| Root is the basis of the fruit trees, root structure and function regulation is the key oforchard soil management. The orchard per-acre yields achieved around10,000kg by QuShoupeng in PengLai in successive years. According to the research survey for many years,we found that the orchard had high content of soil organic horizons, large number ofabsorption roots, and stable surface circumstance. In this paper, the roots origin and formation,two types root function, and inducing application research of cultivation was discussed infield and pot cultivation. Meanwhile, expression profiles of sequencing technologydifferences were applied to compare the differential genes of the two types of new roots. Theapple biological information data base flat was set up by collecting the apple biologicalinformation data. The results were as follows:1. Root group and the origin of two types of new rootsThrough the results of phenotype observation, we put forward a new concept about theroot configuration,‘root group’, which is the branched root system configuration which isinduced by growing root under the condition of organic soil. Multilevel branches of the lateralgrowing root are the sites where root group forms.The difference in root group with tree ageand root mediums is significant. The seedlings absorbing root is less and thin, while strongand long-lived roots are formed in the region of organic matter during fruit stage. In differentstages, root group can induce a large number of absorbing root, and is the main parent root ofabsorbing root.The root anatomy showed that the primary xylem of new roots was divided into diarch,triarch, tetrarchy and pentarch. Growing root and absorbing root are all originated in thepericycle cells, blonging to the lateral root development way. Most of absorbing root iscoming from diarch, while the growing root is coming from tetrarchy or pentarch.2. The function of two types of new rootsThe potted experiment of one year old Malus hupehensis in different mediums indicatedthat,5%biochar fertilizer mixed with10%organic fertilizer treatment made the chlorophyllcontent and net photosynthetic rate increase by15.55%and57.64%respectively, and plantbiomass increase by46.36%. The result of local optimization of potted two years old Malus hupehensis in differentposition indicated that, the treatment of clay loam in central area and water-nitrogen inducingin outer area effectively increased the plant’s height and biomass. Plants grow best under thewater-nitrogen inducing treatment in the middle area, whose plant height, stem coarseness andbiomass increased by23.99%,9.85%and21.90%, respectively. Local optimization had nosignificant effect on leaf quality and storage nutrion of branches.Local optimization in field made the photosynthetic rate of internal, central and externalleaf net increase by27.23%,31.95%and27.23%respectively; Chlorophyll content increaseby19.03%,12.52%and12.06%respectively. Solubility sugar and starch in spring shootsincrease by49%and33.5%, respectively. Solubility sugar and starch in autumn shootsincrease by28.30%and27.27%, respectively. The number of apical and axillary bud scales is1-2pieces more than control. Yield per plant in the second year significantly increasedfor18.38kg.So, absorbing roots can improve leaf quality, prevent the senescence of leaf, increasebranches’ storage nutrition, regulate the growth of autumn shoot, improve the quality offlower bud, and increase fruit yield.3. The inducing cultivation of two types of new rootsThe study of potted experiment with different media indicated that,5%biochar treatmentmade root surface area and root tips number increase4.47times and10.78times than thecontrol. Biochar fertilizer mixed with organic fertilizer treatment made root surface area androot tips number increased by5.03times and14.83times. Biochar fertilizer used alone orcombined with organic fertilizer significantly increased fine root absorption area ratio, for24.99%and22.10%of total root surface area, respectively.Water-nitrogen induced roots regeneration. Water-nitrogen induced most thin roots whenvermiculite as a growing medium, and the new growth roots were thin; the roots had morebranches when rganic matter as a growing medium, Water-nitrogen induced growing rootsand absorbing roots significantly increased, the absorbing roots were long and thick;Water-nitrogen induced more growing roots and the absorbing roots when rganic matteras a growing medium. Water-nitrogen induced potted plants to form a large number ofgrowing roots, surrounded the inside of pots, which was called ‘surface interfacial effect’. Water-nitrogen induced the growing roots lengthened and had less branches when river sandsas a growing medium. So, ensuring the organic matter content and environmental stability inthe fertilizer region is the basis of reasonable induction of the growing roots and the absorbingroots. Layer induction experiments showed that water-nitrogen could induce rootslengthening to72.6cm, which was2.62times than the medium induction; water-nitrogeninduced more absorbing roots, and the thin roots were only1.28%.The result of local optimization of potted two years old Malus hupehensis in differentposition showed that, no roots inducing along the outside and root was concentrated in themiddle and upper soil when the middle area was medium, the roots in upper mediumaccounted for more than62.09%. More thin roots formed outside when the central area wasclay loam, water-nitrogen induced more long roots, most roots formed in the mid-mediumarea, the average dendity of roots were more than5.10per cubic metres, and the spaceutilization efficiency was the best. Water-nitrogen inductive in the middle layer had the besteffect, which induced5to7long roots per cm3.Local optimization in field made fine root number and thick root number increased by45and eight in the first year, respectively, made total surface area increased by6.76times, madethe number of root tips increase by11.14times. Local optimization in field made fine rootnumber, thick root number increase by137and26, respectively, made root surface and roottips number increased by13.60times and19.63times, respectively.4. Local optimization and three layers of water-saving soil management systemDepending on the apple tree roots’ function and the inductive identity, the research groupput forward soil management system “protecting the top soil, optimizing local part,micro-irrigating the moderate soil, collecting water in the subsoil”, The three layers ofwater-saving treatment on ‘Fuji’ and ‘Gala’ showed that, the shoot and flowers quality wasimproved, the energy consumption was reduced, and the production significantly increased.5. To gain insight into the transcriptome dynamics between the two types of new roots,genome-wide gene expression profiling was conducted by Solexa sequencing. More than fivemillion tags were generated from two type new roots, including1,646DEGs were identified,which participated in biosynthesis of secondary metabolites, plant-pathogen interaction, planthormone signal transduction, phenylpropanoid biosynthesis, ribosome and flavonoid biosynthesis. Most genes were identifid in the cell part function (82.7%), catalytic activity(71.1%), ion binding (59.2%) and membrane transcription (24.5%), etc. Next, the expressionpatterns of the ion transporting genes were assessed by quantitative real-time PCR, and theresults obtained showed general agreement with the Solexa analysis.6. To analyze the function and evolution of different genes in root, we developed applegene function and gene family database (AppleGFDB) for collecting, storing, arranging, andintegrating functional genomics information of the apple. The AppleGFDB provides severallayers of information about the apple genes, including nucleotide and protein sequences,chromosomal locations, gene structures, and any publications related to these annotations. Tofurther analyze the functional genomics data of apple genes, the AppleGFDB was designed toenable users to easily retrieve information through a suite of interfaces, including geneontology, protein domain and InterPro. In addition, the database provides tools for analyzingthe expression profiles andmicroRNAs of the apple.Moreover, all of the analyzed andcollected data can be downloaded from the database. The database can also be accessed usinga convenient web server that supports a full-text search, a BLAST sequence search, anddatabase browsing. Furthermore, to facilitate cooperation among apple researchers,AppleGFDB is presented in a user-interactive platform, which provides userswith theopportunity to modify apple gene annotations and submit publication information for relatedgenes. AppleGFDB is available at http://www.applegene.org. |
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