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.

中文翻译：

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野生珍珠粟 (Pennisetum glaucum) 中的两层金缕梅 (Striga hermonthica) 抗性 29Aw

寄生植物紫金缕梅[独脚金(Delile) Benth.] 对撒哈拉以南非洲的谷物生产构成严重威胁。在自然侵染下，野生珍珠粟 [狼尾草(L.) R. Br.] line 29Aw 表现出对寄生虫的抗性，但其抗性机制尚不清楚。独脚金阻力可能是由于：（1）低感应独脚金萌发（附着前抗性）或（2）抑制寄生虫附着和发育（附着后抗性）。发芽生物测定和根室 (rhizotron) 抗性筛选测定用于确定附着前和附着后的程度独脚金与 29Aw 的电阻相比独脚金-敏感的“SOSAT-C88-P10”品种。关于预附着阻力，29Aw 刺激减少 10 倍独脚金种子在距寄主根 7.96 ± 2.75 mm 的最大发芽距离处发芽，而 SOSAT-C88-P10 的最大发芽距离为 35.94 ± 2.88 mm。附着后阻力显示减少 10 到 19 倍，缩短 2.5 倍独脚金与 SOSAT-C88-P10 相比，在 29Aw 上生长的生物量少 28 倍的幼苗。显微分析表明独脚金29Aw 的穿透在内胚层和皮质水平被阻止。更少 (22%) 进一步支持了 29Aw 的附着后阻力独脚金– 29Aw 中的宿主血管连接，而 SOSAT-C88-P10 中为 79%。总之，这些发现表明 29Aw 具有附着前和附着后抗性机制S.hermonthica。