Plant Physiol. 2007 February; 143(2): 745–758
Figure 7. Expression of ABA- and sugar-related genes in response to drought. Plants were grown in soil for 3 weeks, and then subjected to withholding water for 4 d (drought). Control samples were harvested at the same time as drought-treated samples. Three independent experiments were performed, except for control with two independent experiments, each with a duplicate and with consistent results. WT, Wild type; HXK, hexose kinase; Susy, Suc synthase; UBQ, ubiquitin. Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2007 February; 143(2): 745–758
Figure 6. ABA2 promoter activity in response to diverse stress. A, Determination of GUS activity under drought condition. Aerial parts of tissues were removed from 21-d-old plants grown in soil and immediately placed on an electronic dry box with 40% relative humidity for 1.5 and 3 h. B, Determination of GUS activity under diverse stress. Plants were grown in soil for 21 d and subsequently treated with cold (4°C; 3 d), drought (4 d), flooding (1 d), and salt stresses (125 and 250 mm NaCl, each for 1 d), respectively. Control samples were harvested at 21 dap, at the beginning of stress treatments. C, Determination of GUS activity under Suc and NaCl treatments. Seedlings were grown on 1% Suc agar plates with or without 125 or 250 mm NaCl for 14 d. Results in A, B, and C are the means ± sd of three independent experiments, each experiment with a duplicate. Transgenic plants harboring the ABA2GUS transgene were under wild-type (lines 1-11 and 4-12) and aba2 mutant (lines 3-6 and 3-12) backgrounds. Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2007 February; 143(2): 745–758
Figure 5. Effect of salinity on germination and plant growth. A and B, Germination of wild type, aba2, and overexpression lines on 1% Suc agar plates supplemented with 125 (A) or 250 mm (B) NaCl. Germination rates were the means ± sd of three independent experiments using different seed batches, with consistent results, each with 150 to 200 seeds. WT, Wild type. C, Phenotypic comparison of wild type, aba2, and overexpression lines grown on 1% Suc agar plates plus 250 mm NaCl with or without 1 μm fluridone for 14 d. D and E, ABA levels of wild type, aba2, and transgenic lines. Seedlings were grown on 1% Suc agar plates for 5 d, then transferred to the same fresh medium supplemented with 125 mm NaCl for another 7 d (D) or 250 mm NaCl for another 2 d (E). The values are the means ± sd of three independent experiments using different seed batches, each performed in duplicate. F, Phenotypic comparison of wild type, aba2, and transgenic line 4-4. Seedlings were grown on 1% Suc plates supplemented with 200 mm NaCl for 28 d. G, Quantification of bleached plants of wild type, aba2, and transgenic line 4-4 in F. The values are the means ± sd of three independent experiments using different seed batches and with consistent results, each with 200 to 250 seeds. H, Phenotypic comparison of wild type, aba2, and overexpression line 4-4 in response to salinity. A total of 75 plants from each genotype, grown in soil for 21 d, were tested by watering with four increasing concentrations of NaCl (50, 100, 150, and 200 mm), each for 4 d for a total of 16 d. Seeds tested in this study were cold pretreated before planting on agar plates or in soil. Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2007 February; 143(2): 745–758
Figure 4. Effect of osmoticum on seedling growth. A, Seeds with cold pretreatment were grown on 1% Suc agar plates for 5 d, then transferred to the same fresh medium with 40% PEG-infused treatment for another 4 weeks. WT, Wild type. B, Quantification of bleached cotyledons derived from A. The values are the means ± sd of three independent experiments, each genotype with 100 seedlings per experiment. [See online article for color version of this figure.] Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2007 February; 143(2): 745–758
