Continued studies on the genic stability of the progeny of maize anther culture-derived microspore plants
--Ting, YC, Nguyen, DQ

In the last summer, about 200 kernels of a self-pollinated maize ear derived from anther culture of KH-13 were planted in the field. The objective of the experiment was further examining genic stability of this inbred. Before last summer, this line had persistently shown instability in its selfed progeny.

The kernels were randomly picked from a fully filled ear borne on a healthy and dark green plant. The kernels appeared normal. They germinated readily. However, when the plants were three weeks old, some of them began to show symptoms of slow growth. One week later, the slow growth plants started to express other abnormalities, such as yellow-green leaves, and lazy-growth habit by prostrating on the ground. In late July, the results of this experiment were under total evaluation. It was found that 70 plants had reached adult stage with flowering and seed-setting, while 18 of them were defective in height and leaf-chlorophyll content. These defective plants also had yellow-green leaves. Their tassels were small and no anthesis was observed. Their stalks were barren. In addition, the lazy plants were also sterile.

The above abnormal plants were presumably mutations. Due to their sterility, there was no way to test this hypothesis. The ratio between normal plants and abnormal ones did not fit Mendelian expectation. It is assumed that the original parental plant had a silent Ac element which was activated by anther culture per se. IN consequence of this, this inbred became highly mutable.

In parallel with the above, another experiment was conducted on a second inbred which was derived from maize Dan-Sun 91 by anther culture. This inbred line was a product of continued selfings of the original doubled-haploid. Over 120 kernels were employed and sown in the field. Seedlings and adult plants of these plantings were vigorous in growth. Their leaf chlorophyll appeared normal in content. Their stalks were strong and the stalk diameter appeared, on average, greater than that of the parental plant. This structure may account for their resistance of lodging which was discovered a few years ago. There were, on an average, two ears borne on each of these plants. The ears were small in size, but uniform in appearance. No abnormalities of any kind were observed. In other words, this inbred line was genically stable. Thus, it may allow for practical application, such as hybrid seed production, without any needed testing.

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