Molecular genetics of puroindolines and related genes: regulation of expression, membrane binding properties and applications

Kernel texture of wheat is a primary determinant of its technological properties. Soft kernel texture phenotype results when the Puroindoline a and Puroindoline b genes are present and encode the wild-type puroindolines PINA and PINB, respectively, and various mutations in either or both gene(s) result in hard phenotypes. A wealth of information is now available that furthers our understanding regarding the spatial and temporal regulation of expression of Puroindoline genes. Through the use of model membranes and synthetic peptides we also have a clearer understanding of the significance of the cysteine backbone, the tryptophan-rich domain (TRD) and the helicoid tertiary structures of PIN proteins in relation to their membrane-active properties. Many studies suggest individual yet co-operative modes of action of the PIN proteins in determining kernel texture, and significant evidence is accumulating that the proteins have in vivo and in vitro antimicrobial activities, shedding light on the biological roles of this unique ensemble of proteins. The puroindolines are now being explored for grain kernel texture modifications as well as antimicrobial activities.