Mitochondrial DNA variation in long-term tissue cultured rice lines

Area of Science:

• Plant Molecular Biology
• Genetics
• Biotechnology

Background:

• Plant cell suspension cultures are valuable tools for research and propagation.
• Long-term cultivation may induce genetic and epigenetic changes in plant cells.
• Mitochondrial DNA (mtDNA) is susceptible to alterations during in vitro culture.

Purpose of the Study:

• To investigate the effects of long-term tissue culture on rice (Oryza sativa) mitochondrial DNA.
• To analyze variations in mtDNA restriction and hybridization patterns in cell lines under prolonged culture and selective pressure.
• To identify specific mitochondrial genes or regions that are sensitive to tissue culture-induced changes.

Main Methods:

• Isolation of mitochondrial DNA from rice cell suspension cultures, including a long-term cultured line (BL2) and analog-selected derivatives.
• Digestion of mtDNA with ten restriction endonucleases and analysis of Southern blot patterns.
• Hybridization of Southern blots with rice and maize probes containing specific mitochondrial genes (e.g., apt9, atpA, coxI, coxII, rrn18-rrn5, atp6).

Main Results:

• Unique restriction patterns were observed in long-term cultured rice lines (BL2 and A11) compared to the original P. I. 353705.
• Extensive hybridization pattern differences were detected with probes for coxI, coxII, rrn18-rrn5, and atp6, indicating significant mtDNA variation.
• The coxII probe was most effective in highlighting differences in the BL2 line, while rrn18-rrn5 and atp6 were most effective for the analog-selected A11 line.

Conclusions:

• Long-term rice tissue culture leads to unique mitochondrial genomic organizations.
• Both restriction and hybridization analyses reveal substantial mtDNA variation induced by prolonged cell culture.
• Specific mitochondrial genes (coxII, rrn18-rrn5, atp6) are sensitive indicators of tissue culture-induced genomic alterations.