Studies On Material Transport Barriers And Its Differential Gene Expression Profiles In The Process Of Embryo Abortion Of Hazelnut

Hazelnut belongs to Corylus L. plants in Corylaceae. Its fruit is one of the four bestimportant nuts in the world. The fruit have rich nutrients content and high nutritional value.The development of hazelnut plantation can increase farmers’ income. In the process ofgrowth of hazelnut, high rate of embryo abortive have a serious influence on yield of hazelnut.Physiological mechanism of embryo abortion was solved and it has important theoretical andpractical value to hazelnut production. This research will reveal nutrient transportationproblem of hazelnut abortive embryos and physiological mechanism of hormone regulation.The main results were as follows:(1) In our research, we analyze dynamic changes of four plant endogenous hormones innormal and embryo abortive fruit, and reveal the closely relationship of ABA and embryodevelopment. ABA has important regulating effect on ovule growth. There were importantrelationship of plant endogenous hormone and embryo cell tissue structure change. Our studyresults indicated the physiological and biochemical reason of embryo abortive. Our researchprovided the scientific basis for high-yield cultivation of hazelnut.(2) Structure changes of female flower cluster and fruit were observed and patterns ofdisodium fluorescein transport into ovule and funiculus from fruit stalks were studied in theyear of2010–2012. The results indicated that early ovary and ovule of hazelnut were visibleon about20and45days after blooming respectively, and the sizes of two ovules within anovary were equal prior to55days after blooming, then the differences in ovule size becameobviously along with development of the fruit. Ovules within blank fruit had little changes insize and maintained2.0–4.0mm in length until harvest. However, the ovary size of blank wasmuch closed to that of filled one during the whole fruit development stage. For filled nut,disodium fluorescein transport obstacle occurred at junction point of ovules and funiculus andled to the abortion of one ovule from60to90days after blooming, while bright fluorescecould be observed in funiculus until near harvest. For the blank fruit, fluorescein transportobstacle happened at junction point of ovules and funiculus first on55day after blooming,then the funiculus failed to execute the transport function from60to90days after blooming.In conclusion, transport obstacle occurred at junction point of ovules and funiculus first, and then happened in funiculus, and these phenomena were closely related with blank fruitformation in C. heterophylla Fisch.(3) High empty fruit ratio of C. heterophylla Fisch is very usual phenomenon andcauses serious yield loss in Northeast China. Formation of empty fruit of C. heterophyllaFisch was confirmed to closely relate to embryo abortion. However, little was known aboutthe detail molecular mechanism charged for embryo abortion during nut development phase.Genomic information of C. heterophylla Fisch is currently not on hand, therefore, data oftranscriptome and gene express profiling of developing and aborted ovules are required toclarify the molecular biological mechanism of ovule abortion in hazelnut much better. In thisresearch, de novo transcriptome sequencing and RNA-Seq analysis were made by short readsequencing technology (Illumina HiSeqTM2000). Results of the transcriptome assembleanalysis indicated the gene information during fruit development phase. Also, two differentialexpressed gene (DGE) libraries had been made: full (normal developing ovule) and empty(abortive ovule) libraries. Transcriptome sequencing and assembling results indicated115,862contigs and55,353unigenes including18,751clusters and36,602singletons, after that, theywere noted with the public databases of NR, NT, Swiss-Prot, KEGG, COG and GO. Toanalyze the DGE profiling, gene expression changes between developing and abortive ovuleswere compared.1637and715unigenes were significantly upregulated and downregulated inabortive ovules respectively compared with developing ovules. Some DEGs were chosen toperform quantitative real-time PCR (qRT-PCR) analysis in order to verify their different.Inconclusion, the transcriptome and DGE profiling data of developing and abortive ovule inhazelnut provide detailed information which will be good for better understanding ofmolecular mechanism of abortive ovule formation in hazel.