Inhibition of tobacco axillary bud differentiation by silencing CUP-SHAPED COTYLEDON 3

Abstract

Desuckering is a time-consuming, laborious and expensive process in tobacco production. To resolve this problem, pCAMBIA1301-RNAi (an RNAi vector) was constructed based on the conservative region of CUP-SHAPED COTYLEDON 3 (CUC3) in Apocynum venetum (AvCUC3), a key gene in the differentiation of axillary bud. Nicotiana tabacum has been transformed using vector pCAMBIA1301- RNAi mediated by AGL0 through the leaf disc method. A down-regulation (60 to 95%) of CUC3 mRNA level was observed in positive tobacco transgenic lines. Lines whose CUC3 gene had been suppressed exhibited some important phenotypes, such as leaf fusion, leaf curl and incomplete leaf. CUC3 in N. tabacum was silenced successfully by RNA interference (RNAi), which suggested a high homology between AvCUC3 and N. tabacum CUC3. An EST (FG152687) of N. tabacum that had the highest homology (72%) with AvCUC3 was found by retrieving GenBank database and this EST might be a fragment of CUC3 gene of N. tabacum.

Key words: Apocynum venetum, cup-shaped cotyledon 3 (CUC3), conservative region, RNA interference (RNAi), Nicotiana tabacum.