Nuclear DNA amount determination and cytology of some afroalpine angiosperms in Ethiopia

Abstract

This study includes five species of the afroalpine flora- Cardamine obliqua (Brassicaceae), Cotula cryptocephala (Asteraceae), Deschampsia caespitosa (Poaceae), Ranunculus oreophytus and Ranunculus stagnalis (Ranunculaceae) collected from Bale and Simen Mountains. Estimates of 2C-values and DNA-ploidy analysis were done for C. cryptocephala, D. caespitosa, R. oreophytus and R. stagnalis from leaf tissue using flow cytometry. Chromosome counting from mitotic root tips was done for C. cryptocephala, D. caespitosa, R. oreophytus, R. stagnalis and C. obliqua. Mean 2C-values were found to be 10.2 pg, 9.2 pg, 27.5 pg and 14.2 pg for C. cryptocephala, D. caespitosa, R. oreophytus and R. stagnalis, respectively. Chromosome numbers found were the same as earlier reports, 2n=62, 26, 32, 28 for C. obliqua, D. caespitosa, R. oreophytus and R. stagnalis, respectively but for C. cryptocephala 2n= 64 is a new report. For all species analyzed by flow cytometry, no intraspecific DNA-ploidy level difference was found whereas slight intraspecific 2C-value variation up to 1.047-fold was found, which could be either artefactual or real intraspecific variation correlated with molecular, morphological or environmental factors. These results indicate that further morphological, cytological, flow cytometric and molecular investigations of the afroalpine flora will provide data that answer many important biological and evolutionary questions.