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S O M A C L O N A L V A R IA TIO N S OP P L A N T S A N D C U LT U R E D C E L L S
ISOPEROXIDASEPATTERNSINTHEINTACTANDCULTIVATEDMAIZE
TISSUES
M.V.Zabrodina, L.A.Serdobmskii, Yu.I.Dolgykh*, Z.B.Shamina*and
E.E.Khavkin
Instituteo fAgriculturalBiotechnology, RussianAcademy o fAgricultural Sciences,
Moscow,127550, Timiryazevskaya St, 42, E-Mail address: ;
* TimiryazevInstitute o fPlantPhysiology, RussianAcademy o fSciences, Moscow 127276
, BotanicheskayaSt., 35, E-Mail address:
Among 11 peroxidase loci in maize (Zea mays L .), inbred line A188,
on\ypx3 was constitutive. The anodal isoenzyme Px9 was present in most
tissues, however, it was especially active in the roots. Only two loci
manifested clear-cut tissue-specific expression: px2 activity was specific of
mature pollen, while pxl2 was expressed only in the roots. The anodal
peroxidase spectra in the calli obtained from several embryonic and adult
plant tissues were quite sim ilar and differed considerably from the isozyme
patterns of the respective tissues of the intact plant. A new band appeared
in the position of the Pxl2 isozyme, and Px9 band staining was enhanced.
The primary calli from the scutellum and apical meristem were two exceptions
from this pattern: we did not observe the Pxl2 band in these callus tissues.
However, the corresponding band finally appeared in the scutellum callus
after several subcultures. In the roots regenerated from the calli of different
origin (apical meristem, scutellum, leaf, and immature tassel), Px9 and Pxl2
staining was as strong as in the primary roots o f the initial seedlings.
Regenerated plants and their sexual progeny were obtained from the immature
embryo-derived callus cultures. In these somaclones, in contrast to the initial
A188 plants, the leaves manifested a peroxidase band coinciding, by its
mobility, with the root-specific isozyme Pxl2. We presume that cell
dedifferentiation in vitro affects the tissue-specific control over peroxidase
expression, and the newly established pattern of peroxidase manifestation
is inherited at least in four seed generations. Isoperoxidase with the mobility
o f Pxl2 was found in the leaves o f all FI and F2 plants obtained by crossing
R27 somaclone to A188, making the direct effect on this peroxidase gene
rather unlikely. The activity of isoenzyme with the Pxl2 mobility enhanced in
the leaves o f plants affected by salinity stress. We presume that this
isoperoxiodase develops in callus tissues and somaclone leaves as a result
o f the stress produced by in vitro culture.
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