GRAPEVINE PLANT REGENERATION FROM CELL SUSPENSIONS AND INFLORESCENCE FORMATION <i>IN VITRO</i> UNDER THE INFLUENCE OF DIFFERENT VITAMIN AND MINERAL ELEMENT LEVELS IN NUTRIENT MEDIA
Effects of different levels of vitamins (thiamine, pyridoxine and nicotinic acid) and macro-elements (MS, NN and PG) on development of globular, heart- and torpedo-stage embryos and plantlets with green cotyledons and on shoot production from them were studied in grapevine interspecific hybrids: cvs. 'Bianca', 'Podarok Magaracha' and 'Intervitis Magaracha'. Pro-embryogenic calli were derived from petiole explants on solid full-strength NN medium supplemented with different levels of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyladenine (BA) for each cultivar and used to initiate cell suspensions in liquid NN medium supplemented with 1 mg L-1 2,4-D and 0.2 mg L-1 BA. The following formulations of media were optimal for different stages of somatic embryogenesis and for plantlets with green cotyledons development: liquid NN medium supplemented with 0.5 mg L-1 BA − for globular embryo formation; liquid HTE medium (with PG macro-elements, thiamine and pyridoxine at 5 mg L-1 each and 0.5 mg L-1 nicotinic acid): supplemented with 0.2 mg L-1 BA − for heart-stage embryo development, supplemented with 0.1 mg L-1 indole-3-acetic acid (IAA) and 30 mg L-1 sodium humate − for torpedo-stage embryo development and supplemented with 0.5 mg L-1 gibberellic acid (GA3) − for the growth of plantlets with green cotyledons. Solid MS medium modified by the addition of nicotinic acid, pyridoxine and p-aminobenzoic acid (PAB) at 5 mg L-1 each, 0.5 mg L-1 thiamine and 0.5 mg L-1 BA was best efficient for shoot production from plantlets. Inflorescence formation in regenerated plants of cv. 'Podarok Magaracha' grown on solid hormone-free PG medium was induced by addition of nicotinic acid, pyridoxine and PAB at 5 mg L-1 each, 0.5 mg L-1 thiamine and 0.2 mg L-1 BA into liquid modified HTE medium for growth of plantlets with green cotyledons and into solid modified MS medium for shoot production from them.