ЭлБиб

M O L EC U LA R BIO LOGY O F PLA N T C E L L S IN V IT RO

THE SENSITIVITY OFMTDNAOFPEA CALLUS TISSUE TOALKALI,

RNASE A AND RNASE H

A.G.Mardamshin, A .P.Stupin

Biochemistry and Cytochemistry Department, Ufa Science Center, RussianAcademy o f

Sciences, Prospect Octyabrya 69, Ufa, Russia, 450054, E-Mail:

Earlier mtDNA of 4-days etiolated pea shouts were shown to be sensitive

unde rthe action of 0.2M KOH, RNase A and RNase H. It took place due to

th e p resence in m tDNA o f ribonuc leo tides c o va len tly bound w ith

deoxyribonucleotides. It may be the result o f errors in the process of mtDNA

biosynthesis or ribonucleotides play a certain functional role. The analysis

o f ribonucleotide content in plant tissue o f different differentiation level may

g iv e a partial answer to this question. For this purpose pea callus tissue

initiated from mature embryos was chosen. Callus tissue was cultivated for

2 years in darkness on Murashige and Skoog nutrient medium. Passages

took place every 30 days. mtDNA was isolated by phenol deproteinization

method. mtDNA and RNA separation was carried out by electroelution in

agarose gel. mtDNA of callus tissue appeared to be also sensitive to alkali,

RNase A and RNase H. The range o f its sensitivity varied in different passages

from 20 to 50% and fo r mtDNA o f whole plants (different isolations) this

value was more stable (20-30%). Probably a higher variability o f ribonucleotide

content in callus tissue mtDNA is connected with the effect of a number of

uncontrolled factors that influence on physiological callus state. In its turn it

may lead to errors of different degree in mtDNA biosynthesis.

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