Influence of genotype and gelling agents on in vitro regeneration by organogenesis in sunflower

Fourteen recombinant inbred lines of sunflower (Helianthus annuus L.) and their parents (PAC-2 and RHA-266) were tested for their organogenesis ability. Seeds were surface sterilized and germinated on hormone free half strength MS basal medium containing 10 g l(-1) sucrose solidified with five different gelling agents: Phytagar (Gibco laboratoires) 3 g l(-1), Phytagel (Sigma) 3 g l(-1), Agarose (Sigma) 5 g l(-1), Arcagel (Sigma) 4 g l(-1) and Agar-Agar (Fisher France) 7 g l(-1). Cotyledons from 2-day-old seedlings were split in half and the four explants of each seed were cultived in 55 mm diameter petri dishes containing 10 ml of MS medium supplemented with 50 mu M KNO3, 1 mu M myo-inositol, 5 mu M casein hydrolysate, 4.4 mu M of BA and 5.4 mu M of NAA solidified with the same gelling agents. The experimental design was a randomized complete block with 3 replications. A replicate for each genotype consisted of ten petri dishes containing four explants. The statistical analysis showed significant differences among genotypes and gelling agents. Of the fourteen recombinant inbred lines tested 'C93' presented the highest values for all regeneration traits in the five different media and it was better than the best parent. Agarose and Agar-Agar were more better than other gelling agents for shoot induction.