Effect of infection byPhytophthora infestans on phenolics in potato tubers with various degrees of field resistance

Summary Browning of potato tubers infected withPhytophthora infestans was correlated with field resistance. The composition of brown material extracted from tubers was investigated by preparing alkaline-neutral difference spectra, which were similar to those obtained from a model system of tuber cell walls incubated with ferulic or p-coumaric acids and H₂O₂. The activities of L-phenylalanine ammonia lyase, peroxidase and phenolase in wounded tissue were correlated with resistance. After infection, peroxidase and phenolase activities were reduced, the greatest reduction being in the most resistant variety. The relation between field resistance and wounding is discussed.

---

Zusammenfassung Ein Vergleich von drei Kartoffelsorten unterschiedlicher unspezifischer Resistenz (Feldresistenz) gegenPhytophthora infestans zeigte, dass eine zunehmende Resistenz positiv korreliert war mit einer verst?rkten Br?unung des Knollengewebes nach der Infektion. Der Grad der Eindringung des Pilzmyzels war mit der Resistenz negativ korreliert und die Suberinisierung der Schnittfl?che vor der Inokulation erh?hte die Resistenz gegen die Eindringung (Abb. 1). Aus dem infizierten Gewebe wurde mit Phenol-Essigs?ure-Wasser (PAW) mehr braunes Material und von dunklerer Farbe herausgel?st als aus dem nicht infizierten Gewebe. Die Substanz enthielt Chlorogens?ure oder andere Chinas?ureester (Tab. 1). Die Differenz-Spektren der Phenol-Essigs?ure-Wasser-Extrakte im alkalischen bzw. neutralen Bereich von infiziertem und nicht infiziertem Gewebe waren unterschiedlich, was auf Unterschiede in dem phenolischen Material, das in die Zellw?nde eingelagert wurde, hinwies (Abb. 3). Die Spektren waren ?hnlich denen, die mit einem Modellsystem aus Knollenzellw?nden mit zugesetzter Ferula-oder p-Cumars?ure und H₂O₂ erzielt wurden (Abb. 4). Im verletzten Gewebe waren die Aktivit?ten der Enzyme L-Phenylalaninammoniumlyase, Peroxidase und Phenolase mit der Sortenresistenz korreliert (Tab. 3–5). Nach der Infektion waren die Aktivit?ten der Phenolase und der Peroxidase vérringert und die Abnahme war mit der Resistenz korrliert. Die Auspr?gung der unspezifischen Resistenz in Knollen scheint auf zwei Faktoren zu beruhen: der F?higkeit des Gewebes nach der Verletzung Suberin zu bilden, um das Eindringen des Erregers zu hemmen und der Produktion von zus?tzlichen braunen Phenolverbindungen, die in die Wirtszellw?nde eingelagert werden und dadurch deren Struktur so ver?ndern, dass eine Eindringung des Pilzes begrenzt wird.

---

Résumé Une étude portant sur trois variétés de pomme de terre présentant une différence de résistance au champ vis à vis dePhytophtora infestans montre qu'une augmentation de résistance est corrélée positivement à un brunissement croissant des tissus du tubercule après contamination. Le taux de pénétration du mycélium est corrélé négativement à la résistance; la subérisation de la surface coupée avant contamination augmente la résistance à la pénétration (fig. 1). La substance obtenue par extraction dans un mélange phénol-acide acétique-eau est plus brunatre et de couleur plus sombre lorsque le tissu est contaminè par rapport à un tissu non contaminé. L'extrait contient de l'acide chlorogénique ou d'autres esters d'acide quinique (tableau 1). Les spectres obtenus à partir d'extraits du mélange phénol-acide acétique-eau dans les phases alcanine et neutre sont différents entre des tissus contaminés et non-contaminés; ceci indique un changement dans la nature de la substance phénolique déposée dans les parois cellulaires de tubercule avec adjonction d'acides férulique ou p-coumarique et d'H₂O₂ (fig. 4). Les activités d'enzymes L-phenylalanine ammonialyase, peroxidase et phénolase (tableaux 3–5) sont corrélés, pour des tissus endommagés, à la résistance variétale. Après contamination, les activités phénolase et péroxidase sont réduites, la diminution étant liée à la résistance. L'expression de la résistance au champ au niveau des tubercules semble reposer sur deux facteurs: la capacité du tissu à produire la subérine après endommagement afin d'inhiber la pénétration du pathogène et la production de composés phénoliques bruns après contamination, qui se déposent dans les parois cellulaires réceptrices, modifiant ainsi leur structure de fa?on à limiter la pénétration du champignon.

