DNA content of Phaseolus coccineus x P. vulgaris suspensors

Summary At the globular stage of embryo development, the level of DNA, as determined from microspectrophotometric analysis of Feulgen-stained squashes, was significantly higher in the interspecific hybrid suspensor than in suspensors from self-pollination of Phaseolus coccineus, the maternal parent. However, at the early-heart and early-cotyledonary stages of development, DNA content of interspecific hybrid suspensors was significantly lower than that of suspensors formed after self-pollination of either P. coccineus or P. vulgaris. The relationship between DNA content and suspensor cell length for P. coccineus and P. vulgaris at all developmental stages and between DNA content and cell area for P. coccineus at the early-cotyledonary stage was altered in hybrid suspensor cells. Nuclei in large cells of interspecific suspensors exhibited uneven distribution of polytene chromosomes and no clear nuclear outline.Paper number 18,470 of the Scientific Journal Series, University of Minnsota Agricultural Experiment Station, St. Paul, MN. This research was funded by the USDA CRGO under grant number USDA-85-CRCR-1-1676