Impact of high temperatures on the marketable tuber yield and related traits of potato

Kim, Y.U.,Seo, B.S.,Choi, D.H.,Ban, H.Y.,Lee, B.W. Gauthier-Villars ; Elsevier Science Ltd 2017 European journal of agronomy Vol.89 No.-

<P>A rapid warming of 2.8-5.3 degrees C by the end of this century is expected in South Korea. Considering the current temperature during the spring potato growing season (emergence to harvest; ca. 18 degrees C), which is near the upper limit of the optimum temperature for potato yield, the anticipated warming will adversely affect potato production in South Korea. The present study assessed the impact of high temperature on the marketable tuber yield and related traits of cv. Superior (which makes up 71% of the annual potato production in South Korea) in four temperature-controlled plastic houses and an outdoor field (37.27 N, 126.99 degrees E) during 2015-2016. The target temperatures of the four plastic houses were set to ambient (AT), AT+1.5 degrees C, AT + 3.0 degrees C, and AT + 5.0 degrees C. The marketable tuber yield was significantly reduced by 11% per 1 degrees C increase over a temperature range of 19.1-27.7 degrees C. The negative impact of high temperature was associated not only with the yield loss of total tubers, which was mostly explained by the slower tuber bulking rate, but also the reduced marketable tuber ratio under temperatures above 23 degrees C, which was mainly attributed to the reduced number of marketable tubers (r = 0.79***). Under moderate temperatures below 23 degrees C, the source limited the number of marketable tubers without reducing the marketable tuber ratio. In contrast, the number of marketable tubers was, limited by the marketable tuber set at the early growth stage rather than the source under the higher temperatures, which resulted in the reduction in the marketable tuber ratio below 56%. These results suggest that the objectives of breeding and agronomic management for adapting to the rapid warming in South Korea should include maintaining the ability to form tubers at the early growth stage under high temperatures, as well as the photosynthetic capacity and sink strength of the tubers.</P>

Heterologous expression of the gourd E3 ubiquitin ligase gene LsRZF1 compromises the drought stress tolerance in Arabidopsis thaliana

Min, J.H.,Ju, H.W.,Yang, K.Y.,Chung, J.S.,Cho, B.H.,Kim, C.S. Gauthier-Villars ; Elsevier Science Ltd 2014 Vol. No.

Protein ubiquitination is one of the major regulatory processes used by eukaryotic cells. The ubiquitin E3 ligase acts as a main determinant of substrate specificity. However, the precise roles of E3 ligase in plants to drought stress are poorly understood. In this study, a gourd family (Lagenaria siceraria) ortholog of Arabidopsis thaliana RING Zinc Finger 1 (AtRZF1) gene, designated LsRZF1, was identified and characterized. LsRZF1 was reduced by abscisic acid (ABA), osmotic stress, and drought conditions. Compared to wild type, transgenic Arabidopsis plants ectopic expressing LsRZF1 were hypersensitive to ABA and osmotic stress during early seedling development, indicating that LsRZF1 negatively regulates drought-mediated control of early seedling development. Moreover, the ectopic expression of the LsRZF1 gene was very influential in drought sensitive parameters including proline content, water loss, and the expression of dehydration stress-related genes. Furthermore, ubiquitin E3 ligase activity and genetic data indicate that AtRZF1 and LsRZF1 function in similar pathway to control proline metabolism in Arabidopsis under drought condition. Together, these results suggest that the E3 ligase LsRZF1 is an important regulator of water deficit stress during early seedling development.

NADPH-dependent thioredoxin reductase A (NTRA) confers elevated tolerance to oxidative stress and drought

Cha, J.Y.,Kim, J.Y.,Jung, I.J.,Kim, M.R.,Melencion, A.,Alam, S.S.,Yun, D.J.,Lee, S.Y.,Kim, M.G.,Kim, W.Y. Gauthier-Villars ; Elsevier Science Ltd 2014 Vol. No.

