Plant Molecular Biology 33: 923–929, 1997.
1997 Kluwer Academic Publishers. Printed in Belgium.
Expression of an isoﬂavone reductase-like gene enhanced by pollen tube
growth in pistils of Solanum tuberosum
G.J. van Eldik
, R.K. Ruiter
, P.H.W.N. Colla, M.M.A. van Herpen, J.A.M. Schrauwen
Department of Experimental Botany, University of Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen, Netherlands
author for correspondence);
Present address: Laboratorium voor Genetica, Universiteit Gent, K.L.
Ledeganckstraat 35, B-9000 Gent, Belgium;
Present address: Department of Brassica and Oilseeds Research,
John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK
Received 7 October 1996; accepted in revised form 13 December 1996
Key words: isoﬂavone reductase, NAD(P)H oxidoreductase, pistil, pollen tube growth, potato, touch
Successful sexual reproduction relies on gene products delivered by the pistil to create an environment suitable
for pollen tube growth. These compounds are either produced before pollination or formed during the interactions
between pistil and pollen tubes. Here we describe the pollination-enhanced expression of the cp100 gene in pistils
of Solanum tuberosum. Temporal analysis of gene expression revealed an enhanced expression already one hour
after pollination and lasts more than 72 h. Increasein expression also occurred after touching the stigma and was not
restrictedto the site of touch but spread into the style. The predicted CP100 protein shows similarity to leguminous
isoﬂavone reductases (IFRs), but belongs to a family of IFR-like NAD(P)H-dependent oxidoreductases present in
various plant species.
Sexual reproduction in ﬂowering plants involves a
series of interactions between pollen or pollen tubes,
and pistil. These interactions start when pollen grains
when pollen tubes grow through the style towards the
ovary where double fertilisation takes place .
The variousfunctions of the pistil, during the inter-
recognition, guidance, nourishment and protection.
Recognition involves the ability of the pistil to dis-
criminate between different types of pollen it receives
len . This process may be interspeciﬁc (incongru-
ity), preventing pollen from other species to germinate
and to form functional pollen tubes, or intraspecif-
GenBank and DDBJ Nucleotide Databases under theaccession num-
ic (self-incompatibility), in case the pistil recognises
Guidance is provided by the pistil when the pollen
tubes are growing from the stigma towards the ovules.
The morphology of the stigma, transmitting tissue and
ovary determines the direction of pollen tube growth
[14, 21]. There is limited evidence for an additional
tropic substances do determine the direction of pollen
tube growth in vitro [6, 32, 50, 51].
The pistil also produces nourishing compounds for
the growing pollen tubes. These extracellular com-
pounds are present in the stigmatic exudate and in the
stigma itself [25, 31], are excreted by the cells of the
transmitting tissue [6, 18, 26, 27, 29, 51], and of the
Protection against pathogens is crucial because the
pistil is wounded by the penetration of non-aseptic
pollen tubes. The production of defence molecules is
expected during the interactions of the pistil with the
growing pollen tubes, but such molecules would be
GR: 201001861, ZIP: , Pips nr. 129498 BIO2KAP
plan3704.tex; 12/03/1997; 7:00; v.7; p.1