Recovery of dormant vp9 allele
--Jackson, JD

"Botany 100" is a trait I brought from Dr. John Laughnan's lab at the University of Illinois. It is a stock in W23 nuclear background that is recessive for a pale yellow endosperm that gives albino seedlings. He used it in the Botany 100 labs for showing 3:1 Mendelian ratios in seedlings. By planting given numbers of yellow and pale seeds you can easily show a 3:1 ratio of green to albino seedlings. This stock is very useful for teaching and we have supplied it to several people for such purposes. I wanted to further characterize this trait, so it could be properly added to the Stock Center's collection.

Dr. Laughnan's stock traces back to an albino trait in (EP) cytoplasm that he received from Jerry Kermicle in 1973. Also in 1973 Kermicle and Lonquist described a recessive white endosperm trait linked to the Rcm gene (Kermicle J. L. and J.H. Lonquist, MNL 47: 209-211, 1973). Later, Jim Allen stated that the white endosperm trait is allelic to vp9 (D. Robertson, personal communication) and went on to show linkage of Rcm1 with vp9 on the short arm of chromosome 7 (Allen,J.O. et al, Maydica 34:277-290, 1989). Previously Don Robertson had reported on a y7-Wisconsin #2 that turned out to be an allele of vp9 (Robertson, D., J. Hered. 66:67-74, 1975). This allele seemed to consistently produce almost all dormant seeds. This sounded like the stock from Dr. Laughnan, and after reading the Maydica article I thought this might be the same trait.

We have maintained Dr. Laughnan's stock for years by self pollination and selection for ears segregating the pale endosperm trait. Unable to obtain the original sources or their pedigrees, allelism crosses were made between "Botany 100" and the COOP's vp9-R and vp5. "Botany 100" heterozygotes were crossed as females by plants that were also self-pollinated to confirm the presence of vp5 or vp9-R. Five such crosses with vp5 were negative. However, seven crosses with vp9-R confirmed that the "Botany 100" stock we now maintain is allelic to vp9-R. The allele now called vp9-Bot100 has been added to the Stock Center's collection and is available for teaching and research purposes.

The vp9-Bot100 is a dormant allele. On vp9-R self-pollinated ears the pales are viviparous. In comparison, the pale kernels on the vp9-Bot100 stock are never viviparous and the ears of vp9-Bot 100 crossed by vp9-R are predominantly dormant with only rare viviparous kernels. The pale kernels on vp9-R and vp9-Bot 100 have a greenish almost fluorescent cast to them. Crosses were done to determine if Bn1 was present in the stock to give the greenish color . Tests were negative in that the greenish color did not disappear and seems to be associated with the trait.

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