Two anther-expressed genes downstream of SLG(9): identification of a novelS-linked gene specifically expressed in anthers at the uninucleate stage of Brassica campestris (syn. rapa) L.
M. Watanabe et al., Two anther-expressed genes downstream of SLG(9): identification of a novelS-linked gene specifically expressed in anthers at the uninucleate stage of Brassica campestris (syn. rapa) L., SEX PLANT R, 12(3), 1999, pp. 127-134
The sporophytic self-incompatibility (SI) system in Brassica campestris (sy
n. rapa) is controlled by multiple alleles of a single locus, S, in which S
LG and SRK are located. SLG and/or SRK appear to comprise the female compon
ent of the recognition reaction of SI. The gene encoding the male component
must also be located at the S locus but has not been identified to date. R
NA gel blot analysis with regions flanking SLG(9) and SRK9 revealed two ant
her-expressed genes 3' of the SLG(9) gene. Two cDNA clones were isolated us
ing the 3'-flanking region of SLG(9) as probe. Because of sequence similari
ty with the Brassica SLL2 gene, one cDNA clone was designated SLL2-S-9 (for
S Locus-Linked 2-S-9 gene). The 5'-region of SLL2-S-9 was not present in o
ther SLL2 genes examined. The second gene was novel and was designated SAE1
-S-9 (for S locus Anther Expressed 1-S-9 gene). SAE1-S-9 and SLL2-S-9 were
located approximately 2.5 kb and 5.5 kb, respectively, downstream of SLG(9)
. A 1.4-kb transcript for SLL2-S9 was detected in both vegetative and repro
ductive tissues, whereas 1.9-kb and 2.4-kb transcripts were specifically de
tected in the anther of S-9 haplotype. SAE1-S-9 was specifically expressed
in the anther at the uninucleate stage. This gene encoded a novel polypepti
de of 257 amino acids. Database analysis revealed a homologous sequence in
the upstream region of SRK3 of B. oleracea. We discuss possible relationshi
ps between SLL2-S-9 and SAE1-S-9 and SI.