Fusarium on surface of tubers of selected potato varieties

Zentralbl. Mikrobiol. 144 (1989), 399- 404 VEB Gus tav Fischer Verlag Jena

[Institute of Microbiology, Czechoslovak Academy of Sciences, Prague, CSSR]

Fusarium on Surface of Tubers of Selected Potato Varieties J. VRANY , M. RASOCHOVA, 1.

DOBIA~

and V. HORACKOVA

Summary After two consecutive years first data on the occurrence of representatives of the genus Fusarium on healthy tubers of 25 potato varieties of various provenance after harvest and during storage have been obtained. Samples were obta ined in 7 localities of the main potato-growing regions in Czech oslovakia. F. solani (MART .) SACCo, F. solani var. coeruleum (SACC.) BOOTH comb . nov., F. sambucinum (FUCKEL) and F. oxyspor um (SCHLECHT.) were most frequent. The other 5 specie s were also detected. Co ntamination of the tubers by Fusarium differed in indiv idual years depending on the seed origin, soil conditions and properties of a given variety played also a role here. A minor part of the isolate s exhibited in vitro medium to high pathogenicity against potato var. "Radka", Storage did not significantly influence the occurrence and co mposition of Fusarium representatives on the tubers .

Zusammenfassung Von zwei aufeinanderfo lgenden Jahren wurden Daten tiber das Vorkommen von Fusarium-Arten an gesunden Knollen von 25 Kartoffelsorten unterschiedl icher Herkun ft nach der Ernte und wahrend der Lagerung erfaBt. Die Proben stammten von 7 Standorten der Hauptkartoffelanbau gebiete dcrTschecho slovakei. F. solani (MART.) SACC. , F. solani var. coeruleum (SACC.) BOOTH com b. nov. , F. sambucinum (FUCKEL) und F. oxysporu m (SCHLECHT.) traten nebcn 5 weiteren Sorten am haufigsten auf. Ocr Befall der Knollen mit Fusar ium in den einzelnen Jahren war abhangi g von der Herkunft des Pflanzgutes, von den Bodenbedingungen und den Eigenschaften der cntsprechenden Sorte. Nur ein geringer Teil der Fusarium-Isolate zeigte in vitro cine mittlere bis hohe Pathogenitat gegenuber der Kartoffelsorte .Radka", Die Lageru ng beeinflul3te nicht signifikant das Auftreten bestimmter Fusarium-Arlen an den Knollen .

Dry rot (fusaria!) of potato tubers (Solanum tuberosum L. ) has become a seriou s storage disease recently . In spite of the fact that its causes have been studied form various point s of view, their solution is still incomplete. In the soil potato tubers are influenced by a numb er of external factors including infective agents, e .g . repre sentatives of the genu s Fusarium and some others, certain of them living on their surface. When the tubers are damaged during harve st and storage they can be attacked by the fungi , and diseases including dry rot can occur. Fusar ium solani (MART.) SACC., F. solan i var. coeruleum (SACC. ) BOOTH comb. nov . , F. sambucinum (FUCKEL) F. sulphureum (SCHLECHT.) and some other species are the most frequ ent infective agent s. Data of indiv idual authors about their occurrence in potato-growing regions vary (BENKEN et al. 1968; BOOTH 1971; BOYD 1972 ; BRASLAVSKA 1972 ; SCHIPPERS 1962; WOJCIECHOWSKA and MIKOLAJSKAJA 1972 ; SALVET 1986). The occurrence of fung i of the genus Fusarium and the Fusarium dry rot of potato tube rs can be influenced by soil and clim atic conditions, by the agrote chnics and harv est system , and also by other factor s, viz . their tran sfer from the seed and soil (ADAMS and LAPWOOD 1983 ; LEACH 1985 ; MESSIAEN et al. 1976). Therefore, the data on soil contamination and contamination of harvested potatoes by pathogenic species of the genus Fusarium are one of the premi sions of the integrated prote ction against this disease . In our potat o-growing regions this problem has not attracted a pronounced attent ion yet. In the present work we concentr ated our efforts on the effect of seed origin, soil type and course of vegetation on the occurrence and species representation of Fusarium

400

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on the surface of healthy tubers of selected potato varieties during 2 consecutive years. The first results of this investigation are presented here.

