Abstract
Using T-DNA tagging method with leaf disk culture of haploid Nicotiana plumbaginifolia, we have produced some nolac (non-organogenic callus with loosely attached cells) mutants that showed the weak intercellular attachment and lost the ability to form organs. The gene tagged with the T-DNA in nolac-K4 mutant, named NpLRX1 (LRR-EXTENSIN 1), is a novel tobacco gene that encodes a cell-wall protein containing chimeric leucine-rich repeat (LRR) and extensin domains. Tobacco leaf disks transformed with NpLRX1-RNAi construct displayed aberrant adventitious buds and disorganized cell morphogenesis with large intercellular spaces. The shapes of NpLRX1-RNAi-transformed BY-2 cells were irregular, and the arrangement of cortical microtubules was clearly aberrant in these cells. When the LRR domain of NpLRX1 was expressed in BY-2 cells or leaf disks, the similar phenotypes were observed. NpLRX1 may affect the dynamics of the cytoskeleton and have a role in the communication between cytosol and cell wall mediated by LRR domain.
