Drought stress differentially regulates the expression of small open reading frames (sORFs) in <i>Arabidopsis</i> roots and shoots

<p>Characterizing the molecular mechanisms governing the response of plant roots and shoots to drought stress could aid the development of strategies aiming to ameliorate drought stress. Small open reading frames (sORFs), putatively encoding small peptides, may play a significant role in the response to different abiotic stresses. Microarray analyses revealed that after 5, 7 and 9 d of a drought treatment, 2, 77, and 104 sORFs were up-regulated in roots, respectively; while the number of upregulated sORFs in shoots was 12, 45, and 158, respectively. RT-qPCR analysis confirmed the up-regulated expression of <i>ATRIKEN29196</i> and <i>ATRIKEN32280</i> specifically in roots. The identified upregulated sORFs, particularly those in roots, may contribute to drought stress tolerance.</p

Overexpression of oligouridylate binding protein 1b results in ABA hypersensitivity

<p>Oligouridylate binding protein 1b (UBP1b), a marker protein of plant stress granules (SGs), plays a role in heat stress tolerance in plants. A previous microarray analysis revealed that the expression of several ABA signaling-related genes is higher in <i>UBP1b</i>-overexpressing <i>Arabidopsis</i> plants (<i>UBP1b</i>-ox) subjected to both non-stressed and heat stress conditions. Root elongation and seed germination assays demonstrated that <i>UBP1b</i>-ox exhibited hypersensitivity to ABA. RT-qPCR analysis confirmed that mitogen-activated protein kinase (MAPK) cascade genes, such as <i>MPK3, MKK4</i>, and <i>MKK9</i> were upregulated in <i>UBP1b</i>-ox plants. ABA receptor genes, including <i>PYL5</i> and <i>PYL6</i>, were also upregulated in <i>UBP1b</i>-ox plants. mRNA of <i>WRKY33</i> – a downstream gene of MPK3 and an upstream gene of ethylene biosynthesis, exhibited high levels of accumulation, although the level of endogenous ABA was not significantly different between <i>UBP1b</i>-ox and control plants. In addition, RNA decay analysis revealed that <i>WRKY33</i> was more stable in <i>UBP1b</i>-ox plants, indicating that the mRNA of <i>WRKY33</i> was protected within UBP1b SGs. Collectively, these data demonstrate that UBP1b plays an important role in plant response to ABA.</p

Changes in the transcript levels of gibberellin (GA) metabolism genes in the cotyledon end and hypocotyl end of lettuce seeds

(A) Frozen seeds were divided into two parts: cotyledon end, including the cotyledons (Cot), fruit wall (FW), seed coat (SC), and endosperm (ES); and the hypocotyl end, including the hypocotyl (Hyp), root apical meristem (RAM), shoot apical meristem (SAM), and part of the Cot, FW, SC, and ES. (B) Expression levels of GA metabolism genes after light treatment, determined using QRT-PCR. See for light treatments. The results were normalized to the expression of 18S rRNA (internal control), and the highest value was set to 100. Two independent experiments were performed, and means with standard errors are shown.<p><b>Copyright information:</b></p><p>Taken from "Germination of photoblastic lettuce seeds is regulated via the control of endogenous physiologically active gibberellin content, rather than of gibberellin responsiveness"</p><p></p><p>Journal of Experimental Botany 2008;59(12):3383-3393.</p><p>Published online 24 Jul 2008</p><p>PMCID:PMC2529229.</p><p></p

Changes in the transcript levels of gibberellin (GA) metabolism genes in imbibed lettuce seeds after various light treatments

(A) Time-course of lettuce seed germination after light treatment. Zero (0) h indicates seeds imbibed for 3 h in the dark that received no light treatment. FR, FR/R, and FR/R/FR indicate seeds treated with far-red light, far-red followed by red light, and far-red followed by red and then far-red light, respectively. FR/R+ABA indicates seeds treated with far-red followed by red light and 0.1 mM ABA. Triplicate experiments were performed, and means with standard errors are shown. (B) Expression levels of GA metabolism genes after light treatment. The expression levels of these genes were analysed by QRT-PCR. The results were normalized to the expression of 18S rRNA (internal control); the expression levels of all genes examined are given relative to the reference value of the transcript level of at 0 h, set to 1. Three independent experiments were performed, and means with standard errors are shown.<p><b>Copyright information:</b></p><p>Taken from "Germination of photoblastic lettuce seeds is regulated via the control of endogenous physiologically active gibberellin content, rather than of gibberellin responsiveness"</p><p></p><p>Journal of Experimental Botany 2008;59(12):3383-3393.</p><p>Published online 24 Jul 2008</p><p>PMCID:PMC2529229.</p><p></p

Expression of and during germination, and gibberellin (GA) responsiveness in lettuce seeds

(A) Expression levels of and after light treatment. The expression analysis was carried out by QRT-PCR. See for light treatments. The results were normalized to the expression of 18S rRNA (internal control), and the expression levels of all genes examined are given relative to the reference value of the transcript level of at 0 h, set to 1. Three independent experiments were performed, and means with standard errors are shown. (B) Expression levels of and in the cotyledon end and the hypocotyl end of lettuce seeds after light treatment. The results were normalized to the expression of 18S rRNA (internal control), and the highest value was set to 100. Two independent experiments were performed, and means with standard errors are shown. (C) Germination frequency of lettuce seeds in the presence of a GA biosynthesis inhibitor and various concentrations of GA. Five sets of 20 decoated lettuce seeds were incubated in the dark at 25 °C in medium containing 50 μM uniconazol-P and various concentrations of GA. After red light treatment, seeds were incubated at 25 °C in the dark for 24 h and the germination frequency was recorded. Means with standard errors are shown.<p><b>Copyright information:</b></p><p>Taken from "Germination of photoblastic lettuce seeds is regulated via the control of endogenous physiologically active gibberellin content, rather than of gibberellin responsiveness"</p><p></p><p>Journal of Experimental Botany 2008;59(12):3383-3393.</p><p>Published online 24 Jul 2008</p><p>PMCID:PMC2529229.</p><p></p

Effects of abscisic acid (ABA) treatment on the expression levels of gibberellin (GA) metabolism genes in imbibed lettuce seeds

(A) The expression levels of the genes were analysed by QRT-PCR. The results were normalized to the expression of 18S rRNA (internal control), and the expression levels of all genes examined are given relative to the reference value of the transcript level of at 0 h, set to 1. Three independent experiments were performed, and means with standard errors are shown. (B) Expression analysis using seeds that had been cut in half. The results were normalized to the expression of 18S rRNA (internal control), and the highest value was set to 100. Two independent experiments were performed, and means with standard errors are shown.<p><b>Copyright information:</b></p><p>Taken from "Germination of photoblastic lettuce seeds is regulated via the control of endogenous physiologically active gibberellin content, rather than of gibberellin responsiveness"</p><p></p><p>Journal of Experimental Botany 2008;59(12):3383-3393.</p><p>Published online 24 Jul 2008</p><p>PMCID:PMC2529229.</p><p></p