Genetic and cytological studies ofMusa - I. Certain hybrids of the gros michel banana
Artificial pollination of the sterile and parthenocarpic Gros Michel banana (somatic chromosome number 33) by a fertileMusa, identified as a variety ofM. malaccensis Ridl. (somatic chromosome number 22), results in formation of occasional seeds, the average seed production being less than one per hundred flowers.
Of ten plants raised from such seeds and examined cytologically, eight have 44 somatic chromosomes and two about 75. The former resemble their female parent, and have parthenocarpic fruits but an increased pollen fertility; the latter are thick-leaved, dwarf, and apparently sterile.
Of five plants, forming anF2 generation from one of the 44-chromosomeF1 individuals, three have 44 somatic chromosomes, and two have 46.
TheF1 crosses back to its female parent only with extreme difficulty, but crosses readily with its male parent, giving vigorous progeny with 33 somatic chromosomes.
The course of events suggests that the basic haploid chromosome number in this series is eleven. The meiotic phenomena are not inconsistent with that hypothesis, but they further suggest that the eleven is a secondary haploid number, possibly derived from an original eight.
Volume 101, 2022
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