Figure 3. Effect of ABA on primary root elongation. A, Wild type, aba2, and overexpression lines 4-3, 4-4, and 5-1 were grown on 1% Suc agar plates for 5 d, then transferred to the same medium with or without ABA treatment and grown vertically for another 6 d. Arrowheads indicate the position of primary root tips. B, Primary root length of wild type, aba2, and overexpression line seedlings grown on 1% Suc for 5 d, then transferred to the same medium with or without ABA and grown vertically for another 6 d. The values are the means ± sd of 10 to 12 seedlings of each genotype. The experiment was repeated twice with consistent results. C, ABA content of wild type, aba2, and overexpression lines. Seedlings were grown on 1% Suc agar plates for 11 d and then subjected to ABA immunoassay. The values are the means ± sd of three independent experiments using different seed batches, each performed in duplicate. WT, Wild type. D, Primary root length of wild type (Ws) and gin1-1. Seedlings had the same growth conditions as in B, except with vertical growth for 7 d. The values are the means ± sd of 12 seedlings of each genotype. The experiment was repeated twice with consistent results. The seeds in A to D were subjected to cold pretreatment at 4°C for 3 d before planting on agar plates. [See online article for color version of this figure.] Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2007 February; 143(2): 745–758
Figure 2. ABA2 overexpression lines delay seed germination. A, Germination of wild type and overexpression lines without cold treatment. Seeds were grown on 1% Suc agar plates for the times shown. Radicle emergence over 1 mm is referred to as germination. B, Germination of wild type and overexpression lines with cold pretreatment for 3 d at 4°C. The seed growth condition was the same as in A. C, Germination of wild type, aba2, and overexpression lines on 2% Glc agar plates. D, Germination of wild type, aba2, and overexpression lines on 6% Glc agar plates. E, Phenotypes of wild type, aba2, and overexpression lines grown on 6% Glc agar plates with or without 1 μm fluridone for 14 d. Germination rates from A to D were counted as germinated seeds/total germinated seeds at day 10. The results shown were the means ± sd of three independent experiments using different seed batches, with consistent results, each with 200 to 250 seeds. The seeds in B, C, D, and E were subjected to cold pretreatment at 4°C for 3 d before planting; in A, without cold treatment. WT, Wild type. [See online article for color version of this figure.] Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2007 February; 143(2): 745–758
Figure 1. Isolation and characterization of ABA2 overexpression lines. A, Phenotypic comparison of the wild type, aba2, and overexpression line (4-3) grown in soil for 21 d. B, RT-PCR results of wild type, aba2, and overexpression lines (4-3, 4-4, and 5-1). Total RNA was isolated from seedlings grown in soil for 21 d. Two independent experiments were performed, each with a duplicate and with consistent results. WT, Wild type; UBQ, ubiquitin. [See online article for color version of this figure.] Plant Physiol. 2007 February; 143(2): 745–758.
Plant Physiol. 2009 February; 149(2): 1017–1027
Because stomata are the most abundant pores in the leaf surface, they are potential candidates to serve as a way of entry of pathogens into the leaf.
Plant Physiol. 2009 February; 149(2): 1017–1027
Because we determined that MPK3 mutants are impaired in bacteria-induced stomatal closure, but respond normally to ABA, we next studied the stomatal response to ABA of these plants in the presence of Xcc or of an Xcc extract. Unlike what happens in the case of wild-type Arabidopsis, neither living Xcc (Fig. 6C) nor the extract from an Xcc culture supernatant (Fig. 6D) prevented ABA-induced stomatal closure in MPK3 antisense plants. This result shows that the inhibitory effect of Xcc on ABA-induced stomatal closure requires the presence of MPK3. 结构也非常清晰，描述结果，包括四句话： Because we determined that (目的）.........we next studied （研究方法）........Unlike what happens in （观察结果）........This result shows that （最终结果）
Plant Physiol. 2009 February; 149(2): 1017–1027
Figure 5. Ethyl acetate extracts of Xcc strains culture supernatants can complement coronatine deficiency in Pst. Arabidopsis plants were infected by dipping with wild-type Pst DC3000 or coronatine-deficient Pst DC3118 coronatine-deficient mutant strains in the presence of wild-type Xcc or rpf mutant extracts. Bacterial growth was measured after 4 d. The datasets marked with an asterisk are significantly different from controls (Pst cor−) as assessed by Student's t test: *, P < 0.001. The mean and se of two independent experiments are given. Plant Physiol. 2009 February; 149(2): 1017–1027.
