| Zinc（Zn）is an essential element for plants,while it is also a heavy metal which could lead to soil contamination,and too low or high Zn concentration in soil could affect the normal growth of plants.In northern China,Zn deficiency is quite common in the calcareous soils.On the contrary,available Zn in the acidic soils in southern China is rather high,and some soils has been polluted by excess Zn due to the mining of Zn and other reasons.Wine grape regions in China are distributed both in the north and south,and the wine grape could be affected by either Zn deficiency or Zn excess.Foliar fertilization is an effective way for Zn supplementation,and on the other hand,abscisic acid（ABA）is reported to alleviate the stress of Zn excess in some plants.In the present study,three concentrations（（1.0 g/L,4.0 g/L and8.0 g/L））of zinc sulfate were sprayed on Merlot vines in a commercial vineyard on the Yuquanying farm in Yinchuan,where Zn-deficiency was fould in the soil.The ZnSO4·7H2O was sprayed for twice,2 weeks before flowering and 2 weeks after flowering,respectively,aiming to study the effect of Zn on the quality of Merlot grape and wine;To further study the influence of Zn on grape quality,Hoagland solution without Zn was irrigated to the sand cultivated three-year-old Merlot in greenhouse,and some of the plants were foliar sprayed with 4.0 g/L of ZnSO4·7H2O,the control vines were irrigated with normal Hoagland solution;To investigate the influence of ABA and ABA mimic（AM1）on Zn uptake and accumulation in Merlot seedlings exposed to excess Zn,the seedlings were treated with either normal or excess levels(10 mM Zn2+,2880 mg/L)of ZnSO4·7H2O.To two out of three excess Zn treatments,10μM ABA or AM1 solutions were applied to the roots as well.The results were as follows:（1）Foliage sprayed zinc sulfate could effectively improve the merlot grape quality and the components of phenolics and aromatic compounds.Zn treatments enhanced the accumulation of total soluble solids,total phenols,flavonoids,flavanols,tannins and anthocyanins in berry skin,decreasing the concentration of titratable acidity.Zn treatments significantly increased the concentration of acetylated anthocyanins,3′,5′-substituted anthocyanins and methylated anthocyanins,and promoted the accumulation of flavonols and flavanols.Furthermore,foliage sprayed zinc sulfate could significantly influence the expression of phenolics biosynthetic pathway genes throughout berry development.Moreover,Zn treatments significantly increased the concentration of some esters,aldehydes,ketones,terpenes and norisoprenoids.All the treatments significantly increased the concentrations of 3,4-dimethyl-benzaldehyde andβ-Damascenone.The treatment with 4.0 g/L of ZnSO4·7H2O was the most effective on promoting the grape quality.（2）Foliage sprayed zinc sulfate could significantly influence the variety and content of aromatic compounds,and the treatment with 4.0 g/L of ZnSO4·7H2O was the most effective.Zn treatments significantly increased the concentrations of 1-nonanol,1-butanol-3-methyl acetate,ethyl hexanoate,ethyl phenylacetate,ethyl benzoate,ethyl palmitate,p-hydroxyl ethyl cinnamate andβ-damascenone in Merlot wines,and among those,β-damascenone and ethyl hexanoate were also two of the most odor-active compounds.Moreover,among the nine described aroma categories in the sensory analysis,intensities of fruity,vegetative,spicy,nuts and toasty were influenced by Zn treatments.（3）In the sand culture experiment,the effect of foliage sprayed zinc sulfate on the quality of Merlot grape was the same as that of field experiment.Zn defficent treatment decreased the concentration of total soluble solids,while increased the concentration of titratable acidity in matured grape.Foliage sprayed zinc sulfate enhanced the content of Zn in the leaves at veraison and in the grape at mature stage.Zn defficent and foliage sprayed zinc significantly decreased the IAA content in berries at veraison.Zn defficent increased the content of SA in berries at veraison,while decreased at maturation.Besides,Zn defficent decreased the concentrations of individual anthocyanins and non-anthocyanin individual phenolics in the skin of matured berries,while foliage sprayed zinc alleviated the decrease of individual anthocyanins and significantly increased the concentrations of non-anthocyanin individual phenolics.（4）In this study,17 VvZIP genes were identified in grape genome and their character was comprehensively analyzed.Most of the ZIP proteins were of high stability and hydropathicity,and were located in plasma membrane,coinciding with their characteristics of trans-membrane.The Vv ZIPs genes located on 8 of the 19 grapevine chromosomes and four tandem gene clusters were identified.Besides,structure and domain analysis of ZIP members indicated that the ZIP proteins shared conserved trans-membrane domains and the histidine motif were found in most ZIP proteins.The expression patterns in developing berries were identical with that of Zn accumulation.Quantitative real-time RT-PCR analysis on VvZIPs genes confirmed the microarray data,and foliar application of zinc fertilizer could significantly suppress the expression of VvZIPs genes.Foliage sprayed zinc increased the Zn concentrations in petiole,pulp,and skin of Merlot,mitigating the deficient or potential deficient of Zn in Merlot.（5）Excess Zn stress significantly affected the growth of Merlot seedling.Excess Zn treatments resulted in decreased lateral root length,decreased photosynthesis,elevated uptake and accumulation of Zn in roots,trunks,and stems,increased content of jasmonic acid in roots and leaves,and induced expression of Zn transportation（VvZIP2、VvZIP6、VvZIP7and VvZIP13）and detoxification related（VvHMA,VvNAS et al.）genes.Meanwhile,exogenous ABA alleviated the over uptake and accumulation of Zn in roots and trunks at 10days after Zn exposure and induced higher expression of both ZIP genes and detoxification related genes.The results indicated that exogenous ABA enhanced the tolerance of grape seedlings to excess Zn likely by regulating the expression of Zn uptake and detoxification related genes.No evident mitigating effect on excess Zn stress was found by the ABA mimic AM1. |