     

Methods of assessing potato tubers for resistance to bacterial soft rot

Summary The susceptibility to soft rot caused byErwinia carotovora subsp.atroseptica of five potato cultivars and potato clones from the potato breeding programme at J?geva Plant Breeding Institute was assessed in a laboratory test. Three test methods were used: a single site inoculation, vacuum infiltration and slice inoculation. The severity of the disease varied widely with the different methods, which gave different cultivar rankings.     

Studies on the initiation of bacterial soft rot in potato tubers

Summary Non-inoculated whole tubers rot readily under anaerobic conditions when their surface is maintained moist in a water-saturated atmosphere. Rotting is reduced under otherwise similar but aerobic conditions, but there is some rotting under anaerobic conditions even if their surface is dry. The evidence obtained suggests the following sequence of events under wet anaerobic conditions. Water is absorbed causing the lenticels to open. Oxygen deficiency affects cell membrane integrity and there is leakage of water and solutes from turgid cells which establishes a continuous liquid phase between the cortex and the lenticels. Organisms in the lenticels then penetrate deeper into the tuber in this liquid phase. The leaked cell contents, together with the apparent reduction of tuber resistance to infection under anaerobic conditions, allow rapid growth of bacteria. If pectolytic bacteria are present a soft rot lesion is then established.

---

Zusammenfassung Nicht inokulierte Knollen der Sorte Majestic faulten nicht, wenn sie in N₂ bei 93, 95 oder 98% relativer Feuchtigkeit und bei Raumtemperatur w?hrend 10 Tagen gelagert wurden (Tabelle 1). Unter anaeroben Bedingungen faulten sie jedoch sofort, wenn ihre Oberfl?che in einer wasserges?ttigten Atmosph?re feucht gehalten wurde (Tabelle 2). Unter gleichen, jedoch aeroben Bedingungen wurde das Verfaulen gehemmt, aber unter anaeroben Bedingungen und bei trockenen Oberfl?chen trat keine F?ulnis auf (Tabelle 2). Wenn einzelne Lentizellen inokuliert wurden mitE. carotovora var.atroseptica (Isolat 27), entwickelte sich eine L?sion weder unter aeroben noch unter anaeroben Bedingungen, sofern die Lentizellen geschlossen und die Knollenoberfl?che trocken waren (Tabelle 3). Bei offenen und wuchernden Lentizellen trat jedoch sofort F?ulnis ein, aber nur wenn anaerobe Bedingungen vorherrschten (Tabelle 3). Knollen mit teilweise nassen Oberfl?chen, gelagert in N₂, nahmen an Gewicht zu und wurden turgeszenter (Tabelle 4). Gleichzeitig mit diesen Aenderungen ?ffneten sich die Lentizellen zunehmends, und ihr Gewebe begann zu wuchern (Abb. 1). Die Abnahme an Elektrolyten und der Wasserverlust der Knollengewebescheiben waren unter anaeroben Bedingungen gr?sser als unter aeroben (Abb. 2). Die Abnahme an Elektrolyten und der Verlust im Frischgewicht waren unter anaeroben Bedingungen bei Scheiben mit einem hohen (turgeszenten) Wasserstatus gr?sser als bei solchen mit einem niedrigen (nicht turgeszenten) Wasserstatus (Abb. 3). Die Unterschiede im ‘Apparent Free Space’ der turgeszenten und nicht turgeszenten Scheiben, die unter aeroben und anaeroben Bedingungen gehalten wurden, zeigen ferner an, dass die Durchl?ssigkeit der Zellen unter anaeroben Bedingungen und besonders in turgeszenten Gewebe zunimmt (Tabelle 5). Diese Unterschiede werden wiederspiegelt in der Anf?lligkeit der Scheiben für das Entstehen der F?ulnis, das in erster Linie von der An- oder Abwesenheit von O₂ und in geringerem Umfang vom Wasserstatus in den Scheiben abh?ngt. Wenn wir diese Ergebnisse zusammenfassen, k?nnnte die Ausl?sung des F?ulnisprozesses wie folgt beschrieben werden: Unter nassen anaeroben Bedingungen wird das Wasser aufgenommen und veranlasst die Lentizellen, sich zu ?ffnen. Sauerstoffmangel beeinflusst die Integrit?t der Zellmembranen, und es tritt ein Verlust an Wasser und gel?sten Bestandteilen der turgeszenten Zellen ein, was zu einer st?ndigen flüssigen Phase zwischen der Rinde und den Lentizellen führt. Die Organismen in den Lentizellen dringen dann tiefer durch diese flüssige Zone in die Knolle ein. Der abgeflossene Zellinhalt, zusammen mit der offensichtlichen Verringerung der Resistenz der Knolle gegen die Infektion unter anaeroben Bedingungen, erlauben das rasche Wachstum der Bakterien. Wenn pectolytische Bakterien vorhanden sind, bildet sich eine Nassf?ule-L?sion.

