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16 THE BRITISH SMUT FUNGI the chlamydospores, which are uninucleate when mature. The process was found to be similar in V. maydis. Several workers, who have studied the early stages of sporogenesis in species of Ustilago, refer to a tendency for spores to develop in chains (Schroeter, 1877; Fischer von Waldheim, 1869). Massee (1914), working with U. vaillantii, states that the vegetative mycelium is broken up by transverse walls into uninucleate cuboid segments, which become binucleate by the dehquescence and disappearance of alternate septa. Sartoris (1924) has described the formation of spores in JJ. heufleri. Mycelium in the host, Erythronium americanum, is always intercellular, spreading but a little way from the point of infection. The hj^hae cause the separation and disintegration of the host cells, finally forming a pustule, which segments to give mature chlamydospores in seven to ten days. The mycelium, 3 to 5 /u. in diameter, is said to be multinucleate with the nuclei nearly always associated in loose pairs. As segmentation proceeds, two nuclei are left in each cell, which rounds off and becomes free. The wall thickens and the surface becomes gelatinized which makes it difficult to follow the fate of the nuclei. In a few cases binucleate spores were seen, but the probability is that fusion usually takes place as the wall thickens and develops the two distinct layers, which are characteristic of the mature chlamydospore. The development of spores in U. vuijckii, a species inhabiting the capsules of Luzula spp., presents some interesting features. The cells are connected by clamp-connexions, apparently similar to those found in many Hymenomycetes, and the spores develop in chains, alternating with clamps which bear a strong resemblance to antheridia (Liro, 1924). THiLBTiACBAB. In Tilletia and in Entyloma the chlamydospores arise at the ends of short side-branches (Fischer von Waldheim, 1869). Lutman (1910) described the process in E. nympheae as follows: 'A short lateral branch, dense with cytoplasm and binucleate, is put out from one of the larger hyphae. As it grows in length and thickness, the two nuclei, which at first lie parallel with the long axis of the cell, come to be side by side. The stalk of the spore becomes vacuolate, and finally a large vacuole seems to cut off the hypha bearing it and the wall develops .behind. The wall of the spore thickens and becomes covered with minute spines. The axis becomes apiculate by the thickening of the end wall and a large vacuole develops and pushes the nucleus to one side.' Several writers have described the spiral coiling of hyphae which initiates spore formation in Vrocystis (Kiihn, 1858; De Bary, 1866; Wolif, 1873; Winter, 1881). Anderson (1921) studied sporogenesis in U. cepuJae. The onset of spore formation is indicated by the massing of mycelium between the cells. Instead of growing in long, straight, slender strands, the myceUum is branched, twisted, and interwoven into dense tangles, which push the cells apart and increase the areas of intercellular space, within which spores are subsequently formed. The hyphae become highly vacuolated and the protoplasm stains deeply. The spore arises as a lateral or terminal branch which curves back on itself in the form of a crozier. Protuberances mark the origin of branches which ultimately form the sterile cortical cells. The central fertUe cell appears to be the enlarged terminal cell of the crozier, though it is not certain that this is always its origin. As the fertile cell enlarges, the surrounding hyphae become tightly pressed against it
BIOLOGy 17 and united with it, finally breaking up into separate elements, which appear as scattered, conical cells with flat bases firmly attached to the surface of the central cell. There appearsto be no gelatinization of the walls as in the Ustilaginaceae. At maturity the fertile cells contain a single nucleus, 3 to 4 /x in diameter with a prominent, deeply staining nucleolus 0-6 ft in diameter. A single small nucleus (about 0-6 (i) is found in each accessory cell. The corresponding ceUs are without nuclei in U. violae (Dangeard, 1894 a), and Blizzard (1926) records the disappearance of nuclei in the sterile cells of U. cepulae. In U. occulta the cells of the vegetative hyphae are for the most part binucleate. During sporogenesis some of the cells enlarge and their nuclei soon fuse, so that they are almost uniformly uninucleate by the time they can be recognized as spores. At this stage the nucleus is relatively large and a nucleolus is visible. The cells of those hyphae, which envelop the spore initial and form, the sterile cells, remain for a time binucleate but ultimately their nuclei disappear (Stakman, Cassell, & Moore, 1934). In Doassansia deformans the baU of spores begins as a tangled mass of hyphae in one of the intercellular spaces of hypertrophied host tissue. At this stage the cytoplasm is very dense, and, in all ceUs where nuclei can be seen clearly, they are in pairs. At first all the cells are ahke, but those inside soon begin to lose their contents and become transparent. The outer cells divide and contribute to the sterile cells in the centre. Finally, in the nearly mature spore ball the external cells with dense cytoplasm contain two nuclei in