Plant Molecular Biology 40: 807–814, 1999.
© 1999 Kluwer Academic Publishers. Printed in the Netherlands.
Characterization of two subclasses of PR-10 transcripts in lily anthers and
induction of their genes through separate signal transduction pathways
, Jong-Chin Huang and Jia-Hwey Hu
Graduate Institute of Agricultural Biotechnology, National Chung Hsing University, Taichung, Taiwan, 40227
author for correspondence)
Received 10 June 1998; accepted in revised form 24 April 1999
Key words: cDNA, lily, PR proteins, signal transduction, stress-induced
The lily PR-10 belongs to a family of intracellular pathogenesis-related (IPR) proteins. GenomicSouthern analysis
indicates that the PR-10 is encoded by a family of multiple genes. Seven heterogeneous cDNA clones encoding
lily PR-10 from Lilium longiﬂorum are divided into two subclasses based on sequence comparison and Southern
hybridization. A 82% overall sequence similarity was found between the two subclasses (represented by PR-10c
and d). The two cDNAs includean open reading frame of 474 bp encoding 157 amino acids. 5
regions exhibit low similarity, but similarity is high in the coding region. The lily PR-10 genes are induced by
abscisic acid (ABA) and methyl jasmonate (MeJA) in the anther and various other organs of lily plants. The
induction of PR-10 genes by ABA and MeJA in lily anthers occurs by two separate signal transduction pathways.
The protein phosphatase inhibitor okadaic acid inhibits the MeJA-induced expression of PR-10 genes downstream
of MeJA. In addition, the protein kinase inhibitor staurosporine inhibits the MeJA-induced expression of PR-10
genes, implying that an activity of staurosporine-sensitiveprotein kinases exists downstream of MeJA in the anther.
However, okadaic acid does not inhibit the ABA-induced expression of PR-10 genes whereas staurosporine does.
These observationssuggest that, in addition to the known pathway that ABA induces gene expression by activating
JA or MeJA, a MeJA-independent pathway of ABA induction exists in the anther. The alternative pathway of ABA
induction involves a staurosporine-sensitive protein kinase activity downstream of ABA.
Pathogenesis-related (PR) proteins accumulate as part
of a multicomponent defense response in many plants
exposed to pathogens and certain chemical inducers
(Rigden and Coutts, 1988). The synthesis of speciﬁc
PR proteins can also be activated under various stress
conditions, including heat shock, mechanical wound-
ing and anaerobiosis (Bowles, 1990). In addition, en-
vironmental challenges such as freezing, water stress
caused by either high osmoticum, salt or drought in-
crease endogenous abscisic acid (ABA) in plant cells,
resulting in the accumulation of speciﬁc PR mRNAs
The nucleotide sequence data of PR-10a–g cDNAs reported
will appear in the EMBL, GenBank and DDBJ Nucleotide Se-
quence Databases under the accession numbers U76544 (PR-10a)
and AF021848–53 (PR-10b–g).
and proteins (Davies and Jones, 1991). PR proteins
are a heterogeneous group of low-molecular-weight
proteins. They were ﬁrst identiﬁed in tobacco cultivars
virus (van Loon, 1985). Subsequently, related pro-
teins that showed sequence similarity or cross-reacted
immunologically with the tobacco PR proteins were
detected in many other plant species (Bowles, 1990).
Of those PR proteins, two groups have been identiﬁed
as chitinases and β-1,3-glucanases.
as PR-10, has been found in many dicot plants (Wal-
ter et al., 1990) and in two monocots (Warner et al.,
1992; Huang et al., 1997) over the past decade. All
members of this class of proteins are very similar in
molecular mass (about 16 kDa), isoelectric point, and
amino acid sequence, clearly indicating a common an-