Organ accumulation and subcellular location of Cicer arietinum ST1 protein

Abstract

The ST (ShooT Specific) proteins are a new family of proteins characterized by a signal peptide, tan-dem repeats of 25/26 amino acids, and a domain of unknown function (DUF2775), whose presenceis limited to a few families of dicotyledonous plants, mainly Fabaceae and Asteraceae. Their functionremains unknown, although involvement in plant growth, fruit morphogenesis or in biotic and abioticinteractions have been suggested. This work is focused on ST1, a Cicer arietinum ST protein. We estab-lished the protein accumulation in different tissues and organs of chickpea seedlings and plants and itssubcellular localization, which could indicate the possible function of ST1. The raising of specific anti-bodies against ST1 protein revealed that its accumulation in epicotyls and radicles was related to theirelongation rate. Its pattern of tissue location in cotyledons during seed formation and early seed germi-nation, as well as its localization in the perivascular fibres of epicotyls and radicles, indicated a possibleinvolvement in seed germination and seedling growth. ST1 protein appears both inside the cell and inthe cell wall. This double subcellular localization was found in every organ in which the ST1 protein wasdetected: seeds, cotyledons and seedling epicotyls and radicles.