Expression profile matrix of Arabidopsis transcription factor genes suggests their putative functions in response to environmental stresses

Numerous studies have shown that transcription factors are important in regulating plant responses to environmental stress. However, specific functions for most of the genes encoding transcription factors are unclear. In this study, we used mRNA profiles generated from microarray experiments to deduce the functions of genes encoding known and putative Arabidopsis transcription factors. The mRNA levels of 402 distinct transcription factor genes were examined at different developmental stages and under various stress conditions. Transcription factors potentially controlling downstream gene expression in stress signal transduction pathways were identified by observed activation and repression of the genes after certain stress treatments. The mRNA levels of a number of previously characterized transcription factor genes were changed significantly in connection with other regulatory pathways, suggesting their multifunctional nature. The expression of 74 transcription factor genes responsive to bacterial pathogen infection was reduced or abolished in mutants that have defects in salicylic acid, jasmonic acid, or ethylene signaling. This observation indicates that the regulation of these genes is mediated at least partly by these plant hormones and suggests that the transcription factor genes are involved in the regulation of additional downstream responses mediated by these hormones. Among the 43 transcription factor genes that are induced during senescence, 28 of them also are induced by stress treatment, suggesting extensive overlap responses to these stresses. Statistical analysis of the promoter regions of the genes responsive to cold stress indicated unambiguous enrichment of known conserved transcription factor binding sites for the responses. A highly conserved novel promoter motif was identified in genes responding to a broad set of pathogen infection treatments. This observation strongly suggests that the corresponding transcription factors play general and crucial roles in the coordinated regulation of these specific regulons. Although further validation is needed, these correlative results provide a vast amount of information that can guide hypothesis-driven research to elucidate the molecular mechanisms involved in transcriptional regulation and signaling networks in plants

Impact of elevated temperatures on greenhouse gas emissions in rice systems: interaction with straw incorporation studies in a growth chamber experiment

Two pot experiments in a “walk-in” growth chamber with controlled day and night temperatures were conducted to investigate the influence of elevated temperatures along with rice straw incorporation on methane (CH4) and nitrous oxide (N2O) emissions as well as rice yield. Elevated temperature increased GWP while decreased rice yield. This suggests that global warming may result in a double negative effect: higher emissions and lower yields

Effects of two oil dispersants on phototaxis and swimming behaviour of barnacle larvae

The effects of two oil dispersants (Vecom B-1425 GL and Norchem OSD-570) mixed with diesel oil on the survival and behaviour of the stage II nauplii of the barnacle Balanus amphitrite were investigated. The 24 and 48-hour LC50 values for Vecom B-1425 GL:diesel mixture were 514 and 48 mg 1-1 respectively, while respective values for Norchem OSD-570:diesel mixture were 505 and 71 mg 1-1. Under sublethal concentrations, increased levels of the dispersant:diesel mixtures caused a reduction in phototactic responses. Balanus amphitrite nauplii failed to exhibit phototactic responses when exposed to Vecom B-1425 GL:diesel mixtures of 400 mg 1-1 and higher for 24 hours. A longer exposure time of 48 hours further reduced the Lowest Observable Effect Concentrations (LOECs) to 60 mg 1-1. The LOECs for Norchem OSD-570:diesel mixtures under exposure periods of 24 and 48 hours were 400 and 80 mg 1-1 respectively. The curvilinear velocities (VCL) and straight-line velocities (VSL) of the stage II nauplii ranged from 0.7-1.1 and 0.2-0.4 mm s-1 respectively. Increased concentrations of dispersant:diesel mixtures caused a significant change in the curvilinear and straight-line velocities. Both oil dispersants, dispersant:diesel mixtures of 20 to 40 mg 1-1 caused significant increases in VCL, but no significant change in VSL. Dispersant:diesel mixtures of 100 mg 1-1 and higher resulted in a reduction in VSL for both dispersants. ©1997 Kluwer Academic Publishers.link_to_subscribed_fulltex