Indirect somatic embryogenesis from transgenic immature leaf of safflower Carthamus tinctorius (Mohler, Roth, Schmidt & Boudreaux, 1967) (Asterales: Asteraceae)

Abstract

Highly efficient protocol is developed for indirect somatic embryogenesis from transgenic immature leaf of safflower Carthamus tinctorius (Mohler, Roth, Schmidt & Boudreaux, 1967) (Asterales: Asteraceae) explants in solid culture. Here two different half strength mediums like MSG and EMM both were tested in addition to inorganic and organic nitrogen sources and also combination of the reference medium. Inorganic nitrogen source shows about 39.5 number of embryos with 37% embryo germination and organic Nitrogen source like L-glutamine (20 uM) on reference medium influenced 80.5 number of somatic embryos with 44.9% germination. However, maximum of 92.0 number of embryo induction with 52.5% germination was noticed on CH (casein hydrolysate) (1.5 mg/L) containing medium. Combination of inorganic and organic nitrogen sources like NH4NO3 (40 uM) in combinations with reduced form of organic nitrogen casein hydrolysate (CH) (1.5 mg/L) was found to be most suitable for induction of somatic embryos with a maximum of 117 number of somatic embryos with 60.9% germination in immature leaf explants. About 57% plant conversion rate showed in NARI-6 cultivar after 2 weeks of culture. However it showed maximum plant conversion rate about 68% with basal medium along with 1.5% sucrose supplemented with GA3 (1.5 uM) and spermidine (1.0 uM). Germinated embryos with shoot and root poles were isolated and subcultured on suitable root induction medium containing NAA (2.5 uM) + AgNO3 (1.5 uM) showed maximum rooting frequency of about 69.6%.