Project description:The aim of the present work is to apply microarrays to identify candidate genes associated with the strategies adopted by different Solanum wild species to maintain their metabolism and limit the harm under water stress conditions. Wild genotypes are a rich source of novel genes for introduction into cultivated species to enhance stress tolerance. The mechanisms in which genes act can involve different pathways inside the cell, resulting in the expression of stress responsive genes. We will identify genes whose expression change in the leaves of potato plants subjected to drought stress. We will analyze different Solanum genotypes in six moments of water stress (0,1,3,5,7 & 10 days after initiation of stress). We will selected 4 time-points (days 0,5,7 & 10) and 2 genotypes (with divergence behavior) for microarrays analysis. The candidate genes obtained with this approach will be validated by semi-quantitative northern blot analysis (Typhoon scanner) and/or RT-PCR in each time-point of treatment and with all wild genotypes in study. This will help us to get a better understanding respect the dynamics of expression of a great number of genes in response to stress, as well as to establish functional relations between the involved genes. Research Plan: 5-weeks-old Solanum wild species plants were randomly sorted in 2 groups (25 plants per group). One group was submitted to non-irrigated conditions, withholding water and the other was normally watered. For microarray analysis, leaflets tissue from 4 plants per group of 4 time-points (days 0,5,7, & 10) were pooled, frozen in liquid nitrogen and stored at –80°C.RNA of the pool was extracted following TRIZOL method (Invitrogen). RNA integrity was verified on agarose gel. Hybridizations were performed with n genotypes,t time-points and r repeats. The hybridizations proposed in this experiment to enhance statistical robustness of data will be: 32 slides = n*t*r ; (2 genotypes; 4 time-points; 4 repeats (dye-swap). Keywords: Direct comparison
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.