The cytological events, including nuclear fusion, digestion of male organelles and rebuilding of the plasmalemma and cell wall, during zygote formation of the fern Ceratopteris thalictroides (L.) Brongn. are described based on the observations of transmission electron microscopy. When the spermatozoid enters the egg and contacts the cytoplasm, the male chromatin relaxes continually. The microtubular ribbon (MTr) is separated from the male nucleus and then an envelope reappears around the male nucleus. During nuclear fusion, the egg nucleus becomes highly irregular and extends some nuclear protrusions. It is proposed that the protrusions fuse with the male nucleus actively. After nuclear fusion the irregular zygotic nucleus contracts gradually. It becomes spherical before the zygote divides. The male chromatin is identifiable as fibrous structure in the zygotic nucleus in the beginning, but it gradually becomes diffused completely. The male organelles, including the MTr, multilayered structure, flagella and the male mitochondria are finally digested in the zygotic cytoplasm. Finally a new plasmalemma and cell wall are formed outside the protoplast. The organelles in the zygote are rearranged, which produces a horizontal polarity zygote. The zygote divides with an oblique-vertical cell plate facing the apical notch of the gametophyte.

Cao JG, Wang QX, Yang NY, Bao WM (2010) Cytological events during zygote formation of the fern Ceratopteris thalictroides. J. Integr. Plant Biol. 52(3), 254–264

We report the expression profile of acyl-lipid Δ12-desaturase (desA) gene from Synechocystis sp. PCC6803 and its effect on cellmembrane lipid composition and cold tolerance in prokaryotic (Escherichia coli) and eukaryotic (Solanum tuberosum) cells. For this purpose, a hybrid of desA and reporter gene encoding thermostable lichenase (licBM3) was constructed and used to transform these cells. The expression of this hybrid gene was measured using qualitative (Petri dish test, electrophoregram and zymogram) and quantitative methods (spectrometry and gas liquid chromatography assays). The maximum level of linoleic acid in the bacterial cells containing hybrid gene was 1.9% of total fatty acids. Cold stress tolerance assays using plant damage index and growth parameters showed that cold tolerance was enhanced in primary transgenic lines because of increased unsaturated fatty acid concentration in their lipids. The greatest content of 18:2 and 18:3 fatty acids in primary transgenic plants was observed for lines 2 (73%) and 3 (41%). Finally, our results showed that desaturase could enhance tolerance to cold stress in potato, and desaturase and lichenase retain their functionality in the structure of the hybrid protein where the enzymatic activity of target gene product was higher than in the case of reporter lichenase gene absence in the construction.
 

Maali Amiri R, Yur’eva NO, Shimshilashvili KR, Goldenkova-Pavlova IV, Pchelkin VP, Kuznitsova EI, Tsydendambaev VD, Trunova TI, Los DA, Salehi Jouzani G, Nosov AM (2010) Expression of acyl-lipid Δ12-desaturase gene in prokaryotic and eukaryotic cells and its effect on cold stress tolerance of potato. J. Integr. Plant Biol. 52(3), 289–297.

Phytohormone salicylic acid (SA) plays important roles in plant responses to environmental stress. However, knowledge about the molecular mechanisms for SA affecting the stomatal movements is limited. In this paper, we demonstrated that exogenous SA significantly induced stomatal closure and nitric oxide (NO) generation in Arabidopsis guard cells based on genetic and physiological data. These effects were significantly inhibited by the NO scavenger c-PTIO, NO synthase (NOS) inhibitor L-NAME or nitrate reductase suppressor tungstate respectively, implying that NOS and nitrate reductase (NR) participate in SA-evoked stomatal closing. Furthermore, the effects of SA promotion of stomatal closure and NO synthesis are significantly suppressed in NR single mutants of nia1, nia2 or double mutant nia1/nia2, compared with the wild type plants. This suggests that both Nia1 and Nia2 are involved in SA-stimulated stomatal closure. In addition, pharmacological experiments showed that protein kinases, cGMP and cADPR are involved in SA-mediated NO accumulation and stomatal closure induced by SA in Arabidopsis.
 

Hao FS, Zhao SL, Dong H, Zhang H, Sun LR, Miao C (2010) Nia1 and Nia2 are involved in exogenous salicylic acid-induced nitric oxide generation and stomatal closure in Arabidopsis. J. Integr. Plant Biol. 52(3), 298–307.

Suaeda salsa L. is a halophytic species that is well adapted to high salinity. In order to understand its salt tolerance mechanism, we examined the growth and vacuolar H⁺-ATPase (V-ATPase) response to NaCl within the shoots and roots. The growth of shoots, but not roots, was dramatically stimulated by NaCl. Cl⁻ and Na⁺ were mainly accumulated in shoots. V-ATPase activity was significantly increased by NaCl in roots and especially in shoots. Interestingly, antisera ATP95 and ATP88b detected three V₁ subunits (66, 55 and 36 KDa) of V-ATPase only in shoots, while an 18 kDa V₀ subunit of V-ATPase was detected by both antisera in shoots and roots. It suggested that the tissue-specific characteristics of V-ATPase were related to the different patterns of growth and ion accumulation in shoots and roots of S. salsa.

Yang MF, Song J, Wang BS (2010) Organ-specific responses of vacuolar H+-ATPase in the shoots and roots of C₃ halophyte Suaeda salsa to NaCl. J. Integr. Plant Biol. 52(3), 308–314.

