THE STUDY OF THE ANATOMICAL STRUCTURE OF APPLE-TREE TISSUES AND APPLE FRUITS (MALLUS MILL.) - Ecological Consequences of Increasing Crop Productivity - page 134

Such anatomical changes may occur because of the limitation of polar auxin trans-
portation (IAA) through the grafting place and its accumulation in grafting [21]. Polar
auxin is a key regulator of xylem differentiation and division in cambial area and an
initiator of secondary vascular differentiation. The suggested results show (Figures
14.5(A) and 14.5(C)) that to overcome anatomical dysfunction, connected with xylem
structure of transplant tissue, a grafting place has an increase. C.J. Atkinson with other
authors [22, 23] state that this is a typical auxin-answer, which is most likely formed
due to instability caused by large transport of base petal auxin in the rootstock com-
pared with the transport in a grafted rootstock. As a result, auxin is accumulated in
transplant tissues, which explains increased callusogenesis.
Epidermis of apple fruit (Figure 14.5) consists of several cell layers, where the tan-
gential diameter exceeds the radial diameter, lower epidermis cells are of larger size.
New layers are clearly seen on epidermis surface, and they have complicated structure.
A fruit surface is covered with cutin (Figure 14.5(А)).
FIGURE 14.5 Structure of apple fruit epidermis (cv. 'Rubomove Duky') on a radial cut. 1—
growing with inter-stem М9; 2—growing without inter-stem (control). А—cutin; B—soft wax;
C—grains of firm wax. The value of one mark is 100 μκ.