Karyotypic analysis of Plasmodiophora diplantherae

Synaptonemal complexes (SCs) in nuclei of transitional plasmodia of Plasmodiophora diplantherae were counted through serial section analysis. On this basis the haploid chro? mosome number was nine, the lowest haploid number known for Plasmodiophoromycetes. Total length (TL) of SCs per nucleus (approx. 39 /nm) was similar to that of P. brassicae (n = 20, TL = approx. 47 jim, vol. = approx. 15 ixm3), but nuclear volume (approx. 28 /um3) was similar to those of Polymyxa betae (n = 30, TL = approx. 73 /um, vol. = approx. 26 ^m3), P. graminis (n = 30, TL = approx. 70 jim, vol. = approx. 24 /um3), and Sorosphaera veronicae (n = 33, TL = approx. 76 /ttm, vol. = approx. 25 Mm3).