Takuya Tetsumura

Molecular Characterization of Tree Peony Germplasm Using Sequence-Related Amplified Polymorphism Markers

This study examined 63 tree peony specimens, consisting of 3 wild species and 63 cultivars, using sequence-related amplified polymorphism (SRAP) markers for the purpose of detecting genomic polymorphisms. Bulk DNA samples from each specimen were evaluated with 23 SRAP primer pairs. Among the 296 different amplicons, 262 were polymorphic. The maximum parsimony, neighbor-joining, and unweighted pair-group method using arithmetic average trees were largely in congruence. In the three trees, the wild species Paeonia ludlowii and P. delavayi formed separate clusters with strong bootstrap support, and P. ostii was closely related to all cultivars. The cultivars were divided into groups with various corresponding bootstrap values. The genetic similarity among the genotypes ranged from 0.02 to 0.73. These results demonstrate that SRAP markers are effective in detecting genomic polymorphisms in the tree peony and should be useful for linkage map construction and molecular marker assisted selection breeding.

Single-pollen genotyping to estimate mode of unreduced pollen formation in Citrus tamurana cv. Nishiuchi Konatsu.

Key message2n pollen formed by FDR in citrus.AbstractThe Japanese local citrus cultivar, Nishiuchi Konatsu (Citrus tamurana hort. ex Tanaka; NK hereafter), has the ability to produce unreduced 2n pollen grains, allowing generation of polyploid progenies via sexual polyploidization. In this study, we developed a method of single-pollen genotyping for citrus and applied it to the analysis of transmission of heterozygosity in NK 2n pollen grains. Heterozygosity transmission was expressed as the percentage inheritance of a set of heterozygous alleles from the parent to the 2n gamete. The pathway of 2n pollen development was investigated by applying the observed heterozygosity transmission and genetic distance to two different map functions, for first division restitution (FDR) and second division restitution (SDR). The fit of the values observed for both functions was calculated, while virtually moving the centromere position. We screened for six heterozygous SSR (codominant microsatellite marker loci) in NK, all of which were expected to lie within the same linkage group. Pollen germination prior to DNA extraction was essential for this work, and 6-h incubation proved to be optimal for subsequent PCR amplification. Single-pollen genotyping unreduced NK 2n pollen grains revealed that heterozygosity transmission exceeded 50xa0% in all six alleles, and fitness tests indicated that the FDR map function better fitted the heterozygosity transmission observed rather than the SDR function. Our data thus strongly indicate that 2n pollen in NK is a result of first division restitution.

CLAVATA3-like genes are differentially expressed in grape vine (Vitis vinifera) tissues

The CLAVATA3 (CLV3)/endosperm surrounding region [(ESR) CLE] peptides function as intercellular signaling molecules that regulate various physiological and developmental processes in diverse plant species. We identified five CLV3-like genes from grape vine (Vitis vinifera var. Pinot Noir): VvCLE 6, VvCLE 25-1, VvCLE 25-2, VvCLE 43 and VvCLE TDIF. These CLV3-like genes encode short proteins containing 43-128 amino acids. Except VvCLE TDIF, grape vine CLV3-like proteins possess a consensus amino acid sequence known as the CLE domain. Phylogenic analysis suggests that the VvCLE 6, VvCLE25-1, VvCLE25-2 and VvCLE43 genes have evolved from a single common ancestor to the Arabidopsis CLV3 gene. Expression analyses showed that the five grape CLV3-like genes are expressed in leaves, stems, roots and axillary buds with significant differences in their levels of expression. For example, while all of them were strongly expressed in axillary buds, VvCLE6 and VvCLE43 expression prevailed in roots, and VvCLE25-1, VvCLE25-2 and VvCLE TDIF expression in stems. The differential expression of the five grape CLV3-like peptides suggests that they play different roles in different organs and developmental stages.