---

Résumé Des tubercules non inoculés de la variété Majestic ne pourissent pas quand ils sont conservés dans N₂ à 93, 95 ou 98% d'humidité relative (RH) à température ambiante pendant 10 jours (tableau 1). Cependant, quand on maintient une certaine humidité à la surface des tubercules dans un milieu anaérobe la pourriture se developpe rapidement (tableau 2). La pourriture est réduite dans des conditions semblables à d'autres égards mais aérobies; toutefois il n'y a aucune pourriture en condition anaérobie si la surface des tubercules est sèche (tableau 2). Lorsqu'on inocule des lenticelles individuellement avecErwinia carotovora var.atroseptica (isolat 27), aucune lésion ne se produit en conditions aérobies et anaérobies lorsque les lenticelles sont fermées et la surface des tubercules sèche (tableau 3). Toutefois la pourriture apparait rapidement si les lenticelles s'ouvrent et prolifèrent mais seulement lorsque des conditions anaérobies sont prédominantes (tableau 3). Les tubercules présentant une surface partiellement humide et conservés dans N₂ augmentent en poids et deviennent plus turgescents (tableau 4). Simultanement il y a une ouverture progressive des lenticelles et proliférations de leur tissu (fig. 1). Les pertes d'électrolytes et d'eau provenant de disques de tissu de tubercule sont plus importantes en milieu anaérobie qu'aérobie (fig. 2). La perte d'electrolytes et la perte de poids frais en condition anaérobie sont également plus grandes pour les disques ayant une forte teneur en eau (turgescents) que les disques à faible teneur d'eau (non turgescents) (fig. 3). Les différences en espace libre apparent entre disques turgescents et non turgescents tenus dans des conditions aérobie et anaérobie indiquent ultérieurement que la perméabilité cellulaire augmente en condition anaérobie et notablement dans les tissus turgescents (tableau 5). Ces différences se reflètent dans la susceptibilité des disques à pourrir, susceptibilité qui depend en premier lieu de la présence ou de l'absence de O₂ et, dans une moindre mesure, de la quantité d'eau dans les disques. Prenant en considérations ces results, la pourriture dans les tubercules pourrait débuter comme suit. Dans des conditions humides anaérobies, l'eau est absorbée causant l'ouverture des lenticelles. Le manque d'oxygène porte atteinte à l'intégrité de la membrane cellulaire et il y a une fuite d'eau et de produits solubles à partir de cellules turgescentes, ce qui réalise une phase liquide continue entre le cortex et les lenticelles. Dans cette phase liquide, les organismes se trouvant dans les lenticelles pénètrent alors plus profondément dans le tubercule. La perte de matières cellulaires, en meme temps que la réduction apparante de la résistance du tubercule à l'infection en condition anaérobie, permettent un développement rapide des bactéries. Si des bactéries pectolytiques sont présentes, des lésions de pourriture molle s'etablissent dès lors.

---

---

The substance of this paper was presented at a session of the Pathology Section at the 5th Triennial Conference of the EAPR (Norwich, September 1972).     

Induction of systemic resistance and defense-related enzymes after elicitation of resistance by rhizobacteria and silicon application against Ralstonia solanacearum in tomato (Solanum lycopersicum)

