Forest polyploid breeding group analyzes genetic regulatory network of poplar leaf development

As an important source organ, leaves are the main site of photosynthesis in plants, and analyzing the leaf development process can help improve the photosynthetic assimilation ability of plants.

Plants of the genus Populus (Populus spp.) are widely used worldwide in environmental, agroforestry and industrial fields. Poplar is not only a modern urban horticultural greening species, but also a model species for physiological and ecological research.

Currently, no studies have been reported on the developmental stages of poplar leaves. Using high-throughput sequencing technology, regular changes in gene and miRNA expression during poplar leaf development, construction of a dynamic transcriptomic regulatory network of poplar leaf life cycle, influencing leaf growth and development Analysis of the core regulatory factors will elucidate the rules of gene expression during leaf development and will serve as an effective reference for subsequent molecular design and breeding.

of article “Spatiotemporal miRNA and transcriptome networks dynamically regulate poplar leaf development and aging processes” horticultural research.

Researchers discovered that the growth process of poplar leaves is divided into five periods.

During the period of cell origin and functional differentiation of the larval leaf (leaf position 1), the expression of genes related to cell growth and leaf division is higher. During the development of young leaves, the expression of genes associated with the initial formation of photosynthetic capacity (leaf positions 3-7), cell growth and division is reduced. During the period of the strongest photosynthetic capacity of the voluptuous leaves (leaf positions 9-13), photosynthesis and chlorophyll are reduced.

During the period of the strongest photosynthetic capacity of sensual leaves (leaf positions 9-13), photosynthesis and chlorophyll decreased), the expression of photosynthesis and chlorophyll metabolic pathway genes gradually increased. During the period of reduced photosynthetic capacity of sensual leaves (leaf positions 15-27), the expression of photosynthesis-related genes decreased, the expression of senescence factors gradually increased, and the photosynthetic rate gradually decreased.

During the leaf period of senescence (leaf position 29), expression of senescence factors and protein ubiquitylation-related pathway genes was highest, and at this time the photosynthetic rate declined to its lowest level.

The expression of senescence factors and protein ubiquitination-related pathway genes was relatively highest during the senescent leaf period (29th leaf position), at which time the photosynthetic rate also declined to its lowest level.

Therefore, miRNAs and transcription factors involved in the regulation of leaf growth and development in different periods showed period-specific expression patterns. Among them, GRF9, GRF12, KNAT7, and TCP4 play a role in promoting leaf growth and morphogenesis, and the expression of related transcription factors and their regulated functional genes are associated with leaf development, miR396, miR159 and It gradually decreased when adjusted by other factors.

Leaf development is regulated by miR399, miR156 and other factors, so Myb5, Spl4, LRL3, and WRKY23 are involved in regulating leaf cell senescence, chlorophyll degradation and other biological processes, but related The expression of transcription factors and their regulated functions are involved gradually by genes. MYB5, SPL increased as the core of the regulatory network.

The critical position of MYB5 in regulating pigment synthesis was established by constructing a gene expression regulatory network and verified by the phenotype of a MyB5 overexpression line.

The results deepen our understanding of the growth and development process of poplar leaves and their regulatory mechanisms, and provide new directions for molecular design breeding to delay leaf senescence, increase the leaf’s maximum photosynthetic rate, and maximize photosynthesis. Helps increase duration.