An ageotropic primary root mutant

A new mutant, ageotropic (agt), was discovered in the selfed M2 progeny of seeds which were treated with 0.2% EMS for 12 hours. The primary root is unresponsive to gravity and may grow horizontally or may find its way to the surface and grow several centimeters long before dying. The other roots, seminal and adventitious, have normal geotropic responses. Three families, all derived from a single treated kernel, have segregated agt. The segregation was 28 + : 2 agt, 21 + : 2 agt, and 44 + : 3 agt, for a total of 93 + : 7 agt, a ratio of 13.3 + to 1 agt. It is possibly a case of duplicate factors. More likely it is a recessive which is difficult to classify. The primary root may grow down just by chance in some cases.

G. G. Doyle

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