Bacterial wilt caused by Ralstonia solanacearum is a devastating plant disease affecting several economically important crops. To trigger plant-mediated systemic resistance against the pathogen, silicon and the rhizobacteria strain Bacillus pumilis were applied as elicitors. The impact of each elicitor in the induction of systemic resistance was evaluated by individual or dual application in pathogen inoculated tomato genotypes. Application of silicon and B. pumilis significantly reduced bacterial wilt incidence by 50.7 and 26.7%, respectively, in the King Kong 2 genotype (moderately resistant) and by 31.1 and 22.2%, respectively, in the L390 genotype (susceptible) but the dual application of the elicitors did not. The pathogen responsive lipoxygenase (LOX) activity was decreased in the silicon-treated tomato plants and no significant difference was detected in B. pumilis treated-pathogen inoculated plants compared to the control. In addition, a non-significant increases of peroxidase (PO) activity and phenylalanine ammonia lyase (PAL) activity were observed in either silicon/B. pumilis treated and pathogen inoculated plants. However, the PO, PAL and LOX activities declined during the dual application due to antagonistic effect of the two pathways triggered by the two elicitors. Therefore, separate application of each elicitor is recommended as the best strategy for induction of systemic resistance against bacterial wilt in tomato with silicon being a stronger inducer than B. pumilis.     

Suppression of bacterial soft rot in potato tubers by application of kasugamycin

An immersion in aqueous solutions of Kasumin®, containing kasugamycin at 10 to 320 mg/L (ppm) for 1 to 320 sec delayed or prevented the development of soft rot on inoculated (Erwinia carotovora subsp.carotovora) tuber disks incubated over wet filter paper at 24C for 24 to 72 hr. Treatment efficacy decreased as inoculum level and incubation period increased. Short immersion periods were not as effective as longer ones. When stored tubers were inoculated withE. c. carotovora and incubated up to 5 days in fog chamber at 20 C, immersion treatments in 20 to 400 ppm kasugamycin either had no effect or increased soft rot development. By contrast, when the stored tubers were cut into sections before inoculation and treatment, immersion in 300 ppm reduced soft rot development on the cut surfaces from 83% (inoculated controls) to 3.2%. With non-inoculated sections, treatment with 25 ppm reduced the SAD from 13.3 to 0.6%. Wash or rinse treatment of freshly harvested tubers in 40 to 160 ppm produced a significant reduction in the severity of bacterial soft rot among tubers incubated for 72 to 96-hr. The 160-ppm treatment delayed disease onset by at least 24 hr. Pre-washing freshly harvested tubers with clean or chlorinated water prior to antibiotic treatment did not consistently improve the efficacy of the kasugamycin treatment.     

Comparison of the effectiveness of different methods of screening for bacterial soft rot resistance of potato tubers

Tubers from eight potato cultivars (cvs) grown at two different locations in Wisconsin were tested for bacterial soft rot resistance using different inoculation techniques. The procedures included 1) point inoculations of tubers with different inoculum levels followed by incubation in ambient or low oxygen condtions, 2) inoculation of mechanically bruised tubers followed by incubation in a mist chamber, and 3) a standard slice inoculation method. The point titration test followed by incubation in dew chamber and the mist chamber-bruise test showed similar patterns of resistance for cultivars that were used in these experiments. These two methods are considered to be effective for screening potato tubers for bacterial soft rot resistance. Point titration methods are very useful if only limited numbers of tubers are available. The mist chamber-bruise test is simpler than the other procedures; however, to obtain reproducible results large numbers of tubers are required. Because of the great variability of the results obtained in inoculation of slices, the reliability of this approach can be questioned as a standardized method for evaluation of resistance. Tubers of somatic hybrids ofS. brevidens andS. tuberosum and their sexual progeny were significantly more resistant to bacterial soft rot than tubers of moderately resistant cultivars when evaluated by each of the assay procedures.     

Effect of acetylsalicylic acid on soft rot produced byErwinia carotovora subsp.carotovora in potato tubers under greenhouse conditions

Summary The efficiency of acetylsalicylic acid (ASA) in inducing localised acquired resistance against infection byErwinia carotovora subsp.carotovora was evaluated by treating potato tubers with ASA at three concentrations. Three days after treatments, tubers were inoculated withE. carotovora subsp.carotovora by wound inoculation or by irrigation with a bacterial suspension. Experiments were performed for two consecutive years. Statistical analysis revealed that treatment of tubers by immersion in ASA solutions at low concentrations induced a significant reduction in the soft rot incidence. Wounding of the tubers was the most effective inoculation method and ASA at concentration of 0.0125% (w/v), pH 7 was more efficient than at 0.025 or 0.05%. No phytotoxicity of such treatment was observed.     

