Adaptive Defense Mechanism During Flowering Period of Rhododendron decorum Revealed by Comparative Transcriptomic Analysis

<i>Rhododendron decorum</i>, a widely distributed <i>Rhododendron</i> species in southwestern China, is recognized not only for its significant ornamental value but also as a culinary resource for local tribes. However, the defense mechanisms underlying the ecological adaptations of <i>R. decorum</i> remain to be elucidated. In this study, we conducted comparative transcriptomic analyses of various organs (corolla, androecium/gynoecium and leaves) of <i>R. decorum</i> collected from two distinct two regions. Approximately 186.98 Gb of clean data were generated from three organs of <i>R. decorum</i> across these regions. Through de novo assembly, a total of 92,025 unigenes were obtained and nearly half of them (43,515 unigenes) were successfully annotated. Enrichment analysis of differentially expressed genes (DEGs) within three comparative groups of different organs (HQI/LFI, HQO/LFO and HQL/LFL, respectively) revealed that the distribution of <i>R. decorum</i> in the Heqing region exhibited an increased requirement for plant immunity, including resistance to diseases, insects, and herbivores across various plant organs. Conversely, <i>R. decorum</i> in the Lijiang region showed a greater reliance on environmental factors, such as cold tolerance, aromatic compounds production, and the attraction of pollinating insects. Notably, the validation of 21 pivotal genes identified from significantly regulated enrichment pathways across different organs showed functional consistency in the KEGG enrichment analysis among different organs in these two regions. The functional disparities observed in the transcriptome of <i>R. decorum</i> across distinct regions provide valuable insight into the understanding of its adaptive defense mechanism.