Betaine a novel candidate for rapid induction of somatic embryogenesis in tea (Camellia sinensis (L.) O. Kuntze)

Abstract

Addition of betaine to the inductionmedium significantly enhanced the rapid formation ofsomatic embryos directly without callusing from maturefresh seeds of tea within two weeks of cultureinitiation. The induction response was furtherenhanced when ABA (7.5 mgl⁻¹) was co-supplementedwith betaine in the induction medium. The rate ofinduction of somatic embryogenesis increased linearlywith external betaine concentration. Globular somaticembryo-like structures (embryoids) were observed in 4-week old cultures when inoculated on the inductionmedium without ABA and betaine. The positive effectof ABA on the induction process was found to bedependent on the presence of betaine in the medium. ABA alone in the medium could not bring the inductionstimulus in the explants; on the contrary, it provedinhibitory. The optimum response of ABA was observedwhen the medium was supplemented with 500 to1000 mgl⁻¹ of betaine. Primary somatic embryosobtained in the presence of ABA and betaine were ableto produce secondary embryos. A conversion rate of15–20% was achieved upon transfer of somatic embryosof size 3–5 mm in diameter to the basal medium consistof half strength of macro nutrients, full strength ofmicro nutrients and vitamins of MS. Medium wasfurther supplemented with 100 mg l⁻¹ each ofadenine hemisulfate sulphate and L-glutamine, 30 gl⁻¹ sucrose, gelled with 7 gl⁻¹ bitek agar. The plantlets regenerated by this procedure did notshow any visible abnormalities. This report for thefirst time details the potential use of betaine inplant tissue culture.