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

Mbuvi, D A and Masiga, C W and Kuria, E and Masanga, J and Wamalwa, M and Mohamed, A and Odeny, D A and Hamza, N and Timko, M P and Runo, S (2017) Novel Sources of Witchweed (Striga) Resistance from Wild Sorghum Accessions. Frontiers in Plant Science, 8 (116). pp. 1-15. ISSN 1664-462X

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Abstract

Sorghum is a major food staple in sub-Saharan Africa (SSA), but its production is constrained by the parasitic plant Striga that attaches to the roots of many cereals crops and causes severe stunting and loss of yield. Away from cultivated farmland, wild sorghum accessions grow as weedy plants and have shown remarkable immunity to Striga. We sought to determine the extent of the resistance to Striga in wild sorghum plants. Our screening strategy involved controlled laboratory assays of rhizotrons, where we artificially infected sorghum with Striga, as well as field experiments at three sites, where we grew sorghum with a natural Striga infestation. We tested the resistance response of seven accessions of wild sorghum of the aethiopicum, drummondii, and arundinaceum races against N13, which is a cultivated Striga resistant landrace. The susceptible control was farmer-preferred variety, Ochuti. From the laboratory experiments, we found three wild sorghum accessions (WSA-1, WSE-1, and WSA-2) that had significantly higher resistance than N13. These accessions had the lowest Striga biomass and the fewest and smallest Striga attached to them. Further microscopic and histological analysis of attached Striga haustorium showed that wild sorghum accessions hindered the ingression of Striga haustorium into the host endodermis. In one of the resistant accessions (WSE-1), host and parasite interaction led to the accumulation of large amounts of secondary metabolites that formed a dark coloration at the interphase. Field experiments confirmed the laboratory screening experiments in that these same accessions were found to have resistance against Striga. In the field, wild sorghum had low Area under the Striga Number Progressive curve (AUSNPC), which measures emergence of Striga from a host over time. We concluded that wild sorghum accessions are an important reservoir for Striga resistance that could be used to expand the genetic basis of cultivated sorghum for resistance to the parasite.

Item Type: Article
Divisions: Research Program : East & Southern Africa
CRP: CGIAR Research Program on Dryland Cereals
Uncontrolled Keywords: Striga resistance; witchweed; sorghum; wild sorghum relatives; Sub-Saharan Africa Nomenclature: Striga hermonthica benth.; witchweed; sorghum bicolor
Subjects: Mandate crops > Sorghum
Depositing User: Mr Ramesh K
Date Deposited: 10 Mar 2017 11:04
Last Modified: 10 Mar 2017 11:18
URI: http://oar.icrisat.org/id/eprint/9903
Official URL: http://dx.doi.org/10.3389/fpls.2017.00116
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: The National Academies of Science (NAS) supported this research project under the Partnerships Enhanced Engagement in Research (PEER) program (contract number NAS Sub-Grant Award Letter Agreement Number PGA-2000003439). The Sub-Grant Agreement was funded under Prime Agreement Number AID-OAA-A-11-00012, which was entered into by and between the NAS and the United States Agency for International Development (USAID). MPT was supported by grants from the National Science Foundation (DBI-0701748 and IBN-0322420). We further acknowledge the fieldwork support we received from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).
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