Localization and General Properties of Developing Peach Seed Coat and Endosperm Peroxidase Isoenzymes

Abstract

Changes of soluble and ionically bound peroxidase and indoleacetic acid (IAA) oxidase activities were followed during peach seed development. Soluble peroxidase activity was located mainly in the embryo plus endosperm tissue, whereas wall ionically bound activities were found predominantly in the integument tissue. The different peroxidase isoenzymes present in the extracts were characterized by polyacrylamide gel electrophoresis and isoelectric focusing; the main soluble isoenzyme of embryo plus endosperm tissue was an anionic isoperoxidase of R F 0.07. Basic ionically bound isoenzymes were located only in the integument tissue, but two soluble anionic isoenzymes of R F 0.23 and 0.51 were also present in this tissue. In parallel, peroxidase protein content was estimated specifically using polyclonal antibodies. The kinetic data and the changes of seed IAA oxidase activity during fruit development suggested that basic peroxidase isoenzymes from ionically bound extracts of integument might be involved in IAA degradation.The peach fruit is a useful model for studying growthrelated changes in peroxidase isoenzyme patterns and their relationships with some physiological processes because its growth occurs in three well defined development stages (Valpuesta et al. 1991). The seed apparently plays a critical role in growth and viability of the fruit during stage I (Tukey 1936). Changes in indoleacetic acid (IAA) levels and peroxidase activities have been determined previously along with the fruit growth (Valpuesta et al. 1989).The main soluble anionic peroxidase isoenzyme from peach seeds was purified, and rabbit polyclonal antibodies were obtained against this isoenzyme (Quesada et al. 1990). Changes in total IAA oxidase activity of peach complete seed peroxidases and levels of specific peroxidase proteins, detected by polyclonal antibodies, were followed during fruit growth (Alba et al. 1993).Here we report the first differential distribution of peroxidase isoenzymes and changes in the levels of specific protein in each seed tissue, integument (the outer coat of seed) and embryo plus endosperm, during fruit development. The kinetic behavior of IAA oxidase activity of the isoenzymes with the highest activity with this substrate was analyzed in order to study the possible role of peroxidases during peach seed development. Materials and Methods PlantsFruits were obtained from a commercial cultivar (cv. Redhaven) of peach (Prunus persica L. Batsch) during fruit growth. Several samples were collected during the three stages of fruit development defined previously for the cultivar Redhaven (Alba et al. 1995). Stage I extends from 0 to 55 days, stage II from 55 to 79 days, and stage III from 79 to 98 days after anthesis. Seeds were removed from frozen fruit and dissected mechanically into integument and embryo plus endosperm as a unique section. Crude Extract Isolation ProcedureSoluble protein extracts and those ionically bound to cell walls were obtained by grinding the seeds and their different sections with 50 mM sodium ...

A probable crosstalk between Ca+2, reactive oxygen species accumulation and scavenging mechanisms and modulation of protein kinase C activity during seed development in sunflower

“…32 Homogenates were prepared by grinding the tissue in 50 mM of sodium acetate buffer (pH 4) and filtered through 4 layers of muslin cloth. The filtrates were centrifuged at 10 000 g for 20 min at 4 °C.…”

“…32 Change in absorbance was recorded at 460 nm up to 5 min against a blank containing 2.4 ml of substrate solution mixed with sodium acetate buffer (pH 6.0).…”

Oxidative Enzyme Activities and Soluble Protein Content in Leaves and Fruits of Olives During Ripening

“…Alterations in peroxidase (PO) (EC. 1.11.1.7) activity and in its isozyme patterns have frequently been shown to take place during development of flower buds and fruits (Abassi et al 1998;Alba et al 1998;Kadioglu and Yavru 1998). Based on the available information, it appears that these enzymes play an important role in protecting plant tissues from active oxygen damage during growth, development and senescence (Abassi et al 1998).…”

Tyrosine nitration of cytosolic peroxidase is probably triggered as a long distance signaling response in sunflower seedling cotyledons subjected to salt stress

“…Peroxidase (POD) activity was estimated using the following protocol with minor modification [ 32 ]. Cotyledons, frozen with liquid nitrogen, were ground to fine powder using a pestle and mortar and dispersed in 50 mM sodium acetate buffer (pH 4.0) (1:2 w/v).…”