A series of chalcones and their derivatives have been synthesized and identified as novel potential antimalarials using both molecular modeling and in vitro testing against the intact parasite. A large number of chalcones and their derivatives were prepared using one-step Claisen-Schmidt condensations of aldehydes with methyl ketones. These condensates were screened in vitro against both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum and shown to be active at concentrations in the nanomolar range. The most active chalcone derivative, 1-(2,5-dichlorophenyl)-3-(4-quinolinyl)-2-propen-1-one (7), had an IC50 value of 200 nM against both a chloroquine-resistant strain (W2) and a chloroquine-sensitive strain (D6). The resistance indexes for all compounds were substantially lower than for chloroquine, suggesting that this series will be active against chloroquine-resistant malaria. Structure-activity relationships (SAR) of the chalcones in the context of a homology-based model structure of the malaria trophozoite cysteine protease, the most likely target enzyme, are presented.

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A heat stress transcription factor LlHSFA1 in lily and its relationship with LlHSFA2 was investigated, and its function in enhancing thermotolerance was confirmed by analyzing transgenic Arabidopsis thaliana overexpressed LlHSFA1. A large family of heat stress transcription factors that are involved in the heat stress response in plants can induce the expression of multiple genes related to thermotolerance including heat-shock proteins. In this study, a novel class A1 HSF named LlHSFA1 was isolated from leaves of lily (Lilium longiflorum cv. 'White Heaven') using the rapid amplification of cDNA ends technique. Analysis of the deduced amino acid sequence and construction of a phylogenetic tree showed that LlHSFA1 contained five critical domains and motifs and belonged to the A1 family of HSFs. Following the heat treatment of lily leaves, transcription of LlHSFA1 was induced to a varying extent, related to the time of measurement. The induced expression peak of LlHSFA1 occurred prior to that of LlHSFA2, during the early phase of heat stress. Following transient expression of LlHSFA1 in Nicotiana benthamiana, LlHSFA1 was found to be localized in both the nucleus and the cytoplasm. Analysis using bimolecular fluorescence complementation and a yeast two-hybrid assay demonstrated that LlHSFA1 could interact with LlHSFA2. Use of a yeast one-hybrid assay confirmed that LlHSFA1 had transcriptional activation activity. In transgenic Arabidopsis lines overexpressing LlHSFA1 under unstressed conditions, the expression of some putative target genes was up-regulated, in comparison with expression in wild-type plants, and furthermore, the thermotolerance of the transgenic lines was enhanced. Overall, LlHSFA1 was demonstrated to play an important role in the heat stress response of lily and to be a novel candidate gene for application in lily breeding, using genetic modification approaches.

The phytohormone abscisic acid (ABA) regulates plant development and is crucial for abiotic stress response. In this study, cold storage contributes to reducing endogenous ABA content, resulting in dormancy breaking of Gladiolus. The ABA inhibitor fluridone also promotes germination, suggesting that ABA is an important hormone that regulates corm dormancy. Here, we report the identification and functional characterization of the Gladiolus ABI5 homolog (GhABI5), which is a basic leucine zipper motif transcriptional factor (TF). GhABI5 is expressed in dormant vegetative organs (corm, cormel, and stolon) as well as in reproductive organs (stamen), and it is up-regulated by ABA or drought. Complementation analysis reveals that GhABI5 rescues the ABA insensitivity of abi5-3 during seed germination and induces the expression of downstream ABA response genes in Arabidopsis thaliana (EM1, EM6, and RD29B). Down-regulation of GhABI5 in dormant cormels via virus induced gene silence promotes sprouting and reduces the expression of downstream genes (GhLEA and GhRD29B). The results of this study reveal that GhABI5 regulates bud dormancy (vegetative organ) in Gladiolus in addition to its well-studied function in Arabidopsis seeds (reproductive organ).