Transcript and Sequence Analysis of S-RNases in Self-Compatible Tetraploid Chinese Cherry (Prunus pseudocerasus L.)

Chinese cherry （Prunus pseudocerasus L.） is an allotetraploid species and exhibits natural self-compatibility.However,the full-length cDNA sequences,functional analysis and the transcripts of S-RNase alleles in Chinese cherry cultivars are not known.In the two cultivars Taixiaohongying and Laiyang Short Cherry with S1S2S3S4 genotypes,two S-RNases were transcribed in Northern blotting,and the two full-length cDNAs of S-RNase were cloned and analyzed.As the result,the transcribed S-RNases were S1-RNase and S2-RNase.The two complete cDNA sequences of S1-RNase and S2-RNase were registered as EU073938 and EU073939,respectively,and had characteristic structure of rosaceous S-RNases based on their sequences indicating that they had normal function for S-RNase in the style.The S3-RNase and S4-RNase were not transcribed in the style and were nonfunctional for S-RNase,so S3m and S4m could be used to represent the nonfunctional S3-RNase and S4-RNase.The phylogenetic analysis implied that the S-RNases of Prunus,including Chinese cherry,had lower intra-specific similarity and diverged earlier than the divergence of species in Prunus.

Stigma factors regulating self-compatible pollination

Pollination is one of the most important steps during fertilization and sexual reproduction in plants,and numerous cell-cell interaction events occur between the pistil and the pollen grain/tube during this process.The pollen-stigma interaction is a highly selective process which leads to compatible or incompatible pollination.Previous studies in Solanaceae,Papaveraceae,and Brassicaceae provided some important insights into pollen-stigma recognition in self-incompatible systems.In recent years,considerable data have been available regarding pollen-stigma interaction during self-compatible pollination.In this review,we focus on discussing current knowledge on stigma factors that regulate pollen-stigma interaction in self-compatible systems in comparison with self-incompatible systems.

Developing a new model system for potato genetics by androgenesis

High heterozygosity and tetrasomic inheritance complicate studies of asexually propagated polyploids,such as potato.Reverse genetics approaches,especially mutant library construction,can be an ideal choice if a proper mutagenesis genotype is available.Here,we aimed to generate a model system for potato research using anther cultures of Solanum verrucosum,a self-compatible diploid potato with strong late blight resistance.Six of the 23 regenerants obtained(SVA4,SVA7,SVA22,SVA23,SVA32,and SVA33)were diploids,and their homozygosity was estimated to be>99.99%with 22 polymorphic In Del makers.Two lines-SVA4 and SVA32-had reduced stature(plant height≤80 cm),high seed yield(>1,000 seeds/plant),and good tuber set(>30 tubers/plant).We further confirmed the full homozygosity of SVA4 and SVA32 using wholegenome resequencing.These two regenerants possess all the characteristics of a model plant:diploidy,100%homozygosity,self-compatibility,and amenability to transgenesis.Thus,we have successfully generated two lines,SVA4 and SVA32,which can potentially be used for mutagenesis and as model plants to rejuvenate current methods of conducting potato research.

Molecular Characterization and Expression Analysis of S1 self-incompatibility Locus-linked Pollen 3.15 Gene in Citrus reticulata

Gametophytic self-incompatibility （GSI） is controlled by a highly polymorphic locus called the S-locus, which is an important factor that can result in seedless fruit in Citrus. The S 1 self-incompatibility locus-linked pollen 3.15 gene （S1-3.15） belongs to a type of S locus gene. The role of S1-3.15 in the SI reaction of Citrus has not yet been reported. In this study, full-length sequences of cDNA and DNA encoding the S1-3.15 gene, referred to as CrS1-3.15 , were isolated from ‘Wuzishatangju’ （Self-incompatibility, SI） and ‘Shatangju’ （Self-compatibility, SC） . The predicted amino acid sequences of CrS1-3.15 between ‘Wuzishatangju’ and ‘Shatangju’ differ by only three amino acids. Compared to ‘Wuzishatangju’, three bases were substituted in the genomic DNA of CrS1-3.15 from ‘Shatangju’. Southern blot results showed that one copy of CrS1-3.15 existed in the genomic DNA of both ‘Wuzishatangju’ and ‘Shatangju’. The expression level of the CrS1-3.15 gene in the ovaries of ‘Shatangju’ was approximately 60-fold higher than that in the ovaries of ‘Wuzishatangju’. When ‘Wuzishatangju’ was cross-pollinated, the expression of CrS1-3.15 was upregulated in the ovaries at 3d, and the highest expression levels were detected in the ovaries at 6d after cross-pollination of ‘Wuzishatangju’ × ‘Shatangju’. To obtain the CrS1-3.15 protein, the full-length cDNA of CrS1-3.15 genes from ‘Wuzishatangju’ and ‘Shatangju’ was successfully expressed in Pichia pastoris. Pollen germination frequency of ‘Wuzishatangju’ was inhibited significantly with increasing CrS1-3.15 protein concentrations from SI ‘Wuzishatangju’.