various stages of fusion. A felted layer of hyphae surrounds the mature ball (Lutman, 1910). GEAPHIOLACEAB. GrapMola phoenicis, which grows on the fronds of the date palm, has been investigated by KilHan (1924). The vegetative myceUum and the young fructifications are formed of uninucleate cells. Those at the base of the central plectenchyma give rise to a growing tissue composed of elongated cells containing several dicaryons. Finally, these form a block of ceUs, each with two nuclei which ultimately fuse. These cells, which correspond to chlamydospores, are not themselves disseminated. They germinate in situ by budding off uninucleate sporidia which are dispersed through an opening at the top of the fructification. GERMINATION O? THS: CHLAMYDOSPOEES The rest period. The chlamydospores of smuts, Uke seeds, vary widely in longevity. Spores of different species differ in their ability to germinate at the time of dissemination; some are capable of immediate growth, others must pass through an after-ripening period. Many workers have experienced difficulties in obtaining germination and have recorded the variable results given by different collections of the same species. This is not surprising when it is understood that germination depends, not only on the conditions under which a test is made, but also upon the age of the spores, the degree of maturity at the time of harvest, and the method of storage. Moreover, closely related species and physiologic races vary in the time of year when their spores germinate in nature. In the genera Entyloma and Doassansia, where the chlamydospores are held somewhat firmly by the host tissue, germination often occurs in situ as a continuous process of development which results in the dissemination of sporidia
Page 1 and 2: THE BRITISH SMUT FUNGI ^ (USTILAGIN
Page 3: FOREWORD THIS volume was started wh
Page 6 and 7: 6 PBEFACE We also acknowledge the b
Page 9 and 10: INTRODUCTION THE smut fungi, which
Page 11 and 12: INTRODUCTION H of bushels of wheat
Page 14 and 15: FIG. 1. Vstilago avenae on Arrhenat
Page 16: ^^ THE BBITISH SMUT FUNGI Young hea
Page 19: BIOLOGY 15 less than the normal, in
Page 23 and 24: BIOLOGY 19 eermination in a collect
Page 25 and 26: BIOLOGY 21 genus, and the manner of
Page 27 and 28: BIOLOGY 23 species of Entyloma, and
Page 29 and 30: 3036^ BIOLOGY 25 in others. Dickins
Page 31 and 32: CYTOLOGY THE discovery of nuclei in
Page 33 and 34: GENETICS INCOMPATIBILITY KNIEP'S di
Page 35 and 36: GENETICS • 31 direction of growth
Page 37 and 38: GENETICS 35 when a few sporidia fro
Page 39 and 40: GENETICS 37 lines retained their di
Page 41 and 42: TECHNIQUE COLLECTION AND EXAMINATIO
Page 43 and 44: TECHNIQUE 41 be undesirable. Weak a
Page 45 and 46: TECHNIQUE 43 in one season (see p.
Page 47 and 48: TECHNIQUE 45 barley with loose smut
Page 49 and 50: TECHNIQUE 47 (1939), Holton & Heald
Page 51 and 52: TECHNIQUE 49 Allen's, modification
Page 53 and 54: CLASSIFICATION THE morphological ch
Page 55 and 56: THE BRITISH SMUT FUNGI MOST of the
Page 57 and 58: FIG. 2. Spore geimination in Ustila
Page 59 and 60: THE BRITISH SMUT FUJJGI 57 from one
Page 61 and 62: THE BRITISH SMUT FUKGI 59 of exsert
Page 63 and 64: THE BRITISH SMUT FUNGI 61 noticeabl
Page 65 and 66: THE BRITISH SMUT FUNGI 63 Evidence
Page 67 and 68: THE BRITISH SMUT FUNGI 65 winter in
Page 69 and 70: THE BRITISH SMUT FUNGI 67 Ustilago
Page 71 and 72:
THE BRITISH SMUT FUlJGI 69 material
Page 73 and 74:
THE BRITISH SMUT FUNGI 71 results o
Page 75 and 76:
THE BRITISH SMUT FUNGI 73 TTstilago
Page 77 and 78:
THE BRITISH SMUT FUNGI 75 Species i
Page 79 and 80:
" TJSE BRITISH SMUT FUNGI 77 Ustila
Page 81 and 82:
THE BKITISH SMUT FUNGI 79 On Carex
Page 83 and 84:
THE BRITISH SMUT FUNGI 81 Exsiccati
Page 85 and 86:
THE BRITISH SMUT FUNGI 83 Tilletia
Page 87 and 88:
THE BRITISH SMUT FUNGI 85 bunt ball
Page 89 and 90:
THE BEITISH SMUT FUNGI 87 globose t
Page 91 and 92:
THE BRITISH SMUT FUNGI 89 FIG. 13.
Page 93 and 94:
FIG. 15. Spore geimination in Taboi
Page 95 and 96:
FIG. 17. Spore germination in Urocy
Page 97 and 98:
THE BRITISH SMUT FUNGI 95 separate
Page 99 and 100:
THE BRITISH SMUT FUNGI 97 8ori in t
Page 101 and 102:
THE BRITISH SMUT FUNGI 99 Urocystis
Page 103 and 104:
30390 THE BRITISH SMUT FUNGI 101 pr
Page 105 and 106:
FIG. 20. Spore geimination in Entyl
Page 107 and 108:
THE BRITISH SMUT FUNGI 105 Sori in
Page 109 and 110:
On Ranunculus ficariae and B. scler
Page 111 and 112:
THE BRITISH SMUT FUNGI 109 Infectio
Page 113 and 114:
THE BKITISH SMUT FUNGI 111 [Sporidi
Page 115 and 116:
THE BRITISH SMUT FUNGI 113 Ustilago
Page 117 and 118:
REFEEENCES 115 BBETT, M. A. (1940).
Page 119 and 120:
REFERENCES 117 ^ DniON WESTON, W. A
Page 121 and 122:
REFERENCES 119 GRIFFITHS, MAEIOK A.
Page 123 and 124:
REFERENCES 121 HtjTTiG, W. (1933).
Page 125 and 126:
REFEBENCES 123 LiMBOtruN, E. J. (19
Page 127 and 128:
REFERENCES 125 NOBLE, E. J. (1934).
Page 129 and 130:
REFERENCES 127 RoDENHiSEE, H. A., &
Page 131 and 132:
BEFERENCES 129 STAKMAK, E. C, XCEEN
Page 133 and 134:
EEFEEENCES 131 WAXTBE, J. M. (1934)
Page 135 and 136:
INDEX to generic and specific names
Page 137 and 138:
Muscari Ustilago vaillantii, 59 Myo
Page 139 and 140:
Ustilago ficuum Reich., 113 —flps
Page 141 and 142:
2i}:y0 ANDHRA PRADESH AGRICULTURAL
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