and in some instances clonal variation can exceed that found in nature. A recent study in Annals of Botany examines whether zygotic embryos that develop within light-opaque cones differ from somatic embryos developing in dark/light conditions in vitro. Embryogenesis in larch is well understood both in situ and in vitro and thus provides a suitable system for addressing this question.
In larch embryos, light has a negative effect on protein accumulation, but a positive effect on phenol accumulation. Light did not affect morphogenesis, e.g. cotyledon number. Somatic embryos produced different amounts of phenolics, such as quercetrin, depending on light conditions. The greatest difference was seen in the embryonal root cap in all embryo types and conditions.
Effect of light conditions on anatomical and biochemical aspects of somatic and zygotic embryos of hybrid larch (Larix × marschlinsii). Annals of Botany January 20 2015 doi: 10.1093/aob/mcu254
Halophytic plants are characterized by enhanced growth under saline conditions. A recent study in Annals of Botany combines physiological and anatomical analyses to identify processes underlying growth responses of the mangrove Avicennia marina to salinities ranging from fresh to seawater conditions.
Following pre-exhaustion of cotyledonary reserves under optimal conditions (50% seawater), seedlings of A. marina were grown hydroponically in dilutions of seawater amended with nutrients. Whole-plant growth characteristics were analysed in relation to dry mass accumulation and its allocation to different plant parts. Gas exchange characteristics and stable carbon isotopic composition of leaves were measured to evaluate water use in relation to carbon gain. Stem and leaf hydraulic anatomy were measured in relation to plant water use and growth.
The results identified stem and leaf transport systems as central to understanding the integrated growth responses to variation in salinity from fresh to seawater conditions. Avicennia marina is revealed as an obligate halophyte, requiring saline conditions for development of the transport systems needed to sustain water use and carbon gain.
Growth responses of the mangrove Avicennia marina to salinity: development and function of shoot hydraulic systems require saline conditions. Annals of Botany January 19 2015 doi: 10.1093/aob/mcu257
Over 100 years after trypanosomatids were first discovered in plant tissues, Phytomonas parasites have now been isolated across the globe from members of 24 different plant families. Most identified species have not been associated with any plant pathology and to date only two species are definitively known to cause plant disease. These diseases (wilt of palm and coffee phloem necrosis) are problematic in areas of South America where they threaten the economies of developing countries. In contrast to their mammalian infective relatives, our knowledge of the biology of Phytomonas parasites and how they interact with their plant hosts is limited. This review draws together a century of research into plant trypanosomatids, from the first isolations and experimental infections to the recent publication of the first Phytomonas genomes. The availability of genomic data for these plant parasites opens a new avenue for comparative investigations into trypanosomatid biology and provides fresh insight into how this important group of parasites have adapted to survive in a spectrum of hosts from crocodiles to coconuts.
Phytomonas: Trypanosomatids Adapted to Plant Environments. (2015) PLoS Pathog 11(1): e1004484. doi: 10.1371/journal.ppat.1004484
The largest subfamily of orchids, Epidendroideae, represents one of the most significant diversifications among flowering plants in terms of pollination strategy, vegetative adaptation and number of species. Although many groups in the subfamily have been resolved, significant relationships in the tree remain unclear, limiting conclusions about diversification and creating uncertainty in the classification. This study brings together DNA sequences from nuclear, plastid and mitochrondrial genomes in order to clarify relationships, to test associations of key characters with diversification and to improve the classification.
All tested characters show significant association with speciation in Epidendroideae, suggesting that no single character accounts for the success of this group. Rather, it appears that a succession of key features appeared that have contributed to diversification, sometimes in parallel.
J.V. Freudenstein and M.W. Chase (2015) Phylogenetic relationships in Epidendroideae (Orchidaceae), one of the great flowering plant radiations. Annals of Botany, January 11, 2015 doi: 10.1093/aob/mcu253
Osmolytes are low-molecular-weight organic solutes, a broad group that encompasses a variety of compounds such as amino acids, tertiary sulphonium and quaternary ammonium compounds, sugars and polyhydric alcohols. Osmolytes are accumulated in the cytoplasm of halophytic species in order to balance the osmotic potential of the Na+ and Cl− accumulated in the vacuole. The advantages of the accumulation of osmolytes are that they keep the main physiological functions of the cell active, the induction of their biosynthesis is controlled by environmental cues, and they can be synthesized at all developmental stages. In addition to their role in osmoregulation, osmolytes have crucial functions in protecting subcellular structures and in scavenging reactive oxygen species.
This review discusses the diversity of osmolytes among halophytes and their distribution within taxonomic groups, the intrinsic and extrinsic factors that influence their accumulation, and their role in osmoregulation and osmoprotection. Increasing the osmolyte content in plants is an interesting strategy to improve the growth and yield of crops upon exposure to salinity. Examples of transgenic plants as well as exogenous applications of some osmolytes are also discussed. Finally, the potential use of osmolytes in protein stabilization and solvation in biotechnology, including the pharmaceutical industry and medicine, are considered.
Slama, I., Abdelly, C., Bouchereau, A., Flowers, T., & Savouré, A. Diversity, distribution and roles of osmoprotective compounds accumulated in halophytes under abiotic stress. (2015) Annals of Botany, January 5, 2015 doi: 10.1093/aob/mcu239
By August 2012, the Annals of Botany had been published without a break for 125 years. In that time it has become not only the world’s oldest continuously published botanical title but one that has retained a high international standing despite the emergence of numerous popular and well-run competitors. A recent article in the journal is the first of two that, together, look back over the Journal’s long history.
