Abstract
To investigate the molecular mechanism of the mutation of a multiple-branches birch mutant (br), we explored genes that were genome-wide differentially expressed in the main and lateral branches’ apical buds of br. The plant architecture not only has effects on the process of plant growth and development, but also affects the agronomic characters. In woody plants, branches determine the application value of timber. Therefore, analyzing genes that were differentially expressed in br apical buds will bring new insights to understand the molecular basis of plant architecture alteration. Wild type (WT) birch, Cinnamoyl-CoA reductase 1 (CCR1)-overexpressed transgenic birch (OE2) and the mutant br were used as materials to observe phenotype differences between br and the control lines (WT and OE2). The transcriptome sequencing of the main and lateral branches’ apical buds of br and controls were further performed to explore genes that were genome-wide differentially expressed in br. Compared to the control lines, br exhibited a multiple-branches and dwarf phenotype. In addition, biomass, rooting number, leaf area, internal diameter, and external diameter of stomata, and the size of terminal buds of br were less than that of WT and OE2. Transcriptome analysis results indicated that gene expression profiles of br were different from the control lines. The genes that were differentially expressed in br apical buds were involved in multiple pathways, including organogenesis, fertility regulation, cell division and differentiation, plant hormone biosynthesis, and signal transduction. The multiple-branches, dwarf, and small leaves and buds of br might be due to the differentially expressed genes (DEGs) involved in organogenesis, cell division and differentiation, plant hormone biosynthesis and signal transduction.
Highlights
Plant tissues are derived from a group of cells called meristems that reside at the shoot tips and the root tips
The shoot apical meristem (SAM) differentiates into leaf primordia at the vegetative growth stage, while it differentiates into inflorescence meristem, during the stage of transition from vegetative to reproductive growth
The rooting index and dry to wet ratio of br were obviously decreased but the water content was significantly increased, compared with Wild type (WT) and OE2 (Figure 1a–c). These results confirmed that the growth of br was delayed and was weaker, and the roots were underdeveloped at the seedling stage
Summary
Plant tissues are derived from a group of cells called meristems that reside at the shoot tips and the root tips. The shoot apical meristem (SAM) is essential for the development of higher plants, and is responsible for the development of leaves, stems, and flowers. The SAM differentiates into leaf primordia at the vegetative growth stage, while it differentiates into inflorescence meristem, during the stage of transition from vegetative to reproductive growth. The axillary meristem (AM) can differentiate into the lateral bud primordia, which develops into the lateral buds and forms lateral branches of plants [1,2]. The growth and development of plants are determined by the structure and activity of SAM. Plant architecture and organ morphogenesis are influenced by both internal or environmental factors, Forests 2019, 10, 374; doi:10.3390/f10050374 www.mdpi.com/journal/forests
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