Epigenetic Modifications in Plant Development and Reproduction

Plants are exposed to highly fluctuating effects of light, temperature, weather conditions, and many other environmental factors throughout their life. As sessile organisms, unlike animals, they are unable to escape, hide, or even change their position. Therefore, the growth and development of plants are largely determined by interaction with the external environment. The success of this interaction depends on the ability of the phenotype plasticity, which is largely determined by epigenetic regulation. In addition to how environmental factors can change the patterns of genes expression, epigenetic regulation determines how genetic expression changes during the differentiation of one cell type into another and how patterns of gene expression are passed from one cell to its descendants. Thus, one genome can generate many ‘epigenomes’. Epigenetic modifications acquire special significance during the formation of gametes and plant reproduction when epigenetic marks are eliminated during meiosis and early embryogenesis and later reappear. However, during asexual plant reproduction, when meiosis is absent or suspended, epigenetic modifications that have arisen in the parental sporophyte can be transmitted to the next clonal generation practically unchanged. In plants that reproduce sexually and asexually, epigenetic variability has different adaptive significance. In asexuals, epigenetic regulation is of particular importance for imparting plasticity to the phenotype when, apart from mutations, the genotype remains unchanged for many generations of individuals. Of particular interest is the question of the possibility of transferring acquired epigenetic memory to future generations and its potential role for natural selection and evolution. All these issues will be discussed to some extent in this review.

BeeDNA: microfluidic environmental DNA metabarcoding as a tool for connecting plant and pollinator communities

Pollinators are imperiled by global declines that can impair plant reproduction, erode essential ecosystem services and resilience, and drive economic losses. Monitoring pollinator biodiversity trends is key for adaptive conservation and management, but conventional surveys are often costly, time consuming, and require taxonomic expertise. Environmental DNA (eDNA) metabarcoding surveys are booming due to their rapidity, non-invasiveness, and cost efficiency. Microfluidic technology allows multiple primer sets from different markers to be used in eDNA metabarcoding for more comprehensive species inventories whilst minimizing biases associated with individual primer sets. We evaluated microfluidic eDNA metabarcoding for pollinator community monitoring by introducing a bumblebee colony to a greenhouse flower assemblage and sampling natural flower plots. We collected nectar draws, flower swabs, or whole flower heads from four flowering species, including two occurring in both the greenhouse and field. Samples were processed using two eDNA isolation protocols before amplification with 15 primer sets for two markers (COI and 16S). Microfluidic eDNA metabarcoding detected the target bumblebee and greenhouse insects as well as common regional arthropods. Pollinator detection was maximized using whole flower heads preserved in ATL buffer and extracted with a modified Qiagen DNeasy protocol for amplification with COI primers. eDNA surveillance could enhance pollinator assessment by detecting protected and endangered species and being more applicable to remote, inaccessible locations, whilst reducing survey time, effort, and expense. Microfluidic eDNA metabarcoding requires optimization but shows promise in revealing complex networks underpinning critical ecosystem functions and services, enabling more accurate assessments of ecosystem resilience.

Sexual and Apogamous Species of Woodferns Show Different Protein and Phytohormone Profiles

The gametophyte of ferns reproduces either by sexual or asexual means. In the latter, apogamy represents a peculiar case of apomixis, in which an embryo is formed from somatic cells. A proteomic and physiological approach was applied to the apogamous fern Dryopteris affinis ssp. affinis and its sexual relative D. oreades. The proteomic analysis compared apogamous vs. female gametophytes, whereas the phytohormone study included, in addition to females, three apogamous stages (filamentous, spatulate, and cordate). The proteomic profiles revealed a total of 879 proteins and, after annotation, different regulation was found in 206 proteins of D. affinis and 166 of its sexual counterpart. The proteins upregulated in D. affinis are mostly associated to protein metabolism (including folding, transport, and proteolysis), ribosome biogenesis, gene expression and translation, while in the sexual counterpart, they account largely for starch and sucrose metabolism, generation of energy and photosynthesis. Likewise, ultra-performance liquid chromatography-tandem spectrometry (UHPLC-MS/MS) was used to assess the levels of indol-3-acetic acid (IAA); the cytokinins: 6-benzylaminopurine (BA), trans-Zeatine (Z), trans-Zeatin riboside (ZR), dyhidrozeatine (DHZ), dyhidrozeatin riboside (DHZR), isopentenyl adenine (iP), isopentenyl adenosine (iPR), abscisic acid (ABA), the gibberellins GA3 and GA4, salicylic acid (SA), and the brassinosteroids: brassinolide (BL) and castasterone (CS). IAA, the cytokinins Z, ZR, iPR, the gibberellin GA4, the brassinosteoids castasterone, and ABA accumulated more in the sexual gametophyte than in the apogamous one. When comparing the three apogamous stages, BA and SA peaked in filamentous, GA3 and BL in spatulate and DHRZ in cordate gametophytes. The results point to the existence of large metabolic differences between apogamous and sexual gametophytes, and invite to consider the fern gametophyte as a good experimental system to deepen our understanding of plant reproduction.

