Induction of desiccation tolerance in microspore-derived embryos ofBrassica napus

Summary A method was developed to induce desiccation tolerance in microspore-derived embryos ofBrassica napus. Treatment of 14- to 20-day-old embryos with 1×10⁻⁴ M abscisic acid, in the light, induced tolerance to slow desiccation over a 6-day period. Under these conditions 88 to 100% of embryos of the five cultivars tested survived (as measured by moisture uptake, greening, and growth of the shoot and root meristem) after storage for 1 wk at tissue water content levels of less than 20%. The response was found to be dependent on the abscisic acid concentration in the culture medium and time of exposure of the embryos to the abscisic acid-containing medium, with exposure times of as little as 1 day having a beneficial effect. Exposure times to abscisic acid (ABA) of 5–7 days resulted in the highest survival rates. Embryo age and size at the time of ABA exposure also affected the subsequent survival and development of embryos, with older and larger embryos exhibiting the best responses.