Recurrent Somatic Embryogenesis and Plantlet Regeneration in Psidium guajava L.

A simple and efficient protocol for recurrent somatic embryogenesis and plant regeneration is one of the prerequisites for genetic improvement of guava. An efficient reproducible regeneration somatic embryogenesis protocol was developed in four genotypes of Psidium guajava L. using immature zygotic embryo as starter explant. Somatic embryogenesis induction was obtained on MS basal medium supplemented with 2.0 mgL^-1 2, 4-D, 400 mgL^-1 L-glutamine, 6% sucrose and 500 mgL^-1 Malt extract. Following SE induction different developmental stages of somatic embryos (Globular, heart-shaped, torpedo, cotyledonary) was directly obtained and further recurrent embryogenesis also obtained upon prolonged incubation in induction media. Addition of polyethylene glycol (50 mgL^-1) significantly improved the embryos maturation in MS supplemented with and 3% sucrose. The regeneration in MS medium supplemented with BAP (0.5 mgL^-1), NAA (0.2 mgL^-1), casein hydrolysate (100 mgL^-1) and 3% sucrose. High plant regeneration frequency and intensity of somatic embryos (58.5%) obtained. Plant maturation on MS medium supplemented with BAP 2.0 mgL^-1 with 2% sucrose. The rooted plants was successfully acclimatize in the greenhouse with a survival rate of 85%. This somatic embryogenesis protocol developed would be helpful in establishment of genetically modified guava aimed at seedlessness, increased shelf life and wilt disease.