Date of this Version
The purpose of this paper is to report the Mendelian segregation of waxy and starchy carbohydrates in both the sporophytic and gametophytic generations of maize. This is of especial genetic interest because the counts of segregate waxy kernels have very commonly been short of the expected numbers, although this character appears to be a simple Mendelian recessive. Collins (1909) was the first to point out the physical difference in the endosperm of waxy and ordinary starchy varieties.
While the exact difference in their chemical nature has not been established, Weatherwax (1922) considered that the waxy carbohydrate was erythrodextrin because of its reddish color reaction to iodine as compared with the bluish staining of the endosperms of ordinary starchy varieties. Demerec (1924), Brink and MacGillivray (1924), and Longley (1924) have each established a corresponding differential staining of the pollen grains of the two maize sorts. Brink (1925) has more recently reported finding the same chemical distinction for the carbohydrates of the embryo sacs. In a publication of earlier results the writers (1925) failed, through faulty technique, to observe the differential staining of the pollen, but later results conform with those of the above investigators. Our earlier observations as to the wide distribution of starch throughout the sporophytic vegetative tissues have been confirmed.
Taking into consideration the observations of all investigators, it appears that the waxy carbohydrate is restricted to haploid or 1x tissue including pollen, embryo sac, and possibly the tissue developed from the antipodals, and to the 3x tissue of the endosperm. Only ordinary starch has been found in the diploid or 2x tissues which make up the rest of the plant.
The results of this investigation as well as those of Demerec, Brink and MacGillivray, and Longley indicate that those segregated plants following hybridization which come true to endosperm type also come true to the same sort of carbohydrate in the pollen. This is evidence that a single chromosome factor controls both or else that they are very closely linked characters with no observed crossing over.