ACTION OF TRIPLOID INDUCER (TRI) ON MEIOSIS IN BARLEY (HORDEUM-VULGARE-L)

The tri gene has a unique effect on barley meiosis. It suppresses second division in about 50 per cent of embryo sac mother cells (emc’s) at random so that diploid embryo sacs are formed. Otherwise, meiosis is regular in all emc’s and female fertility is normal in all spikes. However, tri does not similarly affect pollen mother cells (pmc’s). Meiosis is regular in over 80 per cent of pmc’s and fertility on selling is normal. A maximum of only 1-2 percent of pmc’s and pollen grains have a doubled chromosome number, but extra chromosomes occur in 0-20 per cent (mean 10 per cent) of pmc’s, probably through spindle abnormalities at the last premeiotic mitosis.The tri gene has cytogenetic potential for aneuploid and polyploid production and centromere mapping. If it occurs in the wild, it may play a significant role in Hordeum evolution. © 1979 The Genetical Society of Great Britain. All Rights Reserved.