Somaclonal Variation in Rice

Retrotransposons of rice involved in mutations induced by tissue culture.

“…The latter character is important to identify the retrotransposon responsible for the specific mutation. This tagging is very useful, especially for rice, because tissue culture-induced mutations have been used as a source of improvement of rice and many mutants are available (8).…”

“…Here we report the first active retrotransposons of rice that are activated by tissue culture. Rice was chosen as a representative of monocotyledonous plants to examine the ubiquity of retrotransposons activated by tissue culture and the possible involvement of retrotransposons in tissue cultureinduced mutations because rice is being studied as a model plant suitable for molecular genetic analysis (7) and many studies on tissue culture-induced mutations have been carried out (8). The present data indicate that retrotransposons are involved in tissue culture-induced mutations.…”

Effect of Genotype and Culture Media on Callus Induction and Plant Regeneration from Matured Rice Grain Culture

“…Many experiments have been conducted to optimize the techniques and composition of culture medium for callus induction from dehulled rice seed for various purposes (Islam et al, 2004, Khatun et al, 2003, Wang et al, 1987. However, its application is still limited by many factors influencing the culture efficiency such as medium composition (Sun and Zheng, 1990), explants source (Torbert et al, 1998), genotype (Shen et al, 1982) and environment (Qu and Chen, 1983). Among them the genotype and nutrient composition are regarded to be the major sources of variation in in vitro culture (Khanna and Raina, 1998).…”

In Vitro Enhancement of Bacoside in Brahmi (Bacopa monnieri) Using Colchicine

“…However, these variations were not continued, when recultured on the same regeneration media, hence these variations are the epigenetic somaclonal variations [18]. Colchicine treatment affects the chromosomal number and expression of genes which further results in cytological abnormalities [19,20], qualitative and quantitative phenotypic mutation [21], sequence change, gene activation and silencing [22]. Epigenetic activation of DNA elements further suggests that epigenetic changes may also be involved in cytogenetic instability through modification of heterochromatin, and as a basis of phenotypic variation through the modulation of gene function [23].…”