Striga seed-germination activity of root exudates and compounds present in stems of Striga host and nonhost (trap crop) plants is reduced due to root colonization by arbuscular mycorrhizal fungi.

Root colonization by arbuscular mycorrhizal (AM) fungi reduces stimulation of seed germination of the plant parasite Striga (Orobanchaceae). This reduction can affect not only host plants for Striga, resulting in a lower parasite incidence, but also false hosts or trap crops, which induce suicidal Striga seed germination, thereby diminishing their effectiveness. In order to better understand these AM-induced effects, we tested the influence of root colonization by different AM fungi on the seed-germination activity of root exudates of the Striga hermonthica nonhost plants cowpea and cotton on S. hermonthica. We also tested the effect of AM fungi on the seed-germination activity of the Striga gesnerioides host plant cowpea on S. gesnerioides. Moreover, we studied whether mycorrhization affects the transport of seed-germination activity to above-ground plant parts. Mycorrhization not only resulted in a lower seed germination of S. gesnerioides in the presence of root exudates of the S. gesnerioides host cowpea but also seed germination of S. hermonthica was also lower in the presence of root exudates of the S. hermonthica nonhosts cowpea and cotton. Downregulation of the Striga seed-germination activity occurs not only in root exudates upon root colonization by different AM fungi but also in the compounds produced by stems. The lowered seed-germination activity does not appear to depend on the presence of seed germination inhibitors in the root exudates of mycorrhizal plants. The implication for Striga control in the field is discusse

The tripartite interaction between sorghum, Striga hermonthica, and arbuscular mycorrhizal fungi

Striga hermonthica is a major biological constraint to cereal production inAfrica. The intricate association between this phytoparasite and the cereal host makes management difficult. Damage to the host begins before Striga comes out of the soil. Also, infestation correlates negatively with soil fertility. Arbuscular mycorrrhizal (AM) fungi have a variety of ecological functions ranging from improved uptake of immobile nutrients, protection of host from pathogens, to soil aggregation. The question whether these beneficial micro-organisms could play a role within the Striga -cereal (patho)systemwas addressed. Inoculating Striga -infested sorghum with AM fungi in pots or in the field resulted in a significant reduction in the performance of Striga in terms of numbers attached to the roots, relative time of emergence, numbers emerged and dry weight of Striga shoots at sorghum harvest. AM effects on Striga were more pronounced with the Striga -tolerant S-35 sorghum cultivar compared to effects with the Striga -sensitive CK60B. Inoculation with AM fungi compensated for damage by Striga in the S-35 cultivar. This compensation was independent of AM inoculum density and was not affected by P application. Germination of preconditioned Striga seeds after exposure to root exudates from sorghum colonized by AM fungi was significantly reduced, with effects more prominent with exudates from S-35 plants. AM fungi have the potential to affect Striga during germination, attachment, emergence, and possibly subsequent growth and development. It is important to understand the kind of management practices that farmers can apply to enhance mycorrhizal performance in an integrated management system

New cassava germplasm for food and nutritional security in central Africa

Open Access Journal; Published online: 01 Apr 2021Cassava is a key food security crop in Central Africa, but its production depends largely on the use of local farmers’ varieties characterized by inherently low yield which is compounded by generally high susceptibility to various growth and yield-limiting pests and diseases. Improved cassava genotypes have demonstrated the potential to substantially improve cassava’s contribution to food security and the development of the cassava industry and the improvement of nutrition status elsewhere in Western Africa. Eleven improved cassava genotypes were compared with a local landrace (LMR) used as a check under field conditions over two years in eight locations, grouped in four agro-ecologies in Cameroon. Pest and disease abundance/incidence and damage severity were evaluated. At harvest, root yield and carotenoid content were measured. Best linear unbiased predictors showed the lowest breeding value for LMR with the cassava mosaic virus disease (+ 66.40 ± 2.42) compared with 1.00 ± 0.02% for the most susceptible improved genotype. Two genotypes (I010040-27 and I011797) stood out for having higher predicted fresh root yield means which were at least 16 times greater compared with LMR. Predicted total carotenoid content was the highest (+ 5.04 ± 0.17) for improved genotype I070593 compared with LMR which showed the lowest (− 3.90 ± 0.06%) and could contribute to the alleviation of vitamin A deficiency from cassava-based food systems. Diffusion of high-yielding and nutritious genotypes could alleviate food and nutritional security in Central Africa

De drieweg interactie tussen sorghum, Striga hermonthica en arbusculaire mycorrhiza schimmels

Striga hermonthica is a major biological constraint to cereal production in Africa. The intricate association between this phytoparasite and the cereal host makes management difficult. Damage to the host begins before Striga comes out of the soil. Also, infestation correlates negatively with soil fertility. Arbuscular mycorrrhizal (AM) fungi have a variety of ecological functions ranging from improved uptake of immobile nutrients, protection of host from pathogens, to soil aggregation. The question whether these beneficial micro-organisms could play a role within the Striga-cereal (patho)system was addressed. Inoculating Striga-infested sorghum with AM fungi in pots or in the field resulted in a significant reduction in the performance of Striga in terms of numbers attached to the roots, relative time of emergence, numbers emerged and dry weight of Striga shoots at sorghum harvest. AM effects on Striga were more pronounced with the Striga-tolerant S-35 sorghum cultivar compared to effects with the Striga-sensitive CK60B. Inoculation with AM fungi compensated for damage by Striga in the S-35 cultivar. This compensation was independent of AM inoculum density and was not affected by P application. Germination of preconditioned Striga seeds after exposure to root exudates from sorghum colonized by AM fungi was significantly reduced, with effects more prominent with exudates from S-35 plants. AM fungi have the potential to affect Striga during germination, attachment, emergence, and possibly subsequent growth and development. It is important to understand the kind of management practices that farmers can apply to enhance mycorrhizal performance in an integrated management syste

Can arbuscular mycorrhizal fungi contribute to Striga management on cereals in Africa?

Witchweeds (Striga spp.) are important root parasites of many cereal and legume crops in savanna and Sahelian regions of Africa. Evidence on the possible role of soil pathogenic bacteria and fungi in Striga control has been obtained. Here, the authors report that arbuscular mycorrhizal (AM) fungi can also affect the interaction between Striga and cereals. AM fungi negatively impacted on Striga seed germination, reduced the number of Striga seedlings attaching and emerging, and delayed the emergence time of Striga both in pot and field experiments. AM fungi enhanced the performance of the cereal host, allowing it to withstand Striga damage better. Management strategies for AM fungi for Striga control as part of an integrated management system are discusse

Can arbuscular mycorrhizal fungi contribute to Striga management on cereals in Africa?

Witchweeds (Striga spp.) are important root parasites of many cereal and legume crops in savanna and Sahelian regions of Africa. Evidence on the possible role of soil pathogenic bacteria and fungi in Striga control has been obtained. Here, the authors report that arbuscular mycorrhizal (AM) fungi can also affect the interaction between Striga and cereals. AM fungi negatively impacted on Striga seed germination, reduced the number of Striga seedlings attaching and emerging, and delayed the emergence time of Striga both in pot and field experiments. AM fungi enhanced the performance of the cereal host, allowing it to withstand Striga damage better. Management strategies for AM fungi for Striga control as part of an integrated management system are discusse