title: Plant growth promotion and Penicillium citrinum.
abstract: BACKGROUND
  Endophytic fungi are known plant symbionts. They produce a variety of beneficial metabolites for plant growth and survival, as well as defend their hosts from attack of certain pathogens. Coastal dunes are nutrient deficient and offer harsh, saline environment for the existing flora and fauna. Endophytic fungi may play an important role in plant survival by enhancing nutrient uptake and producing growth-promoting metabolites such as gibberellins and auxins. We screened roots of Ixeris repenes (L.) A. Gray, a common dune plant, for the isolation of gibberellin secreting endophytic fungi.
  
  
  RESULTS
  We isolated 15 endophytic fungi from the roots of Ixeris repenes and screened them for growth promoting secondary metabolites. The fungal isolate IR-3-3 gave maximum plant growth when applied to waito-c rice and Atriplex gemelinii seedlings. Analysis of the culture filtrate of IR-3-3 showed the presence of physiologically active gibberellins, GA1, GA3, GA4 and GA7 (1.95 ng/ml, 3.83 ng/ml, 6.03 ng/ml and 2.35 ng/ml, respectively) along with other physiologically inactive GA5, GA9, GA12, GA15, GA19, GA20 and, GA24. The plant growth promotion and gibberellin producing capacity of IR-3-3 was much higher than the wild type Gibberella fujikuroi, which was taken as control during present study. GA5, a precursor of bioactive GA3 was reported for the first time in fungi. The fungal isolate IR-3-3 was identified as a new strain of Penicillium citrinum (named as P. citrinum KACC43900) through phylogenetic analysis of 18S rDNA sequence.
  
  
  CONCLUSIONS
  Isolation of new strain of Penicillium citrinum from the sand dune flora is interesting as information on the presence of Pencillium species in coastal sand dunes is limited. The plant growth promoting ability of this fungal strain may help in conservation and revegetation of the rapidly eroding sand dune flora. Penicillium citrinum is already known for producing mycotoxin citrinin and cellulose digesting enzymes like cellulase and endoglucanase, as well as xylulase. Gibberellins producing ability of this fungus and the discovery about the presence of GA5 will open new aspects of research and investigations.
authors.affiliation: Department of Life Science and Biotechnology, Kyungpook National University, South Korea. shumakhan@gmail.com
authors.forename: Sumera Afzal
authors.initials: SA
authors.lastname: Khan
authors.forename: Muhammad
authors.initials: M
authors.lastname: Hamayun
authors.forename: Hyeokjun
authors.initials: H
authors.lastname: Yoon
authors.forename: Ho-Youn
authors.initials: HY
authors.lastname: Kim
authors.forename: Seok-Jong
authors.initials: SJ
authors.lastname: Suh
authors.forename: Seon-Kap
authors.initials: SK
authors.lastname: Hwang
authors.forename: Jong-Myeong
authors.initials: JM
authors.lastname: Kim
authors.forename: In-Jung
authors.initials: IJ
authors.lastname: Lee
authors.forename: Yeon-Sik
authors.initials: YS
authors.lastname: Choo
authors.forename: Ung-Han
authors.initials: UH
authors.lastname: Yoon
authors.forename: Won-Sik
authors.initials: WS
authors.lastname: Kong
authors.forename: Byung-Moo
authors.initials: BM
authors.lastname: Lee
authors.forename: Jong-Guk
authors.initials: JG
authors.lastname: Kim
mesh_terms: D019659:Asteraceae / Q000382:microbiology; D027466:Atriplex / Q000187:drug effects / Q000254:growth & development*; D001681:Biological Assay; D004271:DNA, Fungal / Q000235:genetics; D005874:Gibberella / Q000378:metabolism; D005875:Gibberellins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D012275:Oryza / Q000145:classification / Q000187:drug effects / Q000254:growth & development*; D010407:Penicillium / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology
chemical_list: D004271:DNA, Fungal; D005875:Gibberellins