Properties of starches from nonmutant and mutant endosperm cultures

In order to evaluate the potential mutant expression of endosperm genes in cell cultures, we initiated cultures of normal, ae and wx endosperm in 1983. All lines were in the A636 inbred background. We reasoned that starches of these genotypes could be compared at several levels, including starch granule morphology, starch granule iodine staining and distribution of the starch polymers, amylose and amylopectin. Starch formation was studied in nine-month-old suspension cultures of each genotype. Isolated starches were compared with starches isolated from mature endosperm of the same genotype. Starches from normal cultures and endosperm stained blue-black with iodine, and were round to polygonal in shape. Amylose accounted for 30.4% and 31.6% of the starch from cultures and mature endosperm, respectively. Starch granules from ae endosperm and cultures stained blue-black with iodine, and contained abnormal (budded, oblong) starch granules. However, the frequency of abnormal granules was greater in the mature endosperm. Amylose comprised 67.7% and 39.9% of mature endosperm and culture starches, respectively. Starch granules from wx endosperm and cultures stained brown-orange with iodine, contained no amylose and contained a few large "ragged-edged" granules. Therefore, we concluded that endosperm specific genes are phenotypically expressed in cultures up to nine months of age.

C. D. Boyer and Carole Haemmerle

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