témavezető: Papp István
társ-témavezető: Szegő Anita
helyszín (magyar oldal): Szent István University, Doctoral School of Biological Sciences helyszín rövidítés: SZIE
A kutatási téma leírása:
1. Introduction
Cucumber is a warm-season plant that grows rapidly at 24–29 °C temperatures. This species is sensitive to a range of environmental stresses, such as water shortage, extreme temperature and excess salt. In current horticultural production F1 hybrid lines are cultivated, where a proper choice of genotype is necessary for successful yield and quality. Important characteristics for choosing a line are market acceptance, yield, fruit quality, adaptability to environment/growing region, and disease resistance (Sing and Ram, 2012).
Due to increasing demand for stress tolerant genotypes from the growers and high quality products from the consumer’s side, new hybrids of cucumber are released frequently. Improving relevant traits is largely facilitated by proper understanding the molecular basis of the most important physiological processes. This trend is accelerated by the availability of the full genomic sequence of this species (Huang et al., 2009).
Molecular breeding efforts of cucumber are conducted intensively worldwide. Besides resistance to several biotic agents, tolerances to abiotic stress factors are prime targets of current breeding efforts. Global warming and water shortage puts pressure on farmers to use low quality (high EC) water for irrigation. Therefore, a main target of present day cucumber breeding is improving salt tolerance while keeping other important traits at high quality.
Salt tolerance is a multi-factorial trait including a range of known molecular mechanisms, explored mostly in model species (for a recent review see e.g. Hanin et al., 2016). Detoxification of reactive oxygen species (ROS) and accumulation of protective proteins are two major aspects of the stress response. ROS are produced in osmotically stressed plant tissues and can serve signaling function, but may also present danger to proper functioning of the cells (Apel and Hirt 2004).
2. Main goals of research
During the program an in silico approach will be followed first to identify putative genes of cucumber involved in salt tolerance response. These may include antioxidant enzymes, ion transporters and other proteins implicated in stress protection. Expression of these candidate genes will be followed in different F1 genotypes of cucumber with contrasting tolerance towards salt stress (Zhu et al., 2008). Strong candidate genes will be scrutinized further, their full length ORF will be cloned and transformed into Arabidopsis, opening possibility for functional analysis. Mitigating effects of some agents (e.g. polyamins, Sang et al., 2016) will also be investigated on salt stress tolerance by the successful applicant.
3. Materials and research methods
Plants will be grown in phytotron chambers in soil or in soilless media (perlite or rock-wool). RNA will be prepared from stress treated and control plants of different genotypes, followed by cDNA synthesis, RT-PCR, qRT-PCR amplification of the in silico selected candidate genes. Genotype and treatment specific differences of expression will be noted and the genomic sequence of the corresponding genes selected. Full length cDNA (ORF) of the selected genes will be cloned into plasmid cloning vectors, further transferred into Agrobacterium and used for transformation of Arabidopsis by floral dip method. This will be followed by experiments with the transgenic Arabidopsis lines targeting specific changes in salt tolerance. Several chemical agents (e.g. polyamins) will be applied along with salt stress to cucumber plants. Mitigating effects of the treatments will be followed by various methods, such as measuring antioxidants, MDA levels, electrolyte leakage and photosynthetic capacity.
4. Anticipated results
Genes responsible for salt tolerance of cucumber will be identified, with their role in stress response confirmed by functional analysis in the model plant Arabidopsis. These genes can be further used as candidate genes in breeding efforts for cucumber salt stress tolerance and may provide basis form marker development for MAS. Breeding programs aiming improvements of salt tolerance of cucumber are ongoing therefore results will be directly applicable. Applicability of some exogenous agents will be evaluated for mitigating salt stress. A successful project in this direction may give clues in order to improve yield in soilless, and possibly in open field cucumber production as well.
References:
Apel, K. and Hirt, H. 2004. Reactive oxygen species: metabolism, oxidative stress, and signal transduction. Annu. Rev. Plant Biol. 2004:55:373-399.
Hanin, M., Ebel, C., Ngom, M., Laplaze, L., Masmoudi, K. 2016. New Insights on Plant Salt Tolerance Mechanisms and Their Potential Use for Breeding.Front Plant Sci. 7:1787. eCollection
Huang, S., Li, R., Zhang, Z., Li, L., Gu, X., Fan, W., Lucas, W.J., Wang, X., Xie, B., Ni, P., Li, S. 2009. The genome of the cucumber, Cucumis sativus L. Nat. Gen. 41, 1275–1281.
Sang, T., Shan, X., Li, B., Shu, S., Sun, J. and Guo, S. 2016 Comparative proteomic analysis reveals the positive effect of exogenous spermidine on photosynthesis and salinity tolerance in cucumber seedlings. Plant Cell Rep. (8):1769-82.
Singh, A. and Ram, H. H. 2012. Estimates of stability parameters for yield and its components in cucumber (Cucumis sativus L.). Vegetable Sci., 39 (1): 31-34.
Zhu, J., Bie, Z., and Li, Y. 2008. Physiological and growth responses of two different salt-sensitive cucumber cultivars to NaCl stress, Soil Science and Plant Nutrition, 54:3, 400-407
előírt nyelvtudás: English felvehető hallgatók száma: 1
Jelentkezési határidő: 2018-05-31
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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