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Guizhou, China

Yu H.,Hunan Agricultural University | Yu H.,Sun Yat Sen University | Xiang Z.,Hunan Agricultural University | Zhu Y.,Guangzhou Environmental Sanitation Institute | And 3 more authors.
Journal of Plant Nutrition | Year: 2012

The chemical form and subcellular and molecular distribution of cadmium (Cd) in the roots and leaves was investigated in two rice genotypes: the low Cd-accumulating "Guangyuanzhan No. 3', and the high Cd-accumulating "Zhenguiai." Elevated Cd level in the medium caused a significant increase in Cd concentration in all parts of the roots and leaves. The soluble fractions in leaves and roots of 'Zhenguiai' contained a higher proportion of the Cd than those in 'Guangyuanzhan No. 3'. Furthermore, 'Zhenguiai' had a higher proportion of de-ionized water and 80% ethanol-extractable Cd, which is the most mobile Cd among its various chemical forms. Following gel filtration of the soluble fraction of leaf and root extracts of both genotypes, a compound with a molecular weight of ~3 kDa, probably comprising phytochelatins (PCs), was the major Cd-binding component. The Cd concentrations in the fractions from the roots of 'Zhenguiai' were noticeably higher than those of 'Guangyuanzhan No. 3', which possibly resulted in the latter cultivar having a lower Cd mobility in the roots and less Cd translocation from the roots to the aboveground parts. © 2012 Copyright Taylor and Francis Group, LLC.

Deng R.,Sichuan Agricultural University | Deng R.,Guizhou Fruit Institute | Yang W.,Sichuan Agricultural University | Zhang J.,Sichuan Agricultural University | Wu F.,Sichuan Agricultural University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010

Litter decomposition plays a key role in mass cycle and energy flow of the forest ecosystem, as a consequence of which more attentions have been given to the decomposition process of litters in different forest ecosystems around the world and their relations with biotic and abiotic factors over the past decades. As yet, far less information has been available on changes of litter quality in the subalpine forest over one freeze-thaw season, although seasonal freezing and thawing is a common natural phenomenon, which might give a strong influence on forest litter decomposition and then the forest ecosystem process. In order to understand the effects of seasonal freeze-thaw on the ecosystem process of the Subalpine forest, therefore, changes in litter quality as affected by seasonal freeze-thaw were studied in litters of fir (Abies faxoniana) and birch (Betula platyphylla) trees, which are the representative tree species in the subalpine forest of Western Sichuan, China, employing the method of litter bag. Litter bags were placed on the forest floor before soil freezing in October, 2006, and sampled after thawing in April and October, 2007. Concentrations of C, N, P, lignin and cellulose were also measured in litters, respectively. Lignin (L) in fir and birch litters degraded 14.4% and 16.7% over one freeze-thaw season, which accounted for 71. 3% and 74. 7% of the corresponding degradation rate over one year, respectively. Similarly, cellulose in fir and birch litters degraded 23. 9% and 26. 1% over one freeze-thaw season, which accounted for 73. 6% and 75.4% of the corresponding degradation rates over one year, respectively. Consequently, as the indices of litter quality, the ratios of C/N, C/P, L/N, L/P, cellulose/N and cellulose/P in litters changed with the tree species during the freeze-thaw season. However, C/N, L/N and cellulose/N in both fir and birch litters increased significantly, whereas cellulose/P decreased significantly. In addition, the ratios of C/P and L/P increased in fir litter during the freeze-thaw season, while those decreased in birch litter. The findings showed that repeated freeze-thaw cycles during the freeze-thaw season had strong effects on litter quality in the subalpine forest, implying that seasonal freeze-thaw greatly influence the process of litter decomposition in the subalpine forest ecosystem.

