RNA sequencing reveals transcriptomic changes in tobacco (Nicotiana tabacum) following NtCPS2 knockdown

Abstract

Background Amber-like compounds form in tobacco (Nicotiana tabacum) during leaf curing and impact aromatic quality. In particular, cis-abienol, a polycyclic labdane-related diterpenoid, is of research interest as a precursor of these compounds. Glandular trichome cells specifically express copalyl diphosphate synthase (NtCPS2) at high levels in tobacco, which, together with NtABS, are major regulators of cis-abienol biosynthesis in tobacco. Results To identify the genes involved in the biosynthesis of cis-abienol in tobacco, we constructed transgenic tobacco lines based on an NtCPS2 gene-knockdown model using CRISPR/Cas9 genome-editing technology to inhibit NtCPS2 function in vitro. In mutant plants, cis-abienol and labdene diol contents decreased, whereas the gibberellin and abscisic acid (ABA) contents increased compared with those in wild-type tobacco plants. RNA sequencing analysis revealed the presence of 9514 differentially expressed genes (DEGs; 4279 upregulated, 5235 downregulated) when the leaves of wild-type and NtCPS2-knockdown tobacco plants were screened. Among these DEGs, the genes encoding cis-abienol synthase, ent-kaurene oxidase, auxin/ABA-related proteins, and transcription factors were found to be involved in various biological and physiochemical processes, including diterpenoid biosynthesis, plant hormone signal transduction, and plant-pathogen interactions. Conclusions The present study provides insight into the unique transcriptome profile of NtCPS2 knockdown tobacco, allowing for a better understanding of the biosynthesis of cis-abienol in tobacco.

Identification and Evaluation of Diterpenoids from Glandular Trichome Secretions of Air/Sun-Cured Tobacco Germplasm Resources

“…During tobacco leaf curing, Cembratriene-diol (CBT-diol) is degraded to produce solanone, solanofuran, solandione, and other flavor components. The degradation products of cis-abienol are mainly C-16 compounds, including ambroxide and ambreinolide, and other substances that have a strong ambergris (cypress wood) aroma [5]. Menetrez et al [6] were the first to find that α-CBT-diol and β-CBT-diol have strong inhibitory effects on conidial germination…”

Knockdown of NtCPS2 promotes plant growth and reduces drought tolerance in Nicotiana tabacum

“…Recently, we performed transcriptome analyses of tobacco plants with cis -abienol synthesis gene NtCPS2 knockdown and studied their physiology and biochemistry characteristics ( He et al., 2021a ; He et al., 2021b ). We found that knocking down the cis -abienol synthesis gene NtCPS2 not only reduced the relative expression of NtCPS2 gene and the content of cis -abienol, but also affected related genes in the GA synthesis pathway, thus increasing the GA content.…”