The activities of chitinase, g-l,3-glucanase, peroxidase and phenylalanine ammonia lyase, constitutive and induced by Stagonospora nodorum were examined inthe 10-14 day old seedlings of three triticale and two wheat cultivars under controlled environmental conditions and in flag leaves of two triticale cultivars in the field. Two S. nodorum isolates of different virulence were used. Both the constitutive and induced activities in triticale and wheat depended on genotype and in triticale the effect of growth conditions was also evidenced. The constitutive activities of chitinase, B-1,3-glucanase and peroxidase were several fold lower in flag triticale leaves in plants from the field than in the seedlings, growing under controlled conditions, but induction in the infected flag leaves was significantly more pronounced. In triticale genotypic differences in the response to infection were revealed only upon inoculation by S. nodorum isolate of higher virulence. The enzymatic activities increased several fold during successive days after the infection except for phenylalanine ammonia lyase. Induction of this enzyme was only transient and the activity decreased 48 or 96 h after infection when the activities of other enzymes were rising.In flag leaves in the field this activity was differentiated only after infection with more a virulent strain.A tendency appeared in triticale seedlings for association of the resistance to the pathogen with lower enzymatic constitutive activities. This relationship became more evident in triticale infected by S. nodorum and may imply that although the investigated enzymes are certainly involved in general, non-specific defense mechanism, they do not decide on the resistance to pathogen at least in the early stages of infection and cooperate with other factors in the complex pathogen-plant interaction. One can also assume that the enzymatic activities are associated with severity of infection rather than resistance to pathogen.
Some histological changes were observed in blueberry stems infected by the fungus G.cassandrae. Dead cells of subepidermal collenchyma and cortical parenchyma filled with brown flocculent deposits were seen in the lesion areas. Pycnidia characteristic for the conidial stage of the fungus (Topospora myrtilli) were found in the collenchyma layer. The diseased tissues were found to be separated from the healthy ones by a layer of cork cells which was initiated under the epidermis and ended under the pericycle. Beneath this cork layer lamellar collenchyma and collenchyma-like phelloderma formed. Similar histopathological changes were observed in blueberry stems infected by seven other fungi
Acid phosphatase and ribonuclease extracted with 0.1 M sodium acetate buffer, pH 5.1 from Dactylis glomerata seeds, and partially purified by means of 70% ethanol precipitation showed electrophoretic and Chromatographic heterogeneity. After chromatography on DEAE-cellulose acid phosphatase and ribonuclease were separated into four peaks. Nonadsorbing acid phosphatase on DEAE-cellulose (peak I) was separated into four peaks on CM-cellulose. The highest activity (11 units/mg) was found in fraction b (acid phosphatase Ib). The enzyme was activated by Mg<sup>2+</sup>, Ca<sup>2+</sup>, Li<sup>+</sup>, Cs<sup>+</sup>, K<sup>+</sup> ions and inhibited by Cu<sup>2+</sup>, Zu<sup>2+</sup>, F<sup>-</sup> and Mo<sup>-6</sup> at optimum pH 5.0. Strong absorbing ribonuclease on DEAE-cellulose (peak IV) was further separated on G-200 Sephadex into two molecular forms: RN-asa1 and RN-ase2. Ribonuclease l, a thermolabile enzyme with specific activity 807 units/mg, showed an optimal activity at pH 4.8-5.1.
Two different ribonucleic acids were isolated from barley germs by use of the phenol (RNA I) and chloroform method (RNA II). After separation on Sephadex G-200 RNA I was found to be homogenous, whereas RNA II showed 5 components. Furthermore, both preparations differed in chemical composition and spectrophotometric specificity.
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