Reducing the potential for bacterial soft rot in potato tubers by chemical treatments and drying

The potential for bacterial soft rot caused byErwinia carotovora in freshly inoculated potato tubers was reduced up to 99% by immersion for 5 min in solutions of sodium hypochlorite (chlorine bleach) containing up to 10,000 ppm chlorine. Reductions up to 93% were achieved using a combination treatment of immersion in 1% citric acid for 5 min followed by airdrying. Immersion treatment alone in 1% aqueous solutions of citric, acetic, ascorbic, or malonic acid also significantly reduced the soft rot potential. In contrast, no reductions accompanied treatment with solutions of potassium or calcium acetate. All treatments including the combination immersion/airdrying treatment were much less effective if tubers had been infiltrated initially with soft rotErwinia or had numerous mechanical injuries. If tubers had not been infiltrated with the causal organism, immersing them in 1% citric acid reduced the potential nearly as much as a similar treatment with 1000 ppm chlorine. A 30-sec immersion in the latter was less effective than a similar treatment with 500 ppm a.i. CGA 78039, an experimental bactericide. However, air-drying, coupled with provisions for keeping tuber surfaces free from moisture, remains the most effective means of reducing losses to bacterial soft rot.     

Volatile metabolic profiling for discrimination of potato tubers inoculated with dry and soft rot pathogens

Volatile metabolites from ‘Russet Burbank’ potatoes inoculated withErwinia carotovora ssp.carotovora (ECC),Erwinia carotovora ssp.atroseptica (ECA), andFusarium sambucinum (FSA) were analyzed by sampling the headspace at 3 and 6 days after inoculation and then using a gas chromatograph/mass spectrometer (GC/MS) to identify the compounds. Non-wounded noninoculated and wounded non-inoculated tubers served as checks. Compounds with an abundance of ≥10⁵ and with frequency of ≥3 out of 20 replicates (10 replicates × 2 incubation times) were subjected to further analysis. A total of 81 volatile metabolites were detected, of which 58 were specific to one or common to a few, but not to all inoculations/diseases. Acetic acid ethenyl ester was unique to ECA, while cyclohexene, diazene, and methoxy-(1,1-dimethyl-2-dihydroxy-ethyl)-amine were unique to ECC, and 2,5-norbornadiene and styrene were unique to FSA. Several metabolites were common only to tubers inoculated with ECC and ECA and were not detected in fungus-inoculated or in control tubers. High abundances of acetone and butane were detected in ECC- and ECA-inoculated tubers, respectively. The possible use of differences in volatile metabolic profiles to discriminate diseases of potato tubers in storage is discussed.     

Bacterial soft rot potential in washed potato tubers in relation to temperatures of tubers and water during simulated commercial handling practices

The bacterial soft rot potential in potato tubers was affected by differences in temperature between tubers and suspensions ofErwinia carotovora at the time of inoculation by immersion. In general, disease severity after incubation was higher when tuber temperatures were higher as opposed to equal to or lower than that of water containing cells of the bacterium. Disease severity was also greater when tubers were stored at 20° to 23°C in contrast to 4° or 26° to 30°C for 16–18 h prior to immersion. Tubers with a pulp temperature of 8°C were more prone to bruise injury as compared with those at 18°C when struck with a pendulum type bruising instrument. When the injured tubers were inoculated and incubated, most bruises became infected with soft rot bacteria.     

Resistance to late blight and soft rot in six potato progenies and glycoalkaloid contents in the tubers

Glycoalkaloids are anti-nutritional compounds commonly found in wildSolanum species used as resistance sources to major potato pathogens. It is therefore important for breeding purposes to know whether selecting for resistance using such species necessarily selects also for high glycoalkaloid contents in the tubers. To test this hypothesis, we used six partial progenies from crosses betweenSolanum tuberosum and accessions ofS. andigena, S. berthaultii, S. phureja, andS. vernei to investigate the possible correlation between resistance toPhytophthora infestans and/or toErwinia carotovora subsp.atroseptica and the concentration of glycoalkaloids in tubers. Concentrations of α-solanine and α-chaconine in the tubers segregated in each progeny, as did resistance to each pathogen. Some, but not all, clones from each progeny showed hypersensitive reactions to the isolate ofP. infestans used. Furthermore, clones within each progeny also differed for components of partial resistance toP. infestans, suggesting that all four wild species could be used as sources of both race-specific and partial resistance to late blight. With the exception of low, but statistically significant, correlations between concentration of α-solanine and two late blight resistance components (incubation period and spore production per unit lesion area) in progenies derived fromS. vernei, and despite a trend towards higher glycoalkaloid concentrations in the tubers of the clones most resistant to soft rot within progenies derived fromS. berthaultii andS. vernei, no consistent relationship between resistance to either disease and concentrations of α-solanine and/or α-chaconine was observed. These results indicate that neither race-specific nor partial resistance to late blight and soft rot in the accessions used as progenitors of resistance depend on high solanine or chaconine concentrations. These resistance sources could thus prove useful in breeding programs for improved behaviour againstP. infestans and/orE. carotovora.     