Transitions in development – an interview with Marie Monniaux

Marie Monniaux is a permanent CNRS researcher in the ‘Evo-devo of the flower’ group at the Laboratory for Plant Reproduction and Development (RDP) at the École normale supérieure (ENS) in Lyon, France. Marie uses Petunia to understand the development and evolution of the flower petal. We met Marie over Teams for a virtual chat about her career path, finding a permanent position and her ideas for the future.

Open-top warming chambers reduce animal pollination of two subalpine herbs

Open top chambers (OTCs) are a popular method for studying the biological effects of climate change through passive heating, but their effects on biotic interactions are poorly understood, especially for pollination. Here we use the subalpine plants Delphinium nuttallianum and Potentilla pulcherrima to examine the possibility that the effects of OTCs on plant reproduction are not the result of warming but rather OTCs acting as barriers to pollinator movement. Pollinator observations were conducted and stigmas collected from plants inside and outside of OTCs in a meadow in the Rocky Mountains of Colorado, USA. Very few visitors were observed inside of OTCs, which led to severe reductions in visitation rates, by 92% in Delphinium and 85% in Potentilla. The number of conspecific pollen grains on stigmas was 73% lower in OTCs for Delphinium but not Potentilla, likely because it is capable of autogamous self-pollination. This study clearly shows that OTCs can reduce animal pollination, which is also likely to reduce plant reproductive output of outcrossing plants via decreases in the quantity or quality of pollen. OTCs may therefore confound effects of warming on plant reproduction with pollination effects. Although the unintended effects of OTCs on abiotic conditions are well-studied, this study highlights that their effects on biotic interactions require further investigation.

Epigenetic Modifications in Plant Development and Reproduction

Plants are exposed to highly fluctuating effects of light, temperature, weather conditions and many other environmental factors throughout their life. As sessile or-ganisms, unlike animals, they are unable to escape, hide or even change their position. Therefore, the growth and development of plants is largely determined by interaction with the external environment, the success of this interaction depends on the ability of the phenotype plasticity, which is largely determined by epigenetic regulation. In addi-tion to how environmental factors can change the patterns of genes expression, epige-netic regulation determines how genetic expression changes during the differentiation of one cell type into another, and how patterns of gene expression are passed from one cell to its descendants. Thus, one genome can generate many 'epigenomes'. Epigenetic modifications acquire special significance during the formation of gametes and plant reproduction, when epigenetic marks are eliminated during meiosis and early embry-ogenesis and later reappear. However, during asexual plant reproduction, when meio-sis is absent or suspended, epigenetic modifications that have arisen in the parental sporophyte can be transmitted to the next clonal generation practically unchanged. In plants that reproduce sexually and asexually, epigenetic variability has different adap-tive significance. In asexuals, epigenetic regulation is of particular importance for im-parting plasticity to the phenotype, when the genotype remains unchanged for many generations of individuals. Of particular interest is the question of the possibility of transferring acquired epigenetic memory to future generations and its potential role for natural selection and evolution. All these issues will be discussed to some extent in this review. In the last two decades, a lot of data on the epigenetic regulation of plants has appeared, as well as works summarizing the accumulated knowledge (Verhoeven and Preite 2013; Pikaard and Scheid 2014; Gehring 2019; Ono and Kinoshita 2021), nevertheless, many questions remain unclear, and a number of results are contradic-tory. New in this area data is constantly emerging. We tried to take into account and discuss the main findings and conclusions in this field.