Current opinion in plant biology最新文献

Inflorescence architecture is highly variable across plant lineages yet is critical for facilitating reproductive success. The capitulum-type inflorescence of the Asteraceae is marked as a key morphological innovation that preceded the family's diversification and expansion. Despite its evolutionary significance, our understanding of capitulum development and evolution is limited. This review highlights our current perspective on capitulum evolution through the lens of both its molecular and developmental underpinnings. We attempt to summarize our understanding of the capitulum by focusing on two key characteristics: patterning (arrangement of florets on a capitulum) and floret identity specification. Note that these two features are interconnected such that the identity of florets depends on their position along the inflorescence axis. Phytohormones such as auxin seemingly determine both pattern progression and floret identity specification through unknown mechanisms. Floret morphology in a head is controlled by differential expression of floral symmetry genes regulating floret identity specification. We briefly summarize the applicability of the ABCE quartet model of flower development in regulating the floret organ identity of a capitulum in Asteraceae. Overall, there have been promising advancements in our understanding of capitula; however, comprehensive functional genetic analyses are necessary to fully dissect the molecular pathways and mechanisms involved in capitulum development.

Endosperm is a major evolutionary innovation of flowering plants, and its proper development critically impacts seed growth and viability. Epigenetic regulators have a key function in parental control of endosperm development. Notably, epigenetic regulation of parental genome dosage is a major determinant of seed development success, and disruption of this balance can produce inviable seed, as observed in some interploidy and interspecific crosses. These postzygotic reproduction barriers are also a potent driver of speciation. The molecular machinery and regulatory architecture governing endosperm development is proposed to have evolved under parental conflict. In this review, we emphasize parental conflict as a dialectic conflict and discuss recent findings about the epigenetic molecular machinery that mediates parental conflict in the endosperm.

The stem is one of the major organs in seed plants and is important for plant survival as well as in agriculture. However, due to the lack of clear external landmarks in many species, its developmental and evolutionary processes are understudied compared to other organs. Recent approaches tackling these problems, especially those focused on KNOX1 and BLH transcription factors belonging to the TALE homeodomain superfamily have started unveiling the patterning process of nodes and internodes by connecting previously accumulated knowledge on lateral organ regulators. Fossil records played crucial roles in understanding the evolutionary process of the stem. The aim of this review is to introduce how the stem evolved from ancestorial sporophyte axes and to provide frameworks for future efforts in understanding the developmental process of this elusive but pivotal organ.

Studying morphological novelties offers special insights into developmental biology and evolution. The inflated calyx syndrome (ICS) is a largely unrecognized but fascinating feature of flower development, where sepals form balloon-like husks that encapsulate fruits. Despite its independent emergence in many lineages of flowering plants, the genetic and molecular mechanisms of ICS remain unknown. Early studies in the Solanaceae genus Physalis put forth key roles of MADS-box genes in ICS. However, recent work suggests these classical floral identity transcription factors were false leads. With newfound capabilities that allow rapid development of genetic systems through genomics and genome editing, Physalis has re-emerged as the most tractable model species for dissecting ICS. This review revisits current understanding of ICS and highlights how recent advancements enable a reset in the search for genetic and molecular mechanisms using unbiased, systematic approaches.

Flowering plants exhibit unique DNA methylation dynamics during development. Particular attention can be focused on seed development and the embryo, which represents the starting point of the sporophytic life cycle. A build-up of CHH methylation is now recognized as highly characteristic of embryo development. This process is thought to occur in order to silence potentially harmful transposable element expression, though roles in promoting seed dormancy and dessication tolerance have also been revealed. Recent studies show that increased CHH methylation in embryos inhabits both novel loci, unmethylated elsewhere in the plant, as well as shared loci, exhibiting more dense methylation. The role of DNA methylation in cis-regulatory gene regulation in plants is less well established compared to mammals, and here we discuss both transposable element regulation and the potential role of DNA methylation in dynamic gene expression.

