Ectopic Expression of a Thellungiella salsuginea Aquaporin Gene, TsPIP1;1, Increased the Salt Tolerance of Rice.

Aquaporins play important regulatory roles in the transport of water and small molecules in plants. In this study, a ThellungiellasalsugineaTsPIP1;1 aquaporin was transformed into Kitaake rice, and three transgenic lines were evaluated by profiling the changes of the physiological metabolism, osmotic potential, and differentially expressed genes under salt stress. The TsPIP1;1 protein contains six transmembrane domains and is localized in the cytoplasm membrane. Overexpression of the TsPIP1;1 gene not only increased the accumulation of prolines, soluble sugars and chlorophyll, but also lowered the osmotic potential and malondialdehyde content in rice under salt stress, and alleviated the amount of salt damage done to rice organs by regulating the distribution of Na/K ions, thereby promoting photosynthetic rates. Transcriptome sequencing confirmed that the differentially expressed genes that are up-regulated in rice positively respond to salt stimulus, the photosynthetic metabolic process, and the accumulation profiles of small molecules and Na/K ions. The co-expressed Rubisco and LHCA4 genes in rice were remarkably up-regulated under salt stress. This data suggests that overexpression of the TsPIP1;1 gene is involved in the regulation of water transport, the accumulation of Na/K ions, and the translocation of photosynthetic metabolites, thus conferring enhanced salt tolerance to rice.

[Effects of Fe-Cd interaction on the lipid peroxidation and antioxidative enzyme activities of rice].

Taking rice variety Shennong 265 as test material, a hydroponic experiment was conducted to investigate the effects of Fe (0, 0.1, 0.25 and 0.5 mmol Fe2+ x L(-1)) and Cd (0, 0.1 and 1.0 umol Cd2+ x L(-1)) on the lipid peroxidation and antioxidative enzyme activities of rice plant. When the Fe was supplied alone, the shoot and root dry mass decreased significantly, but this phenomenon would not occur when the Cd was applied simultaneously. Applying Cd alone decreased the root malondialdehyde (MDA) and soluble protein contents, but applying Fe simultaneously alleviated the negative effects of Cd. Applying Fe decreased the Cd concentrations in shoots and roots, whereas applying Cd decreased the shoot and root Fe concentrations, indicating an obvious antagonistic interaction between Fe and Cd. The interaction of high concentration (1.0 micromol x L(-1)) Cd with Fe increased the root MDA and soluble protein contents, and decreased the root superoxide dismutase (SOD) and catalase (CAT) activities. These results indicated that applying definite amount of exogenous Fe could decrease the Cd accumulation in rice under low Cd stress, whereas high Cd stress would decrease the Fe absorption by rice and induce the lipid peroxidation in rice plant.

[Effects of Sedum plumbizincicola--Oryza sativa rotation and phosphate amendment on Cd and Zn uptake by O. sativa].

In a pot experiment, hyperaccumulator Sedum plumbizincicola and low-cadmium accumulating Oryza sativa cultivar "Zhongxiang No. 1" were planted in rotation on a heavy metals-polluted soil, and calcium magnesium phosphate (Ca-P) and rock phosphate (P-R) were amended, aimed to study the effects of the rotation and phosphate amendment on the growth of the two plants and the zinc- and cadmium accumulation in their shoots. After the amendment of 50 g P-R x kg(-1), the Zn and Cd uptake by S. plumbizincicola was 11.5 mg x pot(-1) and 0 x 79 mg x pot(-1), respectively, being significantly higher than that after the amendment of 4 g Ca-P x kg(-1). After the planting of S. plumbizincicola, the Zn and Cd concentrations in "Zhongxiang No. 1" increased, but the amendment of Ca-P decreased the accumulation of Zn and Cd in rice shoot significantly. The rotation with S. plumbizincicola and the amendment of Ca-P and P-R could immobilize the Zn and Cd in the contaminated soil as indicated by the quantitative change of NH4OAc-extractable Cd and Zn, and the efficiency of amendment with Ca-P was better than that of amendment with P-R. Field trial showed that amendment with Ca-P could not only increase the rice yield, but also reduce the Zn and Cd accumulation in rice shoot to a certain extent.

[Transformation of organic matter during thermophilic composting of pig manure].

Thermophilic composting of pig manure was studied in an attempt to elaborate upon organic matter transformation during the process and provided parameters for product maturity using chemical method. The following parameters were measured in 11 samples during the 42 days of composting: organic matter, dissolved organic carbon (DOC), degradable organic matter and humic matter (HM). Organic matter decreased during composting process constantly; DOC concentration increased to maximum at 10 days and declined thereafter; degradable organic matter decreased whole composting, but they increased in start of high-temperature stage; The increasing level of HM at various stages of composting indicate the progression of humification; H/F provide information correlating to conventional chemical parameters (organic matter, DOC) of compost maturity. Moreover, H/F has correlating to degradable organic matter and HM.