GROWTH OF ISOLATED SHOOT APICES OF TOMATO ON CALCIUM-DEFICIENT MEDIA AS RELATED TO LIGHT QUALITY DURING FOR INITIAL SEEDLING GROWTH

Apical shoot meristems were isolated from 20-day-old tomato (Lycopersi con esculentum Mill.) seedlings grown in white (WL), red (RL), or gree n (GL) light. The meristems were cultured in WL for 21 days on the nut rient media defined for stem morphogenesis: full Murashige-Skoog (MS) medium (the control), the MS medium deprived of CaCl2(-Ca), or the MS supplemented with 2 muM EGTA (-Ca + EGTA). The extent of shoot develop ment from the apical meristems cultured on the control medium (stem an d root length and the number of leaves) was shown to depend on the lig ht quality applied during the initial seedling growth. On the (-Ca) me dium, all the shoots derived from the meristem of WL-grown seedlings p roduced stems with dead apices and other developmental abnormalities; half of the shoots that originated from the meristems of RL-seedlings lost the ability for apical growth, and only in 22% of the explants fr om GL-seedlings stem apices die off. On the (-Ca + EGTA) medium, the m eristem of WL-seedlings expanded and produced callus, the RL-explants formed teratic leaf-like structures, and the GL-explants died without visible growth. It is suggested that the quality of light used for see dling growth differentially affected the calcium distribution in apica l meristematic tissues.