Mitigating lipid peroxidation in leaves of Prunus sp. rootstocks using exogenously applied auxins

Abstract

The effect of exogenously applied auxins on mechanical injury induced oxidative stress was studied in 6 promising rootstock selections of Prunus cerasus L., P. mahaleb L., and P. fruticosa Pall. Investigated selections were included in low vigorous rootstock breeding programme for sweet and sour cherries. The standard rootstock PHL-A was used as a control, due to successful rooting. Leaves of investigated rootstocks were collected on: 0, 1st, 3rd and 7th day of inserting softwood cuttings into the rooting substrate under a fogging system with 95-99% average relative humidity. Exogenously applied auxin mixture consisted of 0.8% α-naphthylacetic acid (NAA) and 0.5% indolebutyric acid (IBA). Mechanical injuries during rooting period represent one of the factors that induce stress in softwood cuttings. Intensity of LP is used as a valuable biomarker of plant response to various abiotic factors. Differences in intensity of LP between auxin-treated and -untreated cuttings were examined. Almost all of investigated selections had lower LP intensity after auxin application (11.4-47.2%) between 1st and 3rd day. However, the most prominent change was in leaves of PHL-A (49.2%). The best LP-lowering effect were recorded in leaves of P. fruticosa, SV4 selection (56.9%) on 7th day and in P. mahaleb, M4 selection, on 1st and 3rd day (5.9, 5.8%), in comparison to untreated softwood cuttings. As for OV21 selection, LP intensity significantly increased in both treated and untreated cuttings on the 1st, 3rd and 7th day, but auxin-treated cuttings showed lower LP values, except on 7th day, reaching 221.3 nmol MDA equivalents g-1 fresh weight. Intensity of LP during vegetative propagation of selected genotypes could be used as one of the biochemical parameters in further rootstock selection for sweet and sour cherries.