Material and Method The occurrence of fungi of the genus Fusarium was studied on surface of healthy tubers of potato varieties (Solanum tuberosum L.) cultivated in comparative field experiments at JZD Kouty (Tfebfc district) and at Oseva (state establi shment) VSUB , Valecov. The varieties were cultivated on an area of I ha and crosses on 0.5 ha. In 1984, j ust before the harve st, samples of tuber s of 12 varieties were taken . In 1985 the occurrence of Fusarium was invest igated in the cultivar Radka, which seed was obtained from 6 localities and in I I selected varieties . From the harvest 12 up to 15 tubers of each variety were randomly taken for mycological studie s. The samples were stored in a cold chamber at 4 ± 1 °C. Selected meth ods of the study of the genus Fusar ium in the soil and on the surface of upper plant part s were first compared . As the growth rate of macroc onidia and chlam ydospores is slow and the population of Fusarium is small comp ared to other soil microflora (JEFFRIES et al. 1984) and the pathogen is only rarely different in appearance when associated with non-pathogenic clone s, which is particularly pronounced in Fusarium (SNYDER et al. 1954), we have chosen procedures proposed for the isolation of pathogens and with respect to the aim of the study according to BOOTH (1971 ) and NIRENBERG (1981). Pieces of tuber cortex with attached soil (size I mm", 20-24 parallels) were taken and transferred to nutrient media accordin g to BOOTH (1971 ), JEFFRIES (1984 ), PAPAVIZAS (1967) , and cutivated for 6-16 d at 22 °C and illuminated by fluorescent tubes (300- 400 nm) for 12 h. In enrichment culture s representatives of the genus Fusarium were then detected by means of microscopic method s in combination with monosporic isolation s accordin g to BILAJ (1977) , BOOTH (197 1), DoMSCH and GAMS (1980) and other s. Representative isolates were compared with cultures obtained from the Czechoslovak Collection of Microorgan isms (CCM) at the J. E. Purkyne University , Bmo . Selected isolate s exhibiting a higher growth rate on PDA (BOOTH 1971) were tested for patho genicity with the variety Radka using methods presented by HORACKOVA (1977 ) and JELLIS (1982). The material was analyzed shortl y after the harve st and then after a 4-m onth storage. The occurrence of Fusarium in the samples was expre ssed as the contamination index I k from 9 (no contamination) to I (complete contam ination) and the percentage of the species present was determ ined.

ss

Results The average contamination of the studied varieties of various provenience varied at 40 % during two years (Table I) . In 1984 the average contamination of potatoes by Fusarium was Ik 6.0 , whereas in 1985 it was Ik 5.5 . Most Fusarium representatives belonged to the species Table 1. Fusarium on tubers of selected potato varieties (SV) (%) . Harve st

1984

1985

1984/1985

Number SV

12

18

30

Samples

480

624

11M

4.3 2.1 33.5 0.3 56. 2 3.6

3.2 3.8 22.3 8.7 58.1 3.8

[%J

Fusar1um avenaceum F. culmorum F. oxysporum F. sambucinum

F. solani'Y F. Sp.2)

2.2 5.5

11.1 17.1

60.2 3.9

1) F. solani and F. solani var. coeruleum. 2) F. gram inearum , F. moniliforme and F. sulphureum.

Fusarium on Surface of Tubers

401

Table 2. Fusarium sp. on tubers of selected varieties (%) and contamination index Ok) (harvest 1984). SVI)

"Klara" "Resy" "KE 26" "Otava" "Sarka" "KE 34" "Radka" "HR 32" "VE 37" "Borka" "Svatava" "Blanik"

Fusarium

Ik

solani

aven.

oxysp .

culm.

sambuc .

sp.

65.0 50.0 64.7 78.9 68.0 51.9 50.0 66.7 63.8 66.6 60.0 25.0

0 3.9 0 0 8.0 0 0 0 0 0 0 12.5

0 7.7 11.8 15.8 0 14.8 12.5 20.0 27.3 0 0 25.0

10.0 0 11.8 0 4.0

25.0 38.5 11.8 5.3 12.0 14.8 25.0 0 9.0 0 40.0 12.5

0 0 0 0 8.0 7.4 12.5 13.3 0 0 0 0

11.1

0 0 0 33.3 0 25.0

5.0 4.0 5.5 5.0 4.0 3.5 7.5 6.0 6.5 9.0 8.0 7.5

I) See Table I for explanation.

Table 3. Fusarium sp. on tubers of selected varieties (% ) and contamination index (ld (harvest 1985). SVI)

"Kera" "Karin" "Otava" "Orava" "HR 32" "Radka NO" " Radka PA"

"Radka BE" "Radka BE" "Radka KE" "Radka KE" "Radka VE" "Radka VY" " Nora" "Borka" "Blanik" "Kamyk" "Karnyk"

Fusarium

Ik

solani

awn.

oxysp,

culm.

sambuc.

sp.

