Wyerone Acid Phytoalexin Synthesis and Peroxidase Activity as Markers for Resistance of Broad Beans to Chocolate Spot Disease

Infection of broad bean (Vicia faba L.) leaves with Botrytis fabae (Sard.) resulted in wyerone acid phytoalexin accumulation and increase in peroxidase activities in resistant and susceptible broad bean cultivars. Rapid wyerone acid accumulation was observed in leaves of resistant cultivars that reached levels greater than twofold of the susceptible cultivars. Following infection of broad bean cultivars, either resistant or susceptible to B. fabae, wyerone acid synthesis in resistant cultivars peaked at 5 days then declined, whereas in susceptible cultivars synthesis gradually decreased. While the ethanol‐extract of wyerone acid significantly reduced B. fabae spore germination with increased concentrations, the phytoalexin had no effect on in vitro B. fabae germ‐tube growth. Peroxidase activity in infected leaves of resistant was 10 times higher than the susceptible cultivars and eight times higher in uninfected leaves of the resistant than the susceptible cultivars. Peroxidase activity in infected leaves was greater than twofold in resistant cultivars and less than twofold in susceptible cultivars, when compared with uninfected leaves. The ratio of peroxidase activity in infected to uninfected leaves increased over time in susceptible cultivars but remained unchanged in resistant cultivars. Peroxidase activity in uninfected and infected leaves and wyerone acid biosynthesis in infected broad bean plants were successfully used to ascertain the resistance and susceptibility of four broad bean cultivars to B. fabae. Using wyerone acid synthesis and peroxidase activity as preliminary markers for resistance of broad bean to chocolate spot disease, caused by B. fabae, is suggested in this study.     

小麦与条锈菌互作中过氧化物酶的细胞化学研究

采用细胞化学方法对小麦与条锈菌互作过程中过氧化物酶的分布及其活性大小进行了研究,结果表明：过氧化物酶主要分布于细胞壁和细胞间隙中;在未行接种的小麦叶片中,抗病品种和感病品种的过氧化物酶活性均比较低;条锈菌侵染后,诱导抗、感病品种叶片中的过氧化物酶活性升高,且抗病品种升高的幅度明显大于感病品种;感病品种中过氧化物酶活性在侵染位点附近细胞壁上表现升高,而抗病品种中该酶的活性在侵染点细胞以及远离侵染点的叶肉细胞的细胞壁和细胞间隙中均显著升高。高活性的过氧化物酶是小麦抗条锈性的生化标记和重要机制之一。     

Peroxidase Activity in Leaves of Wheat Cultivars Differing in Resistance to Erysiphe graminis DC.

The peroxidase activities in leaves from resistant and susceptible cultivars of wheat infected and non-infected by Erysiphe graminis DC were studied. In non-infected wheat, soluble and ionic bound peroxidase activity level was found to be higher in the resistant cultivar than that in the one susceptible to Erysiphe graminis DC. After infecting wheat leaves with Erysiphe graminis DC a remarkable increase in the activity of soluble and ionic bound peroxidases was detected 5 days after inoculation only in the resistant cultivar. In the susceptible cultivar a high increase in the activity of the soluble and ionic bound peroxidases occurred only 15 days after inoculation. Using ion exchange chromatography four peroxidase fractions were obtained from infected susceptible and resistant cultivars as from non-infected ones. The fraction II in non-inoculated resistant cultivars was much higher than that in the susceptible one. This fraction increased after inoculation in both cases reaching a higher level in resistant cultivars. Fraction I was higher in the susceptible cultivar. Electrofocusing profiles of peroxidase from the susceptible and resistant cultivar differed from one another. New peroxidase bands after inoculation appeared only in the resistant cultivar.     

