Combined genome-wide association studies and expression quantitative trait locus analysis uncovers a genetic regulatory network of floral organ number in a tree peony (Paeonia suffruticosa Andrews) breeding population

Great progress has been made in our understanding of floral organ identity determination and its regulatory network in many species;however,the quantitative genetic basis of floral organ number variation is far less well understood for species-specific traits from the perspective of population variation.Here,using a tree peony(Paeonia suffruticosa Andrews,Paeoniaceae)cultivar population as a model,the phenotypic polymorphism and genetic variation based on genome-wide association studies(GWAS)and expression quantitative trait locus(eQTL)analysis were analyzed.Based on 24 phenotypic traits of 271 representative cultivars,the transcript profiles of 119 cultivars were obtained,which indicated abundant genetic variation in tree peony.In total,86 GWAS-related cis-eQTLs and 3188 trans-eQTL gene pairs were found to be associated with the numbers of petals,stamens,and carpels.In addition,19 floral organ number-related hub genes with 121 cis-eQTLs were obtained by weighted gene co-expression network analysis,among which five hub genes belonging to the ABCE genes of the MADS-box family and their spatial–temporal co-expression and regulatory network were constructed.These results not only help our understanding of the genetic basis of floral organ number variation during domestication,but also pave the way to studying the quantitative genetics and evolution of flower organ number and their regulatory network within populations.

Histology, physiology, and transcriptomic and metabolomic profiling reveal the developmental dynamics of annual shoots in tree peonies (Paeonia suffruticosa Andr.)

The development of tree peony annual shoots is characterized by“withering”,which is related to whether there are bud points in the leaf axillaries of annual shoots.However,the mechanism of“withering”in tree peony is still unclear.In this study,Paeonia ostii‘Fengdan’and P.suffruticosa‘Luoyanghong’were used to investigate dynamic changes of annual shoots through anatomy,physiology,transcriptome,and metabolome.The results demonstrated that the developmental dynamics of annual shoots of the two cultivars were comparable.The withering degree of P.suffruticosa‘Luoyanghong’was higher than that of P.ostii‘Fengdan’,and their upper internodes of annual flowering shoots had a lower degree of lignin deposition,cellulose,C/N ratio,showing no obvious sclerenchyma,than the bottom ones and the whole internodes of vegetative shoot,which resulted in the“withering”of upper internodes.A total of 36 phytohormone metabolites were detected,of which 33 and 31 were detected in P.ostii‘Fengdan’and P.suffruticosa‘Luoyanghong’,respectively.In addition,302 and 240 differentially expressed genes related to lignin biosynthesis,carbon and nitrogen metabolism,plant hormone signal transduction,and zeatin biosynthesis were screened from the two cultivars.Furtherly,36 structural genes and 40 transcription factors associated with the development of annual shoots were highly co-expressed,and eight hub genes involved in this developmental process were identified.Consequently,this study explained the developmental dynamic on the varied annual shoots through multi-omics,providing a theoretical foundation for germplasm innovation and the mechanized harvesting of tree peony annual shoots.

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.

伊藤杂种‘和谐’组培快繁体系的建立

以伊藤杂种‘和谐’(Itoh hybrids ‘He Xie’)的鳞芽为材料建立离体快繁技术体系,可克服传统方法繁育较慢的缺点,加速伊藤杂种优良品种的繁育推广。采用单因子试验设计,分别探究不同灭菌时间、不同植物生长调节剂浓度、不同根诱导时间以及不同生根苗等级对‘和谐’组培苗启动、增殖、生根和驯化效果的影响。结果表明,用2%次氯酸钠溶液的最佳灭菌时间为12分钟,鳞芽污染率为9.09%;最佳初始培养基配方为MS+1.5 mg·L^(-1)6-BA+0.2 mg·L^(-1)GA_(3)+0.5 mg·L^(-1)AgNO_(3);最佳增殖培养基配方为MS+450 mg·L^(-1)CaCl_(2)+0.5 mg·L^(-1)6-BA+0.2 mg·L^(-1)IBA+0.2 mg·L^(-1)GA_(3)+0.5 mg·L^(-1)AgNO_(3),增殖系数为3.3;无根苗在根诱导培养基1/2MS+1.0 mg·L^(-1)腐胺+2.0 mg·L^(-1)IBA上,经4℃低温暗培养8天后常温光照培养30天,再转入根形成培养基1/2MS+1.0 g·L^(-1)AC,培养20天生根率达66.7%;苗移栽的基质为珍珠岩:蛭石:草炭土=1:1:1 (v/v/v),移栽60天后,一级苗成活率最高为52.0%,二级苗和三级苗则大部分死亡,表明生根质量对移栽成活至关重要。