| Autor: |
Haussmann, B. I. G., Hess, D. E., Omanya, G. O., Reddy, B. V. S., Welz, H. G., Geiger, H. H. |
| Zdroj: |
Crop Science; September 2001, Vol. 41 Issue: 5 p1507-1512, 6p |
| Abstrakt: |
The parasitic angiosperms Striga hermonthica(Del.) Benth. and S. asiatica(L.) Kuntze severely constrain cereal production in sub‐Saharan Africa. A resistance mechanism to these root parasites in sorghum [Sorghum bicolor(L.) Moench] is low exudation of striga seed germination stimulants. The trait is controlled by a single recessive gene in the sorghum × S. asiaticainteraction, but information is lacking for S. hermonthicaObjectives of this investigation were to study the inheritance of stimulation of S. hermonthicaseed germination in three F2and two F3:5recombinant inbred populations of sorghum, and to determine the effects of striga populations from Mali, Niger, and Kenya on the effectiveness of the low‐stimulant character. An agar‐gel assay was employed for this purpose. In this laboratory assay, the maximal distance between sorghum rootlets and germinated striga seed (“maximal germination distance”) reflects the magnitude of germination stimulation. Bimodal frequency distributions supported the hypothesis of one recessive gene with a major effect for low maximal germination distance in progenies from crosses of low‐stimulant lines (Framida, IS 9830) with a high‐stimulant line (E 36‐1), tested with striga from Mali or Niger. However, low‐ versus high‐stimulant classes were not always clearly distinct, indicating that additional minor genes modified maximal germination distance in the progenies. The Kenyan striga population led to higher maximal germination distances and larger overlap of low‐ and high‐stimulant classes than striga from Mali or Niger. Minor genes seemed therefore more important with Kenyan striga seed. The general involvement of minor genes in stimulating S. hermonthicaseed germination was also evident from the heritable, quantitative variation observed in F3:5lines derived from a cross of the high‐stimulant lines N 13 and E 36‐1. Because of the higher sensitivity of Kenyan striga to germination stimulation, the low‐stimulant character may be less effective in Kenyan fields. |
| Databáze: |
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