Differential Expression of Genes Related to the Formation of Giant Leaves in Triploid Poplar
Plant polyploids tend to have large leaves, but their formation mechanism has not yet been well explained. Therefore, daily transcriptomic differences between triploids and diploids from a synthetic Populus sect. Tacamahaca three times a day (i.e., 04:00, 09:00, and 21:00) were investigated using high-throughput RNA-seq analysis. In this study, we identified several transcription factors associated with giant leaves. The combined effects included the high expression of several transcription factors (WRKY, MYB, etc.) and hormone-related genes (e.g., activates auxin, cytokine, and brassinosteroid synthesis-related genes) that accelerate the synthesis and accumulation of endogenous hormones. High levels of growth hormones were maintained by reducing the genes’ expression of hormone metabolism and degradation. The coordination of hormones accumulated sufficient materials and energy for leaf growth and development. Thereby, cell division and growth were accelerated which enhanced the photosynthesis of leaves, and the increased accumulation of photosynthetic products led to giant triploid leaves. This study lays the foundation for revealing the molecular mechanisms in the formation of giant leaves in polyploids.