Gibberellic acid effects on the ultrastructure of endocarp cells of unpollinated ovaries of Pisum sativum

Ultrastructural changes of endocarp cells of unpollinated pea (Pisum sativum L. cv. Alaska) ovaries treated and non‐treated with gibberellic acid (GA3) were studied. Following treatment with GA3, the differentiation of cells of the middle zone of the endocarp into sclerenchyma occurred in 3 phases: initial, elongation and maturation. In the initial phase a proliferation of endocarp cells was produced in both GA3treated and non‐treated ovaries. Changes in the cell membrane system (Golgi apparatus, endoplasmic reticulum, plasmalemma) and the formation of primary and secondary cell wall were observed in the 2nd and 3rd phases of treated ovaries. In nontreated ovaries senescence followed the initial phase. These results indicate that GA3 induced the processes involved in the elongation and maturation phases.