The Molecular Biology Analysis for the Growing and Development of Hydrangea macrophylla ‘Endless Summer’ under Different Light and Temperature Conditions

Hydrangea macrophylla, a celebrated ornamental worldwide, thrives in semi-shaded growth environments in its natural habitat. This study utilizes Hydrangea macrophylla ‘Endless Summer’ as the experimental material to delve into its molecular mechanisms for adapting to semi-shaded conditions. Transcriptome analysis was conducted on leaves from four different natural light growth scenarios, showcasing phenotypic variations. From each sample, we obtained over 276,305,940 clean reads. Following de novo assembly and quantitative assessment, 88,575 unigenes were generated, with an average length of 976 bp. Gene ontology analysis of each control group elucidated the terms associated with the suitable environmental conditions for normal growth, development, and flowering, such as “reproductive bud system development” and “signal transduction”. The exploration of gene interactions and the identification of key genes with strong connectivity were achieved by constructing a protein–protein interaction (PPI) network. The results indicate that hydrangea grows vigorously and blooms steadily under semi-shaded conditions; the photosynthetic efficiency of hydrangea is stabilized through genes related to photosynthesis, such as PHYB, PSBR, FDC, etc. Hormone signal transduction genes like PIN3, LAX2, TIF6B, and EIN3 play important roles in responding to environmental stimulation and regulating growth and development, while genes such as SOC1, COL4/5/16, and AGL24 promote flowering. The expression of genes such as BGLUs and TPSs provides additional energy substances to support flowering.