Genetics

In addition to simple Mendelian genetics (Bonde et al. 1988; Burdon et al. 1986; Hellman and Christ 1991; Shattock et al. 1986a; Spielman et al. 1990) and linkage analysis (May and Royse 1982b), isozymes can be used to distinguish hybrid from nonhybrid progeny in both intra- (May and Royse 1982a; Shattock et al. 1986b) and inter-specific crosses (Goodwin and Fry 1994), and to infer the ploidy level of vegetative hyphae (Goodwin et al. 1994; Shattock et al. 1986b). Dimeric enzymes are ideal for this kind of analysis (Figure 3). Isozymes also can be used to analyze parasexual genetics in fungi. In addition to laboratory genetics, isozyme analysis implicated somatic hybridization as the probable origin of a new forma specialis of cereal rust in Australia (Burdon et al. 1981) and identified naturally occurring hybrids among field isolates of Phytophthora species (Man in't Veld et al. 1998). Estimates of relatedness based on isozyme analysis among strains of Agaricus brunnescens were used to aid the choice of parents in a mushroom breeding program (Royse and May 1982b). Most studies have shown normal Mendelian segregation of isozyme alleles (i.e., the isozymes can be considered allozymes), although instances of aberrant

Table 1 Isozyme systems tested and success rates in various groups of fungi and oomycetes. The 20 enzymes that were tested four or more times and were useful in 50% or more of the surveys are indicated in bold

No. times useful/no. times testeda

Table 1 Isozyme systems tested and success rates in various groups of fungi and oomycetes. The 20 enzymes that were tested four or more times and were useful in 50% or more of the surveys are indicated in bold

Enzyme

E.C. no.b

Ascoc

Basidd

Deute

Oomf

Percent useful

Avg. no. of alleles

Acid phosphatase

3.1.3.2

3/4

6/6

1/3

77

1.6

Aconitate hydratase

4.2.1.3

5/9

3/7

3/5

2/2

56

1.9

Adenosine deaminase

3.5.4.2

0/1

1/1

50

2.0

Adenylate kinase

2.7.4.3

0/3

1/4

0/2

1/1

20

1.0

Alanine aminopeptidase

3.4.11.12

1/3

33

3.0

Alanine dehydrogenase

1.4.1.1

1/1

0/1

0/1

33

1.0

Alcohol dehydrogenase

1.1.1.1

0 4

2/6

0/4

0/1

13

5.0

Aldehyde oxidase

1.2.3.1

0/3

0/2

0

Alkaline phosphatase

3.1.3.1

2/6

1/5

0/3

0/1

20

2.0

a-Amylase

3.2.1.1

0/1

0

Aryl (fluorescent) esterase

3.1.1.2

1/1

3/3

1/2

1/1

86

1.8

l-Ascorbate oxidase

1.10.3.3

0/1

0

Aspartate aminotransferase (glutamate oxalate transaminase)

2.6.1.1

4/7

8/10

3/5

0/1

65

2.3

Aspartate oxidase

1.4.3.16

0/1

0

Carboxylesterase

3.1.1.1

3/7

4/5

1/4

50

2.6

Catalase

1.11.1.6

1/1

6/7

2/2

90

1.7

Catechol oxidase (tyrosinase)

1.10.3.1

0/1

0

Creatine kinase

2.7.3.2

0/1

0

Cytosol (leucine) aminopeptidase

3.4.11.1

7/10

9/14

5/7

1/2

67

2.3

Cytosol nonspecific dipeptidase

3.4.12.18

1/1

1/2

3/5

4/4

75

1.9

Dihydrolipoamide dehydrogenase (diaphorase)

1.8.1.4

2/4

4/8

1/3

1/2

47

2.1

Dipeptidyl carboxypeptidase I

3.4.15.1

0/1

0

Enolase

4.2.1.1

0/1

1/1

50

3.0

Formate dehydrogenase

1.2.1.2

0/1

0

Fructose-bisphosphatase

3.1.3.11

0/2

0/2

1/3

1/1

25

2.0

Fructose-bisphosphate aldolase

4.1.2.13

2/2

1/6

0/3

1/2

31

2.5

Fumarate hydratase

4.2.1.2

3/6

2/4

2/5

1/3

44

1.7

Galactose dehydrogenase

1.1.1.48

0/1

0

b-Galactosidase

3.2.1.23

0/2

0/1

0/1

0

Glucokinase

2.7.1.2

0/1

0

Glucose dehydrogenase

1.1.1.47

0/4

0/1

0/1

0/1

0

Glucose-6-phosphate dehydrogenase

1.1.1.49

7/8

1/5

5/6

2/2

71

1.5

Glucose-6-phosphate isomerase

5.3.1.9

10/10

10/12

5/5

4/4

94

2.3

b-Glucosidase

3.2.1.21

0/1

0/1

2/4

0/1

29

3.5

Glucosyl transferase

2.4.1.11

0/1

0

b-Glucuronidase

3.2.1.31

0/1

0/1

0

Glutamate dehydrogenase

1.4.1.2

3/3

5/11

1/3

1/1

56

1.8

Glutamate dehydrogenase NADP

1.4.1.3

1/1

100

1.0

Glutamate pyruvate transaminase

2.6.1.2

1/2

2/3

60

2.0

Glutathione reductase

1.6.4.2

0/1

1/2

0/1

25

2.0

Glyceraldehyde-3-phosphate dehydrogenase

1.2.1.12

0/1

0/4

1/2

0/1

13

2.0

Glyceraldehyde-3-phosphate dehydrogenase (NADP+)

1.2.1.13

0/1

0/1

0

Glycerate dehydrogenase

1.1.1.29

1/1

0/3

0/1

20

4.0

Glycerol-3-phosphate dehydrogenase (NAD+)

