FEMS Microbiology Letters Poster Prize: Ramona Marasco

The 5th Conference on Microbial Diversity (MD2019) took place in Catania (Italy) from 25-27 September 2019. At the conference FEMS Microbiology Letters awarded a Poster Presentation Prize to Ramona Marasco for her research into the microbiomes associated with desert plants.

You can read her interview below:

What is your current position, and what was your scientific journey to get there?
Ramona Marasco collecting samples of soil for chemical analysis and salt quantification in Chott el Djerid (Tunisia)

Since 2016, I am a research scientist in the Extreme System Microbiology laboratory lead by Professor Daniele Daffonchio affiliated to the Biological and Environmental Sciences and Engineering Division (BESE) at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia.

My scientific interest in microbial ecology and biotechnology began during my B.Sc. degree in Agriculture Biotechnology (University of Milano, Milan, Italy) when I realized how complex are the ecosystems (i.e., soil) and the microorganism-environment interactions within them. Following this interest, during my Master degree in Plant, Food and Environmental Biotechnology (University of Milano, Milan, Italy), I focused my attention to the role of microbial communities in the primary colonization of rock substrates in order to describe the microbial processes driving the soil genesis and plant ecosystem formation in cold deserts ([1]; [2]; [3]).

During my PhD and Post Doc years at the University of Milan, I continued to investigate the microbial diversity associated to extreme environments, mainly focusing my attention to hot deserts. In this contest, I applied the microbial ecology to investigate the diversity of microbial communities associated with both wild plants and crops growing in arid lands (e.g., Sahara desert) in order to understand how plant growth promoting (PGP) microorganisms where selected by the root system of such plants. I further combined the ecological studies on desert plants’ microbiome with in vitro and in vivo “functional screening” of the associated microorganisms for possible biotechnological application. For instance, I demonstrated how the plant root system acts as a “resource island” able to attract and select microbial communities endowed with multiple PGP traits that sustain plant development under water limiting conditions ([4]; [5]; [6]).

Now, as researcher in KAUST, I expanded this research to other models plants (i.e., date palm and desert speargrasses), in order to understand which are the main factors driving the microbial assembly and the plant-microbe interactions in deserts ([7]) and desert agroecosystems ([8]). All these aspect will be instructive in developing agricultural biotechnologies approaches involving the use of PGP formulates that can improve crop production and sustainability ([9]; [10]; [11]) and, possibly, in restoring lands currently undergoing the desertification process ([12]).”

Could you describe the research your presentation covered?

In the unfavorable conditions of desert, only a limited number of plants evolving specific physiological and morphological adaptative traits were able to grow. Among such adaptative traits, the rhizosheath system is used mainly by speargrasses in response to desert conditions. Such unique root structure is made of root hair and sand grains that are packed together by the mucus and other products released by the roots. The rhizosheath protects root tissues and favors the absorption of water and nutrients.

However, it also provides an important ecological niche for macro- and micro-organisms proliferation. Since several cereal crops may develop rhizosheath structures, understanding the benefits that these can confer to the desert plants may help in exploiting the potential of these for improving water and nutrient management in crop plants.

I analyzed three species of desert plants aiming to have an insight into the effect of their associated microbiomes in their adaptation strategy to extreme desert conditions. It was important for me to analyze the plants growing in a restricted area, in this case, a single dune, to nullify the variability determined by the type of soil and the climate.

I discovered that, independently by the plant species, the most abundant members of the microbial communities were shared among the rhizosheath-root system of the three speargrasses. These results revealed how the rhizosheath root system has a crucial role in plant microbe-interaction and adaptation; it acts as a “hot spot” for the growth of microbes (i.e., bacteria and fungi) carrying important traits that would be beneficial to the plant in terms of growth promotion and protection from the stressful conditions of the desert.

These results lead to a better understanding of plant-microbe interactions in hot and arid environments, which is fundamental in predicting plants’ (including food-crops) adaptation to changing environmental conditions and stress.”

What do you hope to focus your research on in the future?

I am working on other deserts, such as the Empty Quarter in Saudi Arabia and the Grand Erg Oriental in the Tunisian Sahara. In these deserts, the local autochthonous plant species present the same rhizosheath structure we observed in the speargrasses of the Namib Desert.

The new data will be lead to a better understanding and modelling of plant-microbe associations in desert speargrasses. Moreover, the rhizosheath-root system was confirmed to be a “hot spot” for microbial diversity that can carry plant growth promoting functions and services.

Thus, for the applied part of this research, I am trying to define which are the common microbial components associated with the rhizosheath and understand their role in favouring the fitness of their hosts. The selection and isolation of such microorganisms can be also a further step to evaluate their protection capacity on agriculture crops, such as wheat or barley.”

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