II. Research Notes

X-ray induced mutations in Einkorn wheats II. Pigment analysis

Kosuke YAMASHITA and Mitsuro OKUDA

Biological Laboratory, Kyoto University, Kyoto, Japan

Various mutations induced by X-ray irradiation in Triticum monococcum have been reported by the senior author, including those regarding pigmentation such as chlorina, carotina, albino and many others, which were proved to be Mendelian recessive. In the seedling stage, a primary leaf of the chlorina is whitish at the base and green at the top with gradation in the middle portion. In the carotina an entire leaf is orange-yellow with carotinoid. The lower portion of a leaf in the albino shows an anthocyanin color.

In the present paper the results of the cytological and microchemical observations on the above mentioned three mutants are reported. The carotina is the name given to the "orange" mutant in the Yamashita's former papers.

A cross section of a leaf blade was observed under the microscope mounted by distilled water, with or without treatment by one per cent silver nitrate solution for more than a half hour. When treated, the chloroplast was clearly demonstrated as a result of reduction of silver nitrate by active chlorophyll.

For the observation of chloroplast in guard cells, lower epidermis was dipped in one percent silver nitrate solution for more than a half hour or mounted by saturated sodium hydroxide, so that the chloroplast was colored black by the former and yellowbrown by the latter treatments.

1) Chloroplasts in the mesophyll of a leaf blade:

In a normal leaf chloroplasts were distributed in the mesophyll uniformly along an entire leaf blade, while no chloroplasts were observed in the carotina and albino mutants. In the chlorina the upper part of a leaf blade contained chloroplasts embedded in the thin layer of cytoplasma as in the normal. In the chlorina mutants the number of chloroplasts per one cell was less and their size was smaller than in the normal as shown in the following table. In the middle portion, both the number of chloroplast per one cell and the number of the cells having chloroplasts decreased gradually from the top to the base, where only a few or no chloroplasts were observed. The same was the fact when treated with silver nitrate. In some cases, a few chloroplasts were distributed to the lower portion, e.g. No. 953. In these cases, the cells having chloroplasts were localized mainly around the bundle sheath or in the mesophyll just under the epidermis. Leucoplasts were observed in the cells of the whitish lower portion of the chlorina.

2) Chloroplasts in the guard cells:

The chloroplasts with the reduced silver nitrate by active chlorophyll were observed in the guard cells irrespective of the leaf portions in the normal and in the chlorina strains as well. The stomatal guard cells contained chloroplasts in the whitish portion of the chlorina, while no chloroplasts were observed in the guard cells of the carotina strain.

3) Corotinoids in the mesophyll of the carotina:

Chromoplasts having carotinoids was distributed in the cytoplasm surrounding the vacuole in all cells of the mesophyll of the corotina.

4) Anthocyanin in the albino:

Anthocyanin was observed in the cells of the outermost layer of the mesophyll in the albino. Carotinoids was identified by the Molisch's "Kalimethode" and the color reaction by concentrate sulphuric acid (1).

(Received April 25, 1958)