Secondary Metabolism,Endogenous Hormone And Transcriptome Analysis Of Apple Stock Cutting Root System

The gravitropic setpoint angle concept,introduced by Digby and Firn,provides a neat system for investigating growth angles that are dependent on graviresponse.In this system an organ being maintained vertically and growing downward has a GSA of 0°?e.g.,a primary root?while an organ growing vertically upward would have a GSA of 180°?e.g.,a primary shoot?.Organs being maintained at non-vertical angles have GSA designations between these two extremes.Because of the strong tree consistency and high fruit commodity,the application of apple self-root stock is the main mode in developed countries.But its weakness is of shallow roots and poor solid ground.While the poor performance on the barren soil of China orchard,apples self-roots stock develops slowly in our country.Therefore,it has important theoretical and practical significance that researching on the influence factor of apple self-root stock adventitious roots GSAs.Three affinis and different rootedness apple self-root stocks are screened by our group,in this study,previously.Compared with each other,these self-root stocks we screened show different rootedness adventitious roots branch angle.These self-root stocks provide appropriate material development for the study of adventitious gravitropism setpoint angle.In this study,pre-screening adventitious GSA different clonal propagation lines were uses as experimental materials.Through the endogenous hormonal dynamic and secondary metabolite of cuttings in critical period of the adventitious root formation are analyzed.The transcriptome technology was used to research on the influence factors in cuttings on adventitious roots GSAs.This study is to reveal the role of secondary metabolism of cuttings in the formation of adventitious roots GSAs.During the development of apple self-root stock adventitious roots,the IAA content was first increased and then decreased;the content of ABA and iPA were on the decline,generally;the variation tendency of ZR content was "W" and the content of GA₃ showed a "V".In the formation period of adventitious roots GSAs,the endogenous IAA content reduced quickly in the deep-root cuttings.The content of endogenous ZR and GA₃ reduced with the increase of adventitious GSAs,while the IAA/ZR ? IAA/GA₃ were increased in turn.Ester compounds?44.34%?and alcohols?41.27%?were the main volatile substances of apple self-root stock twig cutting.Wherein,the relative content of?E?-4-Hexen-1-ol were the highest,followed by Z-3-Hexen-1-ol,acetate,and formic acid,hexyl ester,33.96%,20.18% and 15.11%,respectively.The relative contents of volatiles in the cuttings were different in different adventitious root GSAs.Respectively,the relative content of?E?-2-Hexenal increased gradually with the adventitious root GSAs.Transcriptome of three stage of the development of adventitious roots were analyzed by RNA-seq.Through Illumina HiSeq 2500 sequencing,36,919,140 to 38,793,530 raw reads were obtained from 9 samples.Approximately 24 million reads each sample comparison to the reference genome successfully,and the effective rate was 86.03%-88.87%.in the period of adventitious roots GSAs formation,gene of DFR?HCT1A and CYP78A5 reduced,promoting the synthesis of naringenin,quercetin and other flavonoids and alkaloid compounds.GSAs adventitious root formation period,gene DFR,HCT1 A and CYP78A5 and other down,and promote the synthesis of naringenin,quercetin and other flavonoids and alkaloid compounds.