Differential physiological, transcriptomic and metabolomic responses of Arabidopsis leaves under prolonged warming and heat shock.

BACKGROUND: Elevated temperature as a result of global climate warming, either in form of sudden heatwave (heat shock) or prolonged warming, has profound effects on the growth and development of plants. However, how plants differentially respond to these two forms of elevated temperatures is largely unknown. Here we have therefore performed a comprehensive comparison of multi-level responses of Arabidopsis leaves to heat shock and prolonged warming. RESULTS: The plant responded to prolonged warming through decreased stomatal conductance, and to heat shock by increased transpiration. In carbon metabolism, the glycolysis pathway was enhanced while the tricarboxylic acid (TCA) cycle was inhibited under prolonged warming, and heat shock significantly limited the conversion of pyruvate into acetyl coenzyme A. The cellular concentration of hydrogen peroxide (H2O2) and the activities of antioxidant enzymes were increased under both conditions but exhibited a higher induction under heat shock. Interestingly, the transcription factors, class A1 heat shock factors (HSFA1s) and dehydration responsive element-binding proteins (DREBs), were up-regulated under heat shock, whereas with prolonged warming, other abiotic stress response pathways, especially basic leucine zipper factors (bZIPs) were up-regulated instead. CONCLUSIONS: Our findings reveal that Arabidopsis exhibits different response patterns under heat shock versus prolonged warming, and plants employ distinctly different response strategies to combat these two types of thermal stress.

Identification and characterization of novel lncRNAs in Arabidopsis thaliana.

Long noncoding RNAs (lncRNAs) are important regulators of various biological processes, but few studies have identified lncRNAs in plants; genome-wide discovery of novel lncRNAs is thus required. We used deep strand-specific sequencing (ssRNA-seq) to obtain approximately 62 million reads from all developmental stages of Arabidopsis thaliana and identified 156 novel lncRNAs that we classified according to their localization. These novel identified lncRNAs showed low expression levels and sequence conservation. Bioinformatic analysis predicted potential target genes or cis-regulated genes of 91 antisense and 32 intergenic lncRNAs. Functional annotation of these potential targets and sequence motif analysis indicated that the lncRNAs participate in various biological processes underlying Arabidopsis growth and development. Seventeen of the lncRNAs were predicted targets of 22 miRNAs, and a network of interactions between ncRNAs and mRNAs was constructed. In addition, nine lncRNAs functioned as miRNA precursors. Finally, qRT-PCR revealed that novel lncRNAs have stage- and tissue-specific expression patterns in A. thaliana. Our study provides insight into the potential functions and regulatory interactions of novel Arabidopsis lncRNAs, and enhances our understanding of plant lncRNAs, which will facilitate functional research.

Physiological, Transcriptomic, and Metabolic Responses of Ginkgo biloba L. to Drought, Salt, and Heat Stresses.

Ginkgo biloba L. is highly adaptable and resistant to a range of abiotic stressors, allowing its growth in various environments. However, it is unclear how G. biloba responds to common environmental stresses. We explored the physiological, transcriptomic, and metabolic responses of G. biloba to short-term drought, salt, and heat stresses. Proline, H2O2, and ABA contents, along with CAT activity, increased under all three types of stress. SOD activity increased under salt and heat stresses, while soluble protein and IAA contents decreased under drought and salt stresses. With respect to metabolites, D-glyceric acid increased in response to drought and salt stresses, whereas isomaltose 1, oxalamide, and threonine 2 increased under drought. Piceatannol 2,4-hydroxybutyrate and 1,3-diaminopropane increased under salt stress, whereas 4-aminobutyric acid 1 and galactonic acid increased in response to heat stress. Genes regulating nitrogen assimilation were upregulated only under drought, while the GRAS gene was upregulated under all three types of stressors. ARF genes were downregulated under heat stress, whereas genes encoding HSF and SPL were upregulated. Additionally, we predicted that miR156, miR160, miR172, and their target genes participate in stress responses. Our study provides valuable data for studying the multilevel response to drought, salinity, and heat in G. biloba.