The updated weeping forsythia genome reveals the genomic basis for the evolution and the forsythin and forsythoside A biosynthesis

Weeping forsythia (Forsythia suspensa,Oleaceae) is a deciduous broad-leaved tree species distributed in the warm temperate zone of China.However,the species still lacks a chromosome-level genome.In this study,the former draft genome (Accession No.WIPI00000000) of weeping forsythia was assembled into 14 chromosomes with a 712.9 Mb genome size.Weeping forsythia underwent a and b whole-genome duplication events.After the divergence between weeping forsythia and Olea europaea,1 453 gene families had a significant expansion,and 1 146 gene families had a significant contraction.The enrichment pathways and ontologies of expanded genes suggested that the tillering,photosynthesis and growth capacity of weeping forsythia were enhanced after the divergence of weeping forsythia and O.europaea.The contracted genes suggested that the resistance of weeping forsythia to cold and drought was weakened.The last glacial period led to a significant decline in the effective population size of weeping forsythia.Forty-six candidate genes were identified for the synthesis of the forsythin and forsythoside A by genomic and transcriptomic data.In this study,we improved the previous draft genome of weeping forsythia.Our genome will provide genomic resources for the subsequent evolution and breeding research of weeping forsythia.

The combination of DNA methylation and positive regulation of anthocyanin biosynthesis by MYB and bHLH transcription factors contributes to the petal blotch formation in Xibei tree peony

Xibei tree peony is a distinctive cultivar group that features red–purple blotches in petals.Interestingly,the pigmentations of blotches and non-blotches are largely independent of one another.The underlying molecular mechanism had attracted lots of attention from investigators,but was still uncertain.Our present work demonstrates the factors that are closely related to blotch formation in Paeonia rockii‘Shu Sheng Peng Mo’.Non-blotch pigmentation is prevented by the silencing of anthocyanin structural genes,among which PrF3H,PrDFR,and PrANS are the three major genes.We characterized two R2R3-MYBs as the key transcription factors that control the early and late anthocyanin biosynthetic pathways.PrMYBa1,which belongs to MYB subgroup 7(SG7)was found to activate the early biosynthetic gene(EBG)PrF3H by interacting with SG5 member PrMYBa2 to form an‘MM’complex.The SG6 member PrMYBa3 interacts with two SG5(IIIf)bHLHs to synergistically activate the late biosynthetic genes(LBGs)PrDFR and PrANS,which is essential for anthocyanin accumulation in petal blotches.The comparison of methylation levels of the PrANS and PrF3H promoters between blotch and non-blotch indicated a correlation between hypermethylation and gene silencing.The methylation dynamics of PrANS promoter during flower development revealed a potential early demethylating reaction,which may have contributed to the particular expression of PrANS solely in the blotch area.We suggest that the formation of petal blotch may be highly associated with the cooperation of transcriptional activation and DNA methylation of structural gene promoters.

Systematic Identification of the Light-quality Responding Anthocyanin Synthesis-related Transcripts in Petunia Petals

Previous studies have shown that high light intensity can induce anthocyanin synthesis(AS)in petunia plants.To identifywhich kind of light quality plays a role in inducing such metabolic process,and what transcripts participate in controlling it,we carried out whole-transcriptome sequencing and analysis of petunia petals treated with different light-quality conditions.Among the red and white light treatments,a total of 2205 differentially expressed genes and 15,22,and 20 differentially expressed circRNAs,miRNAs,and lncRNAs,were identified respectively.The AS-related genes,including the structural genes CHSj,F3H,F35H,DFR,and ANS,and the regulatory genes AN4,DPL,PHZ and MYBx were found to be downregulated under red light condition compared with their levels under white light condition.Furthermore,the light photoreceptor Cryptochrome 3(CRY3)and a series of light-dependent genes,such as PIF,HY5,andBBXs,were also determined to respond to the light treatments.The anthocyanin contents in early petunia petals under red light were significantly lower than that under white and blue light.The results of qRT-PCR further confirmed the expression pattern of some AS-related and light-response genes in response to different light quality.Yeast two-hybrid results showed that the key elements in the light signal pathway,HY5 can interact with BBX19,BBX24 and BBX25.And PHZ,the important AS regulator can induce anthocyanin synthesis in response to blue light quality fromtransient expression analysis in petunia petals.These findings presented here not only deepen our understanding of how light quality controls anthocyanin synthesis,but also allow us to explore potential target genes for improving pigment production in petunia flower petals.

The coloring mechanism of a novel golden variety in Populus deltoides based on the RGB color mode

Compared to flower color and red leaf mutants,the mechanism of yellow leaf formation in woody plants is more complicated and less understood.Poplars are common and widely distributed perennial trees.Here,we obtained a golden leaf mutant poplar variety(JHY)and compared it with its original green leaf poplar(Populus sp.Linn.‘2025’)in terms of phenotype,pigment content,the transcriptomes and metabolomes.Through transcriptome sequencing,we found that the chlorophyll degradation genes,and the genes in anthocyanin metabolism in JHY were up-regulated compared to L2025 and the carotenoid synthesis genes were down-regulated.Further based on HPLC-ESI-MS/MS technology,16 differentially expressed anthocyanins were identified,14 reddish anthocyanins of which were significantly up-regulated.According to these results,we proposed a coloring mechanism of JHY based on the RGB color mode.The yellow color of carotenoids and the red color of anthocyanins overlay each other,combined with a reduction in chlorophyll,turning the leaves golden.This study systematic analyzes the causes of golden leaf formation through the omics integration approach,which will provide reference for the breeding of golden leaf trees.

月季红双喜花瓣变色的化学基础及比较转录组分析

月季(Rosa hybrida)花色丰富,是世界著名的观赏花卉。月季红双喜因其花瓣的变色特性而在市场上广受欢迎。该研究通过类黄酮和类胡萝卜素靶向代谢并结合转录组分析,发现红双喜的黄色花瓣呈色主要源于叶绿素、类胡萝卜素以及类黄酮的积累,红色花瓣呈色主要是花青素苷积累增加且糖苷化的结果。花青素苷合成关键基因CHI、ANS和UFGT,以及R2R3-MYB家族的AN2-like成员在红色花瓣中的强烈表达是花青素苷积累的分子基础;类胡萝卜素成分改变及相关基因的表达变化在红双喜花瓣变色过程中也起重要作用,并且miRNA156可能参与其调控过程。该研究揭示了月季红双喜花瓣变色的分子和化学基础,研究结果为观赏植物花色分子设计育种提供了重要理论依据。

蓝色花形成分子机理研究进展

花色是观赏植物的重要特征,在自然界中蓝色花占比很少,很多观赏植物都缺少蓝色种质。因此,研究蓝色花形成的分子机理对于蓝色花定向育种具有重要意义。研究表明,花色的形成主要是通过花青苷积累,花青素通过糖基化形成花青苷,再通过酰基、甲基化修饰及金属离子络合反应,在特定的液泡pH环境中呈现出稳定的蓝色。该文从花青苷合成与代谢途径入手,对蓝色花形成关键基因功能、花青苷各位点酰化的影响、金属离子的作用、液泡pH值相关基因研究及蓝色花分子育种等方面进行综述。