Wood Production, Wood Technology, and Biotechnological ... - GWDG

Molecular Wood Biotechnology
To newly combine genes from a genetic pool of eukaryotic organisms in
nature, sexual reproduction is required and at least two different sexes (male and
female) - but also not more than two. Accordingly, this is the normal common
situation for most eukaryotic species. It is however not fully understood why it is
usually so (Whitfield 2004). Biologists have puzzled about this “two sexes”-phenomenon
ever since the father of theoretical biology, R.A. Fischer, addressed this
scientific-philosophical question and suggested to study species that break the two
sexes-rule by having more (Fischer 1930). Interestingly, most basidiomycetes very
much exceed the number of two sexes in up to ten thousands per species. For
example, the model species C. cinerea has more than 12.000 (Kües 2002). Technical,
sexes in the fungi are termed mating types since they base not on morphological
differences but on physiological self-incompatibilities (Kües & Casselton
1992). Genetically, they are therefore comparable to the multiple self-incompatibility
mechanisms of plants superimposed on the male and female sex-organs
(Hiscock et al. 1996, Charlesworth et al. 2005). The multiple fungal and plant selfincompatibility
systems promote a higher degree of outbreeding (mixing within
the genetic pools) than simple systems with two different sexes - which is a
plausible reason for the development of multiple systems in contrast to the more
general phenomenon of only two sexes (Hiscock & Kües 1999, Kües 2002). The
choice of outbreeding versus inbreeding influences gene flow within populations
and thus the variability and fitness within species and their short-term and longterm
adaptations to the changing environment (Charlesworth 2003, Neiman &
Linksvayer 2006; see also Chapter 8 of this book). Research in the last decade lead
to the identification of the cellular gene functions defining the mating types in
C. cinerea and other basidiomycete and, thereby, controlling sexual development
(Casselton & Olesnicky 1998, Hiscock & Kües 1999, Kües et al. 2001, Kües 2000,
James et al. 2006, Srivilai et al. 2006b, Casselton & Kües 2007). One might expect
that there is no direct link between the academic interest in evolution of sexes and
mating types and any problem in biotechnology. However, the fungal mating type
genes control fruiting body development (Kües et al. 1998, 2002b, James et al.
2006) and are therefore of importance for the production of edible mushrooms, as
well as for breeding programmes of better production strains (Kües and Liu 2000,
Kothe 2001; see Chapters 22 and 23 of this book). Edible and medicinal mushrooms
have a well-balanced nutritional composition and contain various substances
with (potential) positive effects on human health and well-being (Wasser 2002,
Kües et al. 2004, Zaidman et al. 2005). In many instances, such mushrooms are
cultivated on straw, wood and wood wastes, giving a direct link to the field
“Molecular Wood Biotechnology” (see Chapter 22 of this book).
All research examples from the past show that basic and applied research go
hand in hand and profit from each other, regardless of whether basic research
stand at the beginning as in the studies of yeast flocculation, fungal mating types
and fruiting body development, or whether an applied problem initiated the
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