Effect of moisture deficiency on the apple stress-associated protein expression level .

In plants, stress-associated proteins (SAP) are involved in response to adverse biotic and abiotic factors. In order to study the drought effect on changes in the SAP expression level in apple trees and their involvement in stress response, an expression level of fourteen genes belonging to this family was analyzed using qPCR. Their participation in a stress response to drought in the genome of the MM-106 apple tree rootstock was shown. At that, the genes demonstrated a tendency to increase their expression by the fourth hour of drought exposure followed by its decrease by the twenty-fourth hour.

A comparison of the data obtained during the described experiment with the data obtained when modeling drought under milder conditions showed that under more severe drought conditions, an expression of a greater number of gene encoding stress-associated proteins increases, and a more pronounced response occurs. Evaluation of the effect of an identity degree of nucleotide sequences of gene encoding stress-associated proteins on the similarity of their expression profiles under drought exposure did not reveal any direct relationship between the primary structure of genes and the nature of their expression.

In the structure of stress-associated proteins encoded by the genes most strongly response to drought in Malus, Solanum lycopersicum, Gossypium hirsutum, and Cucumis sativus, the A20-AN1 type domain occurs more frequently than other types of zinc finger domains. Analysis of the similarity of stress-associated protein sequences and the expression levels of genes encoding them under drought conditions in different plant species (apple, cotton, tomato, and cucumber) suggests that in each species, the evolution of adaptation mechanisms, including SAP encoding genes, occurred independently and, most likely, after separation of those species from their common ancestor. The results obtained will make it possible to clarify the role of individual genes, encoding SAP, in the formation of an apple stress response to the drought effect.

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