Comparative study of gene expression and major proteins' function of laticifers in lignified and unlignified organs of mulberry.

A laticifer is a cell involved in plant defense against biotic stresses such as herbivores and microorganisms; however, its gene expression is poorly understood. We compared protein accumulation and transcriptomes among laticifers of lignified and unlignified organs of mulberry (Morus alba), which has a non-articulated, branched type of laticifer. LA-a (equivalent to MLX56) and its homolog LA-b (insecticidal chitinase-like proteins containing two chitin-binding domains) were major proteins in laticifers of unlignified organs, and another protein (LA-c) was a major protein in laticifers of lignified organs.

Two chitinase-like proteins abundantly accumulated in latex of mulberry show insecticidal activity.

Background: Plant latex is the cytoplasm of highly specialized cells known as laticifers, and is thought to have a critical role in defense against herbivorous insects. Proteins abundantly accumulated in latex might therefore be involved in the defense system.

Results: We purified latex abundant protein a and b (LA-a and LA-b) from mulberry (Morus sp.