CRISPR-Cas9 Helps Pinpoint Plant Architecture Genes in Tobacco

Strigolactones (SLs) are phytohormones that regulate plant architecture. Carotenoid cleavage dioxygenase (CCD) genes are involved in the biosynthesis of these SLs and are characterized in many plants. However, the function of CCD genes in tobacco remains poorly understood. Junping Gao of the Southwest University in China studied two CCD genes, NtCCD8A and NtCCD8B, in tobacco (Nicotiana tabacum).

The two NtCCD8 genes are orthologs of the tomato (Solanum lycopersicum) carotenoid cleavage dioxygenase 8 (SlCCD8) gene. NtCCD8A and NtCCD8B were revealed to be primarily expressed in tobacco roots, but low levels of expressions were detected in all plant tissues. Their expressions were also found to be significantly increased in response to phosphate limitation.

Using the CRISPR-Cas9 system, mutations were induced in NtCCD8A and NtCCD8B in tobacco to develop ntccd8 mutant lines. The ntccd8 mutants had increased shoot branching, reduced plant height, increased number of leaves and nodes, and reduced total plant biomass compared to wild types. The mutant lines also had shorter primary roots and more lateral roots.

These results suggest that NtCCD8 genes are involved in tobacco plant architecture.

For more information, read the article in International Journal of Molecular Sciences.