Relationship between plant hormone level excreted by ectomycorrhizal fungi and growth of poplar NL-895

Abstract

To explore theeffects of plant hormones levels excreted by ectomycorrhizal (ECM) fungi on the growth of poplars, Populus × euramericana cv. NL-895 seedlings were inoculated with nine species of ECM fungi. We investigated the status of ectomycorrhizal formation and the effects of these fungi on poplar growth, and using the HPLC method, we measured the contents of four kinds of plant hormones, indole acetic acid (IAA), zeatin (Z), gibberellin (GA) and abscisic acid (ABA) in both the culture filtrate and the mycelium of these fungi. The results showed that the effects of nine ECM fungi on the growth of poplar NL-895 varied. The inoculated seedlings, whether or not obvious mycorrhizas were developed, grew better than those non-inoculated ones. All nine ectomycorrhizal fungi excreted the four plant hormones, but at different levels. The hormone contents in culture filtrate were higher than that in mycelium, which show a definite relationship with poplar growth. Significantly, correlation analysis suggested the height and stem diameter of the poplar were positively correlated with zeatin contents in the mycelium, and were negatively correlated with the levels of ABA or IAA in the mycelium.

Key words： ectomycorrhizal fungi; plant hormone; poplar NL-895; HPLC

Acknowledgments

This study was financially supported by the National Natural Science Foundation of China (Grant No. 30571471) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2004217). We are grateful to Professor Zongming HE from the Fujian Agriculture and Forestry University for his help in data analysis, and to the Bioengineering Laboratory of the Nanjing Forestry University for hormone measurements.

References

1 Baser C M, Garrett J E, Mitchell R J (1987). Indolebutyric acid and ectomycorrhizal inoculation increase lateral root initiation and development on container-grown black oak seedlings. Can J For Res, 17: 36-39

2 Beyrle H (1995). The role of phytohormones in function and biology of mycorrhizas. In: Varma A, Hock B, eds. Mycorrhizas: Structure, Function, Molecular Biology. Berlin: Spring-Verlag, 365-390

3 Brenner M L, Chezkh N (1995). The role of hormones in photosynthate partitioning and seed filling. In: Davies P J, ed. Plant Hormones. Netherlands: Kluwer Academic Publishers, 649-670

4 Chen Y M (1978). Effects of mycorrhizal fungi on the growth of poplars. Compilation of reference material for exotic pines, 10: 16-24

5 Craft C B, Miller C O (1974). Detection and identification of cytokinins produced by mycorrhizal fungi. Plant Physiol, 53: 586-588

6 Durand N, Deband J C, Casselton L A (1992). Isolation and preliminary characterization of 5-fluorindole-resistant and IAA-overproducer mutants of the ectomycorrhizal fungus Hebeloma cylindrosporum Romagnesi. New Phytol, 121: 545-553

7 Fu L, Wang J M, Wang M L (1998). Measuring method of ABA and 3-IAA in plant tissue. Shandong Chem Ind, 5: 59-60 (in Chinese)

8 Gong M Q (1997). Mycorrhizal Research and Application. Beijing: China Forestry Publishing House (in Chinese)

9 Han L J, Fan X, Yuan Z H (2005). Isolation and estimation of auxin from marine algaes. Oceanol Et Limnol Sin, 36(2): 167-171 (in Chinese)

10 Levisohn I (1953). Growth response of tree seedlings to mycorrhizal mycelia in the absence of a mycorrhizal association. Nature, 172: 316

11 Ma L, Wu X Q (2007). Mycorrhizal formation of nine ectomycorrhizal fungi on poplar cuttings. J Nanjing For Univ (Nat Sci Ed), 31(6): 29-33 (in Chinese)

12 Simpson D G (1986). Auxin stimulates lateral root formation of container grown Interior Douglas fir seedlings. Can J For Res, 16: 1135-1139

13 Smith S E, Read D J (1997). Mycorrhizal Symbiosis. London: Academic Press

14 Zhou L, Wei Q C (2006). The effect of cytokinins on fruit and seed development. Plant Physiol Commun, 42(3): 549-553

15 Wang Y Z (1997). Plant hormones production by 4 species ectomycorrhizal fungi in pure culture. Microbiol, 24 (2): 72-74 (in Chinese)

16 Wu G X, Bi G H (1994). Determination of indole-3-acetic acid and abscisic acid in apple leaves by high-performance liquid chromatography. J Shandong Agr Univ, 25(1): 51-55 (in Chinese)