The involvement of phenolics and phytoalexins in resistance of potato to soft rot

Summary Phenolics, for example chlorogenic, caffeic and ferulic acid, and phytoalexins, such as rishitin and phytuberin, were identified in potato tubers cv. Kufri Chandramukhi. The tissue of healthy tubers contained no detectable phytoalexins but did contain phenolics. The levels of these compounds were correlated with soft rot development. The rotting tissue either was free of these groups of compounds or had low concentrations. The wound periderm formed as a result of recovery from injury and infection contained high levels of the compounds. Much higher concentrations were detected at lower storage temperatures when oxygen supply was adequate. Antibacterial properties of the phenolics identified were tested againstErwinia carotovora which was inhibited by chlorogenic, caffeic and ferulic acids. The three phenolics were more effective together, in proportions in which they occurred in wound periderm, than individually. It was observed that none of these phenolics could inhibit pectolytic enzymes ofE. carotovora.     

Evaluation of potato varieties and selections for resistance to bacterial soft rot

Potato varieties and selections were evaluated for resistance to bacterial soft rot caused byErwinia carotovora subsp. carotovora and Erwinia carotovora subsp. atroseptica in mist chamber. A randomized complete block design with a single treatment and 3 replications was used in this study. Potato lines were inoculated with bacterial suspension (10 tubers / line) using the puncture inoculation method and incubated for 4 days in a mist chamber at 21 C and 100 % relative humidity in the dark. Although there were differences in incidence of soft rot and in amount of weight reduction, most of the potato lines were susceptible to tuber soft rot. Mean incidence (%) of soft rot ranged from 10 to 100%. Mean reduction of tuber weight (%) ranged from 0.13 to 16.43 %. Among the varieties and selections tested, AF 522-5 was the most resistant to tuber weight loss, while AF 1424-7 was most susceptible. There were also significant differences between years, and a variety by year interaction. Testing over a period of years is recommended. A significant correlation coefficient of soft rot incidence (%) and reduction of tuber weight (%) was obtained (r=0.65; P=0.05), indicating that incidence was a fair measure of soft rot potential. However, the greater variability in results for incidence make weight loss a better measure of soft rot reaction. There was a significant difference among varieties in the reduction of tuber weight when potato lines were inoculated either 1 month or 2 months after harvest, but the interaction of time by year prohibits a conclusion as to which time gives a better test reaction. Late maturing varieties had slightly less weight loss than earlier maturing varieties.     

Subcellular localisation of calcium in potato tubers

Summary Deposits, believed to contain calcium, were located in different cells of the potato tuber after using an antimonate procedure. In the starch-storage parenchyma of the medulla and cortex antimonate deposits were abundant within vacuoles, on the tonoplast, and to a lesser extent in cell walls. Phloem tissues contained a high concentration of deposits, mainly within companion cells and phloem parenchyma, consistent sites of deposition being mitochondria, plastids and tonoplasts. Deposits were abundant within vacuoles of cells of the xylem parenchyma. Within vessel elements deposits were limited to the surface of secondary wall thickenings. Antimonate deposits associated with the middle lamella of xylem parenchyma were rarely found. The results are discussed in relation to previous findings for potato tubers and for higher plant cells in general.     

小麦高温抗条锈性表达与苯丙氨酸解氨酶和多酚氧化酶活性的关系

测定了小麦高温抗条锈性表达过程中小麦叶内苯丙氨酸解氨酶和多酚氧化酶的活性变化。结果表明，高温抗条锈性品种，在小麦高温抗条锈性表达过程中，接种寄主叶内PAL活性对高温非常敏感。在高温处理12h时PAL活性就很快增高，到24h就达到活性高峰，形成一个对高温敏感的特异峰，且该峰可以从高温处理12h持续到72h。小种专化抗锈性的PAL活性也较对照增高，但对温度处理没有明显的活性峰。多酚氧化酶在高温抗条锈性表达过程中变化与对照无明显变化。