25.0 100.0 0 50.0 42 .9 42 .9 62.5 37.5 55.6 50.0 80.0 77.8 66.7 75.0 20.0 80.0 42.9 45.5

0 0 0 0 14.3 0 12.5 12.5

37.5 0 33.3 49.8 28.6 56.9 25.0 49.7

12.5 0 0 0 0 0 0 0 0 0 0 0 0 0 20.0 0 0 0

0 0 0 0.1 0 0.2 0 0.2 0 0 0 0 0 0 0.1 0 0 0

25.0 0 66.6 0 14.3 0 0 0 0 0 0 22.2 0 0 0 0 0 0

11.1

33 .3

0 0 0 I Ll 0 0 0 14.3 0

50.0 20.0 0 22.2 25.0 60.0 20.0 42.9 54.4

5.0 6.0 7.5 7 .0 5.5 5.5 5.0 5.5 5.0 3.0 4.5 5.0 5.5 5.0 6.5 4.0 5.5 4.0

1) See Table I for explanations.

F. solani (M ART. ) SACC . , F. solani var . coeruleum (SCHLECHT.) BOOTH cornp . nov. and further to Fi oxysporum (S CHLECHT. ) and F. sambucinum (F UNKEL). The species F. culmorum (W. G. SMITH) S ACC. , F. avenaceum (C ORDA ex FR . ) SACC . , F. gramineum (S CHWABE), F. sulphureum (S CHLECHTENDAHL) and F. moniliform e (SHELDON) were detected less frequently or rarel y. As far as the occurrence of Fusarium is concerned, irrespective of its specie s classification , the percentage of contamination of tuber s of individual varieties varied during the 2 years . Higher amount s of F. sambucinum were detected in the material obtained from the experiments at JZD Kouty (Treble district), whereas in the following year, when the material was obtained from SS Valeco v

402

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VRANY

et at.

(Havlickiiv Brod district), it was necessary to use selective nutrient media suppressing the accompanying soil microflora in order to demonstrate the genus on the tubers (JEFFRIES 1984). Tubers of early and very early varieties and newly improved specimens obtained at JZD Kouty had more propagules of the genus Fusarium on their surface than the later varieties (Table 2). In the following year, when the potato plants were cultivated under different conditions at SS Valecov, the early character of the varieties played only a limited role and the overall contamination of the tubers was higher (Table 3). The variation of the occurrence of F. solani in samples of the variety Radka originating form different seed is quite interesting. The percentual representation of Fusarium sp. varied from41.2% in samples obtained from the seed of Neustupovske Otradovice to 70.6% in the material from the seed of Stffbme Hory. During the 4-month storage of tuber samples no substantial changes in the occurrence of representatives of the genus Fusarium could be detected. During the 2 years the presence of other micromycetes, viz. representatives of Penicillium sp. and bacteria, primarily sporulating species, could also be detected. For instance, in the newly improved variety Borka (VE 39) the microflora was found to be resistant to antibiotics present in media used for the isolation of Fusarium. The representative collection of isolates of F. solani, out of which one-third to one-fourth belonged to F. solani var. coeruleum, and isolates of F. sambucinum exhibiting a higher growth rate of hyphae on a nutrient agar medium with potatoes and glucose (PDA) exhibited medium to higher pathogenicity on tubers of the variety Radka. However, the infection of the tubers by Fusarium was not detected in the material stored at the 4°C temperature.

