Screening for PGPR to improve growth of Cistus ladanifer seedlings for reforestation of degraded mediterranean ecosystems
- 248 Downloads
A screening for PGPRs was carried out in the rhizosphere of wild populations of Cistus ladanifer. Two hundred and seventy bacteria were isolated, purified and grouped by morphological criteria. Fifty percent of the isolates were selected and tested for aminocyclopropanecarboxylic acid (ACC) degradation, auxin and siderophore production and phosphate solubilisation. Fifty-eight percent of the isolates showed at least one of the evaluated activities, with phosphate solubilisation and siderophore production being the most abundant traits. After PCR-RAPDs (Randomly amplified polymorphic DNA) analysis, 11 groups appeared with 85% similiarity, revealing the low diversity in the system. One strain of each group was tested in a biological assay, and those that enhanced Cistus growth were identified by 16S rDNA sequencing.
Although seven of the 11 assayed strains were phosphate solubilisers and able to produce siderophores, only one was really effective in increasing all biometric parameters in Cistus ladanifer seedlings, the lack of effect of the other six probably being due to the rich substrate used. This suggests that other mechanisms apart from nutrient mobilisation might be involved in growth promotion by this strain. However, the low diversity together with the high redundancy detected by PCR-RAPDs and the predominance of strains able to mobilise nutrients in the rhizosphere of Cistus reveals that the plant selects for bacteria that can help to supply scarce nutrients. This type of plant growth promoting rhizobacteria (PGPR) strains should be succesful in reforestation practices.
Keywordsgenetic diversity PGPR phosphate solubilisation rhizosphere reforestation
Unable to display preview. Download preview PDF.
This study has been financed by project FEDER 1FD97-1441.We would like to thank Linda Hamalainen for editorial help and Mª Josefa Fernandez for technical support. M.T. Pereyra was formerly a Comunidad Autonoma de Madrid postdoctoral student.
- Bowen G D, Rovira A D 1999 The rhizosphere and its management to improve plant growth Adv. Agron. 66: 1–103Google Scholar
- Burdman S, Jurkevith E, Okon Y 2000 Recent advances in the use of plant growth promoting rhizobacteria (PGPR) in agriculture Microb. Interact. Agric. Forest. 2: 229–250Google Scholar
- di Cello F, Bevivino A, Chiarini L, Fani R, Paffetti D, Tabacchioni S and Dalmastri C 1997 Biodiversity of a Burkholderia cepacia population isolated from the maize rhizosphere at different plant growth stages. Appl. Environ. Microbiol. 63, 4485–4493Google Scholar
- Enebak S A, Wei G, Kloepper J W 1997 Effects of plant growth-promoting rhizobacteria on loblolly and slash pine seedlings Forest Sci. 44: 139–144Google Scholar
- Harman J H 1967 Modern Factor Analysis. 2nd ed. Univ. Chicago Press, ChicagoGoogle Scholar
- Kucey R M N 1983 Phosphate-solubilizing bacteria and fungi in various cultivated and virgin Alberta soils Can. J. Soil Sci. 63: 671–678Google Scholar
- Lynch J M 1990 The Rhizosphere. Wiley-Interscience, Chichester, EnglandGoogle Scholar
- Marten P, Brueckner S, Berg G 2001 Biological plant protection using rhizobacteria – an environmental friendly alternative for biologicl control of soilborne and seedborne phytopathogenic fungi Gesunde Pflanzen 53: 224–234Google Scholar
- Probanza A, Mateos J L, Lucas J A, Ramos B, de Felipe M R, Gutierrez Mañero F J 2001 Effects of inoculation with PGPR Bacillus and Pisolitus tinctorius on Pinus pinea L. growth, bacterial rhizosphere colonization and mycorrhizal infection Microbial Ecol. 41: 140–148Google Scholar
- Richardson A E 2001 Prospects for using soil microorganism to improve the acquisition of phosphorus by plants Aust. J. Plant Physiol. 28: 897–906Google Scholar
- Wayne L G, Brenner D J, Colwell R R, Grimont P A D, Kandler O, Kirchevsdy M I, Moore L H, Moore W E C, Murray R G E, Stackerbrandt E, Starr M P, Turper H G 1987 Report of the ad hoc committee on reconciliation of approaches to bacterial systematics Int. J. Syst. Bacteriol. 37: 463–464CrossRefGoogle Scholar
- Wiehe W, Höflich G 1995 Establishment of plant growth promoting bacteria in the rhizosphere of subsequent plants after harvest of the inoculated precrops Microbiol. Res. 150: 331–336Google Scholar