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15 February 2021 Two-Tier Witchweed (Striga hermonthica) Resistance in Wild Pearl Millet (Pennisetum glaucum) 29Aw
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The parasitic plant purple witchweed [Striga hermonthica (Delile) Benth.] poses a serious threat to cereal production in sub-Saharan Africa. Under natural infestation, the wild pearl millet [Pennisetum glaucum (L.) R. Br.] line 29Aw demonstrates resistance against the parasite, but the mechanism of its resistance is unknown. Striga resistance can be due to: (1) low induction of Striga germination (pre-attachment resistance) or (2) inhibition of parasite attachment and development (post-attachment resistance). Germination bioassays and root chamber (rhizotron) resistance-screening assays were used to determine the extent of pre- and post-attachment Striga resistance in 29Aw compared with the Striga-susceptible ‘SOSAT-C88-P10’ variety. Regarding pre-attachment resistance, 29Aw stimulated 10-fold less Striga seed germination at a maximum germination distance of 7.96 ± 2.75 mm from the host root compared with 35.94 ± 2.88 mm in SOSAT-C88-P10. Post-attachment resistance revealed 10- to 19-fold fewer and 2.5-fold shorter Striga seedlings with 28-fold less biomass growing on 29Aw compared with SOSAT-C88-P10. Microscopic analysis showed that Striga penetration in 29Aw was blocked at the endodermal and cortical levels. Post-attachment resistance in 29Aw was further supported by fewer (22%) Striga–host vascular connections in 29Aw compared with 79% in SOSAT-C88-P10. Together, these findings demonstrate that 29Aw harbors both pre- and post-attachment resistance mechanisms against S. hermonthica.

© The Author(s), 2021. Published by Cambridge University Press on behalf of the Weed Science Society of America.
Olivier Dayou, Willy Kibet, Patroba Ojola, Prakash Irappa Gangashetty, Susann Wicke, and Steven Runo "Two-Tier Witchweed (Striga hermonthica) Resistance in Wild Pearl Millet (Pennisetum glaucum) 29Aw," Weed Science 69(3), 300-306, (15 February 2021).
Received: 1 September 2020; Accepted: 1 February 2021; Published: 15 February 2021

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