辣椒感染疫病后生化指标的响应研究

采用生理生化分析方法研究了辣椒感染疫病后叶片中几个生化指标的变化。结果表明,染病前后感病品种叶片中可溶性总糖含量持续高于抗病品种;抗病类型品种和感病类型品种的可溶性蛋白含量变化规律均表现为先升高后下降,但接种前其叶片中可溶性蛋白含量两者间无明显差异;抗病类型和感病类型辣椒接种后保护酶活性均升高,而且感病类型的POD和ASP酶活性在接种后120h显著高于抗病类型;高抗类型叶片中PPO活性增加幅度显著大于感病类型,但抗病类型品种PPO活性上升趋势比较平缓。接种后,感病品种PAL活性上升幅度小于高抗品种,接种后96h PAL活性开始逐渐下降。可溶性总糖含量和苯丙氨酸解氨酶可以作为辣椒苗期抗疫病鉴定的生化指标。     

Postinfectional Changes of Lipid Metabolism in Potato Tuber Resistant and Susceptible to Phytophthora infestans

The effect of Phytophthora infestans on the lipid content and composition as well as lipid acyl hydrolase activity in the potato tuber of two cultivars, Nysa – horizontal resistant and Bintje –susceptible were investigated. In the susceptible cultivar the infection resulted in: a qualitative changes in aminolipids, an increase in steroid content, an inconsiderable decrease in amount of glycolipids and a slight drop in FFA, no significant changes in composition of total, FA and slight loss in acyl hydrolase activity. The following changes were observed in the resistant cultivar: a considerable enhancement of steroid content (reached in about 400 %), a slight increase in amount of glycolipid, a rapid drop of acyl hydrolase activity and FFA content and a considerable increase in oleic acid level in total FA. In the response to both infection and aging in both cultivars no significant quantitative changes in lipid-phosphorus and sulfolipids were noted.     

Changes in the Hill Reaction and the Chlorophyll Fluorescence of Chloroplasts Isolated from Wheat Plants Infected with Stem Rust (Puccinia graminis f. sp. tritici)

Wheat plants with different resistance to stem rust were inoculated with urediospores of Puccinia graminis f. sp. tritici race 32. By means of isolated chloroplasts Hill activity and chlorophyll fluorescence were measured during the first 8–10 days of the infection. Highly resistant cultivars (infection type 0) showed no significant differences in Hill activity whereas resistant (infection type 1) and susceptible plants (infection type 4) exhibited a significant decrease in electron transport. This was associated with an apparent reduction of chlorophyll content. In both the incompatible as well as in the compatible interaction an additional factor had an effect on the inhibition of the Hill activity. Chlorophyll fluorescence was also affected in compatible and in incompatible interactions. However, the two interactions showed different patterns. Whereas the decline in variable fluorescence dominated in resistant varieties, susceptible cultivars showed an additional significant increase in basic fluorescence. The determination of Hill activity and chlorophyll fluorescence demonstrated that photosynthesis was inactivated in different ways in resistant and in susceptible cultivars.     

黄瓜褐斑病菌毒素对抗、感黄瓜品种的作用

在黄瓜褐斑病菌毒素的作用下,黄瓜品种的根数、根长、芽长受到了抑制,根的电导值及叶片的苯丙氨酸解氨酶(PAL)活性升高。抗病品种的根数、根长、芽长受毒素的影响较感病品种小,即感病品种对毒素敏感,且抗、感品种的电导值差异达显著水平。抗病品种的PAL活性增加幅度较感病品种大。     

Change in antioxidant enzymes activity and some morpho-physiological characteristics of strawberry under long-term salt stress

The effects of long term salinity on some morpho-physiological characteristics were studied in strawberry Kurdistan and Queen elisa cultivars. Vegetative and biochemical traits were measured in strawberry cultivars subjected to three levels of salinity including 0, 40 and 80 mM at 20, 40 and 60th days after NaCl addition. Results showed that in both cultivars the dry weight of plant organs decreased in response to NaCl, except of crown weight in cv. Kurdistan. Root to shoot ratio increased due to a greater reduction in above ground biomass under salinity. Strawberry cultivars tended to decrease their stomatal conductance, RWC, proline, soluble carbohydrates and proteins during the different evaluation periods. Compared to the 20th day, peroxidase activity decreased at 80 mM during 40 and 60 days in cv. Queen elisa. On the contrary, ascorbate peroxidase activity elevated until the 40th day and decreased afterwards, in addition application of 40 and 80 mM NaCl increased the ascorbate peroxidase activity of both studied cultivars. Catalase activity increased from 20th until 60th days in cv. Queen elisa, while showed increase in cv. Kurdistan until day 40 and then decreased again at day 60. Application of 40 and 80 mM NaCl resulted in an increase in peroxidase, ascorbate peroxidase and catalase activities of both cultivars. The Queen elisa cv. showed lower tolerance index (45.88%) compared with cv. Kurdistan (67.97%). Finally, higher salinity resistance of cv. Kurdistan is probably associated with its ability to maintain higher RWC and higher activity of antioxidant enzymes.     

