Studies on Chemically Induced Change in Expression of Gene(s) Controlling the Pollen Shapes inPimpinella Monoica

Summary Pollen variability in Pimpinella monoccia was artificially induced by treating seedlings with different chemicals. Positive results in the treated plants were obtained with acsculine, saponin, α-bromonapthalene and 8-hydroxy-quinolene. All these plants were 2n. Their meiosis was typified by multiple and multipolar spindles, laggards, strays, bridge-fragment configuration, spindle breakdown and unequal division of the chromosomes into many groups giving rise to variable number of spores at the sporad stage. Besides polyads the variable grains were asymmetric and nonfixiform while the controls had all radiosymmetric grains. One of the interesting facts was that similar pollen shapes were induced by all these diverse chemicals. The development of variable grains has been traced with the help of a scheme. The causes of pollen variability are discussed.