A Wox3-patterning module organizes planar growth in grass leaves and ligules

Genetic analyses of embryo homology and ontogeny in the model grass Zea mays subsp. mays

The homology of the single cotyledon of grasses and the ontogeny of the scutellum and coleoptile as the initial, highly modified structures of the grass embryo are investigated using leaf developmental genetics and targeted transcript analyses in the model grass Zea mays subsp. mays. Transcripts of leaf developmental genes are identified in both the initiating scutellum and the coleoptile, while mutations disrupting mediolateral leaf development also disrupt scutellum and coleoptile morphology, suggesting that these grass-specific organs are modified leaves. Higher-order mutations in WUSCHEL-LIKE HOMEOBOX3 (WOX3) genes, involved in mediolateral patterning of plant lateral organs, inform a model for the fusion of coleoptilar margins during maize embryo development. Genetic, RNA-targeting, and morphological evidence supports models for cotyledon evolution where the scutellum and coleoptile, respectively, comprise the distal and proximal domains of the highly modified, single grass cotyledon.

Male Germ Cell Specification in Plants

Germ cells (GCs) serve as indispensable carriers in both animals and plants, ensuring genetic continuity across generations. While it is generally acknowledged that the timing of germline segregation differs significantly between animals and plants, ongoing debates persist as new evidence continues to emerge. In this review, we delve into studies focusing on male germ cell specifications in plants, and we summarize the core gene regulatory circuits in germ cell specification, which show remarkable parallels to those governing meristem homeostasis. The similarity in germline establishment between animals and plants is also discussed.

Genetic Analysis and Fine Mapping of QTL for the Erect Leaf in Mutant mths29 Induced through Fast Neutron in Wheat

The erect leaf plays a crucial role in determining plant architecture, with its growth and development regulated by genetic factors. However, there has been a lack of comprehensive studies on the regulatory mechanisms governing wheat lamina joint development, thus failing to meet current breeding demands. In this study, a wheat erect leaf mutant, mths29, induced via fast neutron mutagenesis, was utilized for QTL fine mapping and investigation of lamina joint development. Genetic analysis of segregating populations derived from mths29 and Jimai22 revealed that the erect leaf trait was controlled by a dominant single gene. Using BSR sequencing and map-based cloning techniques, the QTL responsible for the erect leaf trait was mapped to a 1.03 Mb physical region on chromosome 5A. Transcriptome analysis highlighted differential expression of genes associated with cell division and proliferation, as well as several crucial transcription factors and kinases implicated in lamina joint development, particularly in the boundary cells of the preligule zone in mths29. These findings establish a solid foundation for understanding lamina joint development and hold promise for potential improvements in wheat plant architecture.

Coordinated control for the auricle asymmetric development by ZmIDD14 and ZmIDD15 fine-tune the high-density planting adaption in maize

Multiple distinct specialized regions shape the architecture of maize leaves. Among them, the fringe-like and wedge-shaped auricles alter the angle between the leaf and stalk, which is a key trait in crop plant architecture. As planting density increased, a small leaf angle (LA) was typically selected to promote crop light capture efficiency and yield. In the present study, we characterized two paralogous INDETERMINATE DOMAIN (IDD) genes, ZmIDD14 and ZmIDD15, which contain the Cys2-His2 zinc finger domain and function redundantly to regulate auricle development and LA in maize. Loss-of-function mutants showed decreased LA by reducing adaxial sclerenchyma thickness and increasing the colourless cell layers. In addition, the idd14;idd15 double mutant exhibited asymmetrically smaller auricles, which might cause by a failed maintenance of symmetric expression of the key auricle size controlling gene, LIGULELESS(LG1). The transcripts of ZmIDD14 and ZmIDD15 enriched in the ligular region, where LG1 was highly expressed, and both proteins physically interacted with ZmILI1 to promote LG1 transcription. Notably, the idd14;idd15 enhanced the grain yield of hybrids under high planting densities by shaping the plant architecture with a smaller LA. These findings demonstrate the functions of ZmIDD14 and ZmIDD15 in controlling the abaxial/adaxial development of sclerenchyma in the midrib and polar development along the medial-lateral axes of auricles and provide an available tool for high-density and high-yield breeding in maize.

