Consequences of colchicine induced intermeiocyte connections inHelianthus annuus

Abstract

During microsporogenesis sometimes the chromatin materials migrate from one cell to another by intermeiocyte connections. In the present study, during induction of tetraploidy in sunflower, changes in the normal behaviour of chromosomes was detected. Besides chromosomal aberrations, cytomictic connections were frequently recorded. Cytomixis has been reported by many researchers in many diploid or tetraploid plants. In sunflower, cytomixis in colchiploids has not been recorded. In the current study high numbers of cytoplasmic connections were observed in the plants failing to reach higher ploidy level. Formation of cytoplasmic connections was very high, leading to many hyperploids, hypoploids and even empty pollen mother cells (PMCs). Cytomixis occurred frequently, with two to many meiocytes engaged in exchange of chromatin through one or multiple cytoplasmic connections. Few rare polyploid PMCs with cytoplasmic connections were observed, which favours formation of aneuploids and polyploids. Besides various chromosomal anomalies, fertility was also significantly affected. This work envisages the possibility that although polyploidy was not achieved in some plants there is tendency to form higher ploidy levels in this species. This illustrates the potential for formation of various genetic combinations and thus novel traits. Cytomixis is also an additional source of male sterility in sunflower and thus requires intense research.

Cytogenetic effects of chitosan-capped silver nanoparticles in theAllium cepatest

“…polyploidy and aneuploidy) (Prokhorova et al 2008). Several mechanisms have been proposed for the occurrence of polyploidy (Zimmet and Ravid 2000;Gautam and Kumar 2013;Beyaz et al 2013) AgNP at 1 and 2.5 mg l −1 concentrations caused slight, but not statistically significant, increases in MI and prophase index (Table 1). Our results indicate that chitosan-capped AgNP can stimulate mitotic activity in plant tissue and disturb proportions of mitotic phases, which may result in mitotic abnormalities.…”