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A new Microsphaera species on Begonia
Transactions British Mycological Society A NEW MICROSPHAERA SPECIES ON BEGONIA A. SlYANESAN
Commonwealth Mycological Institute, Kew, Surrey Microsphaera begoniae sp.nov. (Text-fig. I). Mycelium epiphylluro, densuro, persistens. Cleistothecia aggregata, brunnea vel atro brunneola, sphaerica, 100-ISO pm diam. Appendices 8-28 (pleruroque 12-20), aequatoriales, I-I'S pm diam, cleistothecii longae, basi 10-18 pm latae, dilute brunneae, pariete crassiore, apicem versus hyalinae et 6-7 pm latae, 1-4 septatae, septis pro parte maxima in dimidio basali, laeves vel granulosae, apice 4-S dichotome ramosae, ramis ultimis rectis vel raro recurvatis. Asci 6- 10, late ovati vel oblongati, breviter pedicellati, S-8 spori, SO-70 x 30-40 usu. Ascosporae ovoideae, 18'5-23'0 x I I 'S-14'o pm. Conidia breviter catenulata, cylindracea, 40-6S x I I-IS pm. In foliis Begoniae sp., Salisbury, Wiltshire, Great Britain, I I. ii, 1970, Audrey V. Brooks. IMI 146562, typus.
Mycelium on the upper surface of leaves, white, dense and persistent. Cleistothecia aggregated in groups, rarely scattered, brown to brownishblack, spherical to subglobose, IOD-I50 pm diam, with abundant yellow oil globules. Cells of the cleistothecia irregularly polygonal and 12-20 pm wide. Appendages 8-28 (commonly 12-20), one to one and a halftimes the diameter of cleistothecia, hyaline and 6-7 pm wide towards the tip, pale brown, more thick-walled and 10-14 pm wide at the base, 1- to 4-septate, septation occurring mostly in the lower half, smooth or granulose, with the apex 4-5 times dichotomously branched, the branches of the first and second orders widely separating and variable in length, ultimate branches straight or seldom recurved. Asci 6-10, broadly ovate to oblong, with a very short stalk, 5- to 8-spored, 50-70 x 30-40 }lm. Ascospores ovoid, onecelled, 18'5-23'0 x 11'5-14'0 usu. Conidia borne in short chains, onecelled, cylindrical with rounded ends, 40-65 x 11-15 }lm. This is the first report of Microsphaera on Begonia. This species resembles M. hypophylla Nevodovskii (1952), which occurs on Q,uercus, in the shape and dimensions of conidia. The most obvious difference between these two species is in the appendages. In M. hypophylla the appendages are nonseptate and hyaline with recurved ultimate branches, while in M. begoniae they are septate, hyaline towards the tip and pale brown below with straight ultimate branches. M. begoniae is distinguishable from M. alphitoides Giffon & Maublanc (19I2), which also occurs on Q,uercus, by the characters of the conidia, which are ellipsoid and smaller in the latter. The powdery mildew Oidium begoniae Puttemans (191 I), which has been known to occur on begonias for more than 50 years in Europe and was first reported in England in a glasshouse in Cambridge in February 1938 (International Bulletin of Plant Protection (1939) 13, 153), differs from M. begoniae in the dimensions of the conidia, which are much smaller and measure 20-36 x 13-17 }lm. Thus O. begoniae cannot be regarded as the imperfectstate of M. begoniae. De Mendonca & De Sequeira (1962) described Trans, Br, mycol. Soc, 56 (2), (1971). Printed in Great Britain
Notes and Brief Articles
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Fig.
I.
A-E, Mi crosphaera begoniae. A, Cleistothecium; B, asci; C, ascospores ; D, conidiophore j E, conidia.
Trans. Br. mycol. Soc. 56 (2), (1971). Printed in Great Britain
306
Transactions British Mycological Society
a larger conidial variety as O. begoniae var. macrosporum. This has almost similar conidial measurements (34-72 x 9-22.8 ,um) and in my opinion can be regarded as the conidial state of M. begoniae. I am grateful to Mr F. C. Deighton for the Latin diagnosis. REFERENCES
DE MENDONl;A, A. & DE SEQUEIRA, M. (1962). Erysiphaceae lusitaniae I. Agronomica Lusitana 24, 109. GIFFON, E. & MAUBLANC, A. (1912). Les Microsphaera des Chenes. Bulletin Trimestrialdela Societe Mycologique de France 28, 100. NEVODOVSKII, G. S. (1952). Griby S.S.S.R. Fasc. I, nr. I, p. 4. PUTTEMANS, A. (191 I). Nouvelles maladies de Plantes cultivees, Bulletin de la Societe Royale de botanique de Belgique 48, 238.