Plant Physiol. 2009 February; 149(2): 1017–1027
Figure 4. The ability of Xcc to migrate through stomata in isolated epidermis is dependent on a functional rpfF/DSF system. Confocal images of the inner side of detached Arabidopsis epidermis were recorded after floating them for 3 h, with the cuticle side in contact with bacterial suspensions of Xcc, rpfF, or rpfC in the presence or not of extracts of supernatants from Xcc, rpfF, or rpfC cultures. An extract from Xcc, but not from rpfF or rpfC, restored the ability of rpfF and rpfC to migrate through the epidermis. An extract from rpfC, which contains a high concentration of DSF, reduced the ability of Xcc to migrate through stomata. The experiment was repeated with similar results. Plant Physiol. 2009 February; 149(2): 1017–1027.
Plant Physiol. 2009 February; 149(2): 1017–1027
To find out the molecular basis of reversal of stomatal closure by Xcc, we investigated whether the activity responsible for the observed suppression of stomatal defense is secreted out of the bacteria. For this purpose, we extracted supernatants of bacterial cultures of Xcc and of rpfC and rpfF mutants with ethyl acetate. Subsequently, we investigated whether the extracts thus obtained can interfere with stomatal movements. We found that extracts from Xcc partially abolish stomatal closure induced by E. coli, Xcc (Fig. 3A), or ABA (Fig. 3B). Extracts from rpfC or rpfF mutants, however, did not have any inhibitory effect (Fig. 3, A and B). Also, Xcc extracts partially abolished ABA-induced stomatal closure in Vicia fava (Fig. 3C), a species evolutionarily distant from Arabidopsis, indicating that the factor capable of inhibiting stomatal closure probably targets some evolutionarily conserved process. In addition, we observed that the Xcc extract failed to prevent ABA-induced inhibition of light-induced stomatal opening (Fig. 3D), suggesting that the factor present in the Xcc extract acts specifically on a signaling element involved in promotion of closure by ABA. The extract did not affect the capacity of ABA to cause postgermination arrest (data not shown), which provides further evidence that it acts on some signaling component or effector required specifically for stomatal closure. 这逻辑结构清晰如下： To find out （目的）......., we investigated whether （提出问题）........ For this purpose, we （采取的方法）........ Subsequently, we investigated whether （进一步提出深层次问题）.......... We found that .（结果发现）......., however, （一些新的发现，不同寻常的发现）........ In addition, we observed that（另外还观察到）......... suggesting that （结果的意义） ------www.medsci.cn编辑评论
Plant Physiol. 2009 February; 149(2): 1017–1027
Further evidence that the ability of Xcc to manipulate stomatal defense is controlled by the rpf/DSF system was obtained from experiments in which different Xcc strains were coinoculated. Previous reports showed that the synthesis of DSF is tightly regulated by a negative feedback mechanism (Barber et al., 1997; Slater et al., 2000), and that both reduced and increased levels of DSF interfere with biofilm formation and pathogenicity (Torres et al., 2007). Therefore, DSF can only activate transcription of genes in the rpf/DSF cluster when it is present in a certain range of concentrations. 用来作结果的更进一步说明，也是三层意思，非常清楚
Plant Physiol. 2009 February; 149(2): 1017–1027
Previous evidence showing that, under some conditions, Xcc is capable of entering Arabidopsis leaves through stomata (Hugouvieux et al., 1998) prompted us to investigate whether this phytopathogen has the ability to manipulate the stomatal defense of the host. These authors reported that Xcc can enter Arabidopsis leaves through stomata in Landsberg erecta (Ler), but not in Columbia (Col-0) ecotype, at 25°C. Therefore, we investigated whether this bacterium has the ability to revert stomatal closure induced by bacteria. For this purpose, we measured promotion of stomatal closure by Xcc and by the nonphytopathogenic bacterium Escherichia coli during 1 and 3 h in both ecotypes. 蓝色表明四层意思，由别人引到自己的发现。非常鲜明，这样的句法非常值得学习！www.medsci.cn注。
Plant Physiol. 2009 February; 149(2): 1017–1027
In this study, we found that Xcc is capable of reverting both pathogen and ABA-induced stomatal closure in Arabidopsis through a virulence factor that is secreted to the extracellular medium and whose synthesis is regulated by the rpf gene cluster. In addition, we found that expression of MPK3 in guard cells is required for both promotion of stomatal closure by bacteria and for inhibition of ABA-induced stomatal closure by the Xcc-secreted virulence factor. 两句话介绍自己的发现，而且有逻辑性
