Transient oxidative shock induced by pretreatment of leaves with H2O2 effectively increased chilling tolerance in mung bean and Phalaenopsis. Seedlings of the chilling-tolerant (V3327) cultivar of mung bean (Vigna radiata L.) were employed to study the mechanism of H2O2-induced chilling tolerance. Pretreatment with 200 mM H2O2 increased survival rates of seedlings chilled at 4 degreesC for 36 h from 30% to 70%. The same treatment also lowered the electrolyte leakage from 86% to 21%. Time-course analysis immediately after the treatment demonstrated that exogenous application of H2O2 did not alter the endogenous H2O2 level of the plants. This observation suggests that the primary receptor for the exogenous H2O2 is localized on the leaf surface or in some other way isolated from the endogenous H2O2 pool. Oxidative shock inhibited the induction of the antioxidant enzymes, ascorbate peroxidase and catalase; however, it substantially increased glutathione content both under chilling and control conditions. Combined pretreatment of mung bean plants with abscisic acid and H2O2 showed no synergistic effect on glutathione content and decreased survival rate relative to treatment with either compound alone. These results suggest that the H2O2-induced chilling tolerance in these plants might be mediated by an elevation of glutathione content and is independent of the ABA mechanism of chilling protection

BackgroundCytokinins are plant-specific hormones that affect plant growth and development. The endogenous level of cytokinins in plant cells is regulated in part by irreversible degradation via cytokinin oxidase/dehydrogenase (CKX). Among the 11 rice CKXs, CKX2 has been implicated in regulation of rice grain yield.ResultsTo specifically down-regulate OsCKX2 expression, we have chosen two conserved glycosylation regions of OsCKX2 for designing artificial short hairpin RNA interference genes (shRNA-CX3 and -CX5, representing the 5′ and 3′ glycosylation region sequences, respectively) for transformation by the Agrobacterium-mediated method. For each construct, 5 independent transgenic lines were obtained for detailed analysis. Southern blot analysis confirmed the integration of the shRNA genes into the rice genome, and quantitative real time RT-PCR and northern blot analyses showed reduced OsCKX2 expression in the young stem of transgenic rice at varying degrees. However, the expression of other rice CKX genes, such as CKX1 and CKX3, in these transgenic lines was not altered. Transgenic rice plants grown in the greenhouse were greener and more vigorous with delayed senescence, compared to the wild type. In field experiments, both CX3 and CX5 transgenic rice plants produced more tillers (27–81 %) and grains (24–67 %) per plant and had a heavier 1000 grain weight (5–15 %) than the wild type. The increases in grain yield were highly correlated with increased tiller numbers. Consistently, insertional activation of OsCKX2 led to increased expression of CKX2 and reduced tiller number and growth in a gene-dosage dependant manner.ConclusionsTaken together, these results demonstrate that specific suppression of OsCKX2 expression through shRNA-mediated gene silencing leads to enhanced growth and productivity in rice by increasing tiller number and grain weight.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-015-0070-5) contains supplementary material, which is available to authorized users.

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This work characterizes a lily (Lilium longiflorum Thunb. cv. Snow Queen) anther (LLA) protein associated with desiccation. Peptide mapping analysis revealed that the abundant LLA-23 doublet contained similar polypeptides, having an isoelectric point of 6.1. Immunoblots of pollen protein from developing anther/pollen confirmed that the LLA-23 protein accumulated only at the later stage of pollen maturation and that the levels remained steady in mature and vital pollen. The accumulation of LLA-23 proteins was correlated with desiccation that naturally occurred in pollen. Subcellular fractionation of pollen proteins revealed that the protein was located in the cytoplasmic fraction. Premature drying of developing pollen confirmed that the concomitant accumulation of LLA-23 was associated with desiccation. Peptide sequence analysis demonstrates similarities between the lily LLA-23 and a family of water-deficit/ripening-induced proteins including LP3 of pine, DS2 of potato, and Asr of tomato and pummelo. In addition, the concomitant accumulation of LLA-23 can be experimentally manipulated by methyl jasmonate (Me-JA) and salicylic acid (SA) as well as by mannitol and methyl viologen. The LLA-23 represents a novel member of the water-deficit/ripening-induced proteins.

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