The Role of Cell Wall Peroxidase in the Inhibition of Leaf and Fruit Growth

The aim of the work presented was to investigate the role of cell wall bound peroxidase in the inhibition of leaf and fruit growth during unfavorable environmental conditions. In the first experiment, plants of two maize genotypes, differing in drought resistance and growth dynamics, were subjected to drought in order to observe leaf growth parameters (LER and SER) in parallel with bulk and segmental peroxidase activity in the growth zone. The results obtained indicated that drought significantly reduced LER, length of elongation zone and local growth rates within it in both genotypes. Bulk peroxidase activity was increased in both genotypes to different degrees (143% in low-LER and susceptible genotype and 238% in high-LER and resistant genotype) while segmental peroxidase activity also increased in almost every segment of the elongation zone with notable peaks in some regions. In the second experiment the same maize genotypes were subjected to nitrogen deficiency, where growth parameters and peroxidase activity were observed in the division and elongation zone separately. Nitrogen deficiency also caused a reduction of LER, cell division and elongation rate and shortening of the growth zone. This was followed by a significant increase in peroxidase activity in both regions of growth zones: in the low LER genotype this increase was expressed most in division zone, while in all other regions investigated the values were almost the same. The third experiment includes the effect of a partial root drying (PRD) treatment on tomato fruit growth and peroxidase activity in cell walls of fruit epidermis. Results obtained in all experiments allowed us to confirm that under stress conditions cell wall associated peroxidase plays an important role in biochemical inhibition of leaf and fruit growth.