A mixed ploidy natural population of Amorphophallus muelleri provides an opportunity to trace the evolution of Amorphophallus karyotype

Abstract

Amorphophallus, a perennial herb belongs to the family Araceae, and is widely distributed in Asia and Africa. As an agricultural crop, it has been cultivated and consumed for ~2000 years in China. Previous studies have found that there are chromosome number and ploidy changes in this genus, but there are a few reports on the evolution of different karyotypes. For this study, we collected 37 samples of a wild population of Amorphophallus muelleri from Myanmar and analysed their karyotypes. The karyotype analysis showed that it is a population with mixed chromosome numbers and ploidy, with four karyotypes of 2n = 24, 26, 28 and 39. Combining the results of this study with previous literature, we speculate that karyotypes with 2n = 26 may be the common ancestor, and further the other three karyotypes were evolved from this by various ways. As far as we know, this is the first attempt to put forward the hypothesis of the evolution of those four karyotypes together. On the other hand, by using inter-simple sequence repeat marker-based unweighted pair group method with arithmetic mean cluster analysis, we found that these individuals of four karyotypes can be divided into four corresponding categories, indicating that they have been differentiated at the genome, providing a theoretical basis for future use of these wild germplasm resources.