POLLEN PIGMENTATION AND THE ACTION OF MUTANT yp

RESEARCH REPORTS

PNL Volume 13

1981

Crowden, R, K. and 1. C. Murfet

Botany Department, University of Tasmania, Hobart, Australia

Murfet (1) identified a recessive gene, yp, determining yellow pollen

which had arisen as a spontaneous mutant in the cultivar 'Vinco' (Hobart

line 51). Chemical tests have now shown that the change in color from orange

in the wild type pollen (Yp) to yellow in the mutant is the result of a

quantitative rather than a qualitative effect on pigment (carotenoid) pro-

duction in the pollen. The yp pollen contains approximately 5% of the caro-

tenoid level occurring in Yp pollen.

For the interest of workers with Pisum we report here the results of

chemical analyses of the carotenoid pigments, made on our behalf by D. G.

Britton, Biochemistry Department, The University of Liverpool, U.K. (Table 1)

Isolation and analysis of pigments

Pollen was treated with 15% KOH in ethyl alcohol : water, 1:1, overnight,

at room temperature, in the dark under nitrogen. Diethyl ether and water

were added dropwise, alternately, to give two phases. The water layer was

re-extracted with ether, and the combined ether layers washed with water,

then evaporated to dryness under nitrogen. The residues so obtained were

examined by TLC on

a] Silica Gel G (incorporating 0.1% KOH) using the solvent systems

(i) petroleum ether (40°-60°)

(ii) 30% diethyl ether/petroleum ether

(iii) diethyl ether

h) MgO/Keiselguhr, 1/1 (incorporating 0.1% KOH) using solvent systems

(i) 5% benzene/petroleum ether

(ii) 20% acetone/petroleum ether

These treatments resolved the presence, in both Yp_ and yp_ pollen, of

two major carotenoids, phytofluene and B-cryptoxanthin. Two minor pigments.

B-carotene and an unidentified dihydroxyxanthophy11, were also present.

Confirmatory evidence of pigment identity was obtained by eluting spots from

TLC plates with acetone and determining absorption spectra.

The co-occurrence of phytofluene and B-cryptoxanthin as major carotenoid

constituents in a plant tissue is somewhat unusual. By comparison examination

of vegetative tissue (leaves) of Vinco showed a "normal" mixture of carotenoid

with 3-carotene; lutein, violaxanthin and neoxanthin occurring as major

pigments, together with a trace amount of a-carotene.

(1) Murfet, I. C. 1967. Heredity 22:602-607.