Essential Plant Nutrients Impair Post-Germination Development of Striga in Sorghum
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Date
2023
Authors
Mwangangi, Immaculate M.
Büchi, Lucie
Runo, Steven
Rodenburg, Jonne
Journal Title
Journal ISSN
Volume Title
Publisher
Plants People Planet.
Abstract
Societal Impact Statement
Infestation by the parasitic weed Striga is a major cause of cereal crop production
losses on smallholder farms in Africa. Essential plant nutrients play an important indirect
role in parasite seed germination, the first prerequisite for successful parasitism.
Here, we demonstrate that increasing the nutrient availability for the host plant can
also impede Striga development beyond its germination, independent of the resistance
levels of the sorghum host. This insight provides additional support for crop
protection recommendations to Striga-affected farmers. Growing a resistant crop
variety combined with adequate levels of fertilisers should be the backbone of
defence against this parasitic weed.
Summary
• Striga hermonthica is a widespread parasitic weed in sub-Saharan Africa and an
important biotic constraint to sorghum production. Resistant varieties and fertilisers
are crucial components of integrated Striga management. N and P fertilisers
reduce the production of host-plant strigolactones, known as Striga
germination stimulants, and thereby reduce infection. Whether essential plant
nutrients affect the parasite–host interaction beyond Striga germination is
unknown.
• We conducted mini-rhizotron assays to investigate the effects of macronutrient
and micronutrient availability on post-germination Striga development. Four
sorghum genotypes (Framida, IS10978, N13, IS9830) covering the complete
array of known mechanisms of post-attachment resistance were compared with
susceptible genotype Ochuti. Plants were infected with pre-germinated Striga
seeds and subjected to four nutrient treatment levels: (1) 25% of the optimal
concentration of Long Ashton solution for cereals; (2) 25% macronutrient and
optimal micronutrient concentration; (3) optimal macronutrient and 25% micronutrient
concentration; and (4) optimal macronutrient and micronutrient
concentrations.
• Compared with the 25% base nutrient level, treatments supplemented with macronutrients
reduced the number of viable vascular connections established by pregerminated
Striga seedlings as well as the total parasite biomass on the sorghum
root system. Macronutrient treatment effects were observed across sorghum
genotypes, independent of the presence and type of post-attachment resistance,
but appeared to specifically improve mechanical resistance, hypersensitive and
incompatibility responses before Striga reaches the host-root xylem.
• This study demonstrates, for the first time, that nutrient availability drives Striga
parasitism beyond the germination stages. Increased availability of nutrients, in
particular macronutrients, enhances host-plant resistance in post-attachment
stages, reinforcing the importance of current fertiliser recommendations
Description
article
Keywords
fertiliser, host resistance, mini-rhizotron, root parasitic weeds, Sorghum bicolor, witchweed
Citation
Mwangangi, I. M., Büchi, L., Runo, S., & Rodenburg, J. (2023). Essential plant nutrients impair post‐germination development of Striga in sorghum. Plants, People, Planet.