Periodic Reporting for period 1 - MYCROPHOS (The genetic bases of mycorrhizal root responses to phosphate)
Reporting period: 2017-03-01 to 2019-02-28
MYCROPHOS aimed at understanding the different root adaptive strategies of arbuscular mycorrhizal (AM) and non-mycorrhizal plants to low phosphate environment. Phosphorous is an essential element for plants, thus its low availability in the soil leads farmers to ensure plant productivity through increasing doses of fertilizers. Prompted by a global consensus encouraging sustainable agricultural intensification, throughout the last decades European researchers have been dealing with the topic through different approaches. Within this project, we have been combining root growth and anion content measurement in response to different levels of phosphate in a large panel of Lotus japonicus and Medicago truncatula natural accessions. In both cases, we were able to implement a high throughput system allowing root image segmentation and root trait quantification. The data has been use for genetic mapping, through Genome Wide Association, and gave as an outcome hundreds of genetic loci associated with variation in root responses to phosphate. Consistently with different targets of Horizon2020 call, MYCROPHOS have set the bases to tackle crop improvement in a holistic manner (considering the huge richness of natural variation among different species as a biodiversity genetic bank), and to seek for novel breeding targets to improve yield. In fact, optimizing high throughput imaging, together with GWAS, is a way to develop novel breeding strategies and tools for a continuous support to a dynamic breeding sector. Moreover wince we identified different genes variants that allowed an increase in accumulation of phosphate in plant tissues of Lotus japonicus, this knowledge could be transferred to other legumes that are used in agriculture.
WIthin the MYCROPHOS project we have: 1) Identified candidate genes and gene networks governing early root traits in phosphate deficiency conditions through Genome Wide Association Studies (GWAS) on 130 Lotus japonicus and 267 Medicago truncatula ecotypes at different time points. 2) Compared the genetic determinants regulating root responses to phosphate in three plant species (Lotus, Medicago and Arabidopsis) and found specific genetic loci, equally important in Lotus and Medicago, that could be the target of future studies. 3) Investigated cross-talk between root system architecture and nutrient uptake in Lotus japonicus, especially under nutrient starvation conditions, and discovered important negative correlation happening between plant size and nutrient concentration.
MYCROPHOS allowed to greatly improved current knowledge of legume early responses to phosphate stress. This has been possible thanks to technical and bioinformatics advancement. In particular an open-source root image analysis software (Brat), previously developed for the study of Arabidopsis thaliana, has been implemented and applied for the investigation of Lotus and Medicago root responses to phosphate. In parallel an efficient bioinformatics pipeline has been used to run GWAS on all the measured traits.