Pollen as a transporter of mutations induced by ion beams in Nicotiana tabacum

Biological effects of ion beams with different ranges and linear energy transfers (LETs) were investigated in Nicotiana tabacum L. Mature pollen was exposed to doses of 1400 Gy of 6 (MeVHe2+)-He-4 or 1000 Gy of 50 MeV He-4(2+), 15 MeV C-12(4+), or 460 MeV Ar-40(13+) and used to pollinate non-irradiated flowers (I-0 generation), resulting in I, seeds. I-1 plants were self-pollinated, and mutations were analyzed in the I-2 generation. Seed formation in the I-0 generation was greatly reduced in all treatments except where C-12(4+) irradiated pollen was used. Germination rate and survival rate in the I, generation were also reduced in the seeds generated from crosses with pollen irradiated with 6 MeV He-4(2+) and C-12(4+) beams. Furthermore, chromosome and morphological aberrations in I-1 plants were observed. However, in 50 MeV He-4(2+) and Ar-40(13+) regimes, no seeds germinated. In the I-2 generation, chlorophyll mutants were very scarce. Morphological mutants were obtained at a frequency of 5.7 x 10(-3) and 7.9 x 10(-3) in the progeny of 6 MeV He-4(2+) and C-12(4+) regimes, respectively. It is concluded that the penetration depth is important for inducing mutation and also that pollen can be used for obtaining mutations induced by ion beams with very short penetration depths.