Project description:Seven different Solanaceae species, Potato (Solanum tubersosum), Tomato (Solanum lycopersicum), Eggplant (Solanum melongena), Pepper (Capsicum annuum), Tobacco (Nicotiana tabaccum), Petunia and Nicotiana benthiamana were subjected to drought stress. Drought stress was applied by stopping watering of the plants, control plants were normally watered with nutrient solution. Samples were collected at 0, 1, 3, 5, 7 and 10 days after the first application of the drought stress. RNA was isolated using Qiagen RNeasy. Keywords: Direct comparison
Project description:A heat and drought tolerant rice cultivar (N22) was grown in the field under control and drought conditions during the dry season in 2013. Drought was applied during early grain filling and resulted in simultaneous heat stress, leading to reduced grain yield and quality. Total RNA was extracted from developing seeds under stress and control (fully flooded) conditions and RNA-seq analysis was performed. These samples are a part of a bigger experiment analysing the responses of three contrasting rice cultivars (N22, Dular, Anjali) to combined heat and drought stress including different organs (developing seeds, flag leaves, flowering spikelets) and developmental stages (early grain filling, flowering) at the transcriptomic level.
Project description:During their co-evolution, plants have learned to counteract bacterial infection by preparing yet uninfected tissues for an enhanced defence response, the so-called systemic acquired resistance or priming response. Primed leaves express a wide range of genes that enhance the defence response once an infection takes place. While hormone-driven defence signalling and generation of defensive metabolites has been well studied, less focus has been set on the reorganization of primary metabolism in systemic leaves. Since primary metabolism plays an essential role for fuelling and optimizing defences in terms of providing energy and chemical building blocks, we investigated medium-term primed changes in primary metabolism at RNA and metabolite levels in systemic leaves of Arabidopsis thaliana plants that were locally infected with Pseudomonas syringae. While known defence genes were still activated 3-4 days after infection, we also found several parts of primary metabolism to be significantly altered. Nitrogen (N)-metabolism and content of amino acids and other N-containing metabolites were significantly reduced, whereas the organic acids fumarate and malate were strongly increased. We suggest that reduction of N-metabolites in systemic, yet non-infected leaves primes defence against bacterial infection by reducing the nutritional value of systemic tissue. The increased organic acids serve as a quickly available metabolic resource of energy and carbon-building blocks for the production of defence metabolites during subsequent secondary infections.
Project description:The root-colonizing endophytic fungus Piriformospora indica promotes root and shoot growth of its host plants. We show that growth promotion of Arabidopsis leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote 15NO3- uptake from agar plates to the leaves of the host under N-sufficient or N-limiting conditions. However, when the roots were co-cultivated with 15N-labelled P. indica, more label can be detected in the leaves of N-starved host plants, but not of plants supplied with sufficient N. Amino acid and primary metabolite profiles, as well as expression analyses of N metabolite transporter genes suggest that the fungus alleviates the adaptation of its host to the N limitation condition. P. indica alters the expression of transporter genes which participate in relocation of NO3-, NH4+ and N metabolites from the roots to the leaves under N limitation. We propose that P. indica participates in the plant´s metabolomic adaptation to N limitation by delivering reduced N metabolites to the host, alleviating metabolic N starvation responses, and reprogramming the expression of N-metabolism related genes.
Project description:Transcriptomics study which main goal is to elucidate the programme of gene expression triggered by water stress in leaflets of the drought-tolerant wild-related tomato Solanum pennellii (acc. PE47) compared with domesticated tomato (S. lycopersicum, cv. P73). In this study we used S. lycopersicum (Sl) (cv. P73) and S. pennellii (Sp) (acc. PE47) species displaying remarkable divergences regarding drought tolerance, to investigate the physiological and molecular responses in leaves of plants grown without stress (control) and after four days of water withholding (water stress, WS), when plant water loss was significant but leaves did not show visual dehydration symptoms yet. Significant physiological differences between species were found, showing Sp leaves higher ability to avoid water loss. Leaf transcriptomic analysis showed important constitutive expression differences between Sp and Sl, including genes with unknown function. In relation to the genes specifically induced by drought in Sp, those linked to stomatal closure, cell wall and primary carbohydrate metabolism and, specially, nitrogen metabolism were identified. Thus, genes linked to NH4+ assimilation, GOGAT/GS cycle and the GDH- and GABA-shunt were specifically induced by water stress in leaves of Sp. Our results showed also the up-regulation in Sp of genes involved in JA biosynthesis pathway, which were induced in both conditions, whereas genes involved in ET biosynthesis were specifically induced under WS. Regarding ET signaling, ERF genes were up-regulated by WS in Sp, hinting at the importance of these transcriptional regulators in the drought response of Sp.
