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34 THE BRITISH SMUT FUNGI with small chlamydospores and short, ovoid smut balls, while brown peridia were associated with larger spores and slender, more elongated sori. GEBMINATION OF HYBRID SPQEES Kniep (1926), in his pioneer work on heterdthallism, paired appropriate sporidial lines from several species of Ustilago. Fusions readily occurred among smuts with smooth or echinulate spores, but failed if these species were mated with reticulate spored species. Whether the cell fusions were followed by nuclear fusions in these so-called interspecific crosses was not then determined, but true hybridization in the UstQaginales has been established since. Several workers have examined hybrid material of the smuts for evidence of heterosis, sterility, or other phenomena commonly revealed by out-crossing. Goldschmidt (1928) found in crosses between certain physiologic races of U. violacea that promycelia of all hybrids were considerably greater than those of the parents. The method of growth was often irregular, the promycelium from some hybrids consisting of only one cell. Vaheeduddin (1936 a, 1936 b) noted the increased size of promycelia and sporidia in the interspecific hybrid Sphacelotheca cruentaxS. reiliana and accepts it as a sign of heterosis. Both the number and viability of sporidia may be reduced in crosses. Primary sporidia isolated from promycelia of hybrid chlamydospores from Ustilago avenaex U. hordei from oats would rarely develop in culture (Holton, 1931 b). Martin (1943) recorded a viability of less than 10 per cent, in sporidia derived from the hybrid Sorosporium syntherismaexSphacelotheca destruens. Peg-like branches, which did not develop either into sporidia or hyphae, were characteristic of promyceHa in the interspecific cross S. sorghi x S. cruenta (Rodenhiser, 1934). Sporidia developed sparsely in 8. sorghixS. reiliana, many promyceUa of the hybrid producing hyphal branches in place of sporidia (Tyler & Shumway, 1935). Some intraspecific crosses of Ustilago maydis behaved in a similar manner (Christensen, 1931). In others the promyceHa were gnarled and distorted and either autolysed before sporidia developed or gave a few sporidia in an irregular manner. Chilton (1943) could find no evidence that lysis in U. maydis was caused by an infectious agent and he believes that the explanation for this behaviour is genetical. The segregation of one or more factors for lysis was demonstrated by crossing appropriate haploid lines (Chilton, 1938, 1943). Lysis in certain inbred lines of Sphacelotheca sorghi persisted through two chlamydospore generations (Laskaris, 1939, 1941). In both species the tendency to germinate abnormally was greater in chlamydospores of unusually large size. Another example of lysis, described by Fischer (1940 c) as a haplo-lethal deficiency, was found in Ustilago bullata. In certain collections half the monosporidial isolates ceased growth after budding off a few sporidia and finally disintegrated; the others continued to bud and produced a normal saprophytic growth on potato dextrose agar. It is not stated if other media were tried (see p. 30). By mating with monosporidial lines of U. hordei and U. avenae Fischer showed that the surviving Unes of U. bullata belonged to one compatibility group. Since infection of the host could be, induced by chlamydospores from these collections of U. bullata, it is concluded that gametes carrying the haplolethal deficiency factor were functional in nature, this factor operating only against saprophytic growth. This was confirmed by finding infection hyphae
GENETICS 35 when a few sporidia from lethal and non-lethal lines were mixed on plain agar (see Bauch test, p. 42). In a single collection of V. bullata from Festuca idahoensis, lysis again occurred in half the isolates, but in this example some of the surviving lines were compatible, indicating that the lethal factors were not linked with those governing fusion as in the other four collections. PATHOGENICITY ' The multiplicity of physiologic races within a species is eloquent of the complexity of the problem of the inheritance of pathogenicity. That an individual chlamydospore from a field collection of U. avenae may be heterozygous for pathogenicity factors was clearly shown by Mcolaisen (1934), who infected a few selected varieties of oats with paired sporidial lines. To quote one example, two sporidial matings from chlamydospore 43/31 produced 100 per cent, smut on the variety Lischower, while two other matings from the same spore gave negative results on this variety (Nicolaisen, 1934, Table 4). In an extensive series of cross-infection experiments conducted with monosporidial lines Nicolaisen showed that the factor or factors for pathogenicity carried by one monosporidial line might be dominant, recessive, or intermediate according to the variety of the host. By crossing, segregates can be obtained which differ in virulence from both parents (Nicolaisen, 1934, 1935; Holton, 1936 a; Bever, 1939). Allison (1937) obtained segregation for pathogenicity in the Fj of U. hordei x U. avenae (medians) and found that some segregates possessed increased virulence on certain barley varieties. The factors for pathogenicity segregate independently from those governing compatibility, head, type, and spore wall. Christensen (in Stakman et al., 1929) found multiple factors for pathogenicity in U. maydis and obtained evidence that they act independently of those governing fusion. As in the oat. smuts, a monosporidial Hne may be strongly pathogenic when in combination with some compatible lines and weakly pathogenic with others. Maize inoculated with a mixture of haploids gave a lower degree of infection than maize inoculated with single pairs of haploid lines (Kemkamp & Martin, 1941). Some varieties of wheat were resistant to mixed inocula, though this included some highly virulent lines of bunt (Holton & Heald, 1936; Rodenhiser & Quisenberry, 1938). No satisfactory explanation of these results is available. MUTATION It is essential in the application of Mendelial principles to an unexplored group of organisms to examine the purity of their gametes. Genetical data on smuts, collected since the discovery of heterothallism (Kniep, 1919), rests on the assumption that meiosis occurs in the promycelium and that the sporidia budded from it are uninucleate, haploid cells. They function as gametes but differ from many other sexual cells in that they can be multiplied almost indefinitely. Theoretically, uniformity is to be expected in the monosporidial cultures derived from single promycelial cell and the colonies should remain stable. Variations, at least in some species, are certainly not rare, and it is pertinent to ask if all have the same origin. Variants in smuts are sudden, abrupt
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 and 20: BIOLOGY 15 less than the normal, in
Page 21 and 22: BIOLOGy 17 and united with it, fina
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: GENETICS • 31 direction of growth
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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