New Base Number for the Chromosomally Abnormal Genus Arthraxon P. Beauv. from Rajasthan

Resumo

During present investigation, 4 populations covering 3 species of the genus Arthraxon P. Beauv. have been worked out cytologically from different localities of Indian hot desert, Rajasthan. Two of the three species show n = 14 (A. lanceolatus and A. lancifolius), whereas, A. hispidus show the chromosome count of n = 18. A. lanceolatus show varaiable sized bivalents i.e. two large and twelve small sized bivalents, whereas, A. lancifolius shows normal equal sized bivalents. These large sized bivalents previously might be confused with quadrivalents but during A–I it clearly indicates the chromosome count of 2n = 28. It (n = 14) is the first time reported chromosomal count for the species of the genus from the world with new proposed base number x = 7 and thus the species are considered to be tetraploid. All the three species are the first chromosome reports from Rajasthan with various meiotic abnormalities like laggards, multiple bridges, cytomixis, chromatin transfer which results in abnormal microsporogenesis and low pollen viability.