Callus Induction from Carob (Ceratonia siliqua L.) Seedlings and Leaves of Mature Tree

Callus induction was successfully carried out from several explants of carob (Ceratonia siliqua L.). Callogenesis from the apex was tested on three different media containing Woody Plant Medium (WPM), Murashige and Skoog (MS) or Schenk and Hildebrandt (SH) macronutrients supplemented with two different hormonal solutions: benzylaminopurine (BAP) at 4.44 µM alone, or 2.22 µM of BAP plus 5 µM of 2-naphthalineacetic acid (NAA). Primary callus formation was obtained on a medium containing 88% WPM macronutrients. Callus formation from other parts of the plant was as follows:

− Cotyledon embryos extracted from immature seeds (85% success rate on WPM medium, containing 4.44 µM BAP and 5 µM NAA);
− Cotyledon leaves taken from 7-day-old seedlings, obtained from in vitro germination of seeds (62% success rate on WPM medium, containing 4.44 µM BAP and 5 µM NAA);
− Hypocotyls taken from 7-day-old seedlings (55% success rate on WPM containing 2.22 µM BAP and 5 µM NAA);
− Differentiated leaves taken from mature tree (84% success rate on WPM medium, containing 4.44 µM of BA and 2.26 µM of NAA).

In general, production of primary calli and their growth after transplantation was better on WPM medium supplemented with 2.5 µM NAA and 2.22 µM BAP.