Deng R.-J.,Sichuan Agricultural University | Deng R.-J.,Guizhou Biotechnological Institute | Fan J.-X.,Sichuan Agricultural University | Fan J.-X.,Guizhou Subtropical Crops Institute | And 3 more authors.
Zhiwu Shengli Xuebao/Plant Physiology Journal | Year: 2014

The dynamic changes of relative electric conductivity (REC), soluble sugar, soluble protein, proline and malonadehyde (MDA) in cold acclimation, chilling stress and recovery growth were investigated using the pitaya cutting seedlings of a wild type (Hylocereus undatus Liangtianchi) and three main cultivars (Hylocereus polyrhizus 'Zihonglong', Hylocereus undatus 'Jinghonglong', Hylocereus monacanthus 'Fenhonglong'). The results indicated that REC increased with the temperature decrease, and there was no significant difference between contrast and recovery growth experiment. The contents of soluble sugar, soluble protein, proline and MDA increased in low temperature treatment and decreased in recovery growth in all materials. Furthermore, the variation of soluble sugar and proline contents were remarkable with different treatments, but MDA and soluble protein contents had no apparent changes in the whole processes. By using fuzzy mathematics method, the cold resistance of these pitaya cultivars were evaluated as Liangtianchi>'Jinghonglong''> 'Fenhonglong'>'Zihonglong', which was in agreement with the results of recovery growth experiment.

Deng R.-J.,Sichuan Agricultural University | Deng R.-J.,Guizhou Biotechnological Institute | Fan J.-X.,Sichuan Agricultural University | Fan J.-X.,Guizhou Subtropical Crops Institute | And 3 more authors.
Zhiwu Shengli Xuebao/Plant Physiology Journal | Year: 2014

Physiological response of annual branches on the adult pitaya trees to chilling stress and synthetic evaluation of their cold resistance will be researched to provide theoretical foundation and reference for screening of cold materials and looking for a new approach to increase the cold hardiness. The relative electric conductivity (REC) were determined in branches (fleshy stem) of pitaya and their semilethal temperatures (LT50) were calculated after the plants had been treated under a series of low temperature (6, 4, 2, 0, -2, -4 and -6℃) for 12 h, respectively. The cold resistance of pitaya was evaluated by LT50 and verified through recovery growth experiments. Then the contents of soluble sugar, soluble protein, free proline (Pro) and malonadehyde (MDA) were analyzed under LT50 after a serial treatment period. The results indicated that the REC of the four types of pitaya increased following an S-curve with the temperature drop and LT50 was between 0.347 and -1.031℃. The soluble sugar, soluble protein and malonadehyde (MDA) increased with the extension of time, and the free proline (Pro) increased at the beginning of 0-24 h, then decreased at the time of 24-48 h when treated at LT50. Based on LT50 and related cold resistance physiological indexes analysis of pitaya, the cold resistance ability of four types was evaluated as 'Liang Tianchi' > 'Jing Honglong' > 'Fen Honglong' > 'Zi Honglong', the result of which was in close agreement with the test result of recovery growth experiment. ©, 2014, Science Press. All right reserved.

Wang X.,Southwest University | Wang X.,U.S. Department of Agriculture | Tan J.,Southwest University | Bai Z.,Southwest University | And 6 more authors.
Journal of Bacteriology | Year: 2013

Miniature inverted-repeat transposable elements (MITEs) are nonautonomous transposons (devoid of the transposase gene tps) that affect gene functions through insertion/deletion events. No transposon has yet been reported to occur in "Candidatus Liberibacter asiaticus," an alphaproteobacterium associated with citrus Huanglongbing (HLB, yellow shoot disease). In this study, two MITEs, MCLas-A and MCLas-B, in "Ca. Liberibacter asiaticus" were detected, and the genome was characterized using 326 isolates collected in China and Florida. MCLas-A had three variants, ranging from 237 to 325 bp, and was inserted into a TTTAGG site of a prophage region. MCLas-A had a pair of 54-bp terminal inverted repeats (TIRs), which contained three tandem repeats of TGGTAACCAC. Both "filled" (with MITE) and "empty" (without MITE) states were detected, suggesting the MITE mobility. The empty sites of all bacterial isolates had TIR tandem repeat remnants (TRR). Frequencies of TRR types varied according to geographical origins. MCLas-B had four variants, ranging from 238 to 250 bp, and was inserted into a TA site of another "Ca. Liberibacter" prophage. The MITE, MCLas-B, had a pair of 23-bp TIRs containing no tandem repeats. No evidence of MCLas-B mobility was found. An identical open reading frame was found upstream of MCLas-A (229 bp) and MCLas-B (232 bp) and was predicted to be a putative tps, suggesting an in cis tps-MITE configuration. MCLas-A and MCLas-B were predominantly copresent in Florida isolates, whereas MCLas-A alone or MCLas-B alone was found in Chinese isolates. © 2013, American Society for Microbiology.

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