ETHYLENE PRODUCTION AND INVOLVEMENT DURING THE FIRST STEPS OF DURUM-WHEAT (TRITICUM-DURUM) ANTHER CULTURE

The role of ethylene in anther culture of durum wheat (Triticum durum Desf. cv. Ardente) was analyzed by testing the effects of 2-chloroethy lphosphonic acid (ethrel), silver thiosulfate (Ag+), alpha-aminooxyace tic acid (AOA) and 1-aminocyclopropane-1-carboxylic acid (ACC) on micr ospore division observed after 21 days of culture and on development o f calli estimated at day 45. The use of ethrel and Ag+ indicated a pos itive effect of ethylene on microspore division, whereas the use of AO A, and to a lesser extent ACC, showed a negative effect. In contrast, the addition of ethrel or Ag+ indicated that ethylene inhibits the dev elopment of microspore-derived calli. AOA gave contradictory results. Ethylene production by anthers was about 7 pi anther(-1) h(-1) and dec reased during culture, ACC content in the anthers was maximal at day 9 , whereas malonyl ACC (MACC) increased sharply from day 0 to day 3 and then decreased. The addition of AOA or ACC to the culture medium decr eased or increased, respectively, ethylene production of anthers and t he ACC and/or MACC content, but at concentrations higher than those th at modified the formation of calli. This formation seems to occur in t wo successive phases: induction and initiation of microspore division, which was promoted by ethylene, followed by callus development, which was inhibited by ethylene.