The article describes how the Annals of Botany first came into being in 1887 and the evolution of its editorship and management over the 50 years to 1937. These developments are described in terms of the people involved, how they organized the starting of the Journal and how they ran and financed it on a not-for-profit basis. The article pays particular attention to the lives of the nine remarkable and mostly rather grand individuals who founded the Journal and who, for the most part, came from privileged backgrounds. Despite being a youthful group (all but one were under 40), most were already establishment figures by 1887, e.g. Fellows of the Royal Society (FRS) or directors/professors of prestigious establishments, while the others were soon to become so. The article also outlines the academic environment which allowed the founders and their vision of modern botanical science to prosper, and describes a notable clash of personalities that almost brought the Journal down after only 12 years. In addition, accounts are given of the creation of the ‘Annals of Botany Company’, the effects on the Journal of the First World War and its aftermath, and how the Journal’s managers looked to the future by planning a ‘New Series’ starting 50 years after its foundation.
Jackson, M.B. (2015) One hundred and twenty-five years of the Annals of Botany. Part 1: the first 50 years (1887–1936). Annals of Botany, 115(1), 1-18
Tinted plates used to illustrate early issues of the Annals of Botany
The relationship between above- and below-ground plant biomass is of considerable interest to researchers attempting to model global climate change and nutrient cycles as well as those interested in evolutionary organographic relationships across taxonomically and ecologically diverse species. Empirical studies and allometric partitioning theory indicate that plant above-ground biomass scales, on average, one-to-one with below-ground biomass at the level of individual trees and at the level of entire forest communities. However, the ability of the allometric partitioning theory to predict the biomass allocation patterns of understorey plants has not been established because most previous empirical tests have focused on canopy tree species or very large shrubs.
In order to test the allometric partitioning theory further, a new paper in Annals of Botany examines 1,586 understorey sub-tropical forest plants from 30 sites in south-east China. The results support the allometric partitioning theory’s prediction that above-ground biomass scales nearly one-to-one with below-ground biomass and that plant biomass partitioning for individual plants and at the community level share a strikingly similar pattern, at least for the understorey plants examined in this study. Furthermore, variation in environmental conditions appears to affect the numerical values of normalization constants, but not the scaling exponents of the relationship. This feature of the results suggests that plant size is the primary driver of the biomass allocation pattern for understorey plants in sub-tropical forests.
Dongliang Cheng, Quanlin Zhong, Karl J. Niklas, Yuzhu Ma, Yusheng Yang and Jianhua Zhang (2015) Isometric scaling of above- and below-ground biomass at the individual and community levels in the understorey of a sub-tropical forest. Annals of Botany (2015) doi: 10.1093/aob/mcu238
Climate change will disrupt the many interactions between biology and climate, from enzymatic reactions to ecological patterns. Climate thoroughly controls key processes such as plant regeneration, as is exemplified by the thermal regulation of seed germination. Temperature drives local adaptation and phenotypic plasticity in germination traits, as well as the physiological processes of dormancy loss and germination elicitation . In seasonal climates, germination traits interplay with annual temperature cycles to ensure that seed emergence and seedling establishment occur in the most favourable season. Given the significance of germination in the life history of a plant, it is not surprising that its timing is a central scenario for natural selection. However, the complex thermal control of germination timing is highly responsive to climate change. New environmental temperatures may not match the temperatures that alleviate dormancy and elicit germination. This mismatch could alter recruitment from the soil seed bank and shift germination timing , compromising plant regeneration and community composition.
A recent paper in Annals of Botany examines the effect of temperature on seed germination using two populations of the wetland sedge Carex diandra, one from a montane site and one from a subalpine site. A cardinal-temperature model was used to simulate changes in germination under two possible future climate scenarios as defined by the Intergovernmental Panel on Climate Change.
Increasing diurnally alternating temperatures decreased the base temperature for seed germination and the thermal time required for germination. The effect of higher alternating temperatures together with the higher temperatures increased germination under both climate scenarios. Carex diandra germination is highly responsive to potential changes in diurnally alternating temperatures, and thus this study highlights the role of temperature changes in seed responses to climate change. Comprehensive cardinal-temperature models, encompassing the different effects of temperature on seed germination, are needed to understand how climate change will affect plant regeneration.
Eduardo Fernández-Pascual, Charlotte E. Seal and Hugh W. Pritchard. (2015) Simulating the germination response to diurnally alternating temperatures under climate change scenarios: comparative studies on Carex diandra seeds. Annals of Botany 115(1): doi: 10.1093/aob/mcu234
The genus Rosa (with 150–200 species) is widely distributed throughout temperate and sub-tropical habitats from the northern hemisphere to tropical Asia, with only one tropical African species. In order to better understand the evolution of roses, this study examines infrageneric relationships with respect to conventional taxonomy, considers the extent of allopolyploidization and infers macroevolutionary processes that have led to the current distribution of the genus.
The ancestral area reconstruction suggests that despite an early presence on the American continent, most extant American species are the results of a later re-colonization from Asia, probably through the Bering Land Bridge. The results suggest more recent exchanges between Asia and western North America than with eastern North America. The current distribution of roses from the Synstylae lineage in Europe is probably the result of a migration from Asia approx. 30 million years ago, after the closure of the Turgai strait. Directions for a new sectional classification of the genus Rosa are proposed, and the analyses provide an evolutionary framework for future studies on this notoriously difficult genus.
Fougère-Danezan, M., Joly, S., Bruneau, A., Gao, X. F., & Zhang, L. B. (2014) Phylogeny and biogeography of wild roses with specific attention to polyploids. Annals of Botany, December 29, 2014, doi: 10.1093/aob/mcu245