Sugar deficiency causes changes in cuticle permeability and cell wall composition that influence fruit postharvest shelf-life

The cuticle is a protective layer synthesized by epidermal cells of the plants and consisting of cutin covered and filled by waxes. In tomato (Solanum lycopersicum) fruit, the thick cuticle embedding epidermal cells has crucial roles in the control of pathogens, water loss, cracking, and postharvest shelf-life. Tomato fruits with reduced expression of the tomato gene LIN5 encoding cell wall invertase exhibits decreases transpirational water loss. Transcriptomic, biochemical, histological, and biomechanical analysis identified several unsual features of RNAi-LIN5 cuticles and the data indicate that, perturbation of endogenous fruit sugar levels affects the composition of the tomato cuticle and cell wall architecture which are an integral and regulated part of the ripening program affecting the postharvest shelf-life. A model is proposed in which sugar levels affects the cuticle formation which has a direct effect in softening of intact tomato fruit both directly, by providing a physical support, and indirectly, by regulating water status.University of Málaga, Campus de Excelencia Internacional de Andalucia Tech. Spanish Ministry of Science and Innovation (Ramón and Cajal contract, RYC2011-09170

Apoplastic diffusion barriers in Arabidopsis.

During the development of Arabidopsis and other land plants, diffusion barriers are formed in the apoplast of specialized tissues within a variety of plant organs. While the cuticle of the epidermis is the primary diffusion barrier in the shoot, the Casparian strips and suberin lamellae of the endodermis and the periderm represent the diffusion barriers in the root. Different classes of molecules contribute to the formation of extracellular diffusion barriers in an organ- and tissue-specific manner. Cutin and wax are the major components of the cuticle, lignin forms the early Casparian strip, and suberin is deposited in the stage II endodermis and the periderm. The current status of our understanding of the relationships between the chemical structure, ultrastructure and physiological functions of plant diffusion barriers is discussed. Specific aspects of the synthesis of diffusion barrier components and protocols that can be used for the assessment of barrier function and important barrier properties are also presented