MORPHOLOGY OF SEEDLING INFECTION BY LEPTOSPHAERIA NODORUM
J. BAKER* Department of Botany, University CELIA
~ Exeter
Leptosphaeria nodorum Muller is seed-borne, and on germination of infected seed, characteristic symptoms develop. These can readily be observed in blotter tests (Kietreiber, 1961) after 10-14 days incubation in darkness at IO °C. Affected seedlings are more stunted than healthy ones and often discrete brown streaks arise at the base of the coleoptile. The coleoptiles may appear twisted or distorted and in some varieties, but not all, characteristic swellings or 'knobs' develop (PI. 34, fig. I). Severe browning of the coleoptile may result in death of the seedling (Scharen, 1964) but usually the roots are undamaged. When infection takes place at the seedling stage the most marked morphological reaction of the host to invasion is observed, later infection gives rise only to lesions. On germination of infected seed, the hitherto subpericarpic mycelium of 1. nodorum grows from beneath the seed-coat on to the outer surface of the coleoptile, penetrating the epidermal cells in this region. In young plant tissue the cuticle is often incomplete or thin here and invading hyphae would have little difficulty in penetrating. In diseased coleoptiles abundant hyphae of the young, sparsely branched type ramified over the outer surface, often running parallel with the long axis of the cells. Hyphae were only seen on the inner surface of the coleoptile, between it and the first leaf, following penetration of the outer epidermis and growth of the fungus through the coleoptile tissue. On the outer coleoptile surface more dense networks of the short-celled, much-branched type of hyphae sometimes occurred. Appressorial swellings developed on branches of the narrow hyphae above adjacent host cell walls . ... Present address: Coffee Research Station, P.O. Box 4, Ruiru, Kenya. Trans. Br. mycol. Soc. 56 (2), (1971). Printed in Great Britain
Commonwealth Mycological Institute, Kew, Surrey Microsphaera begoniae sp.nov. (Text-fig. I). Mycelium epiphylluro, densuro, persistens. Cleistothecia aggregata, brunnea vel atro brunneola, sphaerica, 100-ISO pm diam. Appendices 8-28 (pleruroque 12-20), aequatoriales, I-I'S pm diam, cleistothecii longae, basi 10-18 pm latae, dilute brunneae, pariete crassiore, apicem versus hyalinae et 6-7 pm latae, 1-4 septatae, septis pro parte maxima in dimidio basali, laeves vel granulosae, apice 4-S dichotome ramosae, ramis ultimis rectis vel raro recurvatis. Asci 6- 10, late ovati vel oblongati, breviter pedicellati, S-8 spori, SO-70 x 30-40 usu. Ascosporae ovoideae, 18'5-23'0 x I I 'S-14'o pm. Conidia breviter catenulata, cylindracea, 40-6S x I I-IS pm. In foliis Begoniae sp., Salisbury, Wiltshire, Great Britain, I I. ii, 1970, Audrey V. Brooks. IMI 146562, typus.
