Mutagenic effect of anther culture
--Y. C. Ting and K. Delorey
Individuals derived from selfing the Po (microscope-plant) plants of KH-13 via anther culture in vitro manifested not only reduced vigor but also seedling lethality. However, a few surviving plants grew into the adult stage. It was found that before tasseling the top of these plants bent downward and the flag leaves were wrapped around the young tassels (the first leaf below the tassel). As growth advanced, the tassels gradually turned upward and emerged shortly after. When the whole tassels were completely exposed the tops of the plants were still curled downward. As growth continued to advance, only a few of the florets reached anthesis stage, and their pollen shedding was generally poor. Since their pistillate florets developed normally self-pollinations of the plants were attempted. Some well-developed kernels were subsequently obtained even though the percentage of seed sets of these plants was very low compared with that of the ancestral plants.
When the progeny plants of the selfed Po plants grew into adults the curling tassels (bending downward) were again demonstrated for all of them. Hence, it was suspected that this character might represent a mutation transmitted from one generation to the next by sexual reproduction. In consequence of this, it was designated cur. This characteristic was not found among the progeny plants of its ancestor, and it was originated de novo during culturing.
The above curling tassel plants were subsequently crossed to a commercial inbred B73. The F1 plants from the reciprocal crosses did not show any curling tassel appearance in a population of 115 individuals. However, among the F2 plants from the selfed F1s, 11 out of a total of 49 manifested the curling tassel character. In other words, the curling tassel phenotype reappeared in a ratio of 3 (normal tassel) to 1 (curling tassel) as expected.
In another study in the last summer on the progeny plants derived from
KH-13 via anther culture, it was found that they were very susceptible
to lodging (by hurricane force). After the last hurricane, August, 1991,
all of these progeny plants were blown down. On the other hand the F1 plants
from a cross between the same progeny plants and a commercial inbred B73
were all resistant to lodging. In other words, none of them fell to the
ground after the same storm. In order to know if there is any Mendelian
segregation among the F1 progeny, the F1 plants were selfed. The results
of this test will be available in the near future.
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