Biomedical subjects

Teh-Hui Kao

Publications and source records attributed to Teh-Hui Kao.

6 recordsLinked to original sources

PubMed2006

Identification and characterization of components of a putative petunia S-locus F-box-containing E3 ligase complex involved in S-RNase-based self-incompatibility.

Petunia inflata S-locus F-box (Pi SLF) is thought to function as a typical F-box protein in ubiquitin-mediated protein degradation and, along with Skp1, Cullin-1, and Rbx1, could compose an SCF complex mediating the degradation of nonself S-RNase but not self S-RNase. We isolated three P. inflata Skp1s (Pi SK1, -2, and -3), two Cullin-1s (Pi CUL1-C and -G), and an Rbx1 (Pi RBX1) cDNAs and found that Pi CUL1-G did not interact with Pi RBX1 and that none of the three Pi SKs interacted with Pi SLF(2). We also isolated a RING-HC protein, S-RNase Binding Protein1 (Pi SBP1), almost identical to Petunia hybrida SBP1, which interacts with Pi SLFs, S-RNases, Pi CUL1-G, and an E2 ubiquitin-conjugating enzyme, suggesting that Pi CUL1-G, SBP1, and SLF may be components of a novel E3 ligase complex, with Pi SBP1 playing the roles of Skp1 and Rbx1. S-RNases interact more with nonself Pi SLFs than with self Pi SLFs, and Pi SLFs also interact more with nonself S-RNases than with self S-RNases. Bacterially expressed S(1)-, S(2)-, and S(3)-RNases are degraded by the 26S proteasomal pathway in a cell-free system, albeit not in an S-allele-specific manner. Native glycosylated S(3)-RNase is not degraded to any significant extent; however, deglycosylated S(3)-RNase is degraded as efficiently as the bacterially expressed S-RNases. Finally, S-RNases are ubiquitinated in pollen tube extracts, but whether this is mediated by the Pi SLF-containing E3 complex is unknown.

Molecular Sequence Data↗

PubMed2006

Identification and characterization of PiORP1, a Petunia oxysterol-binding-protein related protein involved in receptor-kinase mediated signaling in pollen, and analysis of the ORP gene family in Arabidopsis.

Oxysterol-binding proteins (OSBPs) and oxysterol-binding-protein related proteins (ORPs) are encoded by most eukaryotic genomes examined to date; however, they have not yet been characterized in plants. Here we report the identification and characterization of PiORP1, an ORP of Petunia inflata that interacts with the cytoplasmic kinase domain of a receptor-like kinase, named PRK1, of P. inflata. PiORP1 is phosphorylated by PRK1 in vitro and therefore may be involved in PRK1 signaling during pollen development and growth. RNA gel blot analysis showed that PiORP1 and PRK1 had very similar expression patterns in developing pollen, mature pollen and pollen tubes. GFP fusion proteins of PiORP1 localized in the plasma membrane of pollen tubes at distinct foci and its PH domain alone was sufficient to mediate this localization. The sequence for the oxysterol-binding domain of PiORP1 was used to search the genome of Arabidopsis; 12 ORPs were identified and phylogenetic analysis revealed that they fell into two distinct clades, consistent with the ORPs of other eukaryotes. RT-PCR analysis showed that all 12 Arabidopsis ORPs were expressed; 10 were expressed in most of the tissues examined under normal growth conditions, but only three were expressed in pollen.

Arabidopsis↗

PubMed2004

Identification of the pollen determinant of S-RNase-mediated self-incompatibility.

