The release and spread of a large number of
basidiospores from the developing fruiting body cause
serious problems in the cultivation of edible mushrooms,
including Pleurotus pulmonarius (Fr.) Quel. The P. pulmonarius
sporeless mutant, TMIC-30058, has a high
potential for breeding sporeless cultivars to reduce these
adverse effects. Our previous study (Okuda et al. in
Breeding Science 59:315–319, 2009) showed two
sequence-tagged site (STS) markers for the sporeless trait
from this mutant. Here, using these STS markers we
present rapid detection of sporeless trait from P. pulmonarius
culture extracts by real-time PCR. This method
enables us to cut down time and labor for screening of the
sporeless trait, suggesting its availability for efficient
breeding of sporeless cultivars.
Keywords Marker-assisted selection Mushroom
breeding Oyster mushroom Sporulation-deficient
mutation STS marker
Pleurotus pulmonarius (Fr.) Quel. (Japanese name: Usuhiratake)
is one of the principal commercial species of oyster
mushroom (Pleurotus spp.) cultivated around the world.
The enormous number of spores produced by fruiting
bodies can adversely affect the health of mushroom
farmers (by respiratory allergic reaction) (Hausen et al.
1974; Sakula 1974; Olsen 1987), the mushroom cultivation
facility, and the genetic diversity of natural populations
(Hibbett and Donoghue 1996; Obatake et al. 2003). These
problems caused by spores are relatively more serious for
the cultivation of Pleurotus spp. because their fruiting
bodies begin to release considerable numbers of spores
from a very early stage in development and continue to do
so throughout their maturation.
Sporulation-deficient (sporeless) mutants are useful for
preventing these problems in mushroom cultivation. To
date, sporeless mutants were obtained for various species
including model and edible mushrooms. To the best of our
knowledge, sporeless strains are currently commercially
cultivated for only three species: Agrocybe cylindracea
(DC.: Fr.) Maire (Murakami 1993), Pleurotus eryngii (De
Cand.) Gillet (Obatake et al. 2006), and Pleurotus ostreatus
(Jacq.: Fr.) (Baars et al. 2000). Development of a commercially
viable sporeless strain of P. pulmonarius is also
highly desirable, but no such strain currently exists. In
addition, the traditional method of mutation breeding,
which uses the artificial or spontaneous mutants as an
initial material, requires much time and labor for the test
cross and the determination of the sporeless trait of materials
through cultivation. Thus, an efficient breeding
method using marker-assisted selection (MAS) is expected
for detecting the sporeless trait rapidly in the breeding
population.
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