L. Miche et al., Physiological and cytological studies on the inhibition of Striga seed germination by the plant growth-promoting bacterium Azospirillum brasilense, EUR J PL P, 106(4), 2000, pp. 347-351
Striga hermonthica (Del.) Benth. is an obligate parasitic weed of tropical
cereals whose rhizosphere can also be colonised by bacteria of the genus Az
ospirillum. A previous study demonstrated that the two organisms (Azospiril
lum and striga) interacted during cerealroot colonisation. Two strains of A
. brasilense isolated from an African sorghum rhizosphere prevented the ger
mination of striga seeds although they were stimulated to germinate by the
presence of sorghum roots. Azospirillum cells suspended in a synthetic germ
ination stimulant (GR24) did not inhibit striga seed germination, but did b
lock radicle elongation. Those radicles had an abnormal morphology, and con
tained no vacuolated cells in the root elongation zone. Lipophilic compound
s extracted from the medium of bacteria in the log and stationary growth ph
ases prevented the germination of striga seeds.