Many flowering plants have adopted self-incompatibility mechanisms to prevent inbreeding and promote out-crosses. In the Solanaceae, Rosaceae and Scrophulariaceae, two separate genes at the highly polymorphic S-locus control self-incompatibility interactions: the S-RNase gene encodes the pistil determinant and the previously unidentified S-gene encodes the pollen determinant. S-RNases interact with pollen S-allele products to inhibit the growth of self-pollen tubes in the style. Pollen-expressed F-box genes showing allelic sequence polymorphism have recently been identified near to the S-RNase gene in members of the Rosaceae and Scrophulariaceae; but until now have not been directly shown to encode the pollen determinant. Here we report the identification and characterization of PiSLF, an S-locus F-box gene of Petunia inflata (Solanaceae). We show that transformation of S1S1, S1S2 and S2S3 plants with the S2-allele of PiSLF causes breakdown of their pollen function in self-incompatibility. This breakdown of pollen function is consistent with 'competitive interaction', in which pollen carrying two different pollen S-alleles fails to function in self-incompatibility. We conclude that PiSLF encodes the pollen self-incompatibility determinant.

Alleles↗

PubMed2004

Chromosome walking in the Petunia inflata self-incompatibility (S-) locus and gene identification in an 881-kb contig containing S2-RNase.

Self-incompatibility (SI) in the Solanaceae, Rosaceae and Scrophulariaceae is controlled by the polymorphic S locus, which contains two separate genes encoding pollen and pistil determinants in SI interactions. The S-RNase gene encodes the pistil determinant, whereas the pollen determinant gene, named the pollen S gene, has not yet been identified. Here, we set out to construct an integrated genetic and physical map of the S locus of Petunia inflata and identify any additional genes located at this locus. We first conducted chromosome walking at the S2 locus using BAC clones that contained either S2-RNase or one of the nine markers tightly linked to the S locus. Ten separate contigs were constructed, which collectively spanned 4.4 Mb. To identify additional genes located at the S2 locus, a 328-kb region (part of an 881-kb BAC contig) containing S2-RNase was completely sequenced. Approximately 76% of the region contained repetitive sequences, including transposon-like sequences. Other than S2-RNase, an F-box gene, named PiSLF2 (S2-allele of P. inflata S-locus F-box gene), was the only predicted gene whose deduced amino acid sequence was similar to the sequences of known proteins in the database. Two different cDNA selection methods were used to identify additional genes in the 881-kb contig; 11 groups of cDNA clones were identified in addition to those for S2-RNase and PiSLF2. RT-PCR analysis of expression profiles and PCR analysis of BAC clones and genomic DNA confirmed that seven of these 11 newly identified genes were located in the 881-kb contig.

Chromosome Walking↗

PubMed2003

S-RNase-mediated self-incompatibility.

The Solanaceae, Rosaceae, and Scrophulariaceae families all possess an RNase-mediated self-incompatibility mechanism through which their pistils can recognize and reject self-pollen to prevent inbreeding. The highly polymorphic S-locus controls the self-incompatibility interaction, and the S-locus of the Solanaceae has been shown to be a multi-gene complex in excess of 1.3 Mb. To date, the function of only one of the S-locus genes, the S-RNase gene, has been determined. This article reviews the current status of the search for the pollen S-gene and the current models for how S-haplotype specific inhibition of pollen tubes can be accomplished by S-RNases.

Fertility↗

PubMed2002

Differentiation in the status of self-incompatibility among Calibrachoa species (Solanaceae).

The overall status of self-incompatibility, as assessed by the rate of capsule-set after self-pollination, was investigated in the genus Calibrachoa (Solanaceae). Thirty-two species were surveyed using a total of 655 individuals collected in 102 different native populations in Argentina, Brazil, Mexico, and Uruguay. The rate of capsule-set in 278 voucher specimens collected from the same native habitats was also measured to obtain additional information to assess the degree of self-(in)compatibility. Only one species, Calibrachoa parviflora, was self-compatible (SC, autogamous) and the other 31 species were found to be self-incompatible (SI). A mixed population (SI and SC individuals in the same population) was not found. The differentiation of C. parviflora as an autogamous species is associated with a successful occupation of different (riparian) habitats within a larger range of geographic distribution compared to the rest of the species in the principally SI genus of Calibrachoa.

Journal Article↗