Study On Histological Localization And Expression Of Genes Related To Cell Wall During Dedifferentiation Of Mature Wheat Embryos

The common wheat cultivar Yumai 18 (Triticum aestivum L.) as experiment material to study the process of mature wheat embryos dedifferentiation from morphology, cell structure to gene expression level. In order to reveal that the histological localization and molecular mechanism. Main results as follows:In this study, we confirmed conformation of cell about dedifferentiation of mature embryos using microscopical technology, and located the start preliminary site dediffrentiating mature embryos. The results show that: Dedifferentiation originally arose from the sheath inner cells of the radicel. in the 2,4-D induced conditions, The process of dedifferentiation of this part of cells starting at 6 h after being trained, Reply to gradually thin-walled cells.There are callose formation at 24 h after induction, For 72 hours after the wheat from mature embryos have divided a larger callus Mission. These callus mainly from dedifferentiation of the radicle ensheathing cells. The main performance for that cell gap, and the volume of nucleus increased,and vacuoles obviously,and the larger nuclei were squeezed out to the cell edge by vacuole. The transmission electron microscopy observation showed that the mature wheat embryos in the process of dedifferentiation wall thinning, mitochondrion, endoplasmic reticulum, and so quantity of organelles increased. Densities of starch grains and lipid bodies decreased to disappear. The cytoplasm re-compositing With the disappearance of the original material and the emergence of new material.In order to study the molecular mechanism of mature wheat embryos dedifferentiation, we analysised the expression of genes related to auxin, cytokinin, gibberellin, abscisic acid and ethylene in vivo during dedifferentiation of mature wheat embryos at transcriptional level, using a Affymetrix wheat Gene Chip. The controlled calli were 0 hours'samples. Those genes whose ratios of 2 h vs 0 h, 6 h vs 0 h, 12 h vs 0 h, 24 h vs 0 h, 72 h vs 0 h, were greater than 2 or shorter than 0.5, namely which exhibited a greater than two folds change in gene expression level during dedifferentiation of mature wheat embryos, were meaningful genes. We analysised the expression profiles of these meaningful genes in dedifferentiation of mature wheat embryos. At the results, using the Affymetrix wheat GeneChip including 61127 probe sets, representing 55085 genes, 15000 genes were meaningful approximately. In mature embryos, the total number of genes related to cell wall was 138, Their expression products is divided into eight categories by function. They are extensin, expansin, cellulose synthase, cellulose,phosphomannomutase,galactokinase,cinnamoyl-CoAreductase,UDP-glucose pyrophosp -horylase.Analysis shows that: the number of genes related to extensin and expansin were 45 and 48 respectively, and most of them were up-regulated, so they might play an important role to cell wall extend in the dedifferentiation of wheat mature embryo. AY543542.1,CD490917,AY543544.1 and BJ249762 were up-regulated more than 200 times in 24h or 72h. CA640232,CA604159 and CA641446 were up-regulated more than 30 times in 24h or 72h. Expression of genes related to expansin and extension in dedifferentiation of mature wheat embryos. It is corresponding to the changes in the cell wall observed, also shows that cell structure and function of the unity.The mumber of genes related to cell wall metabolism was 45, Including cellulose synthase gene 13,cellulose gene 2, phosphomannomutase gene 3,galactokinase gene 8 ,cinnamoyl-CoA reductase gene 16, UDP-glucose pyrophosp -horylase gene 3. These gene were up-regulated of the whole process or some point in time,they played an important role to the synthetic and decomposition in the process of dedifferentiation of mature embryo.