Transgenic Petunia hybrida with Silicon Transporter Protein OsLsi1 and OsLsi2 Genes and Its Drought Resistance Analysis

As one of the important materials in landscaping for flower terrace and border, Petunia hybrida needs high environmental conditions and its growth is seriously influenced by the drought. Silicon is considered to be a necessary element for plant growth, and soluble silicon can improve plant resilience. To improve the drought resilience of Petunia hybrida, the silicon transporter protein OsLsi1 and OsLsi2 genes cloned from rice（Oryza sative） were transferred into Petunia hybrida by Agrobacterium-mediated method, and finally got 26 and 32 positive plants, respectively by PCR and RT-PCR detections. With a control of non-transgenic plants, the obtained transgenic plants were taken by drought treatment stress for 0, 4, 7, 10 and 14 days, then re-watered and measured physiological indexes as malondialdehyde（MDA） content, free proline（Pro） content, superoxide dismutase（SOD） activity and peroxidase（POD） activity to study the effect of Petunia＇s drought resistance. All the results proved that the silicon transporter protein OsLsi1 and OsLsi2 genes were normally transcripted and expressed in transgenic Petunia hybrida; OsLsi1 gene could improve the abilities of plants＇ drought resistance and recover after drought stress, while OsLsi2 gene could reduce the above abilities. The order of the drought resistance ability of the three strains from strong to weak was OsLsi1〉CK〉OsLsi2; and silicon indeed improved the ability of drought resistance as well. All these results provided a new way to improve the drought resistance of Petunia, and laid a foundation to improve the ability of garden plants＇ drought resistance and water saving.

Nodulin 26-like intrinsic protein Cs NIP2;2 is a silicon influx transporter in Cucumis sativus L.

Nodulin 26-like intrinsic proteins(NIPs) are a family of channel-forming transmembrane proteins that function in the transport of water and other small molecules.Some NIPs can mediate silicon transport across plasma membranes and lead to silicon accumulation in plants,which is beneficial for the growth and development of plants.Cucumber is one of the most widely consumed vegetables;however,the functions of NIPs in this crop are still largely unknown.Here,we report the functional characteristics of Cs NIP2;2.It was found that Cs NIP2;2 is a tandem repeat of Cs NIP2;1,which had been demonstrated to be a silicon influx transporter gene.Cs NIP2;2 has a selectivity filter composed of cysteine,serine,glycine and arginine(CSGR),which is different from all previously characterized silicon influx transporters in higher plants at the second helix position.Xenopus laevis oocytes injected with Cs NIP2;2 c RNA demonstrated a higher uptake of silicon than the control,and the uptake remained unchanged under low temperature.Cs NIP2;2 was found to be expressed in the root,stem,lamina and petiole,and exogenous silicon treatment decreased its expression in the stem but not in other tissues.Transient expression of Cs NIP2;2-e GFP fusion sequence in onion epidermal cells showed that Cs NIP2;2 was localized to the cell nucleus,plasma membrane and an unknown structure inside the cell.The results suggest that Cs NIP2;2 is a silicon influx transporter in cucumber,and its subcellular localization and the selectivity filter are different from those of the previously characterized silicon influx transporters in other plants.These findings may be helpful for understanding the functions of NIPs in cucumber plants.

Carrier Transport Across Grain Boundaries in Polycrystalline Silicon Thin Film Transistors

We established a model for investigating polycrystalline silicon（poly-Si） thin film transistors（TFTs）.The effect of grain boundaries（GBs） on the transfer characteristics of TFT was analyzed by considering the number and the width of grain boundaries in the channel region,and the dominant transport mechanism of carrier across grain boundaries was subsequently determined.It is shown that the thermionic emission（TE） is dominant in the subthreshold operating region of TFT regardless of the number and the width of grain boundary.To a poly-Si TFT model with a 1 nm-width grain boundary,in the linear region,thermionic emission is similar to that of tunneling（TU）,however,with increasing grain boundary width and number,tunneling becomes dominant.

Reduction and Reoxidation of Silicon in Blast Furnace Hearth

This paper introduces both laboratory experi- ment and equilibrium calculations concerned with the Si reduction and reoxidation.The results give evidence that the Si transport in different directions just exists in the furnace hearth synchronistically, by which the desulphurization is also affected.The problems noticed for smelting tow Si pig iron are given.

Thermoelastic stresses in SiC single crystals grown by the physical yapor transport method

A finite element-based thermoelastic anisotropic stress model for hexagonal silicon carbide polytype is developed for the calculation of thermal stresses in SiC crystals grown by the physical vapor transport method. The composite structure of the growing SiC crystal and graphite lid is considered in the model. The thermal expansion match between the crucible lid and SiC crystal is studied for the first time. The influence of thermal stress on the dislocation density and crystal quality is discussed.