Population genomics analysis reveals footprints of selective breeding in a rapid-growth variety of Paulownia fortunei with apical dominance.

Paulownia fortunei is an ecologically and economically valuable tree cultivated for its rapid growth and high-quality timber. To enhance Paulownia germplasm, we have developed the elite variety QingT with patented advantages in growth rate and apical dominance. To illuminate the genetic basis of QingT's superior traits, here we harness comparative population genomics to analyze genomic variation patterns between QingT and common Paulownia. We performed whole-genome re-sequencing of 30 QingT and 30 common samples, detecting 15.6 million SNPs and 2.6 million indels. Phylogeny and population structure analyses robustly partitioned common and QingT into distinct groups which indicate robust genome stabilization. QingT exhibited reduced heterozygosity and linkage disequilibrium decay compared to common Paulownia, reflecting high recombination, indicating hybridizing effects with common white-flowered string is the source of its patented advantages. Genome selection scans uncovered 25 regions of 169 genes with elevated nucleotide diversity, indicating selection sweeps among groups. Functional analysis of sweep genes revealed upregulation of ribosomal, biosynthesis, and growth pathways in QingT, implicating enhanced protein production and developmental processes in its rapid growth phenotype. This study's insights comprehensively chart genomic variation during Paulownia breeding, localizing candidate loci governing agronomic traits, and underpinnings of future molecular breeding efforts to boost productivity.

[Research on optimization system on tissue culture and rapid propagation of Pueraria mirifica].

OBJECTIVE: To study the tissue culture and rapid-proliferation techniques of Pueraria mirifica. METHOD: The tender branch were used as explants and cultivated in different media. The optimum media for inducing buds, proliferation and rooting were selected by adjusting the kinds and doses of plant hormones and special compounds. RESULT: The medium of MS + IBA 0.05 mg L(-1) + BA 0.5 mg L(-1) was suitable for buds inducing and could be used in the first generation cultivation; MS + IBA 0. 02 mg L(-1) + BA 0.2 mg L(-1) and MS +BA 0.1 mg L(-1) were employed by turns in subculture, 25 days propagation coefficient was 3.0; and the medium of 1/2MS + IBA 0.1 mg L(-1) + IAA 0.2 mg L(-1) + C (special compound) 10 mg L(-1) was used for roots inducing, the rooting rate was 76.9%. Rooting plantlets were transplanted in spring and summer; the surviving rate was 81.0%. CONCLUSION: This technique system could be employed for rapid propagation of P. mirifica.