Clonal fidelity investigation of micropropagated hardened plants of jackfruit tree (Artocarpus heterophyllus L.) with RAPD markers.

Background: Artocarpus heterophyllus is an important tropical agroforestry species that bears multiple applications. However, the population of this species is reduced due to various anthropogenic activities. For this reason, in vitro approach is needed to propagate or conserve this species as in vivo propagation methods face various obstacles. In this respect, the present investigation was undertaken to produce genetically stable jackfruit trees through in vitro technology. In vivo grew shoot tips were harvested on Murashige and Skoog (MS) medium containing several plant growth regulators to achieve this.

Results: The 6-benzylaminopurine (BAP) at the concentration of 1.5 mg L, indole-3-butyric acid (IBA) at 0.5 mg L, and α-naphthaleneacetic acid (NAA) at 0.1 mg L in combination on MS media yielded superior shoot response (94.44%), longest shoot length (4.02 cm), and the maximum number of shoots per explant (4.78). They were further multiplied by repeated subculturing on the same media composition and the third subculture resulted in a maximum number of shoots (5.92) with the largest shoot length (5.85 cm). Among the different media screened for rooting, the ¼ MS media yielded 94.44% rooting response, the longest root length (3.78 cm), and the maximum number of roots per shoot (8.44) with 0.1 mg L NAA, 0.5 mg L IBA and 0.1 mg L BAP in combination. Primary hardening showed 88.89% of plant survival under greenhouse conditions after 4 weeks of incubation having a sterilized mixture of garden soil and vermiculite mixture (1:1, w/w). It increased to 90.60% after the secondary hardening process in a vermiculite-soil mixture (2:1; w/w). No polymorphism was detected on random amplification of polymorphic DNA (RAPD) profiling between the mother plant and hardened plants, indicating high genetic stability among the clones.

Conclusions: This is the first report of the genetic fidelity study of in vitro grown regenerants of A. heterophyllus. This study established a micropropagation protocol for genetically uniform in vitro regeneration of this species to supply plant resources to various industries or conservation of elite germplasm.