Discussion F. solani (MART.) SACC., F. solani var. coeruleum (SACC.) BOOTH comb. nov., F. oxysporum (SCHLECHT.) and F. sambucinum (FUCKEL) were the predominating species on samples of potato tubers taken at various places of the Czech potato-growing region. In numerous potato-growing regions all over the world F. solani var. coeruleum and F. solani were detected among the most frequent causes of the fusarium potato dry rot. However, it follows from other data that F. sambucinum or F. sulphureum can be significant as infective agents of this disease in stores (McKEE 1952; JANKE 1976; LANGERFELD 1970; BRASLAVSKA 1972; WOJCIECHOWSKA-KoT and KISZCZAK 1981; TIVOLI et al. 1986; SEPPANEN 1983). F. solani var. coeruleum is considered to be a Fusarium species adapted best to soil life conditions, it belongs to rapidly growing fungi in which the effect of roots and other underground plant parts is quite intensive, similarly to F. solani f. sp. phaseoli (SMALL 1944; SCHROTH and HILDEBRAND 1964; TIVOLI etal. 1983). However, its occurrence on secondary tubers is influenced by a number of factors such as the extent of soil contamination (LEACH 1985). It follows from our experiments that the soil and climatic conditions under which the varieties and newly improved specimens were cultivated also played a role in the contamination of harvested tubers. Sandy loam soil contained higher numbers of F. solani compared to heavier soil. Whereas in the first year, differences in the contamination of tubers of early, semi-early, semi-late and late varieties were observed, they disappeared at an increased occurrence of Fusarium propagules in the next year. However, this fact did not playa significant role due to pathogenicity of Fusarium representatives occurring in the studied potatoes. It is known that the extent of contamination of the environment and tubers may be associated with the occurrence of dry-fusarium rot (BOYD 1960; NIELSEN and JOHNSON 1972; TIVOLI et al. 1983). However, even other factors, e.g. resistance of potato tubers to the fusarium rot under given environmental conditions, are involved in the interaction between the tubers and the pathogen (HORAl:KOVA and DOBIA~ 1986). The abovementioned interactions can be influenced not only by agrotechnique using chemical means for stand protection but also by the use of suitable microorganisms including microscopic fungi (VRANY et al. 1986; BAKER 1986; COOK and BAKER 1983).

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403

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471-481. JELLlS, G. J.: Laboratory asses sments of the susceptibility of potat o tube rs to gangrene (Phoma exigua var.foveata). PI. Pathol. 31 (1982),171- 177. LANGERFELD, E .: Lagerfaulen an Kartoffeln 1969170. Nachr. bl. Deut sch . Pfl, Schutzdien st 22 (1970), 109-110. LEACH, S. S .: Contamination of soil and tran smission of seed-borne potato dry rot fungi (Fusarium spp .) to progeny tubers. Amer. PotatoJ. 62 (1986),1 29- 136. McK EE, B. K. , BoYD, A. E . W.: Dry rot disease of pota to. III . A biological method of assess ing soil infectivity . Ann . Appl. BioI. 39 (1952), 44-53. MESSIAEN, C. M. , BELLIARD-ALONZO, L., BARRIERE, Y. , DE LA T ULLAYE , n.: Etude qualitati ve des Fusarium roseum dan s les sols des enviro ns de Versai lles , sous diverses rota tions ou assoc iations vegetates. Ann. Phytopathol. 8 (1976), 269-281. NIELSEN, L. W., JOHNSON , J . T .: Seed potat o contamination with fusarial prop agules and thei r removal by washing. Amer . Potato J. 49 (1972), 391- 396. NIRENBERG, H. I. : A simplified method for identifying Fusarium spp. occurring on whe at. Can . J . Bot. 59 (1981),

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(1967),848 -852. SALVET, V. : Contribution to learnin g the mycoflora of stored potatoes. Proc . X Czechoslovak Plant Protection Conference Bmo, K. VEVERKA et al. (eds .), VURV 1986, Praha, 97-98 . SClIIPPERS, P. A .: Dry rot of potato. Eur. Potato J . 5 (1962), 129-145 . SCHROTH , M. N. , HILDEBRAND, D. C .: Influence of plant exudates on root-infecting fungi. Ann. Rev. Phytopatho l. 2

(1964), 101-132. SEPPANEN, E. : Fusarium of the potato in Finland VIII. Occurrence of the patho gen s causing potat o dry rot and gangrene. Ann . Agric . Fenn iae, ser. Phytopatho l. 22 (1983), 115-119. SMALL, T .: The soil as a source of infect ion of dry rot of potato. Natur e (Lond.) 153 (1944), 436. SNYDER , W. C. , HANSEN, H. N.: Variat ion and speciation in the genus Fusarium. New York Acad . Sci. Ann . 60

(1954), 16- 23. TIVOLI , B. , JOVAN, B. , LEMARCHAND, E .: Etude de la transmission 11 la descendence de differentes especes ou varie tes de Fusarium respon sables de la pourriture seche des tuber cules de pom me de terre: role du tubercule de semence , du sol et de la plant s. Potato Res. 29 (1981), 141-1 62. - - Etude des facteu rs modifi ant la mesure du potential infectieux des sols infestes par les Fusarium responsables de la pourriture seche des tubercules de pomme de terre . Potato Res. 26 (1983), 203-218.

