Seedless fruits and the disruption of a conserved genetic pathway in angiosperm ovule development Jorge Lora1,2, José I. Hormaza1, María Herrero3 & Charles S. Gasser2 1 Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora” - CSIC, 29750 Algarrobo-Costa, Málaga, Spain 2Department of Molecular and Cellular Biology, University of California, Davis, Davis, California 95616, USA 3Dep. Pomology, Estación Experimental “Aula Dei” ‐ CSIC, Apdo. 202, 50080 Zaragoza, Spain. Corresponding Author: Charles S. Gasser Molecular and Cellular Biology University of California, Davis 1 Shields Ave. Davis, CA 95616 USA Phone: 530 752‐1013 FAX: 5530 752‐3085 Email:
[email protected] Edited by Martin F. Yanofsky, University of California at San Diego, La Jolla, CA, and approved February 23, 2011 (received for review September 27, 2010) Although the biological function of fruiting is the production and dissemination of seeds, humans have developed seedless fruits in a number of plant species to facilitate consumption. Here we describe a unique spontaneous seedless mutant (Thai seedless; Ts) of Annona squamosa (sugar apple), a member of the early-divergent magnoliid angiosperm clade. Ovules (seed precursors) of the mutant lack the outer of two normal integuments, a phenocopy of the inner no outer (ino) mutant of Arabidopsis thaliana. Cloning of the INO ortholog from A. squamosa confirmed conservation of the outer integument-specific expression pattern of this gene between the two species. All regions of the gene were detectable in wild-type A. squamosa and in other members of this genus. However, no region of the INO gene could be detected in Ts plants, indicating apparent deletion of the INO locus.