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Augusto Ramírez-Godoy, María del Pilar Vera-Hoyos, Natalia Jiménez-Beltrán, and Hermann Restrepo-Diaz

Protection Sci. 48 131 141 Bartwal, A. Mall, R. Lohani, P. Guru, S.K. Arora, S. 2013 Role of secondary metabolites and brassinosteroids in plant defense against environmental stresses J. Plant Growth Regulat. 32 216 232 Bates, L.S. Waldren, R.P. Teare, I

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Ekaterina Papadopoulou and Rebecca Grumet

The cucurbit family is noted for diversity in sex expression phenotypes.

Typically, a phase of male flowers precedes the appearance of female or hermaphrodite flowers. Sex determination of individual flowers is regulated by genetic, environmental, and hormonal factors. Ethylene, auxins, and gibberellins all influence flower sex, with ethylene, which promotes femaleness, playing a predominant role. In this study, we tested whether brassinosteroids, a more recently identified class of plant hormones, also influence cucurbit sex expression. Applied epi-brassinolide (epi-BL) caused a significant decrease in time of appearance of the first female flower on monoecious cucumber plants, and increased total female flowers on the main stem. Increasing concentrations had a stronger effect. Of the three species tested, cucumber, melon, and zucchini, cucumber was the most responsive. Application of epi-BL also caused an increase in ethylene production by cucumber and zucchini seedlings, suggesting that the BR effect may be mediated by ethylene. To investigate the possible relationship between BR and ethylene on sex expression, we identified the concentration of ethephon (5 ppm) that caused an increase in ethylene production comparable to that induced by 10 μm epi-BL (about two-fold). Treatment with 5 ppm ethephon was sufficient to increase femaleness of cucumber plants, but not zucchini plants, suggesting that the difference in response to epi-BL may reflect differences in sensitivity to ethylene. Collectively, our results indicate that application of brassinosteroids to cucumber cause earlier and increased female flower production, and that the effects may be mediated, at least in part, by brassinosteroid-induced increased production of ethylene.

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Abha Upadhyaya, Tim D. Davis, and Narendra Sankhla

Moth bean (Vigna aconitifolia Jacqu. Marecbal cv. Jaadia) seeds were germinated in 0, 0.1, 1, or 2 μm EBL. After 72 hours, seedlings were exposed to 22 or 48C for 90 minutes. At 48C, EBL increased total electrolyte, K+, and sugar leakage from the seedlings relative to the control. Following exposure to 48C, EBGtreated seedlings bad higher malondialdebyde concentrations than controls, indicating that EBL enhanced high-temperature-induced lipid peroxidation. At 48C, EBL increased ascorbic acid oxidase activity but decreased superoxide dismutase activity relative to the control. Taken collectively, these data do not support a hypothesis that brassinosteroids confer beat shock tolerance to moth bean. Chemical name used: 24-epibrassinolide (EBL).

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Clíssia Barboza da Silva, Julio Marcos-Filho, Pablo Jourdan, and Mark A. Bennett

. Bot. 88 171 177 Ahammed, G.J. Choudhary, S.P. Chen, S. Xia, X. Shi, K. Zhou, Y. Yu, J. 2013a Role of brassinosteroids in alleviation of phenanthrene-cadmium co-contamination-induced photosynthetic inhibition and oxidative stress in tomato J. Expt. Bot

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Yingmei Gao, Jingkang Hu, Tingting Zhao, Xiangyang Xu, Jingbin Jiang, and Jingfu Li

drought, hypoxia, and osmotic stress ( Fujioka and Yokota, 2003 ). BES1 is phosphorylated and appears to be destabilized by the glycogen synthase kinase-3 BRASSINOSTEROID INSENSITIVE2 (BIN2), a negative regulator of the BR pathway ( Yin et al., 2002 ). It

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Jiaqi Hu, Hye-Ji Kim, Houbin Chen, and Biyan Zhou

, abscisic acid was shown to promote flowering, whereas GAs inhibit flowering ( Chen et al., 2014 ; Cui et al., 2013 ). Brassinosteroids are a group of polyhydroxylated plant steroid hormones that are ubiquitously present throughout the plant kingdom and

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Cristhian Camilo Chávez-Arias, Sandra Gómez-Caro, and Hermann Restrepo-Díaz

), inoculated plants without waterlogging ( C ), inoculated plants with waterlogging and botanicals extracts application ( D ), inoculated plants with waterlogging and salicylic acid application ( E ), and inoculated plants with waterlogging and brassinosteroids

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Tripti Vashisth, D. Scott NeSmith, and Anish Malladi

and ‘Suziblue’. Three genes were differentially expressed between the two genotypes ( Fig. 5 ). Interestingly, all these genes were potentially associated with phytohormone metabolism or signaling, specifically that of auxins, JAs, and brassinosteroids

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Ekaterina Papadopoulou and Rebecca Grumet

The Cucurbitaceae family is noted for a diversity of sex expression phenotypes. Typically, a phase of male flowers precedes either female or bisexual flower production. Sex determination of individual flowers is regulated by a combination of genetic, environmental, and hormonal factors. Ethylene, auxins, and gibberellins have all been shown to influence flower sex expression in cucurbits. Ethylene, which promotes femaleness, plays a predominant role. In this study, we tested whether brassinosteroids (BR), a more recently identified class of plant hormones, also influences cucurbit sex expression. Applied epi-brassinolide (epi-BL) caused a significant decrease in time of appearance of the first female flower on monoecious cucumber plants, and increased total female flowers on the main stem. Increasing concentrations had a stronger effect. Of the three species tested, cucumber, melon and zucchini, cucumber was the most responsive to BR. Application of epi-BL also caused an increase in ethylene production by cucumber and zucchini seedlings, suggesting that the BR effect may be mediated by ethylene. To investigate the possible relationship between BR and ethylene on sex expression, we identified the concentration of ethephon (5 ppm) that caused an increase in ethylene production comparable to that induced by 10 μm epi-BL (approximately two-fold). Treatment with 5 ppm ethephon was sufficient to increase femaleness of cucumber plants, but not zucchini plants, suggesting that the difference in response to epi-BL treatment may reflect differences in sensitivity to ethylene. Collectively, our results indicate that application of brassinosteroids to cucumber cause earlier and increased female flower production, and that the effects may be mediated, at least in part, by brassinosteroid-induced production of ethylene.

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Abha Upadhyaya, Tim D. Davis, and Narendra Sankhla

Seeds of moth bean (Vigna aconitifolia Jacqu. Marechal cv. Jaadia) were germinated in the presence of 0, 0.1, 1, or 2 μm 24-epibrassinolide (EBL). After 72 h, cotyledons were excised and the seedlings exposed to 22 or 48 °C for 90 min. At 48 °C EBL increased total electrolyte, K+, and sugar leakage relative to the untreated control. Following exposure to 48 °C, EBL-treated seedlings had higher malondialdehyde concentrations than controls indicating that EBL enhanced high temperature-induced lipid peroxidation. At 48 °C, EBL increased ascorbic acid oxidase activity and decreased superoxide dismutase activity relative to the control. Taken together, these data do not support the hypothesis that brassinosteroids confer thermotolerance to plants. On the contrary, EBL increased high temperature-induced damage and reduced the activity of some antioxidant systems that may protect against stress-induced cellular damage.