New phenotypes of the drought-tolerant cbp20 Arabidopsis thaliana mutant have changed epidermal morphology.

This paper provides a detailed phenotypic analysis of the abscisic acid (ABA) hypersensitive Cap Binding Protein 20 (cbp20) mutant. Some hitherto undescribed changes were found in the tissue structure and epidermal morphology of this mutant. These include more and smaller cells in the epidermis, a thicker cuticle and more frequent occurrence of trichomes on leaf surfaces. Some of these traits may contribute to the physiological processes responsible for the water-saving behaviour of the mutant. Abnormal spatial patterns between stomatal pore complexes were also found on various organs of the mutant. All these observations indicate profoundly disturbed development of epidermal tissue in the cbp20 mutant, which has not previously been reported for this class of mutants. A potential connection between the new phenotypes and disturbed miRNA metabolism and mRNA splicing of the mutant is discussed.