Pollen tube growth has been studied in peach and has been related to changes in the pistil structures which the pollen tube has to traverse in its way from the stigma down to the ovule. Growth of the pollen tubes along the pistil is not continuous. While pollen tubes reach the base of the style 7 days after pollination, fertilization does not take place until 12 days later. Pollen tubes stop for 5 days at the top of the obturator and they further stop for 3 days before entering the ovule. The pollen tube growth is heterotrophic; starch, present all along the pistilar tract at anthesis, vanishes as the pollen tubes pass by. Discontinuous pollen tube growth appears to be controlled by the pistil. At anthesis the pistil is not fully matured. Maturation of the pistil implies a number of secretory processes that occur in a basipetal way starting from the stigma down to the style and ending in the ovule. Some of these secretions at the stigma and the style are triggered by pollination; others appear to be a maturative stage of the pistil and are produced in a discrete way. The fact that the pollen tube depends on these secretions together with the fact that these secretions are not continuously produced confer upon the pistil a role of controlling pollen tube kinetics and point out that, for a successful fertilization, male gametophyte development and pistil maturation need to by synchronized.

SUMMARYChanges in the ovular tissues of peach (Prunus persica (L.) Batsch) were studied from anthesis to fertilization or degeneration in pollinated and unpolHnated flowers. During this time the ovule undergoes a continuous developmental process. At anthesis the megagametophyte is immature and is not fully developed until 12 days later. Durmg the first three weeks following anthesis the ovule increases in length from 400 to 1200/fm, and the nucellus and integuments undergo various changes particularly in the distribution of starch and cutin. These appear to be connected with early embryo sac nutrition and protection. As the ovule matures, starch accumulates mainly in the embryo sac, integuments and at the nucellar tip. This starch disappears during early embryo sac elongation. Concomitant with starch depletion, the cutin that separated the integuments from the nucellus vanishes. Other cutin accumulates between cells in the nucellar tip, thus protecting and isolating the embryo sac. Most of these changes appear to be a fixed feature of ovule development since they were also observed in a few long lived ovules in unpollinated flowers. However, in unpolHnated fiowers development of most of the ovules is soon interrupted: callose accumulates at the chaiaza, starch disappears and the ovules degenerate.

No abstract

Pollen tube growth has been studied in peach and has been related to changes in the pistil structures which the pollen tube has to traverse in its way from the stigma down to the ovule. Growth of the pollen tubes along the pistil is not continuous. While pollen tubes reach the base of the style 7 days after pollination, fertilization does not take place until 12 days later. Pollen tubes stop for 5 days at the top of the obturator and they further stop for 3 days before entering the ovule. The pollen tube growth is heterotrophic; starch, present all along the pistilar tract at anthesis, vanishes as the pollen tubes pass by. Discontinuous pollen tube growth appears to be controlled by the pistil. At anthesis the pistil is not fully matured. Maturation of the pistil implies a number of secretory processes that occur in a basipetal way starting from the stigma down to the style and ending in the ovule. Some of these secretions at the stigma and the style are triggered by pollination; others appear to be a maturative stage of the pistil and are produced in a discrete way. The fact that the pollen tube depends on these secretions together with the fact that these secretions are not continuously produced confer upon the pistil a role of controlling pollen tube kinetics and point out that, for a successful fertilization, male gametophyte development and pistil maturation need to by synchronized.

Pistachio (Pistacia vera L.) cultivars need to be grafted on suitable rootstocks for their propagation, but grafting success is uncertain, preventing producers to meet plant demand. Thus, there is a need for a better grafting method that in addition to increase success rate, allows us an early detection of success. Here, we have developed an alternative grafting technique that achieves these goals using young potted seedlings of terebinth rootstock and reduced size micropropagated scions from commercial cultivars. During micropropagation of pistachio cultivars we studied the effects of the application of antioxidants together with the growth regulators meta-Topolin and paclobutrazol on in vitro cultures to overcome the issues identified in the different phases of micropropagation: culture initiation, multiplication and rooting. Grafting succeeded using scions derived from in vitro cultured micro-shoots both from acclimated and non-acclimated plants. With this protocol, up to 75.7 % successful grafts were obtained, and grafted plants resumed growth from day 3, being ready for transplant a few months later. Sustained on our results, we present a simple and reliable system to reduce production time by ex-vitro grafting of shoottips from in vitro cultures onto 4 weeks old terebinth (Pistacia terebinthus L.) rootstock seedlings grown in pots.