Abstract
The increase of the global population in the next decades, expected to be 9.2 billion in 2050, will require several and huge efforts in improving crop productivity and quality, while limiting resources, climate change, weeds and pests resistance are the main challenges to be addressed. Therefore, scientists together with farmers have to develop new strategies taking into account both the crop productivity and environmental safety issues. Recently, one of the most promising approach fighting the dramatic increase of weeds and pests resistance, is represented by the allelopathy phenomenon, i.e. an intrinsic and inner ability of plants to generate positive and/or negative effects into its nearby environment thanks to the release of specific compounds, the so-called allelochemicals. At the same time, plants use allelopathy to interact with the surrounding soil environment, i.e. the rhizosphere. However, although allelopathic crops, i.e. rice, wheat, barley and sorghum, have been known since the beginning of agriculture for their ability, it seems that the domestication and selection processes, improving agronomical traits, has depleted their competitiveness against weeds and pests. Therefore, rediscovering wild relative or landraces with allelopathic traits might be very useful in order to understand this phenomenon, to exploit it and to eventually reintroduce it into modern cultivars. Barley (Hordeum vulgare L.) is one of the most important staple crops worldwide and modern cultivars show the so-called “domestication effect” in terms of absence of certain allelochemicals, in particular the two alkaloids gramine and hordenine, respect to the wild genotypes. Therefore, the present work aims at i) giving new insights regarding the allocation, accumulation and root exudation of the two barley alkaloids gramine and hordenine in wild-relatives and modern barley, ii) a detailed characterization of hordenine production, in time-course and in nutrient deficiencies experiments, and its fate in agricultural soil and iii) evaluating the effects of the presence of gramine on the rhizosphere microbiota composition in modern barley. These experiments will identify the most promising wild barley for further investigations, and test hypothesis of secondary metabolites as modulators in the rhizosphere microbiota.