Open AccessEcological studies of the bio‐inoculant T richoderma hamatum LU 592 in the root system of P inus radiata
Author(s) -
Hohmann Pierre,
Jones Elisabeth Eirian,
Hill Robert A.,
Stewart Alison
Publication year - 2012
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2012.01340.x
Subject(s) - biology , pinus radiata , mycelium , trichoderma , rhizosphere , spore , radiata , botany , propagule , microbial inoculant , root system , potting soil , horticulture , vigna , inoculation , bacteria , genetics
The plant health‐ and growth‐promoting biological inoculant (bio‐inoculant) T richoderma hamatum LU 592 was transformed with the constitutively expressed green fluorescent protein ( gfp ) and hygromycin B resistance ( hph ) genes to specifically monitor the isolate in the root system of P inus radiata within a strong indigenous T richoderma population. A modified dilution plating technique was developed to allow the determination of the mycelia proportion of total propagule levels. LU 592 was shown to colonize the rhizosphere most effectively when 10 5 spores per pot were applied compared with inoculum concentrations of 10 3 and 10 7 spores per pot. LU 592 extended its zone of activity beyond the rhizosphere to at least 1 cm away from the root surface. A positive relationship was shown between P . radiata root maturation and the spatial and temporal proliferation of LU 592 in the root system. A steep increase in mycelia levels and proportion of penetrated root segments was observed after 12 weeks. This study reinforces the value of genetic markers for use in ecological studies of filamentous fungi. However, despite isolate‐specific recovery of the introduced isolate, it was shown that total propagule counts do not always correlate with the amount of viable mycelium present in the root system. Therefore, it is proposed that the differentiation of mycelia from spores and root penetration is used as more accurate measures of fungal activity.