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PNL Volume 18 1986 RESEARCH REPORTS
PHOTO- AND THERMO-SUSCEPTIBLE CHLOROPHYLL MUTANTS OF PISUM SATIVUM
Gottschalk, W.
Institute of Genetics, University of Bonn
Federal Republic of Germany
The penetrance and expressivity of many mutant genes controlling
chlorophyll content of plants depends on temperature. Examples are known
in Avena, Hordeum, Tagetes, and Arabidopsis, among others. In other cases,
light intensity influences the action of chlorophyll genes. Examples of
this may be found in mutants of Lupinus, Lycopersicon, Antirrhinum, and
Arabidopsis.
The X-ray induced mutant 159 of our collection belongs to the first
group. The plants are almost free of chlorophyll when grown under normal
field conditions. They die after having formed four small leaves, behaving
like typical lethal mutants. The lethal effect of the recessive gene,
however, can be overcome by growing the mutant under higher temperatures.
In phytotron trials, mutant plants were chlorotic at temperatures below 17C
whereas normal chlorophyll synthesis occurred at 19C and higher.
A representative of the second group is mutant 11A of our collection
which appears identical with Lamprecht's albina terminalis (alt) mutant
(1). When grown in the field, the lowest three or four foliage leaves have
normal dark green chlorophyll content. The fourth leaf is light olive
green and the leaves above are almost free of chlorophyll. The plants form
9-10 leaves but die before flower buds are formed. Degeneration of
chlorophyll typically occurs above the fifth foliage leaf.
However, the pattern of chlorosis just described appears only under
normal insolation. When the plants are grown in pots in dim light, they
also produce normal leaves in the upper region of the shoot. If these
plants are returned to normal light, the newly formed leaves again show
chlorosis. Thus, light conditions strongly influence the expression of
mutant 11A.
Lamprecht, H. 1955. Agri Hort. Genet. 13:103-114.
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