Desynapsis in Coix lacryma-jobi caused by genotype-environment-interaction.

Desynapsis leading to total sterility was observed in one plant of Job's tears, Coix lacrymajobi. L., during summer months, while the other neighbouring plants were quite normal. Pachytene chromosome pairing in the desynaptic was apparently normal but a diakinesis and metaphase I several univalents were found. Perennial suckers of this plant in the rainy season showed regular meiosis and good fertility. It is probable that desynapsis was caused by an interaction of genotype and environment, in which the desynaptic gene became activated by the rapid increase in summer temperatures whilst its effect on chromosome synapsis was completely lost in the cooler periods.