Expression profile analysis of the oxygen deficit response in Carrizo citrange rootstock

The deficit of oxygen in plants is a frequent phenomenon in nature. The main causes may be due to flooding or excessive irrigation or to an excess of aerobic microflora in the soil. The Intergovernmental Panel on Climate Change (IPCC) reported that the anthropogenically induced change of world climate increases the frequency of heavy precipitation and tropical cyclone activity. This is likely to engender more frequent flooding events in river flood plains and arable farmland, particularly affecting the world’s poorest farmers. The stress caused by lack of oxygen in plants mainly produces a reduction of the respiration, and then a low energy production and accumulation of toxic compounds of anaerobic metabolism. To alleviate this problem plants have developed morphological and metabolic adaptations, the main of which include the induction of anaerobic and fermentative pathways. In the present study we used a Combimatrix platform, made up of around 8,000 ESTs of roots isolated in citrus and its rootstocks. The chip was hybridized with RNA wild type Carrizo citrange roots and a transgenic line highly expressing a transcription factor involved in the response to the deficiency of oxygen in Oryza sativa. The aim of the work consists in the study of the up and down expressed genes in wild type and transgenic lines subjected and not to anaerobiosis, in order to understand the mechanisms that are activated under anoxia. In general, the hybridization of the chip has led to the activation of 492 genes, of which 28.95% is involved in redox processes, 28.41% in the response to stress, 18.28% in response to chemical stimuli. The up and down-regulation of differentially expressed transcripts in response to oxygen deficiency were confirmed through real-time RT-PCR The results obtained showed the activation of main genes involved in the glycolytic and fermentative pathways, such as pyruvate decarboxylase, alcohol dehydrogenase and sucrose synthase. In transgenic plants of Carrizo the response to oxygen deficit appears to be more pronounced, therefore genes of glycolytic, fermentation and pentose phosphate pathway are activated. Comparison of wild type Carrizo citrange and a transgenic line subjected and not to anaerobiosis in triplicate samples