In vitro culture establishment from Cotyledon and Embryonic Axis Explants of two Bangladeshi Sunflower (Helianthus annus L.) varieties

Abstract

Sunflower is considered as source of cholesterol free edible oil. Because of cross pollinating nature of this plant, it is difficult to identify true breeding homozygous line, thus, breeding becomes intricate. Besides, due to biotic and abiotic stresses, development of this crop is urgent. This study was aimed to develop a potential alternative to improve qualitative and quantitative production of this crop through basic tissue culture regeneration. Several attempts with various explants have already discovered in past but no initiative was reported for Bangladeshi sunflower varieties. In present study, optimum seed sterilization method; the efficiency of different explants; effect of different growth hormones in different combinations and concentrations and rooting efficiency of initiated shoots were demonstrated for two farmer popular Bangladeshi sunflower varieties, namely BARI Surjomukhi 2 and BRAC Hysun 33. The seeds were washed with 70% ethanol for 3 minutes followed by vigorous hand shaking with 14% Clorox for 20 minutes. To collect explant, named embryonic axis, testas were removed and 3 mm piece from proximal portion of the seed was excised and inoculated in different combinations and concentrations of hormone supplemented media. For explant cotyledon, sterilized seeds were inoculated in germination media to obtain different ages seedlings, thus five, seven and nine days cotyledon explant was collected. In case of explant embryonic axis, BRAC Hysun 33 variety showed maximum (58.33%) regeneration in 1.0 mg/l BAP with 0.1 mg/l NAA hormone supplemented media while in BARI Surjomukhi 2 variety, 2.0 mg/l BAP gave highest (46.67%) regeneration. Elongated shoots were inoculated in 0.2 mg/l IBA containing media for root induction but further studies are needed to optimize rooting media concentration. The second explant, cotyledon remained nonregenerative in both varieties. Further studies need to be done to develop regeneration system from this explant. In future reproducibility of this protocol using embryonic axis needs to be evaluated.