Telomere-to-telomere pear (Pyrus pyrifolia) reference genome reveals segmental and whole genome duplication driving genome evolution

Previously released pear genomes contain a plethora of gaps and unanchored genetic regions.Here,we report a telomere-to-telomere(T2T)gap-free genome for the red-skinned pear,‘Yunhong No.1’(YH1;Pyrus pyrifolia),which is mainly cultivated in Yunnan Province(southwest China),the pear’s primary region of origin.The YH1 genome is 501.20 Mb long with a contig N50 length of 29.26 Mb.All 17 chromosomes were assembled to the T2T level with 34 characterized telomeres.The 17 centromeres were predicted and mainly consist of centromeric-specific monomers(CEN198)and long terminal repeat(LTR)Gypsy elements(≥74.73%).By filling all unclosed gaps,the integrity of YH1 is markedly improved over previous P.pyrifolia genomes(‘Cuiguan’and‘Nijisseiki’).A total of 1531 segmental duplication(SD)driven duplicated genes were identified and enriched in stress response pathways.Intrachromosomal SDs drove the expansion of disease resistance genes,suggesting the potential of SDs in adaptive pear evolution.A large proportion of duplicated gene pairs exhibit dosage effects or sub-/neo-functionalization,whichmay affect agronomic traits like stone cell content,sugar content,and fruit skin russet.Furthermore,as core regulators of anthocyanin biosynthesis,we found that MYB10 and MYB114 underwent various gene duplication events.Multiple copies of MYB10 and MYB114 displayed obvious dosage effects,indicating role differentiation in the formation of red-skinned pear fruit.In summary,the T2T gap-free pear genome provides invaluable resources for genome evolution and functional genomics.

Synthesis of porous carbon from orange peel waste for effective volatile organic compounds adsorption: role of typical components

Volatile organic compounds have posed a serious threat to the environment and human health,which require urgent and effective removal.In recent years,the preparation of porous carbon from biomass waste for volatile organic compounds adsorption has attracted increasing attention as a very cost-effective and promising technology.In this study,porous carbon was synthesized from orange peel by urea-assisted hydrothermal carbonization and KOH activation.The role of typical components(cellulose,hemicellulose,and lignin)in pore development and volatile organic compounds adsorption was investigated.Among the three components,hemicellulose was the major contributor to high porosity and abundant micropores in porous carbon.Higher hemicellulose content led to more abundant–COOR,amine-N,and pyrrolic/pyridonic-N in the derived hydrochar,which were favorable for porosity formation during activation.In this case,the toluene adsorption capacity of the porous carbon improved from 382.8 to 485.3 mg·g^(–1).Unlike hemicellulose,cellulose reduced the>C=O,amine-N,and pyrrolic/pyridonic-N content of the hydrochar,which caused porosity deterioration and worse toluene adsorption performance.Lignin bestowed the hydrochar with slightly increased–COOR,pyrrolic/pyridonic-N,and graphitic-N,and reduced>C=O,resulting in comparatively poor porosity and more abundant micropores.In general,the obtained porous carbon possessed abundant micropores and high specific surface area,with the highest up to 2882 m^(2)·g^(–1).This study can provide guidance for selecting suitable biomass waste to synthesize porous carbon with better porosity for efficient volatile organic compounds adsorption.