JOINTLESS is a MADS-box gene controlling tomato flower abscission zone development

Abscission is a universal and dynamic process in plants whereby organs such as leaves, flowers and fruit are shed, both during normal development, and in response to tissue damage and stress. Shedding occurs by separation of cells in anatomically distinct regions of the plant, called abscission zones (AZs). During abscission, the plant hormone ethylene stimulates cells to produce enzymes that degrade the middle lamella between cells in the AZ. The physiology and regulation of abscission at fully developed AZs is well known, but the molecular biology underlying their development is not. Here we report the first isolation of a gene directly involved in the development of a functional plant AZ. Tomato plants with the jointless mutation fail to develop AZs on their pedicels and so abscission of flowers or fruit does not occur normally. We identify JOINTLESS as a new MADS-box gene in a distinct phylogenetic clade separate from those functioning in floral organs. We propose that a deletion in JOINTLESS accounts for the failure of activation of pedicel AZ development in jointless tomato plants.     

Trachytes kaliszewskii , n. sp. (Acari: Uropodina), from the Great Basin (Utah, USA), with remarks on the habitats and distribution of the members of the genus Trachytes

Trachytes kaliszewskii, n. sp., is described from the Great Basin, Utah, USA. SEM photography illustrates morphological detail. An annotated list is included of currently recognized species of the genus Trachytes , with comments on their distribution and habitat characteristics.