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1

Adaptive strategy to drought conditions: diurnal variation in water use of a Central Asian desert shrub

100%
Wang S.-S., Chen X., Zhou K.-F., Wang Q.
Polish Journal of Ecology
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2015
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tom 63
|
nr 1
Water availability is one of the most important factors limiting photosynthetic assimilation of carbon dioxide and growth of individual plants in terrestrial ecosystems. It is especially important for desert shrubs because the diurnal water availability is particularly sensitive to climate change in arid ecosystems. Water use efficiency (WUE) is an indicator of water availability and is frequently used to assess plant performance in various ecosystems, particularly in arid ecosystems. The WUE of plants has been widely assessed using ecological methods and field measurements; however, these approaches are impractical to obtain numerous near-simultaneous estimates of plant water status at the landscape-scale. Consequently, landscape-scale assessments of plant water status are practically pursued through modeling. In this study, measurement and modeling of the diurnal variations of WUE were conducted for a native dominant desert shrub, Tamarix ramosissima, in its original habitat on the periphery of the Gurbantunggut Desert, China. The diurnal net photosynthesis (An), stomatal conductance (gs), and transpiration (Tr) were measured for each individual using a portable photosynthesis system. A coupled model of stomatal conductance, photosynthesis, and transpiration was applied to simulate the diurnal dynamics of An, gs, Tr, and WUE. The model explained 83, 47, 83, and 55% of the variance in the measured An, gs, Tr, and WUE values, respectively, for this desert ecosystem in which T. ramosissima is sparsely distributed. The results demonstrated that the coupled photosynthesis-stomatal conductance-transpiration model strategy is a promising approach to estimate water availability in desert ecosystems in Central Asia.
2

Ectopic expression of the apple mhgai2 gene brings about GA-intensitive phenotypes in tomatoes

76%
Wang S.-S., Sun C., Liu Z.-Z., Shi Q.-H., Yao Y.-X., You C.-X., Hao Y.-J.
Acta Physiologiae Plantarum
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2012
|
tom 34
|
nr 6
Bioactive gibberellins (GAs) are phytohormones that regulate plant growth and development. DELLA proteins are highly conserved growth repressors that modulate all aspects of GA responses. In this study, an apple MhGAI2 gene, which encoded a DELLA protein, was isolated from the tea crabapple (Malus hupehensis Redh. Var. pingyiensis). MhGAI2-GFP fusion protein was localized in the nucleus. Anti-MhGAI2 antibody was prepared to test GA sensitivity of the MhGAI2 protein. To elucidate the function of MhGAI2, its GA-insensitive gene mhgai2 was artificially generated via a bridge-PCR approach. Subsequently, mhgai2 was genetically transformed into tomato, while transgenic tomato line pBI containing the empty vector pBI121 was used as control. Transgenic tomato lines TL1 and TL2 ectopically expressed mhgai2 transcripts at high levels, and produced GA-insensitive mhgai2 protein. As a result, the seed germination as well as the growth of roots, hypocotyls and seedlings were much more insensitive to exogenous GA₃ application in transgenic tomato lines TL1 and TL2 than pBI control. TL1 and TL2 exhibited smaller plant statures and produced more compacted inflorescences with smaller flowers, fruits and seeds than pBI control. Therefore, mhgai2 ectopic expression affected not only the vegetative growth but also the reproductive development of transgenic tomatoes. In addition, transgenic seedlings were more resistant to drought and salt stress than pBI. In summary, ectopic expression of apple mhgai2 gene caused GA-insensitive phenotypes in tomatoes.
3

Overexpressions of dihydroxyacetone synthase and dihydroxyacetone kinase in chloroplasts install a novel photosynthetic HCHO-assimilation pathway in transgenic tobacco using modified Gateway entry vectors