Mechanism associated with nonstructural carbohydrate accumulation in submergence tolerant rice (Oryza sativa L.) cultivars

Nonstructural carbohydrate (NSC) accumulation in submergence tolerant rice cultivars (cv) was studied in six Indica rice [Oryza sativa (L.)] cv under control and simulated submerged conditions. Tolerant cultivars accumulated greater contents of NSC compared to the susceptible cultivars. Starch and total NSC content showed significant positive association with survival percentage. On the other hand, elongation due to submergence was significantly a negative association with survival. The CO₂ photosynthetic rate, chlorophyll content, maximum photochemical efficiency of PS II (Fv/Fm), and activities of Rubisco were not significantly different between tolerant and susceptible cv under control condition. The ADP glucose pyrophosphorylase (AGPPase) activity was significantly higher in the tolerant cv and was a positive association with starch/NSC, whereas Fructose 1,6-diphosphatase (FDPase) activity was significantly higher in susceptible cv compared to tolerant cv and was a negative association with starch/NSC. Greater activities of AGPPase along with lower activities of FDPase might facilitate greater accumulation of NSC in tolerant rice cultivars.     

Influence of inoculation with Ascochyta rabiei on the mineral contents of resistant and susceptible cultivars of chickpea

The determination of mineral contents of healthy as well as Ascochyta rabiei inoculated resistant, moderately resistant, moderately susceptible and susceptible cultivars revealed that the amount of N, P, Zn and Fe did not vary much in healthy plants of the resistant and susceptible cultivars. The amount of K and S was greater in the susceptible cultivars compared to the resistant cultivars while the reverse was true for Cu and Mn. Barring the recovery of Cu and Fe, the amount of all other elements (N, P, K, S, Zn and Mn) was enhanced upon inoculation of resistant, moderately resistant, moderately susceptible and susceptible cultivars. There was a noticeable increase in the amount of K in the resistant cultivars and the reverse was true for P, S and Mg contents after inoculation.     

The activity of antioxidative enzymes,contents of H<Subscript>2</Subscript>O<Subscript>2</Subscript> and of ascorbate in tomato leaves of cultivars more or less sensitive to infection with <Emphasis Type="Italic">Botrytis cinerea</Emphasis>

The aim of the present studies was to compare H₂O₂ and ascorbate contents as well as peroxidase (PO) and catalase (CAT) activities in leaves of less susceptible cultivar Perkoz and more susceptible Corindo after B. cinerea infection. Increase in H₂O₂ contents in both Perkoz and Corindo cytosol was observed, however, it appeared earlier in the less susceptible cultivar. The increase in PO activity in the cytosol fraction was observed 48 hours after infection in both cultivars but it was greater in the less susceptible Perkoz. No significant differences between the tested cultivars were observed in ascorbate peroxidase (APX) activity and in reduced and oxidated ascorbate contents. PO activity was thoroughly analyzed in the apoplast fraction. It was measured with syringaldazine (S), tetramethylbenzidine (TMB) and ferulic acid (FA)—substrates characteristic of isoenzymes involved in lignification and stiffening of a cell wall. Increase in PO activity with these substrates was observed earlier in cultivar Perkoz than in cultivar Corindo. Similarly, increase in PO activity with NADH appeared significantly earlier in cultivar Perkoz. Apoplastic PO was separated with DEAE Sepharose and two fractions binding and non-binding were obtained. Binding PO fraction was significantly more active especially with S, TMB and NADH after B. cinerea infection. The increase in the enzyme activity was mostly observed in cultivar Perkoz. Binding PO was separated by electrophoresis on acrylamide gel and revealed six enzymatic forms from which three were much more active after infection in cultivar Perkoz. The obtained results suggest that cell wall strengthening mediated by apoplast PO is a key factor responsible for different resistance of tomato cultivars Perkoz and Corindo to B. cinerea infection.     

