The mutagenic activity of diethyl sulfate in peanuts

Seeds of two peanut (A. hypogaea L.) varieties, "Virginia Sihit Meshubahat" (VSM) and "Dixie Anak" (DA) were soaked in a saturated solution of diethyl sulfate (DES) for periods of 5, 15 and 25 min. Later, VSM seeds were treated also for 35 and 48 min but these treatments produced poor seed yields due to the short growing period. Examinations were conducted through the M₁, M₂, M₃ and where necessary, the M₄ generation. DES proved to be an efficient mutagen in peanuts despite their amphiploid nature, but there were varietal differences in mutation yield and in physiological sensitivity. In VSM the M₁ plants from the first 3 treatments were normal, while in the 2 longer treatments some non-heritable physiological disturbances were found. In DA M₁ survival was much lower, and one dominant mutation was discovered in this generation. In the M₂ more than 25 per cent of the VSM rows contained mutant plants whereas in DA only 10·7 to 17·5 per cent of the M₂ rows contained such plants. Mutation rates per embryo bud were significantly higher in VSM than in DA, and within VSM they were significantly higher in the 15 and 25 min treatments. Most of the mutations induced proved to be monogenic, and all but one were recessive or partially dominant. Of the 101 mutations induced in VSM 66 affected one trait while 35 were pleiotropic, and in DA 12 of the 13 induced mutations were pleiotropic. The proportion of chlorophyll mutants was not high, with more xantha type in DA and more viridis in VSM. Very few mutants may be of value in peanut improvement. In addition to the above mutations there were 8 cases in DA in which all the M₂ progenics of typical M₁ plants had a deviating growth habit and pod shape. These deviations persisted uniformly in subsequent generations in 7 families, while in 1 there was some segregation. Crosses designed to test the nature of these mutants are now in progress.