Overview of molecular mechanisms of plant leaf development: a systematic review

Leaf growth initiates in the peripheral region of the meristem at the apex of the stem, eventually forming flat structures. Leaves are pivotal organs in plants, serving as the primary sites for photosynthesis, respiration, and transpiration. Their development is intricately governed by complex regulatory networks. Leaf development encompasses five processes: the leaf primordium initiation, the leaf polarity establishment, leaf size expansion, shaping of leaf, and leaf senescence. The leaf primordia starts from the side of the growth cone at the apex of the stem. Under the precise regulation of a series of genes, the leaf primordia establishes adaxial-abaxial axes, proximal-distal axes and medio-lateral axes polarity, guides the primordia cells to divide and differentiate in a specific direction, and finally develops into leaves of a certain shape and size. Leaf senescence is a kind of programmed cell death that occurs in plants, and as it is the last stage of leaf development. Each of these processes is meticulously coordinated through the intricate interplay among transcriptional regulatory factors, microRNAs, and plant hormones. This review is dedicated to examining the regulatory influences of major regulatory factors and plant hormones on these five developmental aspects of leaves.

Integrating genome-wide association and transcriptome analysis to provide molecular insights into heterophylly and eco-adaptability in woody plants

Heterophylly is regard as an important adaptive mechanism in response to different environments within plants. However, the genetic mechanisms responsible for heterophylly in woody plants are still poorly understood. Herein, the divergence of heterophyllous leaves was investigated at morphogenesis and using microdissection and physiological indexes in paper mulberry, and the genetic basis of heterophylly was further revealed combined with genome-wide association study (GWAS), transcriptome analysis and weighted gene coexpression network analysis (WGCNA). Our results revealed that the flavonoid content and antioxidant activity increased gradually from the entire leaf to the palmatisect leaf, while the hormone content and net photosynthetic rate decreased. Through GWAS and transcriptome analysis, a total of 98 candidate genes and 2338 differentially expressed genes associated with heterophylly were identified. Importantly, we uncovered critical variations in the candidate genes Bp07g0981 (WOX) and Bp07g0920 (HHO), along with significant differences in haplotypes and expression levels among heterophyllous leaves. Our results also suggested that the genes involved in hormone signaling pathways, antioxidant activity, and flavonoid metabolism might be closely related to the heterophylly of paper mulberry, which could account for the physiological data. Indeed, CR-wox mutant lines showed significant changes in leaf phenotypes, and differential expression profile analysis also highlighted the expression of genes related to phytohormones and transcription factors. Together, the genetic variations and candidate genes detected in this study provide novel insights into the genetic mechanism of heterophylly, and would improve the understanding of eco-adaptability in heterophyllous woody plants.

The maize preligule band is subdivided into distinct domains with contrasting cellular properties prior to ligule outgrowth

The maize ligule is an epidermis-derived structure that arises from the preligule band (PLB) at a boundary between the blade and sheath. A hinge-like auricle also develops immediately distal to the ligule and contributes to blade angle. Here, we characterize the stages of PLB and early ligule development in terms of topography, cell area, division orientation, cell wall rigidity and auxin response dynamics. Differential thickening of epidermal cells and localized periclinal divisions contributed to the formation of a ridge within the PLB, which ultimately produces the ligule fringe. Patterns in cell wall rigidity were consistent with the subdivision of the PLB into two regions along a distinct line positioned at the nascent ridge. The proximal region produces the ligule, while the distal region contributes to one epidermal face of the auricles. Although the auxin transporter PIN1 accumulated in the PLB, observed differential auxin transcriptional response did not underlie the partitioning of the PLB. Our data demonstrate that two zones with contrasting cellular properties, the preligule and preauricle, are specified within the ligular region before ligule outgrowth.