Chemodiversity in flowers of Tanacetum vulgare has consequences on a florivorous beetle.

The chemical composition of plant individuals can vary, leading to high intraspecific chemodiversity. Diversity of floral chemistry may impact the responses of flower-feeding insects. Tanacetum vulgare plants vary significantly in their leaf terpenoid composition, forming distinct chemotypes. We investigated the composition of terpenoids and nutrients of flower heads and pollen in plants belonging to three chemotypes - dominated either by ß-thujone (BThu), artemisia ketone (Keto) or a mixture of (Z)-myroxide, santolina triene, and artemisyl acetate (Myrox) - using different analytical platforms. We tested the effects of these differences on preferences, weight gain and performance of adults of the shining flower beetle, Olibrus aeneus. The terpenoid composition and diversity of flower heads and pollen significantly differed among individuals belonging to the above chemotypes, while total concentrations of pollen terpenoids, sugars, amino acids, and lipids did not differ. Beetles preferred BThu over the Myrox chemotype in both olfactory and contact choice assays, while the Keto chemotype was marginally repellent according to olfactory assays. The beetles gained the least weight within 48 h and their initial mortality was highest when feeding exclusively on floral tissues of the Myrox chemotype. Short-term weight gain and long-term performance were highest when feeding on the BThu chemotype. In conclusion, the beetles showed chemotype-specific responses towards different T. vulgare chemotypes, which may be attributed to the terpenoid composition in flower heads and pollen rather than to differences in nutrient profiles. Both richness and overall diversity are important factors when determining chemodiversity of individual plants and their consequences on interacting insects.

A high throughput method for quantifying number and size distribution of Arabidopsis seeds using large particle flow cytometry.

BACKGROUND: Seed size and number are important plant traits from an ecological and horticultural/agronomic perspective. However, in small-seeded species such as Arabidopsis thaliana, research on seed size and number is limited by the absence of suitable high throughput phenotyping methods. RESULTS: We report on the development of a high throughput method for counting seeds and measuring individual seed sizes. The method uses a large-particle flow cytometer to count individual seeds and sort them according to size, allowing an average of 12,000 seeds/hour to be processed. To achieve this high throughput, post harvested seeds are first separated from remaining plant material (dust and chaff) using a rapid sedimentation-based method. Then, classification algorithms are used to refine the separation process in silico. Accurate identification of all seeds in the samples was achieved, with relative errors below 2%. CONCLUSION: The tests performed reveal that there is no single classification algorithm that performs best for all samples, so the recommended strategy is to train and use multiple algorithms and use the median predictions of seed size and number across all algorithms. To facilitate the use of this method, an R package (SeedSorter) that implements the methodology has been developed and made freely available. The method was validated with seed samples from several natural accessions of Arabidopsis thaliana, but our analysis pipeline is applicable to any species with seed sizes smaller than 1.5 mm.

Learning from nature: the use of non-model species to identify novel acclimations to flooding stress.

Excess water in the form of waterlogged soil or deeper submergence (generically termed 'flooding') influences plant growth, survival and species distribution in many natural ecosystems. It also has a negative impact on crop growth and yield since many agricultural species are flooding intolerant. The often devastating effect of flooding on plant performance is related to its interference with gas exchange between the plant and its environment. This results in energy deficiency and carbohydrate starvation. In the near future, flooding frequency is expected to increase due to global climate change and the human population is expected to increase to ∼9 billion people by 2050. The need for increased agricultural productivity is self-evident and this will require a better mechanistic understanding of the interaction between plants and abiotic stresses such as flooding. We argue that, in seeking this understanding, we should not restrict the research to model species such as rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana). This is because some stress-tolerance mechanisms are not found in these species. Examples are given of how flooding tolerance is achieved by non-model species of Rumex and Rorippa that have evolved to cope with flooding in natural environments. These findings will add usefully to the spread of resources available to plant breeding programmes aimed at improving flooding tolerance in crop plants.

Ethylene--and oxygen signalling--drive plant survival during flooding.

Flooding is a widely occurring environmental stress both for natural and cultivated plant species. The primary problems associated with flooding arise due to restricted gas diffusion underwater. This hampers gas exchange needed for the critical processes of photosynthesis and respiration. Plant acclimation to flooding includes the adaptation of a suite of traits that helps alleviate or avoid these stressful conditions and improves or restores exchange of O2 and CO2 . The manifestation of these traits is, however, reliant on the timely perception of signals that convey the underwater status. Flooding-associated reduced gas diffusion imposes a drastic change in the internal gas composition within submerged plant organs. One of the earliest changes is an increase in the levels of the gaseous plant hormone ethylene. Depending on the species, organ, flooding conditions and time of the day, plants will also subsequently experience a reduction in oxygen levels. This review provides a comprehensive overview on the roles of ethylene and oxygen as critical signals of flooding stress. It includes a discussion of the dynamics of these gases in plants when underwater, their interaction, current knowledge of their perception mechanisms and the resulting downstream changes that mediate important acclimative processes that allow endurance and survival under flooded conditions.

Natural variation of submergence tolerance among Arabidopsis thaliana accessions.

• The exploitation of natural variation in Arabidopsis thaliana (Arabidopsis) provides a huge potential for the identification of the molecular mechanisms underlying this variation as a result of the availability of a vast array of genetic and genomic resources for this species. Eighty-six Arabidopsis accessions were screened for natural variation in flooding tolerance. This forms the first step towards the identification and characterization of the role of candidate genes contributing to flooding tolerance. • Arabidopsis accessions at the 10-leaf stage were subjected to complete submergence in the dark. Survival curves were plotted to estimate median lethal times as a measure of tolerance. Flooding-associated survival parameters, such as root and shoot oxygen content, initial carbohydrate content and petiole elongation under water, were also measured. • There was a significant variation in submergence tolerance among Arabidopsis accessions. However, the order of tolerance did not correlate with root and shoot oxygen content or initial amounts of shoot starch and total soluble sugars. A negative correlation was observed between submergence tolerance and underwater petiole elongation. • Arabidopsis accessions show considerable variation in the ability to tolerate complete submergence, making it a good species in which to identify and characterize genes and to study mechanisms that contribute to survival under water.

Pregnancy and breast cancer.

Breast cancer is one of the most commonly diagnosed malignancies during pregnancy. Pregnancy-associated breast cancer (PABC) presents a challenging clinical situation. This article reviews the current evidence around the management of PABC and the safety of pregnancy after breast cancer. The trend towards later age at first childbirth has resulted in an increase in the number of breast cancer cases coexistent with pregnancy. The management of breast cancer during pregnancy requires a multidisciplinary team approach. Breast surgery can be safely performed during any trimester of pregnancy. Radiation therapy, if required, must be delayed until after delivery. The majority of patients with PABC require chemotherapy. The timing of delivery in relation to chemotherapy administration should be carefully considered. There is no evidence to date that pregnancy termination influences overall survival for the mother. To date, there is no clear evidence that subsequent pregnancy after breast cancer is associated with worse maternal survival. There is a suggestion that subsequent pregnancy may in fact be associated with an improved survival. However, the available studies are limited by potential biases.