Cytogenetic Studies on Diploid Hybrids Between Annual Ryegrass (Lolium multiflorum Lam.) and Perennial Ryegrass (Lolium perenne L.)

Authors: Bilal DENİZ, Ayten TUFAN

Abstract: This study was carried out in the glasshouse of the Agronomy Department of Agricultural Faculty. Atatürk University in summer 1995. In this study. metaphase 1 (MI) chromosome pairing. numbers of chromosome arms bound and anaphase 1 (AI) segregation were studied in diploid annual (Lolium multiflorum Lam.) and perennial ryegrass (Lolium perenne L.) and their intermediate hybrid plants (Lolium hybrİdum). Diploid annual and perennial ryegrass had very regular meiosis with mainly ring bivalent and high number of chromosome arms bound. Chromosome segregation was also balanced at AI in these species. The intermediate hybrids showed a high Ievel of meiotic chromosome pairing and numbers of chromosome arms bound at MI. Most chromosomes formed bivalents though univalents and trivalents were rarely observed. Chromosome segregation was mostly balanced at AI in the diploid hybrids. However artificial hybrids had unbalanced chromosome distribution and other disjunction abnormalities at AI. Meiosis in the hybrids were somewhat Iess regular than their parents in general. The hybrids between annual and perennial ryegerass are easily produced and also fertile. However. there is also evidence of genetic breakdown in Iater generations of the annual and perennial ryegrass hybrid (24). Therefore. in an effort to overcome the genetic instability of the intermediate hybrid. the chromosome number of interspecific hybrids has been doubled using colchicine to produce fertile allopolyploids.

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