Changes in activity of lysine decarboxylase in winter triticale in response to grain aphid feeding

Changes in lysine decarboxylase (LDC) activity caused by Sitobion avenae (F.) feeding on two winter triticale cultivars (cvs) were studied. The aphid fecundity and values of intrinsic rate of natural increase showed that cv Witon was less susceptible to S. avenae than cv Tornado. The grain aphid feeding on more susceptible triticale caused a decrease in the LDC activity, with exceptions of root tissues after two weeks of the feeding. In case of less susceptible cv Witon reduction of the LDC activity was observed only during initial period of S. avenae feeding. Later the aphid infestation induced activity of the LDC within tissues of cv Witon.     

Regulation of superoxide dismutase isoforms in resistant and susceptible strawberry cultivars subjected to leaf spot disease

Abstract

Macroscopic symptoms were observed in two strawberry cultivars, with the degree of symptom intensity varying depending on the susceptibility of the cultivars, i.e. resistant or susceptible. The symptoms presented as red spots and were observed 30 d following leaf tissue inoculation with the Mycosphaerella fragariae pathogen. A comparison of the superoxide dismutase isoform profiles obtained by gel electrophoresis in all samples extracted from both resistant and susceptible cultivars indicated one constant sharp band, identified as Mn[sbnd]SOD with a molecular mass of 19 kDa. The intensity of this band was higher in all samples derived from the resistant cultivar than in those from the susceptible cultivar. Another superoxide dismutase (SOD) isoform, identified as CuZn[sbnd]SOD with a molecular mass of 16 kDa, was detected in all soluble proteins derived from the resistant cultivar. This isoform was not observed in the susceptible cultivar; however, following an incremental increase in the amount of loaded protein, it was illuminated as a faint band in a sample collected 3 d after inoculation, indicating insufficient production of the CuZn[sbnd]SOD isoform in the susceptible cultivar during an oxidative burst induced by the M. fragaria pathogen. Several bands were also characterized in both cultivars containing Fe and Mn as their co-factors (Fe, Mn[sbnd]SOD). Unlike in the resistant cultivar, where the activity of Fe, Mn[sbnd]SOD isoforms gradually and regularly increased and reached its highest level on the third day after inoculation, the activity of the isoforms changed irregularly over 20 days of study in the susceptible cultivar.     

Suppression of phenylalanine ammonia-lyase activity elicited in date palm by Fusarium oxysporum f. sp. albedinis hyphal wall elicitor

The inoculation of the seedling roots of the resistant (Bousthami Noir) and susceptible (Jihel) date palm (Phoenix dactylifera) cultivars by Fusarium oxysporum f. sp. albedinis induced an increase in phenylalanine ammonia-lyase (PAL) activity. The response of the PAL activity in the resistant cultivar was faster and higher than in the susceptible one. However, the elicitation of the seedlings with the hyphal wall elicitor (HWE) of the pathogen induced identical PAL activity in both cultivars. In the resistant cultivar, the the PAL activity elicited with the HWE was not influenced by the addition of the fungal culture filtrate (FCF) whereas it was suppressed in the susceptible cultivar. This FCF suppressor effect was dose-dependent, not influenced by sodium periodate, whereas it was strongly reduced by the heat (121 °C for 45 min) and pronase E. These results show that differential induction of the defence mechanisms in both cultivars was not related to differences in the induction of the PAL activity, but to the suppression of its elicitation in the susceptible cultivar.     

Role of Phenylalanine Ammonia Lyase and Polyphenol Oxidase in Host Resistance to Bacterial Wilt of Tomato

Plants respond to bacterial pathogen attack by activating various defence responses, which are associated with the accumulation of several factors like defence-related enzymes and inhibitors which serve to prevent pathogen infection. The present study focused on the role of the defence-related enzymes phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) in imparting resistance to tomato against bacterial wilt pathogen Ralstonia solanacearum . The temporal pattern of induction of these enzymes showed maximum activity at 12 h and 15 h for PAL and PPO, respectively, after the pathogen inoculation (hpi) in resistant cultivars. Twenty different tomato cultivars were analyzed for PAL, PPO and total phenol content following pathogen inoculation. The enzyme activities and total phenol content increased significantly (P < 0.05) in resistant cultivars upon pathogen inoculation. The increase in enzyme activities and total phenol content were not significant in susceptible and highly susceptible cultivars. The role of PAL and PPO in imparting resistance to tomato against bacterial wilt disease is discussed.     

