Induction of Embryogenic Callus and Somatic Embryo of Durian (Durio zibethinus Murr.) on Various Media Composition

Abstract

Durian is a valuable tropical fruit. Durian agribusiness in Indonesia is still lags behind neighboring countries such as Thailand and Malaysia, whereas genetic, land and climatic resources for durian in Indonesia are better than those of other countries. Durian tissue culture can be applied for durian genetic improvement and mass propagation of elite varieties which finally can promote durian agribusiness in Indonesia. However, researches on durian tissue culture are still very limited. The objective of this study is to obtain the suitable type of explants, media, and plant growth regulator in embrogenic callus and somatic embryo induction of durian. The study was conducted in 2 successive trials. The first experiment was callus induction and the second trial was somatic embryogenesis induction of callus obtained from the first experiment. There were 4 type of explants used on callus induction experiment, namely flower receptacle, petal, endosperm and immature zygotic embryo of durian. Callus induction from flower receptacle and petal explants were arranged as a factorial two factors experiment. The first factor was durian genotype, namely Dramaga, Matahari and Simas, and the seond factor was 14 media composition which were composed of two types of basal media (MS and B5) and 7 level of plant growth regulator (PGR ), i.e., without PGR, 2, 4, 6 ppm of NAA and 2, 4, 6 ppm of picloram. Callus induction with endosperm and immature zygotic embryo explants using 1 genotype, viz. Otong. Experiments on endosperm explant was arranged as a factorial two factors experiment, that is benziladenin (BA) treatment (0 and 1 ppm) and thidiazuron (TDZ) treatment (0.0, 0:01, 0:05, 0.5 ppm) in the MS basal medium + B5 media vitamin with 100 ppm glutamine, 100 ppm asparagine, 500 ppm casein hydrolysate, and 0.5 ppm picloram. The treatments on callus induction from immature zygotic embryo explant were 5, 10, 15, and 20 ppm of picloram on MS basal medium. The second experiment was the induction of somatic embryogenesis of petal explants derived calluses by treatment with 0.0, 0.3, 0.5, 1.0, and 2.0 ppm BA on MS basal medium with B5 vitamin, 100 ppm glutamine, 100 ppm asparagine, 500 ppm casein hydrolysate, and 0.5 ppm picloram. The best medium composition on callus induction from flower receptacle explant was B5 basal medium with addition 2 ppm of NAA. The best one for petal explant was B5 basal medium with addition 2 ppm of picloram. Based on the result of percentage of explant producing calluses and callus emergence rate on petal and flower receptacle explants, it was indicated that Matahari variety was more responsive than Dramaga accession and Simas variety. The type of calluses derived from flower receptacle explant at the beginning of its emergence was watery friable callus (type 3 callus) which the cells were easily separated from one another. In one to two weeks after the callus emergence, this type of callus turned into a whitish to yellowish compact callus (type 1 callus) or pure white compact callus (type 2 callus). All three type of calluses, from morphological and histological observations, were supposed to be non-embryogenic ones. The type of calluses that grew from petal explants since the beginning of their emergence were of type 1 and type 2 calluses. All calluses produced from endosperm explant were of type 1 callus. Globular stage somatic embryos have been obtained from 6 mm immature zygotic embryo explant cultured on MS basal medium + 15 ppm picloram at 18 days after culture. All calluses originated from immature zygotic embryo explants other than that medium composition were type 2 calluses. The treatment of 0.0, 0.3, 0.5, 1.0, and 2.0 ppm of BA on MS basal medium with B5 vitamin, 100 ppm glutamine, 100 ppm asparagine, 500 ppm casein hydrolysate, and 0.5 ppm picloram did not give significant effect on all variables observed on second trial. The type 1 callus derived from petal explant of Simas genotype that were cultured on those media did not form somatic embryo or embryogenic callus.