Mycelium on the upper surface of leaves, white, dense and persistent. Cleistothecia aggregated in groups, rarely scattered, brown to brownishblack, spherical to subglobose, IOD-I50 pm diam, with abundant yellow oil globules. Cells of the cleistothecia irregularly polygonal and 12-20 pm wide. Appendages 8-28 (commonly 12-20), one to one and a halftimes the diameter of cleistothecia, hyaline and 6-7 pm wide towards the tip, pale brown, more thick-walled and 10-14 pm wide at the base, 1- to 4-septate, septation occurring mostly in the lower half, smooth or granulose, with the apex 4-5 times dichotomously branched, the branches of the first and second orders widely separating and variable in length, ultimate branches straight or seldom recurved. Asci 6-10, broadly ovate to oblong, with a very short stalk, 5- to 8-spored, 50-70 x 30-40 }lm. Ascospores ovoid, onecelled, 18'5-23'0 x 11'5-14'0 usu. Conidia borne in short chains, onecelled, cylindrical with rounded ends, 40-65 x 11-15 }lm. This is the first report of Microsphaera on Begonia. This species resembles M. hypophylla Nevodovskii (1952), which occurs on Q,uercus, in the shape and dimensions of conidia. The most obvious difference between these two species is in the appendages. In M. hypophylla the appendages are nonseptate and hyaline with recurved ultimate branches, while in M. begoniae they are septate, hyaline towards the tip and pale brown below with straight ultimate branches. M. begoniae is distinguishable from M. alphitoides Giffon & Maublanc (19I2), which also occurs on Q,uercus, by the characters of the conidia, which are ellipsoid and smaller in the latter. The powdery mildew Oidium begoniae Puttemans (191 I), which has been known to occur on begonias for more than 50 years in Europe and was first reported in England in a glasshouse in Cambridge in February 1938 (International Bulletin of Plant Protection (1939) 13, 153), differs from M. begoniae in the dimensions of the conidia, which are much smaller and measure 20-36 x 13-17 }lm. Thus O. begoniae cannot be regarded as the imperfectstate of M. begoniae. De Mendonca & De Sequeira (1962) described Trans, Br, mycol. Soc, 56 (2), (1971). Printed in Great Britain
Notes and Brief Articles
25
J
JIm
o
Fig.
I.
A-E, Mi crosphaera begoniae. A, Cleistothecium; B, asci; C, ascospores ; D, conidiophore j E, conidia.
Trans. Br. mycol. Soc. 56 (2), (1971). Printed in Great Britain
306
Transactions British Mycological Society
a larger conidial variety as O. begoniae var. macrosporum. This has almost similar conidial measurements (34-72 x 9-22.8 ,um) and in my opinion can be regarded as the conidial state of M. begoniae. I am grateful to Mr F. C. Deighton for the Latin diagnosis. REFERENCES
DE MENDONl;A, A. & DE SEQUEIRA, M. (1962). Erysiphaceae lusitaniae I. Agronomica Lusitana 24, 109. GIFFON, E. & MAUBLANC, A. (1912). Les Microsphaera des Chenes. Bulletin Trimestrialdela Societe Mycologique de France 28, 100. NEVODOVSKII, G. S. (1952). Griby S.S.S.R. Fasc. I, nr. I, p. 4. PUTTEMANS, A. (191 I). Nouvelles maladies de Plantes cultivees, Bulletin de la Societe Royale de botanique de Belgique 48, 238.
MORPHOLOGY OF SEEDLING INFECTION BY LEPTOSPHAERIA NODORUM
J. BAKER* Department of Botany, University CELIA
~ Exeter
Leptosphaeria nodorum Muller is seed-borne, and on germination of infected seed, characteristic symptoms develop. These can readily be observed in blotter tests (Kietreiber, 1961) after 10-14 days incubation in darkness at IO °C. Affected seedlings are more stunted than healthy ones and often discrete brown streaks arise at the base of the coleoptile. The coleoptiles may appear twisted or distorted and in some varieties, but not all, characteristic swellings or 'knobs' develop (PI. 34, fig. I). Severe browning of the coleoptile may result in death of the seedling (Scharen, 1964) but usually the roots are undamaged. When infection takes place at the seedling stage the most marked morphological reaction of the host to invasion is observed, later infection gives rise only to lesions. On germination of infected seed, the hitherto subpericarpic mycelium of 1. nodorum grows from beneath the seed-coat on to the outer surface of the coleoptile, penetrating the epidermal cells in this region. In young plant tissue the cuticle is often incomplete or thin here and invading hyphae would have little difficulty in penetrating. In diseased coleoptiles abundant hyphae of the young, sparsely branched type ramified over the outer surface, often running parallel with the long axis of the cells. Hyphae were only seen on the inner surface of the coleoptile, between it and the first leaf, following penetration of the outer epidermis and growth of the fungus through the coleoptile tissue. On the outer coleoptile surface more dense networks of the short-celled, much-branched type of hyphae sometimes occurred. Appressorial swellings developed on branches of the narrow hyphae above adjacent host cell walls . ... Present address: Coffee Research Station, P.O. Box 4, Ruiru, Kenya. Trans. Br. mycol. Soc. 56 (2), (1971). Printed in Great Britain