A high-quality genome provides insights into the new taxonomic status and genomic characteristics of Cladopus chinensis(Podostemaceae)

The Podostemaceae are ecologically and morphologically unusual aquatic angiosperms that survive only in rivers with pristine hydrology and high water quality and are at a relatively high risk of extinction.The taxonomic status of Podostemaceae has always been controversial.Here,we report the first high-quality genome assembly for Cladopus chinensis of Podostemaceae,obtained by incorporating Hi-C,Illumina and PacBio sequencing.We generated an 827.92 Mb genome with a contig N50 of 1.42 Mb and 27,370 annotated protein-coding genes.The assembled genome size was close to the estimated size,and 659.42 Mb of the assembly was assigned to 29 superscaffolds(scaffold N5021.22 Mb).A total of 59.20%repetitive sequences were identified,among which long terminal repeats(LTRs)were the most abundant class(28.97%of the genome).Genome evolution analysis suggested that the divergence time of Cladopus chinensis(106 Mya)was earlier than that of Malpighiales(82 Mya)and that this taxon diverged into an independent branch of Podestemales.A recent whole-genome duplication(WGD)event occurred 4.43 million years ago.Comparative genomic analysis revealed that the expansion and contraction of oxidative phosphorylation,photosynthesis and isoflavonoid metabolism genes in Cladopus chinensis are probably related to the genomic characteristics of this growing submerged species.Transcriptome analysis revealed that upregulated genes in the shoot group compared to the root group were enriched in the NAC gene family and transcription factors associated with shoot development and defense responses,including WUSCHEL(WUS),ASYMMETRIC LEAVES(ASL),SHOOT MERISTEMLESS(STM),NAC2,NAC8,NAC29,NAC47,NAC73,NAC83 and NAC102.These findings provide new insights into the genomic diversity of unusual aquatic angiosperms and serve as a valuable reference for the taxonomic status and unusual shoot apical meristem of Podostemaceae.

Insights into salvianolic acid B biosynthesis from chromosome-scale assembly of the Salvia bowleyana genome

Salvia bowleyanais a traditional Chinese medic-inal plant that is a source of nutritional supple-ments rich in salvianolic acid B and a potentialexperimental system for the exploration ofsalvianolic acid B biosynthesis in the Labiatae.Here,we report a high‐quality chromosome‐scalegenome assembly of S.bowleyana covering 462.44 Mb,with a scaffold N50 value of 57.96 Mband 44,044 annotated protein‐coding genes.Evolutionary analysis revealed an estimateddivergence time betweenS.bowleyanaand its close relativeS.miltiorrhiza of~3.94 millionyears.We also observed evidence of a whole‐genome duplication in theS.bowleyanagenome.Transcriptome analysis showed that SbPAL1(PHENYLALANINE AMMONIA‐LYASE1)ishighlyexpressed in roots relative to stem and leaves,paralleling the location of salvianolic acid Baccumulation.The laccase gene family in S.bowley anaoutnumbered their counterparts inbothS.miltiorrhiza and Arabidopsis thaliana,suggesting that the gene family has undergoneexpansion inS.bowleyana.Several laccasegenes were also highly expressed in roots,wheretheir encoded proteins may catalyze the oxida-tive reaction from rosmarinic acid to salvianolicacid B.Thesefindings provide an invaluable ge-nomic resource for understanding salvianolicacid B biosynthesis and its regulation,and will beuseful for exploring the evolution of the Labiatae.

Optimization of fermentation medium for xylanase-producing strain Xw2

To improve the fermentation yield of xylanase by optimizing the fermentation conditions for strain Xw2, a Plackett-Burman design was used to evaluate the effects of eight variables on xylanase production by strain Xw2. The steepest ascent （descent） method was used to approach the optimal response surface experimental area. The optimal fermentation conditions were obtained by central composite design and response surface analysis. The results showed that the composition of the optimal fermentation medium was corn cob ＋ 1.5% wheat bran （1：1）, 0.04% MnSO4, 0.04% K2HPO4. 3H2O, and an inoculum size of 6% in 50 mL liquid volume （pH = 6.0）. The optimal culture conditions were 28oc at 150 r/min for 54.23 h. The results of this study can serve as the basis for the industrial production and application of xylanase.

Multi-omics Analyses Provide Insight into the Biosynthesis Pathways of Fucoxanthin in Isochrysis galbana

Isochrysis galbana is considered an ideal bait for functional foods and nutraceuticals of humans because of its high fucoxanthin(Fx)content.However,multi-omics analysis of the regulatory networks for Fx biosynthesis in I.galbana has not been reported.In this study,we report a high-quality genome assembly of I.galbana LG007,which has a genome size of 92.73 Mb,with a contig N50 of 6.99 Mb and 14,900 protein-coding genes.Phylogenetic analysis confirmed the monophyly of Haptophyta,with I.galbana sister to Emiliania huxleyi and Chrysochromulina tobinii.Evolutionary analysis revealed an estimated divergence time between I.galbana and E.huxleyi of~133 million years ago.Gene family analysis indicated that lipid metabolism-related genes exhibited significant expansion,including IgPLMT,IgOAR1,and IgDEGS1.Metabolome analysis showed that the content of carotenoids in I.galbana cultured under green light for 7 days was higher than that under white light,andβ-carotene was the main carotenoid,accounting for 79.09%of the total carotenoids.Comprehensive multi-omics analysis revealed that the content ofβ-carotene,antheraxanthin,zeaxanthin,and Fx was increased by green light induction,which was significantly correlated with the expression of IgMYB98,IgZDS,IgPDS,IgLHCX2,IgZEP,IgLCYb,and IgNSY.These findings contribute to the understanding of Fx biosynthesis and its regulation,providing a valuable reference for food and pharmaceutical applications.