<P>NADPH-dependent thioredoxin reductases (NTRs) are key-regulatory enzymes determining the redox state of the thioredoxin (Trx) system that provides reducing power to peroxidases or oxidoreductases. Moreover, it also plays an essential function in the direct reduction of ROS and acquiring stress tolerance in plant. Cytoplasmic NTRA, mitochondrial NTRB, and chloroplastic NTRC are the three conserved NTRs which cooperate with specific sub-cellularly localized Trxs in Arabidopsis. However, cytosolic NTRs such as NTRA in Arabidopsis have not previously been identified in plants or mammals as a source of functional redundancy with mitochondrial NTRs. Here, we show the involvement of NTRA in the plant stress response counteracting oxidative and drought stresses. Methyl viologen (MV), an inducer of oxidative stress in plants, enhanced the NTRA transcripts. To identify the physiological role of NTRA influencing ROS homeostasis by stress, NTRA overexpression (NTRAOX) and knock-out mutants (ntra-ko) were generated. After exposure to oxidative stress, wild-type and ntra-ko plants were sensitive, but NTRAOX plants tolerant. ROS range was increased by MV in wild-type and ntra-ko plants, but not in NTRAOX. Investigating the involvement of Arabidopsis NTRA in drought, NTRAOX plants exhibited extreme drought tolerance with high survival rates, lower water loss and reduced ROS compared to wild-type and ntra-ko plants. Transcripts of drought-responsive genes, such as RD29A and DREB2A, were highly expressed under drought and antioxidant genes, namely CuZnSOD and APX1 were enhanced in the absence of drought in NTRAOX plants. The results suggest that NTRA overexpression confers oxidative and drought tolerance by regulation of ROS amounts. (C) 2014 Elsevier Masson SAS. All rights reserved.</P>

Expression of potato S-adenosyl-l-methionine synthase (SbSAMS) gene altered developmental characteristics and stress responses in transgenic Arabidopsis plants

Kim, S.H.,Kim, S.H.,Palaniyandi, S.A.,Yang, S.H.,Suh, J.W. Gauthier-Villars ; Elsevier Science Ltd 2015 Vol. No.

S-adenosyl-l-methionine (SAM) synthase (SAMS) catalyze the biosynthesis of SAM, which is a precursor for ethylene and polyamines, and a methyl donor for a number of biomolecules. A full-length cDNA of SAMS from Solanum brevidens was expressed in Arabidopsis thaliana to study its physiological function. RT-PCR analysis showed that SbSAMS expression was enhanced significantly in S. brevidens leaves upon treatment with salt, mannitol, ethephon, IAA and ABA. The transgenic SbSAMS overexpression lines accumulated higher levels S-adenosyl homocysteine (SAHC) and ethylene concomitantly with increased SAM level. Expression levels of genes related to ethylene biosynthesis such as ACC synthase, but not polyamine biosynthesis genes were enhanced in SbSAMS overexpressing Arabidopsis lines. In addition, ABA responsive, wound and pathogen-inducible genes were upregulated in SbSAMS transgenic Arabidopsis plants. Transgenic Arabidopsis lines exhibited higher salt and drought stress tolerance compared to those of vector control. Based on these results we conclude that SbSAMS is expressed under abiotic stress to produce SAM as a broad-spectrum signal molecule to upregulate stress-related genes including ethylene and ABA biosynthetic pathway genes responsible for ABA, pathogen and wound responses.

Foliar application of methyl jasmonate induced physio-hormonal changes in Pisum sativum under diverse temperature regimes

Shahzad, R.,Waqas, M.,Khan, A.L.,Hamayun, M.,Kang, S.M.,Lee, I.J. Gauthier-Villars ; Elsevier Science Ltd 2015 Vol. No.

Global climate change brings with it unwarranted shifts in both abiotic (heat stress, cold stress, wind, precipitation) and biotic (pathogens, pests) environmental factors, thus posing a threat to agricultural productivity across the world. In plants, lodging due to storms or herbivory causes wounding stress and consequently enhances endogenous jasmonates. In response, the plant growth is arrested as plant defense is prioritized. We pre-treated pea plants with elevated methyl jasmonate (MeJA) levels i.e. 50 μM, 100 μM and 200 μM under controlled growth chamber conditions. The pre-treated plants were then kept at 40 <SUP>o</SUP>C (heat stress-HS), 4 <SUP>o</SUP>C (cold stress-CS) and 20 <SUP>o</SUP>C (optimum/control temperature-OT) for 72 h. The effect of such treatments on plant growth attributes, photosynthesis, stomatal conductance, cell death rate, and regulation of endogenous hormones were observed. Elevated MeJA application hindered plant growth attributes under HS, CS and OT conditions. Moreover, elevated MeJA levels lowered the rate of photosynthesis and stomatal conductance, induced stomatal closure, caused higher cells mortality in leaves under HS, CS, and OT conditions. Endogenous ABA contents significantly declined in all MeJA treatments under HS and OT, but increased under CS conditions. Exogenous MeJA enhanced endogenous jasmonic acid contents of pea plants, but altered endogenous salicylic acid contents under varying temperatures. Current study shows that higher concentrations of exogenous MeJA strengthen plant defense mechanism by hindering plant growth under stress conditions.

