Caryologia (Sep 2022)
First record of nucleus migration in premeiotic antherial cells of Saccharum spontaneum L. (Poaceae)
Abstract
The occurrence of nucleus migration is reported for the first time in a clone (2n = 64) of ‘Thatch’ grass (Saccharum spontaneum L.) of the family Poaceae. Usually, its premeiotic antherial cells are thin-walled, uninucleate and without trace of chromosome individuality. However, these cells of flood affected anthers showed variation in nucleus number. Out of 2567 cells analyzed, two and three cells were connected to each other through a well-defined cytoplasmic channel, respectively in nineteen and two instances. The nuclei were at various stages of their migration in interconnected cells. The remaining cells exhibited a mosaic of anucleate to hexanucleate cells in varying frequencies with dominance of binucleate condition (43.75%). The anucleate ‘ghost’ cells were much smaller in size than the uninucleate, binucleate and multinucleate cells showing insignificant variation among themselves. The anucleate, binucleate and multinucleate cells appeared to be the products of nucleus migration through cytoplasmic channels between two cells. The presence of a nucleus in donor cell united with recipient cell having four nuclei of different sizes, diminutive anucleate cell in the neighbourhood of uninucleate/trinucleate cell or connected with cytoplasmic channel/pentanucleate cell, and disorganizing cytoplasmic channel attached with binucleate/ tetranucleate cell withnessed the accomplishment of nucleus migration. This rare phenomenon seemed to be triggered by flood stress and facilitated by feeble cell wall. The variation in size of nuclei in multinucleate cells might be due to the transfer of nucleus/nuclei of different size(s). The prominent features of nucleus migration distinguishing it from the cytomixis have been discussed in detail.
