11. Water‑soluble pigments in corn.

The work carried out at the University of Missouri on the constitution of water‑soluble pigments in various genotypes of corn is being continued at the California Institute of Technology.

The purple tissues of corn plants containing a full complement of dominant genes for anthocyanin production (A₁ A₂B Pl r^r Pr Bz) were found chromatographically to have three anthocyanin pigments one of which is chrysanthemin, in accordance with the finding of Sando (1920). The other pigments are believed to be derivatives of chrysanthemin, since mild hydrolysis results in formation of a single pigment. In plants recessive for b gene, anthocyanin pigments can be produced through the action of gene r^r (r^ch allele was tested exclusively), when leaf tissues are supplied with excess of sugar. The pigments induced in leaf sections of such plants by floating them on glucose solutions were found to be identical with those produced naturally in leaf sheaths of plants containing dominant B gene.

The sun‑red plants, homozygous recessive for the pl gene, were found to have three pigments chromatographically identical with those produced in purple plants, but much reduced in quantity. The same three pigment fractions in reduced amounts were found in plants containing various alleles of gene A (A‑D4, A^d‑41, A^d‑31), and in plants homozygous for recessive b_z gene.

In two families, purple plants were found to segregate a factor responsible for production of a single anthocyanin pigment instead of the usual three fractions. The single pigment was found to be chrysanthemin. The factor behaves as a simple recessive gene. Chromosomal location of this gene and its action when in combination with other genes controlling pigment production is being studied.

		Plants Analyzed	Plants (3‑Pigment)	Plants (1‑Pigment)
Original Family Percentage		75	53	22
			70.3%	29.3%
F1:	1‑pigment plant selfed	9	0	9
	1‑pigment plant selfed	18	0	18
	3‑pigment plant selfed	11	11	0
	3‑pigment plant selfed	11	8	3
	1‑pigment plant crossed to 3-pigment plant	12	12	0
F2:	1‑pigment plant selfed	23	0	23

Chromatographic work reveals the presence of a large number of water soluble substances in plants where anthocyanin production has been decreased by substitution of gene A by any of its alleles, such as A^d-41, a^p, and a. Most of these substances are believed to be flavonoid or phenolic in nature. They are detected in chromatographs by means of their fluorescence in ultra-violet light. Determination of the chemical nature of these substances in plants containing the A^d‑41 gene, in the presence of other complementary genes, is in progress.

Katerina Zarudnaya