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Jiao Chen, De-bao Yuan, Chao-zheng Wang, Yi-xing Li, Fen-fang Li, Ke-qian Hong, and Wang-jin Lu

rapa RING finger protein gene BrRZFP1 overexpression conferred increased tolerance to cold, salt, and dehydration stresses ( Jung et al., 2013 ). Suppression of arabidopsis AtATL78 increased tolerance to cold stress ( Kim and Kim, 2013 ), and

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Xiaobo Sun, Yanming Deng, Lijian Liang, Xinping Jia, Zheng Xiao, and Jiale Su

′-GCCGGATCCATGGAAGGAAAGGAGGAAGATG-3′ and SbOF4: 5′- GCCGAGCTCTCACTTGGATTTAAATGGGATTGC-3′). The PCR products were subcloned into BamH I/ Sac I sites of pCAMBIA2301 expression vector under control of the CaMV 35S promoter, and overexpression construct pCAMBIA2301-SbPIP1 was obtained

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Aneta K. Studzinska, David S. Gardner, James D. Metzger, David Shetlar, Robert Harriman, and T. Karl Danneberger

, inactivation of bioactive gibberellins GA1 and GA4 is ensured by GA2-oxidases (GA2ox) that catalyze their 2β-hydroxylation yielding GA8 and GA34 ( Hedden and Proebsting, 1999 ). Overexpression of OsGA2ox1 in rice caused a dwarf phenotype with leaves that were

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Lili Dong, Tongrui Liu, Di Gao, Jing Li, and Jie Qian

found that PhSDG8 was detected in five transgenic lines, but not in the WT and sdg8-2 mutants ( Fig. 5D ). Overexpression of PhSDG8 restored the branch and height phenotype of sdg8-2 to the wild type ( Fig. 5A–C ), suggesting that PhSDG8 can

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An Qin, Xiaosan Huang, Huping Zhang, Juyou Wu, Jie Yang, and Shaoling Zhang

) and pepper ( Aloni et al., 2008 ). We wanted to know whether overexpression of PbDHAR2 had contributed to increased AsA content. On the other hand, the pear is a perennial ligneous plant and only slow progress has been made in the improvement of salt

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Yueju Wang, Michael Wisniewski, Richard Meilan, Minggang Cui, Robert Webb, and Leslie Fuchigami

Ascorbate peroxidase (APX) plays an important role in the metabolism of hydrogen peroxide in higher plants, affording them protection against oxidative stress. We studied the effect of overexpressing a cytosolic ascorbate peroxidase (cAPX) gene—derived from pea (Pisum sativum L.)—in transgenic tomato plants (Lycopersicon esculentum L.). Transformants were selected in vitro using kanamycin resistance and confirmed by polymerase chain reaction (PCR) and northern analyses. An APX native-gel assay indicated that, in the absence of stress, APX activity in transgenic plants was several times greater than that measured in wild-type (WT) plants. Several independently transformed lines were propagated and evaluated for resistance to chilling and salt stress. After placing seeds at 9 °C for 5 weeks, percent germination was greater for seeds obtained from transgenic lines (26% to 37%) compared to the WT (3%). Plants from transgenic lines also had lower electrolyte leakage (20% to 23%) than WT (44%) after exposure to 4 °C. Visual assessment of transgenic and WT lines exposed to salinity stress (200 or 250 mm) confirmed that overexpression of APX minimized leaf damage. Moreover, APX activity was nearly 25- and 10-fold higher in the leaves of transgenic plants in response to chilling and salt stresses, respectively. Our results substantiate that increased levels of APX activity brought about by overexpression of a cytosolic APX gene may play an important role in ameliorating oxidative injury induced by chilling and salt stress.

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Yu Liu, Miao He, Fengli Dong, Yingjie Cai, Wenjie Gao, Yunwei Zhou, He Huang, and Silan Dai

significantly inhibited, which enhanced the resistance of A. thaliana to salt stress ( Wang and Dane, 2013 ). Overexpression of the TaNAC2 homolog gene TaNAC2a in tobacco ( Nicotiana tabacum ) proved that TaNAC2a could enhance tolerance to drought in

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Jiyu Zhang, Min Wang, Zhenghai Mo, Gang Wang, and Zhongren Guo

gene, isolated from developing flowers, plays a crucial role in stamen specification and gynoecium development ( Wang et al., 2012 ). Overexpression of a Brassica rapa MADS-box gene, BrAGL20 , induces early flowering time phenotypes in Brassica

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He Huang, Yuting Liu, Ya Pu, Mi Zhang, and Silan Dai

roots and leaves under drought stress ( Fig. 8C and D ). Fig. 8. Effect of ClAKT2 overexpression on growth of Arabidopsis thaliana ( A ) and Na + , K + content in different plant organs ( B ) under salt treatment. Effect of ClAKT overexpression on

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Yu-Jen Chiang, C. Stushnoff, A.E. McSay, M.L. Jones, and H.J. Bohnert

Petunia ×hybrida (Hook) Vilm. cv. Mitchell was transformed with an E. coli gene encoding mannitol-1-phosphate dehydrogenase (mtlD). Four plant lines that grew on kanamycin and contained the mtlD transgene were identified. Two of these lines contained high levels of mannitol [high-mannitol lines M3 and M8; mean mannitol = 3.39 μmol·g-1 dry weight (DW)] compared to nontransformed wild-type plants (0.86 μmol·g-1 DW), while two lines had mannitol levels similar to wild-type plants (low-mannitol lines M2 and M9; mean mannitol = 1.05 μmol·g-1 DW). Transgenic and control plants were subjected to chilling stress (3 ± 0.5 °C day/0 ± 0.5 °C night, 12-hour photoperiod and 75% relative humidity) to evaluate the role of mannitol in chilling tolerance. Based upon foliage symptoms and membrane leakage after a 3-week chilling treatment, the high-mannitol containing lines, M3 and M8, were more tolerant of chilling stress than the low-mannitol containing transgenic lines, M2 and M9, and wild-type. Under nonchilling conditions mannitol was the only carbohydrate that differed among transgenic lines, but all carbohydrates were present. When subjected to chilling stress, mannitol levels dropped by 75%, sucrose by 52%, and inositol by 54% in the low-mannitol lines (M2 and M9). In M3 and M8, the high-mannitol lines, mannitol levels decreased by 36%, sucrose by 25%, and inositol by 56%, respectively. Raffinose increased 2- to 3-fold in all lines following exposure to low-temperature chilling stress. In the higher mannitol lines only 0.04% to 0.06% of the total osmotic potential generated from all solutes could be attributed to mannitol, thus its action is more like that of an osmoprotectant rather than an osmoregulator. This study demonstrates that metabolic engineering of osmoprotectant synthesis pathways can be used to improve stress tolerance in horticultural crops.