Effect Of Exogenous Hydrogen Sulfide On Root Growth And Leaf Photosynthetic Rate In Peach Trees

Hydrogen sulfide is involved in the regulation of many life processes of plant growth and development,but its effect on the growth and development of peach trees is still unclear.Peach seedlings [ Prunus persica（L.）Batsch] and the 7-year-old "Ruiguang 33/Maotao" were used to investigate the effects of different concentrations(0,0.05,0.1,0.2,0.3 mmol·L^-1)of Na HS as H₂S donor on root architecture,leaf photosynthetic characteristics,expression characteristics of H₂S synthase encoding genes（Pp DCD and Pp LCD）in roots and leaves and H₂S content in roots.The effects of exogenous H₂S on the gene expression of peach seedling roots were studied by transcriptome.And the effect of exogenous H₂S on the expression of auxin synthesis,transport and cell cycle regulatory genes in peach roots was detected by realtime fluorescent quantitative PCR.The results show that:1.Compared with control,H₂S content in root,root activity,primary lateral root number,total root length,total root volume,total root surface area,average diameter,number of root tips,number of root branches,root fractal dimension,leaf net photosynthetic rate,plant biomass and root-shoot ratio of peach seedlings were significantly increased under 0.1⁰.3 mmol·L^-1 Na HS treatments.0.2 mmol·L^-1 Na HS treatment showed the best effects.Higher concentration(0.3 mmol·L^-1)of Na HS treatment weakened the promotion of root growth and leaf photosynthesis.The promotion of root growth,leaf photosynthesis and plant biomass accumulation were partially eliminated under 0.2 mmol·L^-1 Na HS + 0.1 mmol·L^-1 HT treatment.0.1 mmol·L^-1 HT treatment reduced root H₂S content,inhibited root growth,and decreased leaf photosynthesis and plant biomass accumulation.Otherwise,there had no significant effects on the root growth of peach seedlings under the treatments with other sodium salt including Na2SO4,Na2SO3,Na AC,Na HSO4 and Na HSO3.It indicated that the promoting effect of Na HS on the root growth of peach seedlings is attributed to the release of H₂S.2.The expression of Pp DCD and Pp LCD within 2 and 4 h reached the highest level in roots and leaves,and then dropped to the initial level.The H₂S content in the roots of peach seedlings was significantly increased under 0.2 mmol·L^-1 Na HS treatment.These results indicated that the expression of H₂S synthase encoding genes in roots and leaves of peach seedlings can be induced by exogenous H₂S.And exogenous H₂S can increased H₂S content in root,and promoted the root growth and the leaf photosynthetic rate.3.Under the conditions of peach orchard,the 7-year-old ‘Ruiguang 33/Maotao’ was used to study the effect of exogenous H₂S on the root architecture of mature peach trees.The results show that: Exogenous H₂S can promote the growth of fine roots of mature peach trees to a certain extent.Compared with the control,the total length,the total root surface area,the total root volume,the number of root tips,the branching tree and the number of crossings of the root system increased by 12.79%,19.26%,12.86%,12.96% 10.83% and 25.28% under the H₂S treatment,significantly.The average diameter of the root system significantly decreases by 17.46% under H₂S treatment.The length,surface area,volume and dry matter accumulation of fine roots of mature peach trees with 0-2.0mm diameter significantly increased by 15.54%,27.88%,33.52% and 36.22%,respectively,but had no significant effect on the coarse roots when the application of exogenous H₂S was applied for one year.Moreover,the fractal dimension of the roots of mature peach trees significantly increased by 2.89% compared with the control after exogenous H₂S treatment.4.It was found that after treatment with 0.2 mmol·L^-1 Na HS for 2 hours,the results of real-time quantitative PCR showed that exogenous H₂S increased the expression level of the auxin synthesis genes YUC1 and YUC2,auxin transporter genes AUX1,PIN1,PIN2 and PIN3 and cell cycle regulatory coding gene CDKA1,CYCA2;1,CYCA3;1.