红松雌球花原基分化过程中内源激素含量变化及转录组分析OA

To elucidate the changes in major hormone contents and investigate the related molecular mecha-nisms of endogenous hormones during female cone primordium differentiation in Pinus koraiensis,female cones from 50-year-old Pinus koraiensis trees were used as materials.Paraffin sections were prepared to ob-serve the morphological structure at different differentiation stages,and endogenous hormone content deter-mination and transcriptome sequencing were performed.Paraffin section observations revealed that during the four stages of female cone differentiation in Pinus koraiensis,the female cone primordium continuously enlarged,with distinct morphological changes.Determination of 8 endogenous hormones belonging to 5 clas-ses(gibberellins(GA3,GA4,GA7),auxins(IAA,IPA),abscisic acid(ABA),brassinolide(BR),and cy-tokinin(tZR))across the four stages showed that the content trends of these hormones varied during each stage of female cone differentiation.Among them,the contents of GA3,IAA,and ABA changed markedly;ABA content accounted for the highest proportion,showing an initial decrease followed by an increase,while GA3 exhibited an initial increase followed by a decrease.Correlation analysis revealed that ABA/GA3,ABA/IAA,and ABA/tZR were significantly positively correlated with ABA.Principal component analysis identified BR and ABA/GA3 as key factors for evaluating the differentiation status of female cone primordia in Pinus koraiensis.ABA and GA3 contents were significantly negatively correlated,demonstrating a clear antagonistic relationship.Transcriptome comparative analysis showed that endogenous hormones were significantly differ-entially enriched in the plant hormone signal transduction(ko04075)pathway.Hormone-related differentially expressed genes exhibited pronounced expression in the four hormone pathways of gibberellin,abscisic acid,auxin,and cytokinin.Taken together,these results indicated that late June to early July was the critical peri-od for the initiation of female cone primordium differentiation in Pinus koraiensis.The differentially expressed genes related to plant hormone signal transduction were consistent with the trends of endogenous hormone content changes,demonstrating that female cone primordium differentiation in Pinus koraiensis was regulated by ABA,GA3,and the ABA/GA3 ratio,with genes such as AUX/IAA,PP2C,PYR/PYL,GID1,GID2,and SnRK2 being highly expressed.