Sensitivity of developmental stages of peanut (A. hypogaea) embryos and ovaries to several chemical mutagen treatments

Peanut embryos at successive stages of development were treated while still attached to the parent plant with the mutagens DES, EMS, MNNG, ICR-170, acriflavine, ethidium bromide, hydroxylamine, nitrous acid and sodium azide, and with the protein synthesis inhibitors chloramphenicol and erythromycine, for periods varying from 2 hr to 15 days. The results show that chronic treatments of fertilized ovaries with chemical mutagens are possible. However, differences in sensitivity were found between the stages of development of the embryos, with the earlier stages being the most sensitive. The alkylating agents were the most injurious while the acridines (ethidium bromide, ICR-170 and especially acriflavine) caused little damage as measured by the survival of the treated embryos and their subsequent germination. Within the mutagens, especially in treatments lasting more than 24 hr, the concentration of the mutagen during the treatment was the most important factor affecting the survival of the treated embryos. In the short treatments, the duration was as important as the concentration. Treatments of young embryos with chemical mutagens could be valuable in crops whose ovaries contain many ovules, because of the large M₁ seed populations obtainable from each fruit. The advantages of embryo treatments are discussed.