P6 - Ecological interactions of cereals with root-associated microorganisms with crop health promoting features

Status:         Ongoing

Duration:     2021 - 2025

Keywords:   Plant Pathology, Soil Ecology, Plant Genetics, Plant-microbe interactions, soil microbial ecology

Description

Striga spp. is a major threat to cereal and legume production, putting the food security and economy of small-holder farmers in sub-Saharan Africa at severe risk. This is manifested in the fact that Striga spp. infestation can result in up to 90 % loss of both cereal and legume production. A consensus exists that there is yet no single measure to efficiently control Striga spp. This is mainly because of the limited fundamental knowledge of the genetics and ecology of Striga spp. and its interaction with its hosts and host root-associated microorganisms, including fungal biocontrol agents (BCA) and plant-growth promoting rhizobacteria (PGPR). Since Striga spp. is a root parasite, it is speculated that BCA and PGPR play a key role in controlling the emergence and development of Striga spp. At the same time, PGPR may exhibit beneficial effects on growth promotion of the host to strengthen its tolerance against Striga spp. attacks, while on the other hand, PGPR may also induce, similar to BCA, direct suicidal effects on Striga spp. Such hypothesized associations between Striga spp. and crops (e.g. cereals such as sorghum and maize), as well as BCA and PGPR remain largely unknown. Taking the PhD study of W. Anteyi (CLIFOOD 1) as fundamental baseline, the central question can be set if both BCA and PGPR play an integrative role in the Striga-crop pathosystem. This is specifically related to the unknown potential of PGPR to colonize the inner parts of the hyphae of fungal BCA enabling a more efficient colonization of the root system of the host. This knowledge gap is the central impetus of this PhD project.

This PhD study will elaborate the complex and fascinating ecological system of cereals (e.g. maize, sorghum), and root associated microorganisms, including PGPR and BCA. Regarding the first objective, the study will emphasize the colonization pathway of both PGPR and BCA in the root system, focusing at the microbe-microbe interaction (hyphae colonization of PGPR). It includes the investigation of uptake (signaling pathways between the two microbial organisms), transport and release patterns of the PGPR in association with the BCA. For the second objective, the plant perspective will be regarded. The plant reveals a response to the colonization of endophytic microorganisms in the root (e.g. lignification of the central root cortex as response to the colonization of the BCA). It will central research task to understand to what extent the colonizing PGPR may compensate this potential negative effect of BCA colonization, as prompted by the hypothesized more efficient colonization of the PGPR through the fungal hyphae. Likewise, the third research objective of the PhD study will be the investigation how the fungal BCA in terms of its survival and colonization efficiency in the root system of the host might benefit from the PGPR presence (e.g. utilization of resources (e.g. metabolites, hormones) released by the PGPR). 

Involved persons

Prof. Dr. Frank Rasche
Mekuria Wolde Assena

Involved institutions

Agronomy in the Tropics and Subtropics (490 e), Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim

Sponsors

Supported by the DAAD program Bilateral SDG Graduate Schools, funded by the Federal Ministry for Economic Cooperation and Development (BMZ)