No abstract

The efficient recovery of plants from avocado somatic embryos has been difficult to achieve by manipulating maturation and conversion conditions in vitro. The production of morphologically normal, bipolar somatic embryos occurs at low frequency, usually <2%, and conversion is sporadic. In order to utilize the embryogenic system for improving avocado by genetic transformation and in vitro mutagenesis, different protocols for rescuing the shoots that develop from somatic embryos were evaluated. Shoots derived either from somatic embryos or from shoot tip and nodal cultures were either micrografted or grafted ex vitro onto seedling rootstocks. Depending on scion type, micrografting was 59-100% successful. For ex vitro grafting, several genotypes derived from shoot tip/nodal cultures were used as scions with either top slit or side grafting. Plant recovery after ex vitro grafting was 52-76%, and flushing generally occurred 20-25 days after grafting. Top slit and side grafting were equally successful (68-72%); however, the former resulted in earlier flushing (21 versus 29 days). These grafting procedures have been adopted for routine rescue of avocado regenerants from somatic embryos.

Dendrobium anosmum is one of natural orchids in Indonesia. Optimization of medium composition for orchid propagation through in vitro culture is necessary to enhance propagule multiplication capabilities and quality. This study was aimed to study the influence of concentration of coconut water in culture medium on in vitro growth and development of D. anosmum orchid species and to determine the optimal coconut water concentration in culture media.  The experiment were arranged in a Completely Randomized Design with four treatments and eight replications. The treatments consisted of the addition of coconut water with concentrations: 0 ml•l -1 (control), 50 ml•l-1, 100 ml•l-1 and 150 ml•l-1. The results showed that addition of coconut water in culture medium gave different effect on shoot growth and multiplication of D. anosmum orchids.  Coconut water concentration of 100 ml•l-1 was the best concentration for growth and multiplication of D. anosmum orchids, based on both shoots and roots growth, plantlet height and wet weight.

Embryogenic avocado cultures derived from 'Hass' protoplasts were genetically transformed with the plant defensin gene (pdf1.2) driven by the CaMV 35S promoter in pGPTV with uidA as a reporter gene and bar, the gene for resistance to phosphinothricin, the active ingredient of the herbicide Finale® (Basta) (Bayer Environmental Science, Research Triangle Park, Durham, NC ). Transformation was mediated by Agrobacterium tumefaciens strain EHA105. Transformed cultures were selected in the presence of 3.0 mg l −1 phosphinothricin in liquid maintenance medium for 3-4 mo. Liquid maintenance medium consisted of modified MS medium containing (per liter) 12 mg NH 4 NO 3 and 30.3 mg KNO 3 and supplemented with 0.