Genome-wide Analysis and Functional Characterization of the Della Gene Family Associated With Stress Tolerance in B. Napus

Background: Brassica napus is an essential crop for oil and livestock feed. Eventually, this crop’s economic interest is at the most risk due to anthropogenic climate change. DELLA proteins constitute a significant repressor of plant growth to facilitate survival under constant stress conditions. DELLA proteins lack DNA binding domain, but can interact with various transcription factors or transcription regulators of different hormonal families. Significant progress has been made on Arabidopsis and cereal plants. However, no comprehensive study regarding DELLA proteins have been delineated in B. napus . Results: : In our study, we have identified 10 BnDELLA genes. All of the BnDELLA s are closely related to five AtDELLA genes, suggesting a relative function and structure. Chromosomal mapping revealed the uneven distribution of BnDELLAs on eight chromosomes, and site-specific selection assessment proposes BnDELLAs purifying selection. The motifs composition in all BnDELLA genes is uneven; however, every BnDELLA gene contains 12 highly conserved motifs, encoding DELLA and GRAS domain. The two known miRNAs (bna-miR6029 and bna-miR603) targets, BnC07RGA and BnA09GAI, were also predicted. Furthermore, quantitative real-time PCR (qRT-PCR) analysis has exhibited the BnDELLA genes’ diverse expression patterns in various plant organs. Additionally, cis-acting element prediction shows that all BnDELLA genes contain light, stress, and hormone-responsive elements on their promoters. The gene ontology (GO) enrichment report indicated that BnDELLA genes mainly regulate stress responses. Through publicly available RNA-seq analysis, we determined the induced expression of BnDELLA genes by different biotic and abiotic stress treatments. Conclusion: The present study provides essential information on the BnDELLA gene family in B. napus , illustrates the significance of BnDELLA s in stress adaptation, and suggests modulating BnDELLAs expression is a promising way to intensify B. napus stress tolerance and harvest index.