Plant hormones activate receptors, initiating intracellular signaling pathways. Eventually, hormone-specific transcription factors become active in the nucleus, facilitating hormone-induced transcriptional regulation. Chromatin plays a fundamental role in the regulation of transcription, the process by which genetic information encoded in DNA is converted into RNA. The structure of chromatin, a complex of DNA and proteins, directly influences the accessibility of genes to the transcriptional machinery. The different signaling pathways and transcription factors involved in the transmission of information from the receptors to the nucleus have been readily explored, but not so much for the specific mechanisms employed by the cell to ultimately instruct the chromatin changes necessary for a fast and robust transcription activation, specifically for plant hormone responses. In this review, we will focus on the advancements in understanding how chromatin receives plant hormones, facilitating the changes necessary for fast, robust, and specific transcriptional regulation.

Reiterative shoot branching largely defines important yield components of crops and is essentially controlled by programs that direct the initiation, dormancy release, and differentiation of meristems in the axils of leaves. Here, we focus on meristem determinacy, defining the number of reiterations that shape the shoot architectures and exhibit enormous diversity in a wide range of species. The meristem determinacy per se is hierarchically complex and context-dependent for the successively emerged meristems, representing a crucial mechanism in shaping the complexity of the shoot branching. In addition, we have highlighted that two key components of axillary meristem developmental programs may have been co-opted in controlling flower/ear number of an axillary inflorescence in legumes/maize, hinting at the diversification of axillary-meristem-patterning programs in different lineages. This begs the question how axillary meristem patterning programs may have diversified during plant evolution and hence helped shape the rich variation in shoot branching systems.

Although plant metabolic engineering enables the sustainable production of valuable metabolites with many applications, we still lack a good understanding of many multi-layered regulatory networks that govern metabolic pathways at the metabolite, protein, transcriptional and cellular level. As transcriptional regulation is better understood and often reviewed, here we highlight recent advances in the cell type-specific and post-translational regulation of plant specialized metabolism. With the advent of single-cell technologies, we are now able to characterize metabolites and their transcriptional regulators at the cellular level, which can refine our searches for missing biosynthetic enzymes and cell type-specific regulators. Post-translational regulation through enzyme inhibition, protein phosphorylation and ubiquitination are clearly evident in specialized metabolism regulation, but not frequently studied or considered in metabolic engineering efforts. Finally, we contemplate how advances in cell type-specific and post-translational regulation can be applied in metabolic engineering efforts in planta, leading to optimization of plants as metabolite production vehicles.

Floral spurs, widely recognized as a classic example of key morphological and functional innovation and thought to have promoted the origin and adaptive evolution of many flowering plant lineages, have attracted the attention of researchers for centuries. Despite this, the mechanisms underlying the development and evolution of these structures remain poorly understood. Recent studies have discovered the phytohormones and transcription factor genes that play key roles in regulating patterns of cell division and cell expansion during spur morphogenesis. Spur morphogenesis was also found to be tightly linked with the programs specifying floral zygomorphy, floral organ identity determination, and nectary development. Independent origins and losses of spurs in different flowering plant lineages, therefore, may be attributed to changes in the spur program and/or its upstream ones.

VAMP721 and VAMP722, play crucial roles in membrane fusion at post-Golgi compartments. They are involved in cell plate formation, recycling, endocytosis, and secretion. While individual SNARE actors and regulators exhibit significant overlap, specificity is achieved through distinct combinations of these components. Cytokinesis-related SNAREs traffic as preformed CIS-complexes, which require disassembly by the NSF/αSNAP chaperoning complex to facilitate subsequent homotypic fusion at the cell plate. Recent findings suggest a similar mechanism may operate during secretion. Regulation of VAMP721 activity involves interactions with tethers, GTPases, and Sec1/Munc18 proteins, along with a newly discovered phosphorylation at Tyrosine residue 57. These advances provide valuable insights into the fascinating world of cellular trafficking and membrane fusion.