Co-suppression of NbClpC1 and NbClpC2 alters plant morphology with changed hormone levels in Nicotiana benthamiana.

KEY MESSAGE: Co-suppression of chaperonic ClpC1 and ClpC2 in Nicotiana benthamiana significantly affect the development and exogenous application of gibberellin partially rescue the developmental defects. Over the past decade, the Clp protease complex has been identified as being implicated in plastid protein quality control in plant cells. CLPC1 and CLPC2 proteins form the chaperone subunits of the Clp protease complex and unfold protein substrates to thread them into the ClpP complex. Here, using the technique of virus-induced gene silencing (VIGS), we suppressed both Nicotiana benthamiana ClpC1 and ClpC2 (NbClpC1/C2) functioning as chaperone subunits in the protease complex. Co-suppression of NbClpC1/C2 caused chlorosis and retarded-growth phenotype with no seed formation and significantly reduced root length. We found that co-suppression of NbClpC1/C2 also affected stomata and trichome formation and vascular bundle differentiation and patterning. Analysis of phytohormones revealed significant alteration and imbalance of major hormones in the leaves of NbClpC1/C2 co-suppressed plant. We also found that application of gibberellin (GA3) partially rescued the developmental defects. Co-suppression of NbClpC1/C2 significantly affected the development of N. benthamiana and exogenous application of GA3 partially rescued the developmental defects. Overall, our findings demonstrate that CLPC1 and CLPC2 proteins have a pivotal role in plant growth and development.