Mj. Mayer et al., EARLY STAGES OF INFECTION OF MAIZE (ZEA-MAYS) AND PENNISETUM-SETOSUM ROOTS BY THE PARASITIC PLANT STRIGA-HERMONTHICA, European journal of plant pathology, 103(9), 1997, pp. 815-827
Infection of young roots of maize (Zea mays L.) by the parasitic plant
Striga hermonthica (Del.) Benth, was examined. Attachment to and pene
tration of roots occurred within 1-2 days after inoculation. Subsequen
t growth through the cortex to the host stele and proliferation of par
asite xylem tissue was commonly completed by 3-4 days after inoculatio
n. Histochemical staining showed that young maize roots Clo not contai
n major wall-thickening components. However, an increase in cell wall
fluorescence and endodermal cell wall thickness was often seen at the
site of infection and in the surrounding maize root tissue at 3 days a
fter inoculation. This host response was variable and did not prevent
rapid and successful penetration by the parasite. In contrast, uninfec
ted roots of Pennisetum setosum (Sw.) L. Rich., a species resistant to
S. hermonthica, had substantial thickening of the inner endodermal ce
ll walls and exhibited further cell wall thickening at the stele upon
infection. Examination of infections on both hosts demonstrated the pr
esence of autofluorescent material at the host-parasite interface. Thi
s material was thicker and more extensive at the P. setosum-S. hermont
hica interface than at the maize-S. hermonthica interface, and contain
ed polyphenols and lignin. Examination of the host-parasite xylem conn
ections in maize revealed substantial invasion of the host stele by bo
th parenchyma and tracheary elements. In a few cases of P. setosum inf
ection, parasite cells entered the stele; however, this did not lead t
o successful establishment of the parasite.