Genetic Behavior of Distinct B Chromosome in Safflower

Abstract

SummaryThe present study documents the presence of 3 B chromosomes in safflower, which is one of the first such reports. During the present investigation, B chromosomes were found to induce a twofold effect on planting, firstly a reduction in chiasma frequency in euchromatic region, and secondly depression in the percentage of pollen fertility due to an increase in the number of unpaired chromosomes. Although the presence of B s depressed the chiasma frequency of the regular complement, the frequency of A and B chromosomes does not appear to be related. No correlation between B chromosomes and phenotype has been reported. Thus, it can be predicted that the presence of additional DNA as B chromosomes can bring about some structural or numerical changes in the long run and may affect the genetic integrity of the plant and thus result in a changed genotype with negligible effect on the morphology and vigor of the plant.

Effect of B-chromosomes on meiotic behaviour and genetic recombination in Artemisia nilagirica (C. B. Clarke) Pamp.

“…In case of maize, a high number of Bs show signifi cant reduction in pollen fertility and plant vigor (Randolph 1941). A decrease in pollen fertility percentage has been observed in Maize (Weberl et al 2007); Saffl ower (Kumar and Srivastava 2010). The presence of laggards at anaphases and telophases clearly points out the possibility of unpaired b-chromosomes lie on spindle as laggards.…”

Cytological evidences of pollen abortion in Ornithogalum caudatum Ait

“…Phenomenon of pollen abortion in O. caudatum is very common, and it could be related to abnormality of euchromosome pairing in meiosis; further, B chromosomes may affect the pollen fertility (Wiegas, 1980;Parker et al, 1990;González-Sánchez et al, 2004;Kumar and Srivastava, 2010). The B chromosomes are accessory genomic elements to the so-called A or standard genome.…”