| Populus, typical of the fast-growing tree, grows fast and has a short rotation period.Populus are widely cultivated in China. Populus with rich genetic rescources, is the modelplant in genetic study of wood plant. Sequencing of Populus was the third perenial woodyplant that genome has been finished after Arabidopsis thaliana and Oryza sativa. That measPopulus can be more in-depth studies in molecular genetics.Among the five kind of plant hormone, auxin was the first be discovered; in the plants,the rapid elongation induction of stems and coleoptile in vitro is the fasteset, the mostsignificant hormonal response. Auxin is involved in many growth and development processesof plants that promoting the growth of roots, stems, leaves, affecting development of embroys,controlling the top edge, participating in the formation of vascular, etc.We constructed the over-expression vectors of PtAUX1and PtPIN1, and transformedthem into Populus and Arabidopsis by using the method of agrobacterium tumefaciens. Wehad the over-expression transgenic plants of35S::PtAUX1and35S::PtPIN1. Phenotypes oftransgenic plants were analyzed, the phenotypes provided evidence for researching functionof PtAUX1and PtPIN1, and they also laid the groundwork for studying the molecularmechanism of genes. The results were as follows:The first, protein homology analyses showed PtAUX1was most similar to Populustrichocarpa Torr. PttLAX1and AtAUX1of Arabidopsis Aux gene family of with97.3%and83%. PtPIN1was also most similar to Medicago truncatula MtPIN1and Arabidopsis AtPIN7with82%and79%. According to analyses of phylogenetic tree, PtAUX1gene was similar toAtAUX1and PttLAX1of Arabidopsis Aux gene family. So PtAUX1and AtAUX1werehomologous genes. And PtPIN1belonged to PIN-like family of the auxin efflux carrier.The second, there were many phenotypes that of PtAUX1transgenic plants. PtAUX1promoted the increasing of leaves,regulated appearence of ovary-like structure aroundregeneration of buds liking flowers, induced appearance of somatic embryos on the leaves. Mature somatic embryos developed into complete plants after being removed and cultured inMS medium.There were many phenotypes after transformation of PtAUX1into Arabidopsis. PtAUX1kept root geotropism, promoted lateral root initiation and root elongation. Made increasednumber of trichome and more two fork branches. Showed sensitivity to6-BA and lowsensitivity to ZT. There were curling and cupule-like leaves, enveloping and transparentpetals, curled calyces. Transgenic plants showed that some stamen had no flower silk, pistilwas transparent and some of them emerged hyperplasis. Moreover, there were antheradhesion, many types of pods.According to phenotype of PtAUX1transformation into Populus tomentosa andArabidopsis thaliana, we know that, PtAUX1gene participated in leaves, buds, flower organs,ovary and somatic embryos devolopment process. The basis of the above coming ture wasthat PtAUX1regulated auxin polar transpotation as auxin influx carrier.The third, transgenic plants of PtPIN1tranformation into Populus tomentosa showed thatplants were tall and strong, leaves had coarse serrate and growed asymmetrically,regeneration buds gathered lile flowers, buds were white and then became mahogany partly.Some buds were rod-like and crystal. Auxin promots plants’development, regulatesleaves’polarity building and development of leaves and buds. Phenotypic of transgenic plantsexactly consistent with the function of auxin. This showed that PtPIN1participated indevelopment of many organs by regulating polar transportation of auxin.The results provided us reliable evidence that we sutied function of PtAUX1and PtPIN1with this. PtAUX1was the auxin influx carrier and PtPIN1was the anxin efflux carrier, theyregulate polar transportation of auxin with spectific mechanisms, then involed inplants’development. |
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