Ultrastructural aspects of pollen tube growth inhibition after gamma irradiation in Lycopersicum peruvianum.

Gamma ray treatments at various doses were applied to flowers after cross-compatible pollinations (S1S4 × S12S13) and self-incompatible pollinations (S1S4 × S1S4). After 200 kR treatment (highest dose) a high percentage of pollen became non-viable, and tube growth of all the germinated pollen was inhibited at the first third, or just before half the length of the style. Observations on the ultrastructural aspects revealed that the pollen tubes were destroyed by a precise degradation process which led to the disappearance of the inner wall, lysis of the tube, accumulation of several bipartite particles and alteration of endoplasmic reticulum into a whorl of concentric circles. These results indicated that the high dose of gamma rays probably interferes with protein synthesis. The ultrastructural aspects of compatible pollen tubes after gamma irradiation were similar to those of self-incompatible tubes and therefore it is suggested that cessation of protein synthesis might also be a result of incompatibility.Electron microscopy observations after treatment with 200 kR gamma rays on flowers after self-incompatible pollination (S1S4 × S1S4) showed that gamma irradiation affects the self-incompatibility reaction; but the results obtained so far are difficult to explain.