Fig. 1

Classification of microspores based on developmental stages. Developmental stages of microspores were judged by microscopic observation after low temperature treatment, and the classes of anthers or calli were defined on the basis of these stages. a Microspores stained with acetocarmine at different developmental stages. Bar, 10 µm. b Categorization of microspore developmental stages into classes A to E. 1N, 2N, and 3N indicate uninucleate, binucleate, and trinucleate stages, respectively