On the role of a Lipid-Transfer Protein. Arabidopsis ltp3 mutant is compromised in germination and seedling growth.

Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in vitro. LTPs have been involved in diverse physiological processes but conclusive evidence on their role has only been presented for a few members, none of them related to seed physiology. Arabidopsis seeds rely on storage oil breakdown to supply carbon skeletons and energy for seedling growth.

Phloem sap of tomato plants contains a DIR1 putative ortholog.

Arabidopsis thaliana defective in induced resistance 1 (At-DIR1) has been characterized as a protein responsible for the generation or transmission of the still unknown signal involved in systemic acquired resistance. This acidic apoplastic protein is a member of the family of lipid transfer proteins and was detected in vascular fluids. To our knowledge, no DIR1-like protein has been described in other plant species.

A germin-like protein of wheat leaf apoplast inhibits serine proteases.

A protein resistant to heat and proteolysis that inhibits serine proteases was isolated from wheat leaf apoplasts. Based on trypsin inhibition, its more active form was a 66-69 kDa oligomer. It was dissociated in an 18-21 kDa monomer having an amino terminal sequence identical to the Box A of germins and germin-like proteins.