Université de Lausanne
Department de Biologie Moléculaire végétale
Tel: +41 (0)21 692 42 33
Arbuscular mycorrhiza symbiosis (AMs) is the oldest and the most common type of mycorrhiza on the planet that occurs between vascular plants and fungi of the phylum Glomeromycota. AM symbiosis is a mutualistic relation based on bidirectional nutrient exchange: the fungus receives photosynthate and in return it improves the nutrition of the plant, notably by increasing phosphate uptake.
Defining responsiveness in maize
It is well known that under Pi–limiting conditions mycorrhizal plants usually grow bigger than plants not colonized by AM fungi (Smith and Read 1997). Different plant species are known to vary in their responses to AM colonization (Smith et al., 2004). The magnitude of response to AMF colonization can vary from a negative growth response, through neutral up to considerably enhanced biomass production (Johnson et al., 1997). Responsiveness has been defined as the difference in performance between colonized and non-colonized plants at a given level of nutrient availability. Absolute responsiveness is calculated as R=M-NC, where M is a total shoot or root weight of colonized plant, NC- total shoot or root weight of colonized plant. I’m interesting in defining molecular components of such a complex trait as responsiveness, for this reason I want to study phosphate (Pi) transporters, that has been shown to be a key feature of a symbiosis (Karandashov and Bucher 2005). Invastigate Pi transport mechanisms and its gene regulation will further our understanding of the intimate interaction between the plant and AM fungus.
Pi transporters in maize
Phosphate nutrition is one of the major benefits that plants derive from AM fungi, thus responsiveness to AM colonization might be linked to Pi uptake efficiency. The acquisition of Pi is generally mediated by Pi transporter proteins belonging to the PHT1 class. Two classes of Pi transporters have been suggested to be involved in symbiotic Pi transport: the AM-Induced (AMI) Pi transporters such as potato PT3 and Lotus japonicus PT3 and the AM-Specific (AMS) Pi transporters like rice PT11, M. truncatula PT4 of and tomato/potato/petunia PT4 (Javot et al., 2007a). Interestingly, studies on AM-specific MtPT4 revealed that MtPT4 is essential for development of AM symbiosis.
Still little is know about Pi transporters in maize. To determine and confirm which Pi transporters are involved in the symbiotic and/or direct Pi -uptake pathway, I want to determine the expression level of Pi transporters relative to changes of colonization levels and to different Pi and fertilization. Furthermore I also want to investigate functionality of the candidate transporter genes by complementation of the yeast pam2 mutant, that lacks high-affinity Pi transporters (Martinez and Persson 1998). Moreover it would be very interesting to examine the kinetics of the transport quantitative 32 Pi uptake.
The role of arbuscular mycorrhiza in facilitating the uptake of nutrients from the soil has been well documented (Smith and Read, 1997). However regulation, coordination and respective contribution of direct and symbiotic Pi acquisition pathways are still not understood and differ across and within plant species. For this reason, I am very interested in investigating the uptake, transfer and accumulation of phosphorus by mycorrhizal and nonmycorrhizal in different maize genotypes.
Genetic traits determining mycorrhizal responsiveness in maize (preliminary title)
2009 - present: PhD in Plant Molecular Biology, University of Lausanne
2004/09 -2009/06: Master of Science in Biotechnology (Jagiellonian University,Poland)
2008/03 -2009/03: Scholarship at University of Milan, Production of Plant Department
2007/10 - 2008 /02: Training at Parco Tecnologico Padano, Piattaforma Genomica
1999/09 - 2003/09: The Króla Jan III Sobieskiego High School in Kraków (Poland)