Asr (abscisic acid, stress, ripening induced) genes are typically upregulated by a wide range of factors, including drought, cold, salt, abscisic acid (ABA) and injury; in addition to plant responses to developmental and environmental signals. We isolated an Asr gene, MpAsr, from a suppression subtractive hybridization (SSH) cDNA library of cold induced plantain (Musa paradisiaca) leaves. MpAsr expression was upregulated in Fusarium oxysporum f. sp. cubense infected plantain leaves, peels and roots, suggesting that MpAsr plays a role in plantain pathogen response. In addition, a 581-bp putative promoter region of MpAsr was isolated via genome walking and cis-elements involved in abiotic stress and pathogen-related responses were detected in this same region. Furthermore, the MpAsr promoter demonstrated positive activity and inducibility in tobacco under F. oxysporum f. sp. cubense infection and ABA, cold, dehydration and high salt concentration treatments. Interestingly, transgenic Arabidopsis plants overexpressing MpAsr exhibited higher drought tolerance, but showed no significant decreased sensitivity to F. oxysporum f. sp. cubense. These results suggest that MpAsr might be involved in plant responses to both abiotic stress and pathogen attack.
 

Liu HY, Dai JR, Feng DR, Liu B, Wang HB, Wang JF (2010) Characterization of a novel plantain Asr gene, MpAsr, that is regulated in response to infection of Fusarium oxysporum f. sp. cubense and abiotic stresses. J. Integr. Plant Biol. 52(3), 315–323.

This research was conducted to determine the optimum moisture content (MC) that gave maximum longevity to seeds. Three species were used to represent seeds with different dry matter reserves, which gives them different sorption properties: maize (Zea mays L.), elm (Ulmus pumila L.) and safflower (Carthamus tinctorius L.). The seeds of elm, safflower, and maize embryos with MC ranging from 0.00–0.15 g H₂O/g dry weight (DW) were stored at 35 ℃ for different periods of time. The results showed that the optimum MC for seed and embryo storage varied between species (0.057 g H₂O/g DW for maize embryos, 0.045 g H₂O/g DW for elm, and 0.02 g H₂O/g DW for safflower). Drying below this optimum MC increased the aging rate and there were detrimental effects of drying. The relative humidity corresponding to optimum MC in embryos of maize, elms and safflower was about 15%, 12% and 7% respectively, according to the lipid composition of the embryos. The data provided confirmatory evidence that molecular mobility (△Azz) in elms, maize and safflower embryos was compatible with the optimum moisture content.

Zhang M, Zhuo JJ, Wang X, Wu S, Wang XF (2010) Optimizing seed water content: relevance to storage stability and molecular mobility. J. Integr.Plant Biol. 52(3), 324–331.

Tobacco (Nicotiana tabacum) transformed with the sense and antisense constructs of tomato (Lycopersicon esculentum) violaxanthin de-epoxidase gene (LeVDE) was obtained under the control of the cauliflower mosaic virus 35S promoter (35S-CaMV). Reverse transcription-polymerase chain reaction and western blot analysis demonstrated that the exogenous gene was integrated into the tobacco genome. Wild type (WT), the sense-transgenic line T₁-24(+) and the antisense-transgenic line T₁-17(−) were used for physiological measurement. The ratio of (A+Z)/(V+A+Z) and non-photochemical quenching in WT were lower than that in sense plants and higher than that in antisense ones under high light and chilling stress with low irradiance. The maximal photochemical efficiency of photosystem II (PSII) (Fv/Fm) and the net photosynthetic rate (Pn) in the sense line decreased less, while Fv/Fm and Pn in the antisense line decreased most obviously among all lines. These results suggest that the expression of the violaxanthin de-epoxidase gene in transgenic plants affects the sensitivity of PSII photoinhibition to high light and chilling stress.

Gao S, Han H, Feng HL, Zhao SJ, Meng QW (2010) Overexpression and suppression of violaxanthin de-epoxidase affects the sensitivity of photosystem II photoinhibition to high light and chilling stress in transgenic tobacco. J. Integr. Plant Biol. 52(3), 332–339.

 The ability of abscisic acid (ABA) to modulate positive interactions between Arabidopsis thaliana individuals under salinity stress was investigated using abi1-1 (insensitive to ABA), era1-2 (hypersensitive to ABA) mutant and wild type plants.  The results showed that sensitivity to ABA affects relative interaction intensity (RII) between Arabidopsis thaliana individuals.  The neighbor removal experiments also confirmed the role of phenotypic responses in linking plant-plant interactions and sensitivity to ABA.  For abi1-1 mutants, the absolute value differences between neighbor removal and control of stem length, root length, leaf area, leaf thickness, flower density, above biomass/belowground biomass (A/U), photosynthetic rate, stomatal conductance, leaf water content and water-use efficiency were smaller than those of the wild type, while for era1-2 mutants, these absolute value differences were larger than those of the wild type. Thus, it is suggested that positive interactions between Arabidopsis thaliana individuals are at least partly modulated by different sensitivity to ABA through different physiological and phenotypic plasticity.

Zhang H, Shen Z, Wang G, Dai X, Huang Q, Zheng K (2010) Sensitivity to abscisic acid modulates positive
interactions between Arabidopsis thaliana individuals. J. Integr. Plant Biol. 52(3), 340–346.