Novel Sources of Witchweed (Striga) Resistance from Wild Sorghum Accessions

Mbuvi, Dorothy Annah; Masiga, Clet Wandui; Kuria, Erick Kimani; Masanga, Joel; Wamalwa, Mark; Mohamed, Abdallah; Odeny, Damaris Achieng; Hamza, Nada Babiker; Timko, Michael P.; Runo, Steven

doi:10.3389/fpls.2017.00116

Cited by 46 publications

(76 citation statements)

References 40 publications

(51 reference statements)

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“…Such specificity may be related to differences in quality, identity and/or quantity of the haustorium factor. The observed differential response is consistent with a previous report by Mbuvi et al (2017) who reported that the potential number of haustoria is a product of the concentration and/or quality of haustoria inducing factor and the parasite's individual ability to respond. The host specificity and variability of S. hermonthica populations might affect the efficiency of introducing new resistant cultivars as a control measure against the parasitic weed.…”

Section: Effects Of In-situ Root Exudates Of Sorghum Cultivars On Pensupporting

confidence: 92%

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Dafaallah

2020

J. Res. Weed Sci.

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Striga hermonthica (Del.) Benth., Orobanchaceae, is an obligate root parasite on important cereal crops. The aim of this study is to investigate variability and host specificity in the early developmental stages of S. hermonthica parasitism in response to in-situ root exudates of sorghum. Field surveys were conducted during the seasons 2013/14 in Striga endemic areas in Sudan to collect seeds from the parasite. Fifteen S. hermonthica populations were collected. An in vivo experiment was conducted at the University of Gezira, Sudan to study the effects of in-situ root exudates of three sorghum cultivars on percentage of seed germination, haustorium initiation, attachment and penetration. Treatments were arranged in a factorial completely randomized design with three replicates. Data were subjected to the analysis of variance (P  0.5). The results revealed the highest percentage of seed germination (46.9-57.5 %), haustorium initiation (73.8-77.9 %), attachment (38.4-40 %) and penetration (20.7-23.7 %) into sorghum root was induced by in-situ root exudates of sorghum cv. Abu-70 and by sorghum cv. Wad Ahmed. While, the lowest percentage of seed germination (53.5 %), haustorium initiation (45.2 %), attachment (5.8 %) and penetration (1.5 %) into sorghum root was induced by in-situ root exudates of Hakika. The results also revealed that percentage of seed germination, haustorium initiation, attachment and penetration of S. hermonthica populations collected from infected sorghum in response to sorghum in-situ root exudates was the highest. While, the percentage of seed germination, haustorium initiation, attachment and penetration of S. hermonthica populations collected from infected millet in response to sorghum in-situ root exudates was the lowest. This study confirms the existence of two levels of physiological specialization in S. hermonthica populations in Sudan. Moreover, two strains of S. hermonthica are one specific to sorghum and the other to millet.

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Section: Effects Of In-situ Root Exudates Of Sorghum Cultivars On Pensupporting

confidence: 92%

Untitled

Dafaallah

2020

J. Res. Weed Sci.

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“…Our ndings underscore the need to continuously screen hosts for Striga resistance as a rmed by successful identi cation of new Striga resistant sorghum genotypes. The resistance by the genotypes, as determined by the number, size and biomass of Striga seedlings attached, is comparable to what has been reported in previous work that used rhizotrons [12,17]. For example, we found an average of 57 attachments on N13 compared to a mean of 56 reported by [12] and 75 [18].…”

Section: New Sources Of Striga Resistance From the Sorghum Diversity supporting

confidence: 89%

GWAS Provides Biological Insights into Mechanisms of the Parasitic Plant (Striga) Resistance in Sorghum

Kavuluko

Kibe

Sugut

et al. 2020

Preprint

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Background: Sorghum yields in sub-Saharan Africa (SSA) are greatly reduced by parasitic plants of the genus Striga (witchweed). Vast global sorghum genetic diversity collections, as well as the availability of modern sequencing technologies, can be potentially harnessed to effectively manage the parasite. Results: We used laboratory assays – rhizotrons to screen a global sorghum diversity panel to identify new sources of resistance to Striga; determine mechanisms of resistance, and elucidate genetic loci underlying the resistance using genome-wide association studies (GWAS). New Striga resistant sorghum determined by the number, size and biomass of parasite attahements were identified. In total 13 sorghum genotypes had higher or comparable resistance levels as IS9830 and N13 used as resistance checks. Resistance was by; i) mechanical barriers that blocked parasite entry, ii) elicitation of a hypersensitive reaction that interfered with parasite development, and iii) the inability of the parasite to develop vascular connections with hosts. Resistance genes underpinning the resistance corresponded with the resistance mechanisms and included pleiotropic drug resistance proteins that transport resistance molecules; xylanase inhibitors involved in cell wall fortification and hormonal regulators of resistance response, Ethylene Response Factors. Conclusions: Our findings are of fundamental importance to developing durable and broad-spectrum resistance against Striga and have far-reaching applications in many SSA countries where Striga threatens the livelihoods of millions of smallholder farmers that rely on sorghum as a food staple.

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“…5). The differential response in N13 could possibly be attributed to mechanical resistance, as reported by Grenier et al (2007) and Mbuvi et al (2017). In addition, high proportions of sorgomol in some genotypes, such as Wad Fahel, did not necessarily result in higher germination-stimulating activity, although it was associated with a higher Striga infection level in the pot experiment (Fig.…”

Section: Discussionmentioning

confidence: 65%

Genetic variation in Sorghum bicolor strigolactones and their role in resistance against Striga hermonthica

Mohemed¹,

Charnikhova²,

Fradin³

et al. 2018

Journal of Experimental Botany

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Sorghum is an important food, feed, and industrial crop worldwide. Parasitic weeds of the genus Striga constitute a major constraint to sorghum production, particularly in the drier parts of the world. In this study we analysed the Striga germination stimulants, strigolactones, in the root exudates of 36 sorghum genotypes and assessed Striga germination and infection. Low germination-stimulating activity and low Striga infection correlated with the exudation of low amounts of 5-deoxystrigol and high amounts of orobanchol, whereas susceptibility to Striga and high germination-stimulating activity correlated with high concentrations of 5-deoxystrigol and low concentrations of orobanchol. Marker analysis suggested that similar genetics to those previously described for the resistant sorghum variety SRN39 and the susceptible variety Shanqui Red underlie these differences. This study shows that the strigolactone profile in the root exudate of sorghum has a large impact on the level of Striga infection. High concentrations of 5-deoxystrigol result in high infection, while high concentrations of orobanchol result in low infection. This knowledge should help to optimize the use of low germination stimulant-based resistance to Striga by the selection of sorghum genotypes with strigolactone profiles that favour normal growth and development, but reduce the risk of Striga infection.

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Novel Sources of Witchweed (Striga) Resistance from Wild Sorghum Accessions

Cited by 46 publications

References 40 publications

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GWAS Provides Biological Insights into Mechanisms of the Parasitic Plant (Striga) Resistance in Sorghum

Genetic variation in Sorghum bicolor strigolactones and their role in resistance against Striga hermonthica

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