Induksi mutasi dengan iradiasi sinar gamma untuk pengembangan klon unggul anggrek Spathoglottis plicata Blume aksesi Bengkulu.

Abstract

Spathoglottis plicata Blume. is one species of orchids with lower level of genetic diversity, especially in flower color compared to other orchids. S. plicata accession Bengkulu usually produce pink to purple flower with a bright purple stems and flower stalk. The aimed of the research were (1) to find the tissue culture protocols to propagate S. plicata though protocorm like bodies, (2) to induce the genetic diversity of S. plicata accession Bengkulu using gamma irradiation to plantlets, (3) to determine a lethal dose 50% (LD50) for plantlets through gamma irradiation, and (4) to identify genetic variations of orchids S. plicata and its mutants using morphological characters and ISSR markers. The growth and multiplication of protocorm like bodies can be induced by using MS medium supplemented with 50 to 100 ml L-1 coconut water. The best treatment to develope plb into plantlet was MS medium containing of vitamin B5 with addition of 75 ml L-1 coconut water and 2% activated charcoal or MS medium supplemented with 20 μM BA and 2% activated charcoal. Furthermore, MS medium containing of B5 vitamin enriched with 20 μM BA or MS medium containing of vitamin B5 with addition of 75 ml L-1 coconut water was the best treatment for plantlet multiplication. Induced mutation using gamma-ray irradiation to the plbs and plantlets could increase the genetic diversity of S. plicata. Lethal Dose 50% (LD50) of plb survival rate was 47.71 Gy, while LD50 of plantlet survival rate was 50.74 Gy. Gamma-ray irradiation to the plantlet resulted nine potential mutants (0.36%) that be selected by morphological characters of the shape and color of flowers. Morphological characters and ISSR markers can be used to identify the mutants. Clustering analysis by using Unweighted Pair Group Method and Arithmatic Average and Principal Component Analysis of 12 samples and its mutants based on ISSR markers could clearly distinguish the wild type and its mutants. It formed five groups of coefficient similarity at 0.68 with goodness of fit correlation matrix value of 0.91 (very suitable). The grouping of those samples was more accurate and more efficient by using ISSR markers compared to the morphologycal markers. This clustering successfuly separated the wild type and its mutants.