Comparative transcriptome analysis of Lupinus polyphyllus Lindl. provides a rich molecular resource for research on coloration mechanism

Lupinus polyphyllus is rich in color, making it a well-known horticultural ornamental plant. However, little is known about the genes related to anthocyanin and carotenoid biosynthesis in L. polyphyllus. In this study, transcriptome sequencing was performed on eight different colors of L. polyphyllus. A total of 1.13 billion clean reads were obtained and assembled into 89,124 unigenes, which were then aligned with six databases, resulting in the identification of 54,823 annotated unigenes. Among these unigenes, 76 and 101 were involved in the biosynthetic pathway of carotenoids and anthocyanins, respectively. In addition, 505 transcription factors were revealed, which belonged to the MYB, R2R3-MYB, NAC, bHLH, and WD40 families. A total of 6,700 differentially expressed genes (DEGs) were obtained by comparative transcriptome analysis. Among them, 17 candidate unigenes (four carotenoid genes, seven anthocyanin genes, and six TFs) were specifically up-regulated for one or more colors of L. polyphyllus. Eight representative candidate unigenes were analyzed by qRT-PCR. The findings enrich the transcriptome database of lupine, and provide a rich molecular resource for research on the coloration mechanism of L. polyphyllus.