Transgenic alfalfa plants expressing AtNDPK2 exhibit increased growth and tolerance to abiotic stresses

Wang, Z.,Li, H.,Ke, Q.,Jeong, J.C.,Lee, H.S.,Xu, B.,Deng, X.P.,Lim, Y.P.,Kwak, S.S. Gauthier-Villars ; Elsevier Science Ltd 2014 Vol. No.

In this study, we generated and evaluated transgenic alfalfa plants (Medicago sativa L. cv. Xinjiang Daye) expressing the Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SN plants) to develop plants with enhanced tolerance to various abiotic stresses. We selected two SN plants (SN4 and SN7) according to the expression levels of AtNDPK2 and the enzyme activity of NDPK in response to methyl viologen (MV)-mediated oxidative stress treatment using leaf discs for further characterization. SN plants showed enhanced tolerance to high temperature, NaCl, and drought stress on the whole-plant level. When the plants were subjected to high temperature treatment (42 <SUP>o</SUP>C for 24 h), the non-transgenic (NT) plants were severely wilted, whereas the SN plants were not affected because they maintained high relative water and chlorophyll contents. The SN plants also showed significantly higher tolerance to 250 mM NaCl and water stress treatment than the NT plants. In addition, the SN plants exhibited better plant growth through increased expression of auxin-related indole acetic acid (IAA) genes (MsIAA3, MsIAA5, MsIAA6, MsIAA7, and MsIAA16) under normal growth conditions compared to NT plants. The results suggest that induced overexpression of AtNDPK2 in alfalfa will be useful for increasing biomass production under various abiotic stress conditions.

Molecular characterization of BZR transcription factor family and abiotic stress induced expression profiling in Brassica rapa

Saha, G.,Park, J.I.,Jung, H.J.,Ahmed, N.U.,Kayum, Md.A.,Kang, J.G.,Nou, I.S. Gauthier-Villars ; Elsevier Science Ltd 2015 Vol. No.

BRASSINAZOLE-RESISTANT (BZR) transcription factors (TFs) are primarily well known as positive regulators of Brassinosteroid (BR) signal transduction in different plants. BR is a plant specific steroid hormone, which has multiple stress resistance functions besides various growth regulatory roles. Being an important regulator of the BR synthesis, BZR TFs might have stress resistance related activities. However, no stress resistance related functional study of BZR TFs has been reported in any crop plants so far. Therefore, this study identified 15 BZR TFs of Brassica rapa (BrBZR) from a genome-wide survey and characterized them through sequence analysis and expression profiling against several abiotic stresses. Various systematic in silico analysis of these TFs validated the fundamental properties of BZRs, where a high degree of similarity also observed with recognized BZRs of other plant species from the comparison studies. In the organ specific expression analyses, 6 BrBZR TFs constitutively expressed in flower developmental stages indicating their flower specific functions. Subsequently, from the stress resistance related expression profiles differential transcript abundance levels were observed by 6 and 11 BrBZRs against salt and drought stresses, respectively. All BrBZRs showed several folds up-regulation against exogenous ABA treatment. All BrBZRs also showed differential expression against low temperature stress treatments and these TFs were proposed as transcriptional activators of CBF cold response pathway of B. rapa. Notably, three BrBZRs gave co-responsive expression against all the stresses tested here, suggesting their multiple stress resistance related functions. Thus, the findings would be helpful in resolving the complex regulatory mechanism of BZRs in stress resistance and further functional genomics study of these potential TFs in different Brassica crops.

Survival of Azospirillum brasilense flocculated cells in alginate and its inoculation effect on growth and yield of maize under water deficit conditions

Joe, M.M.,Karthikeyan, B.,Chauhan, P.S.,Shagol, C.,Islam, Md.R.,Deiveekasundaram, M.,Sa, T. Gauthier-Villars ; Elsevier Science Ltd 2012 European journal of soil biology Vol.50 No.-