1.1.1.8

0/2

0/1

0/2

0

Glyoxalase

4.4.1.5

1/1

100

2.0

Guanine deaminase

3.5.4.3

0/1

0

Hexokinase

2.7.1.1

2/5

4/8

3/4

2/3

55

1.9

Hexosaminidase

3.2.1.30

1/1

100

1.0

3-Hydroxybutyrate dehydrogenase

1.1.1.30

0/1

0/1

0/1

0

l-Iditol (sorbitol) dehydrogenase

1.1.1.14

0/3

0/1

0/1

0

Isocitrate dehydrogenase (NADP1)

1.1.1.42

5/5

0/5

5/6

2/3

63

1.8

Laccase

1.10.3.2

0/1

0

l-Lactate dehydrogenase

1.1.1.27

2/5

0/1

0/3

3/3

17

2.0

Leucine dehydrogenase

1.4.1.9

0/1

0/1

0

Lysine dehydrogenase

1.4.1.15

0/1

0

Malate dehydrogenase

1.1.1.37

8/9

7/10

5/6

4/4

83

1.9

Malate dehydrogenase (NADP+) (malic enzyme)

1.1.1.40

2/4

3/7

1/4

2/2

47

1.4

Mannitol dehydrogenase

1.1.1.67

3/3

0/2

0/1

50

1.7

Mannose-6-phosphate isomerase

5.3.1.8

1/3

3/5

2/3

3/3

64

1.6

Menadione reductase

1.6.99.2

1/1

3/6

2/3

1/2

58

1.1

NAD dehydrogenase

1.6.99.3

0/1

0

NADPH dehydrogenase

1.6.99.1

0/1

0

Nucleoside diphosphate kinase

2.7.4.6

1/1

100

2.0

Nucleoside phosphorylase

2.6.1.1

1/2

50

2.0

Octanol dehydrogenase

1.1.1.73

0/1

0

Peroxidase

1.11.1.7

1/2

0/1

33

2.0

Phosphoenolpyruvate carboxylase

4.1.1.31

0/2

0

6-Phosphofructokinase

2.7.1.11

0/1

0

Phosphoglucomutase

5.4.2.2

9/9

7/10

5/5

1/2

85

2.3

Phosphogluconate dehydrogenase

1.1.1.44

6/6

4/6

2/3

4/4

84

1.5

Phosphoglycerate kinase

2.7.2.3

0/3

1/1

25

3.0

Polyphenol oxidase

1.14.18.1

0/3

0

Pyruvate kinase

2.7.1.40

0/1

0

Shikimate dehydrogenase

1.1.1.25

1/4

0/4

0/2

0/1

9

1.0

Succinate dehydrogenase

1.3.99.1

0/3

0/1

0

Superoxide dismutase

1.15.1.1

1/5

0/2

1/3

2/3

31

2.0

Trehalase

3.2.1.28

0/2

0/1

0

Triose-phosphate isomerase

5.3.1.1

2/2

2/2

3/4

1/1

89

2.4

Uridine diphosphoglucose pyrophosphorylase

2.7.7.9

1/1

100

1.0

Uridine monophosphate kinase

2.7.4.4

0/1

0

Xanthine dehydrogenase

1.1.1.204

2/5

0/3

0/2

1/2

25

1.7

X-Pro dipeptidase

3.4.13.9

1/1

100

4.0

a Based on an analysis of 27 published enzyme surveys plus three surveys of septoria pathogens (G. Zhang and S. B. Goodwin, unpublished). The published surveys were those of: Altomare et al. (1997); Andrews et al. (1988); Burdon and Roelfs (1985a); Damaj et al. (1993); Gaur et al. (1991); Goodwin et al. (1993); Huss (1996); Leuchtmann and Clay (1989); (1990); Leung and Williams (1986); Linde et al. (1990); Nyasse et al. (1999); Old et al. (1984); Otrosina and Cobb (1987); Otrosina et al. (1992); Oudemans and Coffey (1991a); Riley et al. (1998); Royse and May (1982a); Six and Paine (1999); Surve-Iyer et al. (1995); Tooley and Fry (1985); Tuskan and Walla (1989); Vogler et al. (1991); Welz et al. (1994); Yoon et al. (1990); Zambino and Harrington (1989); Zhu et al. (1988). bEnzyme Commission number. International Union of Biochemistry and Molecular Biology (1992). Enzyme Nomenclature. Academic Press, Inc. c Ascomycates. d Basidiomycetes. e Deuteromycetes.

a Based on an analysis of 27 published enzyme surveys plus three surveys of septoria pathogens (G. Zhang and S. B. Goodwin, unpublished). The published surveys were those of: Altomare et al. (1997); Andrews et al. (1988); Burdon and Roelfs (1985a); Damaj et al. (1993); Gaur et al. (1991); Goodwin et al. (1993); Huss (1996); Leuchtmann and Clay (1989); (1990); Leung and Williams (1986); Linde et al. (1990); Nyasse et al. (1999); Old et al. (1984); Otrosina and Cobb (1987); Otrosina et al. (1992); Oudemans and Coffey (1991a); Riley et al. (1998); Royse and May (1982a); Six and Paine (1999); Surve-Iyer et al. (1995); Tooley and Fry (1985); Tuskan and Walla (1989); Vogler et al. (1991); Welz et al. (1994); Yoon et al. (1990); Zambino and Harrington (1989); Zhu et al. (1988). bEnzyme Commission number. International Union of Biochemistry and Molecular Biology (1992). Enzyme Nomenclature. Academic Press, Inc. c Ascomycates. d Basidiomycetes. e Deuteromycetes.

segregation have been noted (Spielman et al. 1990). It is important to remember that no isozyme should be referred to as an allozyme until a proper genetic analysis has been completed.

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