76%
Xiao S.-Q., Sun Z., Wang S.-S., Zhang J., Li K.-Z., Chen L.-M.
Acta Physiologiae Plantarum
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2012
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tom 34
|
nr 5
Dihydroxyacetone synthase (DAS) and dihydroxyacetone kinase (DAK) are two key enzymes for formaldehyde assimilation in methylotrophic yeasts. In order to using a Gateway LR recombination reaction to construct a plant expression vector that contains the expression cassettes for the das and dak genes and allow the proteins encoded by the two target genes to be localized to the chloroplasts of transgenic plants, the entry vector pEN-L4*-PrbcS-*T-gfp-L3* contained the tomato rbcS 3C promoter (PrbcS) with its transit peptide sequence (*T) and a GFP reporter gene (gfp) was constructed in this study. To verify the applicability of pEN-L4*-PrbcS-*T-gfp-L3*, we generated an entry vector for the dak gene by replacing the gfp gene in this entry vector with the dak gene. We also generated an entry vector for the das gene by replacing the gus gene in another entry vector (pENTR*-PrbcS-*T-gus) with the das gene. Using these entry vectors and pK7m34GW2-8m21GW3, we successfully constructed the pKm-35S-PrbcS-*T-gfp-PROLD-PrbcS-*T-gus and the pKm-35S-PrbcS-*T-dak-PROLD-PrbcS-*T-das expression vectors. Our results showed that high expression of GUS was achieved in leaves, and the expressed GFP, DAS and DAK proteins could be targeted to the chloroplasts after the two expression vectors were used to transform tobacco. The overexpressions of DAS and DAK in the chloroplasts successfully created a novel photosynthetic HCHO-assimilation pathway in transgenic tobacco. By utilizing these expression vectors, we not only successfully expressed two target genes with one transformation but also localized the expressed proteins to chloroplasts via the transit peptide sequence (*T). Therefore, the construction of pEN-L4*-PrbcS-*T-gfp-L3* establishes a technique platform that provides a convenient means for chloroplast genetic engineering.
4
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Cloning and expression analysis of LeTIR1 in tomato

76%
Qiao Y., Feng X.-M., Liu Z.-Z., Wang S.-S., Hao Y.-J., You C.-X.
Acta Biologica Cracoviensia. Series Botanica
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2011
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tom 53
|
nr 2
The full-length cDNA of LeTIR1 gene was isolated from tomato with EST-based in silico cloning followed by RACE amplification. LeTIR1 contained an open reading frame (ORF) 1872 bp long, encoding 624 amino acid residues. The predicted protein LeTIR1 had one F-box motif and eleven leucine-rich repeats (LRRs), all of which are highly conserved in TIR1 proteins of other plant species. Phylogenetic analysis showed that the LeTIR1 protein shared high similarity with other known TIR1 proteins. Both sequence and phylogenetic analysis suggested that LeTIR1 is a TIR1 homologue and encodes an F-box protein in tomato. Semi-quantitative RT-PCR indicated that LeTIR1 was expressed constitutively in all organs tested, with higher expression in stem than root, leaf, flower and fruit. Its expression level was positively correlated with the auxin distribution in stem or axillary shoot, and was induced by spraying exogenous IAA.
5

Physiological and transcriptional analysis of the effects of formaldehyde exposure on Arabidopsis thaliana

64%
Wang S.-S., Song Z.-B., Sun Z., Zhang J., Mei Y., Nian H.-J., Li K.-Z., Chen L.-M.
Acta Physiologiae Plantarum
|
2012
|
tom 34
|
nr 3
Formaldehyde (HCHO) is highly toxic to all living organisms. In this study, the toxic effects of HCHO exposure on Arabidopsis thaliana were analyzed at the physiological and transcriptional levels. Exposure to 2 mM HCHO led to a significant decrease in plant growth and a massive increase in anthocyanin content. A remarkable increase in H₂O₂ content and elevation in the levels of protein carbonyl and DNA–protein crosslinks were detected in Arabidopsis plants exposed to 2 mM HCHO for a period of 17 h. In contrast, the malondialdehyde content decreased during this period. These results suggested that HCHO stress caused significant oxidative damage to proteins but not membrane lipids during this period. The Affymetrix ATH1 Genome Array was used to evaluate changes in the global gene expression in Arabidopsis plants exposed to 2 mM HCHO over the 17-h period. A total of 620 transcripts were shown to be regulated significantly (at least twofold). The number of down-regulated genes (467) was approximately threefold greater than the number of up-regulated genes (154). Down-regulation in a large number of genes encoding cell surface receptors, cell wall proteins, enzymes related to toxin metabolism, peroxidase, disease resistance protein, multidrug and toxin extrusion and ATP-binding cassette transporters might be an important part of the toxic effects of HCHO exposure on Arabidopsis at the transcriptional level. Up-regulation in many genes encoding heat shock proteins was suggested to be an important protective mechanism for Arabidopsis plants in response to the oxidative damage of proteins. Verification of microarray data by reverse transcription polymerase chain reaction analysis identified typical HCHO-induced and -repressed genes.
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