![Figure: Tomato flowers and gametophytic organs (mechanically opened stamen crown [middle] and dissected ovary [right])](/im/1366715289_1943_0.jpg "Figure: Tomato flowers and gametophytic organs (mechanically opened stamen crown [middle] and dissected ovary [right])")
Bettina Hause
Prof. Bettina Hause
Leibniz Institute of Plant Biochemistry
Deparment of Metabolic and Cell Biology
Weinberg 3
06120 Halle (Saale)
phone: +49 (0) 345-5582 1540
Bettina.Hause@ipb-halle.de
Susanne Forner
PhD student
Function of proteinase-inhibitor II (PIN2) in the jasmonate-regulated flower development of tomato
Jasmonates are ubiquitously occurring plant hormones, which are involved in regulation of plant defenses against biotic and abiotic stresses, but also of plant development. Jasmonates consist of jasmonic acid (JA) and its metabolites, such as the methyl ester and amino acid conjugates. Most prominent example for their role in plant defense is the plant response to wounding by herbivores. Herbivore attack or mechanical wounding leads to endogenous rise in JA followed by expression of proteinase inhibitors, which affect negatively the digestion of plant material within insects. Among the proteinase-inhibitors, PIN2 is the best characterized one. PIN2 inhibits specifically serine proteases, such as chymotrypsin und trypsin. It occurs, however, constitutively in floral organs, here mainly in ovules of developing flower buds. PIN2 expression level is closely related to the endogenous content of JA in such organs. Despite its function as defense protein, its role in ovules is still unclear. Jasmonate-insensitive tomato plants (jai1) are female sterile; an expression of PIN2 is not detectable in ovules of jai1. Therefore, the question rises whether PIN2 contributes to female fertility in tomato. To answer this question we will follow two complementary approaches: (i) developing ovules of wild type and jai1 plants will be compared in respect to programmed cell death and expression of ovule-specific serine proteases. Here, cytological methods as well as gene expression studies will be applied; (ii) jai1 plants will be transformed with the cDNA encoding PIN2 under the control of an ovule-specific promoter. If activity of PIN2 is essential for proper flower development, jai1-flowers should be rescued by transgenic overexpression of PIN2 and should be fertile again. To this end, the role of PINs and/or proteases in the development of plant gametophytes including the role of programmed cell death in female gametophyte development will be elucidated.