The Gene slm1-1 Regulates Abscission, Dehiscence, Meristem Arrest, and Apical Dominance in Arabidopsis thaliana

Abstract

Cell separation regulates basic developmental processes such as abscission and dehiscence and is one of the horticultural traits first to be selected by mankind. Abscission is characterized by an active cell separation process where organs are detached from the main body of the plant through the dissolution of the middle lamella. Crops with early abscission can have significant reduction in yield. For example, canola, Brassica napus, loses 5% to 10% of crop due to early pod shatter. By screening T-DNA mutagenized populations of A. thaliana for delayed abscission, we have identified several genes that regulate cell separation, slm1-1 (slender lasting inflorescence and meristem) is one such genes. During our investigation of slm1-1 we have employed phenotypic, physiological, genetic, and molecular assays. Phenotypically, slm1-1 displays traits such as delayed abscission of floral organs, lack of anther pollen dehiscence (making slm1-1 functionally male sterile), delayed meristem arrest, and strong apical dominance. Phenotypic characterization includes scanning electron microscopy, bright field microscopy, and stereoscope microscopy. Physiological assays include reporter gene expression and break strength analyses. Genetically, slm1-1 is regulated by a single recessive gene. Molecular assays characterizing slm1-1 include TAIL-PCR, RT-PCR, and preliminary microarray of abscission zones. We have also begun to map based cloning of slm1-1. We believe that understanding genes that regulate cell separation in A. thaliana will contribute to crop improvement. Applications could include reducing loss during harvesting, regulation of pollination, changes in branching patterns, and longevity of flowering.