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Wheat Information
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Number 72: 85-87 (1991)
Characterization
of alloplasmic common wheat with Agropyron
cytoplasms
T. Suzuki, K. Kasai, H. Sakagami and C. Nakamura
Department of Plant Protection, Faculty of Agriculture, Kobe
University, Kobe 657, Japan
Alloplasmic wheat with alien cytoplasms have provided good
experimental materials for studying nuclear and cytoplasmic
interactions between Triticum and its related genera
(Tsunewaki 1988). In alloplasmic common wheat (T. aestivum)
with Agropyron cytoplasms, a gross reduction in plant
vigor and male sterility occurred and telocentric Agropyron
chromosomes (telosomes) restored normal plant vigor and male
fertility (Tsujimoto et al 1987, Nakamura et al 1991).
We studied four alloplasmic lines having two common wheat nuclei
(cultivars Penjamo 62 and Siete Cerros 66) and two Agropyron
cytoplasms (trichophorum and glaucum).
Table 1
shows effects of
Agropyron cytoplasms and telosomes on plant hight and selfed
seed set. It is evident from the Table that Agropyron
cytoplasms cause severe growth depression and high sterility in
these alloplasmic lines, and that the presence of Agropyron
telosomes restore normal plant vigor and fertility.
We reported that the alloplasmic lines showed significantly lower
photosynthetic capacity than the euplasmic lines and the alloplasmic
lines with telosomes and that the lower photosynthetic capacity was
due to higher rates of dark respiration in green leaves (Nakamura et
al 1991). To further characterize respiration in the alloplasmic
lines we studied respiratory electron flows through the cytochrome
and alternative paths and in vitro cytochrome c oxidase (cox)
activity using 2-day-old seedlings and 2-week-old seedling leaves and
roots. The reduction in plant vigor occurred in such early stages of
development of the alloplasmic lines (Nakamura et al 1991). The
respiratory parameters were measured by an oxygen electrode based on
the rates of oxygen uptake in the presence and absence of respiratoty
inhibitors (1 mM KCN, 5 mM salicylhydroxamic acid) and an uncoupler
(2 and 10 microM carbonylcyanide m-chlorophenyl hydrazone). All the
parameters differeed significantly at different ages and/or in
different tissues: 2-day-old seedlings showed significantly higher
activity than 2-week-old seedling leaves and roots. The activity of
the cytochrome path agreed well with the in vitro cox
activity. In 2-day-old seedlings the cox activity was higher in the
alloplasmic lines with telosomes than in the euplasmic lines and the
alloplasmic lines without telosomes, while in 2-week-old seedling
leaves and roots the activity was higher in the alloplasmic lines
without telosomes. Our results suggest that the interaction between
common wheat nuclei, Agropyron cytoplasms and Agropyron
telosomes is related to mitochondrial function (Table
2).
The specificity of the effects of Agropyron telosomes on
Agropyron cytoplasms was studied by evaluating the ability of
telosomes for recovering plant vigor in the alloplasmic lines in
which telosomes from one Agropyron species were introduced
into cytoplasms of the other species. Table
3 shows that
Agropyron telosomes could recover plant vigor in the
alloplasmic lines only when cytoplasms and telosomes were from the
same Agropyron species. The result clearly shows that the
effects of Agropyron telosomes on Agropyron cytoplasms
are species-specific.
Cytological examinations of root tip cells showed that all
Agropyron telosomes found in the alloplasmic lines were
short-arm telosomes of Agropyron satellite chromosomes.
References
Nakamura C, Yamakawa S and Suzuki T (1991) Recovery of normal
photosynthesis and respiration in common wheat with Agropyron
cytoplasms by telocentric Agropyron chromosomes. Theor Appl
Genet (in press).
Tsujimoto H, Panayotov I and Tsunewaki K (1987) Behavior of an extra
chromosome carried by alloplasmic common wheat lines having
Agropyron trichophorum cytoplasm. Jpn J Genet 62:
291-299.
Tsunewaki K (1988) Cytoplasmic variation in Triticum and
Aegilops. Proc VII Int Wheat Genet Symp: 53-62.
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