The objective of this study was to compare the efficiency of Azospirillum brasilense MTCC125 flocculated cells with standard grown cells under in vitro conditions and in association with maize (Zea mays L.) under field conditions. The results revealed that A. brasilense flocculated cells had higher survivability in alginate bead (37 x 10<SUP>6</SUP> CFU g<SUP>-1</SUP> dry wt.) and disinfected soil (11 x 10<SUP>6</SUP> CFU g<SUP>-1</SUP> dry wt.) after 12 months of storage in room temperature. A. brasilense flocculated cells offered a higher degree of resistance to dehydration in terms of reduction in water availability (a<SUB>w</SUB>) and their survivability was 12% higher in soil and 27% higher in alginate compared to standard grown cells. The adhesion efficiency of A. brasilense flocculated cells was 54% higher to hydrophobic polystyrene and 101% higher to maize roots when compared to standard grown A. brasilense cells. Furthermore, flocculated cells had better spermoplane survivability (48%) and spermosphere colonization (73%) along with a concomitant enhancement on the germination percentage (11%) and vigor index (23%) of maize. Field studies with A. brasilense flocculated cells conducted under normal irrigated conditions and by withholding irrigation at 25, 50, and 75% available water-holding capacity (AWHC) showed a significant increase in plant height (19%), plant dry weight (16%), grain yield (31%), stover yield (17%) and nitrogen uptake (18%) compared with standard grown cell treatment.

Effects of transgenic poplars expressing increased levels of cellular cytokinin on rhizosphere microbial communities

Nam, K.J.,Kim, D.Y.,Nam, K.H.,Pack, I.S.,Park, J.H.,Jeong, S.C.,Choi, Y.I.,Noh, E.W.,Kim, C.G. Gauthier-Villars ; Elsevier Science Ltd 2014 European journal of soil biology Vol.63 No.-

Considerable effort has been made in biotechnology to increase plant biomass. Altering cellular levels of plant hormones, including cytokinin, by genetic modification, has been one way to achieve the goal as it is involved in a variety of processes related to plant growth and development. However, the alteration inevitably may change physiological and biochemical characteristics of plants, and thus could affect the relationship between plants and other organisms interacting with the plants such as microorganisms inhabiting in the rhizosphere. To determine if these indirect effects on rhizosphere microorganisms, mediated by hormonal changes in plants, do occur, we investigated the microbial biomass and community structure associated with transgenic Populus trees with altered cellular cytokinin levels, using phospholipid fatty acid (PLFA) analysis. Three transgenic lines expressing increased levels of cellular cytokinin (T1403, T1410, and T1413) and their non-transgenic isoline (BH) were planted at three locations (Suwon, Cheongwon, and Jinju) in 2011. Soil samples were collected near the base of each tree monthly, from May to September. Indicator PLFAs were utilized to calculate the microbial (bacterial and fungal) biomass, and PLFA profiles were developed to characterize the structure of those communities. Over the growing season, soils from Cheongwon and Jinju had similar microbial biomasses (PLFAs indicating functional groups) whereas, at Suwon, the biomass associated with the rhizosphere of Line T1413 was significantly different from that of the other transgenics and the control. At Cheongwon and Jinju, the structure of the rhizosphere microbial communities differed significantly between Lines T1403 or T1410 and BH, but only in May and June. By contrast, those structures were similar in all sampling months for each line at Suwon. Our results indicate that the influence resulting from genetic modification of the poplar trees on the rhizosphere microbial community is only temporary and inconsistent depending upon location and genetic line.

The frequency characteristics of the shear layer oscillation in hybrid rocket post-chamber

Lee, S.,Kim, D.Y.,Lee, C. Gauthier-Villars ; Elsevier Science Ltd 2017 Aerospace science and technology Vol.70 No.-

Visualizing flame images revealed the occurrence of LFI (Low Frequency Instability <20 Hz) in hybrid rocket combustion is significantly related with pressure and combustion fluctuations of around 500 Hz in the post chamber. In this study, numerical calculations for cases with different ER (Expansion Ratio) and the wall blowing effect were conducted to investigate which factor has a more influence on pressure fluctuation of 500 Hz band. In addition, the flow structure change in each case was examined and compared with the baseline. Results show that both wall blowing and the increment of ER increases the turbulent energy of the time-averaged flow and pushes the reattachment point to downward. And it seems that the wall blowing effect considerably increases the recirculation length by modifying the turbulent flow structures. Moreover, results indicate that the wall blowing effect promotes the vortices generation from the inlet and supplies the vortices with more energy to appear in the wake. In the spectrum analysis, also, the wall blowing effect was found to oscillate re-attachment point, resulting in the appearance of additional oscillatory characteristics of St = O (0.3) in the downstream otherwise completely dissipated. Note that the oscillation frequency of St = O (0.3) is corresponding to a dimensional frequency of 490 Hz, which approximately coincides with a measured frequency band of 500 Hz. Therefore, the pressure oscillation in about 500 Hz band in the experiment is strongly related with temporal characteristic of the modified flow structure by wall blowing.