title: Plant growth-promoting traits of epiphytic and endophytic yeasts isolated from rice and sugar cane leaves in Thailand.
abstract: A total of 1035 yeast isolates, obtained from rice and sugar cane leaves, were screened primarily for indole-3-acetic acid (IAA) production. Thirteen isolates were selected, due to their IAA production ranging from 1.2 to 29.3 mg g(-)(1) DCW. These isolates were investigated for their capabilities of calcium phosphate and ZnO(3) solubilisation, and also for production of NH(3), polyamine, and siderophore. Their 1-aminocyclopropane-1-carboxylate (ACC) deaminase, catalase and fungal cell wall-degrading enzyme activities were assessed. Their antagonism against rice fungal pathogens was also evaluated. Strain identification, based on molecular taxonomy, of the thirteen yeast isolates revealed that four yeast species - i.e. Hannaella sinensis (DMKU-RP45), Cryptococcus flavus (DMKU-RE12, DMKU-RE19, DMKU-RE67, and DMKU-RP128), Rhodosporidium paludigenum (DMKU-RP301) and Torulaspora globosa (DMKU-RP31) - were capable of high IAA production. Catalase activity was detected in all yeast strains tested. The yeast R. paludigenum DMKU-RP301 was the best IAA producer, yielding 29.3 mg g(-)(1) DCW, and showed the ability to produce NH3 and siderophore. Different levels of IAA production (7.2-9.7 mg g(-)(1) DCW) were found in four strains of C. flavus DMKU-RE12, DMKU-RE19, and DMKU-RE67, which are rice leaf endophytes, and strain DMKU-RP128, which is a rice leaf epiphyte. NH(3) production and carboxymethyl cellulase (CMCase) activity was also detected in these four strains. Antagonism to fungal plant pathogens and production of antifungal volatile compounds were exhibited in T. globosa DMKU-RP31, as well as a moderate level of IAA production (4.9 mg g(-)(1) DCW). The overall results indicated that T. globosa DMKU-RP31 might be used in two ways: enhancing plant growth and acting as a biocontrol agent. In addition, four C. flavus were also found to be strains of interest for optimal IAA production.
authors.affiliation: Department of Microbiology, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Pumin
authors.initials: P
authors.lastname: Nutaratat
authors.affiliation: Department of Microbiology, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900, Thailand; Center for Advanced Studies in Tropical Natural Resources, NRU-KU, Kasetsart University, Chatuchak, Bangkok 10900, Thailand. Electronic address: fscints@ku.ac.th.
authors.forename: Nantana
authors.initials: N
authors.lastname: Srisuk
authors.affiliation: Department of Chemistry, Faculty of Science, Srinakharinwirot University, Bangkok 10110, Thailand.
authors.forename: Panarat
authors.initials: P
authors.lastname: Arunrattiyakorn
authors.affiliation: Department of Microbiology, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900, Thailand; Center for Advanced Studies in Tropical Natural Resources, NRU-KU, Kasetsart University, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Savitree
authors.initials: S
authors.lastname: Limtong
mesh_terms: D000641:Ammonia / Q000378:metabolism; D002130:Calcium Phosphates / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D060026:Endophytes / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D012275:Oryza / Q000382:microbiology*; D063245:Plant Development; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000382:microbiology; D011073:Polyamines / Q000378:metabolism; D031786:Saccharum / Q000382:microbiology*; D017262:Siderophores / Q000378:metabolism; D013785:Thailand; D015003:Yeasts / Q000145:classification* / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D015034:Zinc Oxide / Q000378:metabolism
chemical_list: D002130:Calcium Phosphates; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011073:Polyamines; D017262:Siderophores; C030737:indoleacetic acid; D000641:Ammonia; C020243:calcium phosphate; D002374:Catalase; D015034:Zinc Oxide
keywords: IAA; Plant growth promotion; Rice endophyte; Rice epiphyte; Yeast