1. A new gene for pollen abortion, pa, is located in chromosome 1. Plants heterozygous for pa are semisterile in the pollen and have normal cars. It is transmitted rarely if at all through the pollen, but gives normal ratios through the eggs. The locus of pa is between P and br, the recombination values bring: P-30-pa 34 br. It differs from sp and sp2 in that pollen carrying it is for the most part devoid of starch.
Cytological examination shows no visible deficiency in chromosome 1.
C. R. Burnham