Transcriptome Analysis Provides Valuable Insights into Leaf Size Variation in Rhamnus heterophylla

The size of leaves is a vital factor in the development and overall biomass of a plant, serving as a key indicator of how a plant adapts to its environment. Rhamnus heterophylla, a species known for its heteromorphic leaves of varying sizes, presents an intriguing case for studying leaf development at the molecular level. To gain insights for further studies on the underlying mechanisms, we constructed a comprehensive reference transcriptome database using both SMART sequencing and Illumina RNA-seq technologies. Our analysis of the transcriptome data identified 88,546 isoforms, featuring an N50 size of 2386 base pairs. Furthermore, we identified 2932 transcription factors from 55 gene families, along with 14,947 unigenes that underwent alternative splicing. By comparing the gene expression patterns between large and small leaves, we pinpointed 982 differentially expressed genes (DEGs). Among these DEGs, 116 genes exhibit significantly greater activity in small leaves, while 866 genes display significantly greater activity in large leaves. Functional enrichment analyses revealed the significant involvement of these DEGs in various hormone signaling pathways. Notably, we detected a significant decrease in the expression of several genes associated with auxin synthesis, such as ARFs, GRF8, and IAA27, in small leaves. This finding sheds light on their potential role in leaf size regulation in R. heterophylla, providing valuable insights into the genes underlying this mechanism.