Project description:Genetic and molecular evidence to support the hypothesis that fungal secondary metabolites play a significant role in protecting the fungi against fungivory is scarce. We investigated the impact of fungal secondary metabolites on transcript regulation of stress related expressed sequence tags (ESTs) of the Collembola Folsomia candida feeding on mixed vs. single diets. Aspergillus nidulans wildtype (WT; Ascomycota) able to produce secondary metabolites including sterigmatocystin (ST) and a knockout mutant with reduced secondary metabolism (A. nidulans ΔLaeA) were combined with the high quality fungus Cladosporium cladosporioides as mixed diets or offered as single diets. We hypothesized that (i) A. nidulans WT triggers more genes associated with stress responses compared to the A. nidulans ΔlaeA strain with suppressed secondary metabolism, (ii) C. cladosporioides causes significantly different transcript regulation than the A. nidulans strains ΔlaeA and WT, and (iii) mixed diets will cause significantly different transcript expression levels than single diets. All three hypotheses are generally supported despite the fact that many functions of the affected ESTs are unknown. The results bring molecular evidence for the existence of a link between fungal secondary metabolites and responses in springtails supporting the hypothesis that fungal secondary metabolites act as a shield against fungivory.
Project description:Drought is one of the major factor that limits crop production and reduces yield. To understand the early response of plants under nearly natural conditions, pepper plants were grown in a greenhouse and drought stressed by withholding water for one week. Plants adapted to the decreasing water content of the substrate by adjustment of their osmotic potential in roots by accumulation of raffinose, glucose, galactinol and proline. In contrast in leaves levels of fructose, sucrose and also galactinol increased. Due to the water deficit cadaverine, putrescine, spermidine and spermine accumulated in leaves whereas the concentration of polyamines was reduced in roots. These polyamines are suggested to rather act as stress protectants than for osmotic adjustment. To understand the molecular basis of the response to this early drought stress better, four suppression subtractive hybridisation libraries from leaves and roots were constructed. Microarray technique was used to identify differentially expressed genes. A total of 109 unique ESTs were detected. The diversity of the putative functions of all identified genes confirms the complexity of the plant response to drought stress. Keywords: Transcription profiling Two-condition experiment in roots and leaves, control leaves (CL) vs. drought-stressed leaves (DL) and control roots (CR) vs. drought-stressed roots (DR). Biological replicates: 4 control (1-4), drought-stressed (1-4), independently grown and harvested. One swap replicate per array.
Project description:Rice is susceptible to both heat and drought stress, in particular during flowering and grain filling, when both grain yield and quality may be severely compromised. However, under field conditions, these two stresses rarely occur separately. Under well-watered conditions, plants avoid heat stress by transpirational cooling, while this is not possible under drought conditions. Although investigating combined heat and drought stress is clearly more agronomically relevant than analyzing the effects of the single stresses, only a few studies of this stress combination, in particular under field conditions, have been published. Furthermore, little is known about how plants respond during recovery from drought stress, which also determines plant survival. To address these knowledge gaps, three rice cultivars differing in heat and drought tolerance were grown in the field under control and drought conditions in three consecutive years. Drought was applied either during flowering or during early grain filling, resulting in simultaneous heat stress, leading to reduced grain yield and quality. Analysis by gas chromatography-mass spectrometry (GC-MS) showed distinct metabolic profiles for the three investigated organs (flag leaves, flowering spikelets, developing seeds). The metabolic responses of the plants also strongly differed between cultivars and organs, and between stress and rewatering conditions. Correlation analysis identified potential metabolic markers for grain yield and quality under combined heat and drought stress from stress- and rewatering-regulated metabolites and from metabolites with constitutive differences between the cultivars. These results show that GC-MS can resolve metabolic responses to combined heat and drought stress and subsequent rewatering in different organs of field-grown rice. The metabolite profiles can be used to identify potential marker metabolites for yield stability and grain quality that are expected to improve breeding efforts towards climate change resilient rice.