Localization of tobacco germin-like protein 1 in leaf intercellular space

• Some intrinsic proteins were released from tobacco leaf cell wall by treatment with lithium chloride.
• Germin-like protein 1 (NtGLP1) was identified in the LiCl extracts from cell wall fraction.
• NtGLP1 localizes at bifurcated sites on cell wall between mesophyll adjacent cells.

To characterize leaf cell wall proteins relating the architectural changes of leaves, we analyzed Nicotiana tabacum leaf cell wall proteins that were extracted by the treatment with lithium chloride. Some of these proteins showed amino acid sequence homology to some germin-like proteins (GLP). Based of those sequences, we isolated the cDNA encoding the GLPs (NtGLP1-1, NtGLP2-1). Phylogenetic analysis including de novo assembled tobacco GLPs using EST clones, revealed that tobacco GLPs belong to at least 5 different subgroups of GLP and both NtGLP1 and NtGLP2 belong to GLP subfamily 3. We showed that the NtGLP1 actually localizes to cell wall and revealed that it predominantly localized at specific sites on the leaf cell wall where intercellular attachment was just bifurcated. Expression of the NtGLP1 mRNA was mainly detected in leaves especially at elongating stage. NtGLP1 is possibly relevant to development of leaf intercellular space.

GLP1 localizes in tricellular junctions of young leaves, and later in bifurcated regions of adult leaves.Figure optionsDownload as PowerPoint slide