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VRANY , J., DOBIAS, K. , HORA<': KOVA, V.: Fusaria on the tuber surface of selec ted potato cultivars . Proc. X Czechoslovak Plant Protection Conference Bmo. K. VEVERKA et a!' (eds.) . VURV 1986, Praha , 99- 100. WOJCIECHOWSKA, H. , MtKOLAJSKA, J.: Grzyby powodujace sucha zgnilizne ziemniaka w Polsce. Biu!. Inst. Ziem. 9 (1972),9 1- 101. WOJCIECHOWSKA-KoT, H ., KISZCZAK, E.: Patogeniczne Fuzaria w przechowalniach ziemniaka oraz ich rola W powstawaniu suchej zgnilizn y. Biu!. lust. Ziem. 26 (1981), 95-102. Authors ' addresses : RNDr JAN VRANY, CSc., Institute of Microbiology, Czechoslovak Academy of Sciences, 142 20 Praha 4 - Krc , lng. M. RASOCHOVA, CSc ., lng. K. DoBIAS, CSc ., lug. V. HOti<'::KOVA, Oseva , Research and Breed ing Institute for Potato , 58003 Havlfckiiv Brod , CSSR.

Zentralb!. Mikrobio!. 144 (1989), 404 VEB Gustav Fischer Verlag Jena

Buchbesprechung J. M . HARDI E, S. P. BORRIELLO (eds .): Anaerobes Today. Proceed ing of the Fifth Anaerobe Discussion Group Symposiu m 1987 Cambridge. John Wiley a. Sons Ltd., Chichester, New York, Brisbane , Toronto , Singapo re 1988, Preis : £ 34.50. Das vorliegende Buch ist weder eine Einfiihrung in die Anaerobier-Problematik noch ist es ein Manual mit vollstand iger Erfassung aller Anaerobier. Zu diesen, bereits vorhandenen Monographi en, ist es eine wichtige Erganzun g, Es werden spezielle , hochaktuelle Aspekte besprochen , die Yommikrobiol ogischen und infektiologischen Geschehen iiberleiten zu mikrookologischen bis hin zu molekularbiologischen Untersuchungen bei Anaerobiem . Das vorliegende Buch ist ein Ausdruck der Arbe it der Anaerobe Discussion Group, die eine der kreativsten mikrobiologischen Vereinigungen der Welt darstellt . Das einleitende Kapitel ist von Nestor S. M. FINEGOLD geschrieben und faBt medizinisch-diagnostische Gesichtspunkte zusammen. Dabei spielt die Betrachtung der Effektivitat und Klinikwirksarnkeit cine wichtige Rolle . Das I . Kapitel behand elt die immunologischen Abwehrproz esse der Anaerobier. Neben der Opsonisation ist vor allem die Phagoz ytose Gegenstand der Betrachtung. Virulenz-Marker und Oberflachenstrukturen von Bacteroides fr agilis werden ausgezeichnet dargestellt. Neue Denkansatze zur moglichen Immuntherapie bei menschlichen Periodont alerkrankungen werden belegt . 1m 2. Kapitel werden spezielle Toxine der Anaerobier besprochen : Hypothetisches Modell von Toxin A und B von Clostri dium difficile; Mechanismus der Aktion des Tetanus-Toxins ; Endotoxine der gramnegativen Anaerobier. Das 3. Kapitel ist den Archaebacteria gewidrnet , insbesonder e der Genetik der Methanbildn er und der Continuous flow culture. Mit der Genetik der Clostridien beschaftigt sich das 4. KapiteI. Toxi n-Gen-Lokalisation, Sequenzanalysen , Gentran sfer und Vektoren-Konstruktionen seien nur einige Stichworte der behandelten Aspekte. Hervorragend ist auch das 5. Kapitel zur Immunochemie der Anaerobier. Hier werden die modem sten Methoden geschildert in ihrer Anwendu ng bei Anaerobiern . Ausgezeichnete Abbildungen belegen die Ergebnisse. Rel ativ kurz ist das 6. Kapitel zum Thema Behandlung und Kontrolle der Anaerobier gestaltet. Irn 7. Kapitel sind 38 Kurzmitteilungen gedruckt, die eine wichtige Erganzung und viele Details zu den Hauptk apiteln bringen . "Anaerobes Today" wird seinem Tilel voll gerecht. Das Buch ist ein unentbehrliches Arbeitsmate rial fur die auf diesem Gebiet tatigen Wissenschaftler . Das Buch hat 272 Seiten mit gutem Sachregister. Die einzeln en Kapitel sind selbstandig, die Literatur ist nach jedem Beitrag angeordnet. Hervorzuheben ist auch die gute drucktechnische Qualitat und die sehr schonen Abbildungen . H. BERNHARDT, GreifswaJd