Correlation of cytological and biochemical parameters with resistance and tolerance to Mycosphaerella graminicola in wheat

This study investigated the infection process of Mycosphaerella graminicola and enzyme activities related to reactive oxygen species (ROS) or oxylipin biosynthesis in four French wheat cultivars with variable resistance to M.?graminicola infection. At field level, cultivars Caphorn, Maxyl and Gen11 were susceptible, whereas Capnor showed high levels of quantitative resistance. Moreover, Capnor and Gen11 were tolerant, i.e., their yield was less affected by infection compared to non-tolerant Maxyl and Caphorn. These four cultivars were inoculated under laboratory conditions with the M.?graminicola IPO323 reference strain. Cytological and biochemical responses were studied on collected first plantlet leaves and several features discriminated between cultivars. However, resistance and tolerance had no impact on the fungal infection process. Levels of lipoxygenase (LOX), peroxidase (PO) and glutathione-S-transferase (GST) activities were also compared with regard to cultivar resistance or tolerance to M.?graminicola. LOX, PO and GST activities did not discriminate resistance and tolerance profiles, although a low level of PO in inoculated and non-inoculated plants could be associated with tolerance. In addition, cell necrosis correlated positively with LOX in non-tolerant cultivars, while mycelia surrounding stomata were positively correlated with PO in the resistant cultivar. GST activity presented correlations between cytological and biochemical parameters only for susceptible cultivars. Stomatal and direct penetration were positively correlated with GST activity in the susceptible non-tolerant cultivars, while these correlations were negative in the tolerant cultivar. When combining cytological and biochemical observations with resistance and tolerance profiles, for each cultivar and at each time point, cultivars could be classified in tight accordance with their previous field characterisation. Moreover, tolerance allowed us to distinguish susceptible cultivars when both biochemical and cytological parameters were considered together.     

Relationship between Cell Wall Susceptibility to Cellulases and Pectinases of Fusarium oxysporum and Susceptibility of Date Palm Cultivars

Fusarium oxysporum f. sp. albedinis, the bayoud disease agent of date palm, grows on a mineral medium containing the cell walls of date palm roots as a sole carbohydrate source. The growth and development of pathogen under these conditions was related to the production of extracellular cell wall-degrading enzymes (CWDE): cellulases, polygalacturonases, polygalacturonate transeliminases, and pectinmethylesterases. The mycelial growth and the sporulation of pathogen were higher in the presence of cell walls of susceptible cultivars (BFG, JHL, BSK) than in the presence of those of resistant cultivars (IKL, SLY, BSTN). After 8 d of fungal culture, the activity of CWDE was equal whatever is the origin of the cell walls (resistant or susceptible cultivars). After 16 d of culture, the activity of these CWDE was higher when the parasite was cultivated on the cell walls of the susceptible cultivars than on those of the resistant cultivars. A positive correlation was observed between CWDE activities and the growth and the sporulation of F. oxysporum after 16 d of culture. These results clearly show a relation between the susceptibility/resistance of the cell walls of the roots of the date palm to the parasitic CWDE and the susceptibility/resistance of the cultivars.     

The Relationship Between Peroxidase Activity and the Resistance of Tomatoes (Lycopersicum esculentum) to Verticillium dahliae

The levels of peroxidase activity in roots of non-infected tomato plants resistant to Verticillium dahliae Kleb., were found to be considerably higher than those in the roots of susceptible plants. Similar differences were found in the leaves but were not significant as in the roots. Peroxidase activity increased in leaves, stems and roots of both susceptible and resistant plants after infection with V. dahliae. The ratio of the increase in leaves and roots of susceptible plants was greater than those of resistant plants. A positive correlation was found between the peroxidase activity in the roots of eleven cultivars/breeding lines and presence of Ve gene.