A new perception about cytomixis: Causes, mechanisms and role

Abstract

Till date, several classical and modern methodological tools had been employed to investigate the phenomenon of cytomixis for developing a clear understanding about its occurrence, causes, mechanism, and role in plant evolution. These attempts have succeeded to some extent in modifying general perception about it ever since its discovery. Based on the published literature as well as own work, the authors opined that cytomixis has no correlation with ploidy level/genomic status. Rather, it is the genetic makeup and environmental conditions which are responsible for cytomixis. We also assume that recipient meiocytes adjust to extra chromatin either through exclusion or condensation of chromatin. Otherwise, meiocytes depicted spindle abnormalities leading to gametes with the variable genetic constitution. Such gametes led to the origin of aneuploids/polyploids. High frequency of cytomixis during early stages has a direct correlation with the easier passage of genetic material. In some cases, whole nucleus migration resulted into syncytes which yielded unreduced pollen, leading to the origin of polyploids. Another evolutionary aspect of cytomixis is that it induces high pollen sterility in plants of cold deserts acquiring perennial habits and vegetative modes of propagation. We are of the opinion that like other cytological processes, cytomixis is a natural meiotic aberration of potential evolutionary significance.