Embryo sac development is affected in Petunia inflata plants transformed with an antisense gene encoding the extracellular domain of receptor kinase PRK1

Abstract

In a previous study of the function of a pollenexpressed receptor kinase of Petunia inflata, P R K I, it was found that transgenic plants carrying an antisense-PRKI gene were unable to transmit the transgene c through either the male or, unexpectedly, the female. In this report, the nature of this female phenotype was stud ied using one of the transgenic plants, ASRK-13. Elec tron and light microscopic examination of the embryo sac and seed development of ASRK-13 and a wild-type plant revealed that embryo sac development of approxi mately half of the ovules of ASRK-13 was abnormal. The development of the affected embryo sacs was arrest ed at the late stages of megagametogenesis. The majority of the affected embryo sacs completed three rounds of mitosis normally, but failed to progress through the mat uration stages when cell expansion, nuclear migration, and differentiation take place. The remaining small num ber of abnormal embryo sacs were arrested at either the four-or eight-nucleate stages. The ovules containing the defective embryo sacs apparently failed to be fertilized,

Isolation and Characterization of Kinase Interacting Protein 1, a Pollen Protein That Interacts with the Kinase Domain of PRK1, a Receptor-Like Kinase of Petunia

“…First, RNA gel-blot analysis shows that PRK1 and KIP1 transcripts are detected only in pollen, and that the temporal expression patterns of these two genes during anther development are very similar, with the first detection around the stage of pollen mitosis I. (It should be noted that very low levels of the PRK1 transcript were previously detected in ovaries when poly(A) ϩ RNA, instead of total RNA, was used for RNA gel-blot analysis; see Lee et al, 1997.) Second, the in situ hybridization results show that the transcripts of PRK1 and KIP1 are present in the cytoplasm of the pollen grain and not in the sporophytic tissue of the anther.…”

“…Since PRK1 is expressed in mature pollen, it cannot be ruled out that PRK1 is also involved in late stages of pollen development and/or postpollination events. It is interesting that antisense PRK1 transgenic plants that showed the pollen abortion phenotype also showed abnormal embryo sac development, with the two polar nuclei failing to migrate and fuse to form the central cell (Lee et al, 1997). However, although the PRK1 transcript was detected in the ovary, its level was much lower than in pollen, making it difficult to definitively establish the cause-and-effect relationship between downregulation of PRK1 and the embryo sac phenotype (Lee et al, 1997).…”

“…It is interesting that antisense PRK1 transgenic plants that showed the pollen abortion phenotype also showed abnormal embryo sac development, with the two polar nuclei failing to migrate and fuse to form the central cell (Lee et al, 1997). However, although the PRK1 transcript was detected in the ovary, its level was much lower than in pollen, making it difficult to definitively establish the cause-and-effect relationship between downregulation of PRK1 and the embryo sac phenotype (Lee et al, 1997). Two other pollen-expressed RLKs, LePRK1 and LePRK2, have recently been identified in tomato, but they are thought to be involved in post-pollination events rather than in pollen development because their transcripts are not detected until pollen is nearly mature and because they are localized to the wall/membrane of pollen tubes (Muschietti et al, 1998).…”

Genetic and molecular identification of genes required for female gametophyte development and function inArabidopsis

“…A transmembrane receptor protein was identified (line EDA 23, Table 3) as well as a guanine nucleotide exchange protein (Line EDA 10, Table 3). The latter protein is an interactor of PRK1 (Park et al, 2000), which is a receptor-like kinase with serine/threonine kinase activity isolated from petunia and involved in embryo sac development (Lee et. al, 1997).…”

Cytological study of pollen tube growth and early seed development inPetunia inflata

“…3h) were visualized at higher magnification. In P. inflata, an ovary contains approximately 200 ovules which become fully mature by anthesis (Lee et aL, 1997). The embryo sac developmerit of Petunia follows the pattern of Polygonum type (van Went, 1970a;Lee et al, 1997).…”