Establishment Of A New And Efficient Grape Adventitious Root Formation Research System

Adventitious root formation（ARF）is the key to asexual propagation of grapes,and it is time-consuming and laborious to study the causes of grape rooting difficulties through conventional genetic methods.Current studies do not clearly explain the laws of ARF in grapes,especially the regulatory mechanisms of adventitious root（AR）induction and initiation.Grape ARF was studied using field cuttings,and the sample heterogeneity was large,and its phenotypic error often masked the differences caused by the treatment.where we need a quantifiable study system with ARF phenotypic consistency.In this study,the ARF experiment using different types of explants in grape tissue culture found that the heterogeneity of the ARF phenotype is closely related to the explant type.Leaf with petiole（LP）is the simplest unit of ARF of selected explants.Grape LP explants material is readily available,with high rooting rate,fast and synchronized AR formation.In the absence of the provision of exogenous mineral nutrients and auxin,LP directly generate ARs from the base of the petiole.The effect of factors such as plant growth status,nodal position,leaf size and health status on the homogeneity of ARF phenotype in grape LP was confirmed.By controlling these factors,LP was cultured on 6 g/L agar and 10 g/L sucrose medium under dark conditions,and rooting began at 6 to 7 days,and the rooting rate reached 100%at 13 to 14 days.By measuring the rooting rate,the effects of different compounds and concentrations on ARF can be quantified.Using this system,the central role of auxin on ARF was verified by exogenous administration of indolebutyric acid（IBA）and N-1-naphthalic acid（N-1-naphthalic acid,NPA）;at the same time,it was found that light promoted LP rooting without exogenous addition of sucrose,while in the presence of sugar（10g/L）,light significantly inhibited LP ARF,and low concentration of 0.1 mg/L NPA can partially lifted the inhibition.The system reveals a complex relationship between sugar-light-auxin in grape ARF.In addition,this study also confirmed the significant inhibitory effect of a number of exogenous plant growth regulators（PGR）,including 6-benzylaminopurine（6-Benzylaminopurine,6-BA）,gibberellin3（Gibberellin 3,GA₃）and 2,4-epibrassinolide（2,4-Epibrassinolide,EBR）,The complexity of the effects of methyl jasmonate（Me JA）on grape ARF was explored.Finally,based on the significant inhibitory effect of GA₃ treatment on grape ARF,in order to explore the early response of grape cells to exogenous gibberellin treatment,this study intensively sampled two concentrations of GA₃ after treating grape germ cells within 72 h and conducted compare the transcriptomics analysis.Through comparison,it was found that grape cells had peak responses to GA₃ treatment in three stages:0.5-2h,4-12h,and 24-72h.Differential genes reveal that an association between gibberellin and auxin may be a key reason why GA₃ inhibits ARF.In the auxin signaling pathway,the AUX1/LAX family gene VIT＿13s0074g00550 exhibited specific expression trends in each comparison sample.From this,it can be assumed that GA₃ may be connected to endogenous auxins through AUX1/LAX family genes,which in turn affect grape ARF.