ZEF IPADS Soil Fertility Management 7 Nutrient acquisition through microbial association

Transcription

1 International Program in Agricultural Development Studies (IPADS) 21 January 2016 ZEF IPADS Soil Fertility Management 7 Nutrient acquisition through microbial association Department of Global Agricultural Sciences IPADS Kensuke OKADA (akokada@mail.ecc.u tokyo.ac.jp) 1 (Llanos Orientales in Colombia, photo by KO)

2 Lecture outline 1. Mycorrhiza 2. Endophyte

3 1. MYCORRHIZA

4 Arbuscular Mycorrhiza (AM) Formerly it was called vesicular arbuscular mycorrhiza (VAM) V: vesicle A: arbuscule Spore Bar = 0.1 mm (Ueda et al 1992)

5 Three types of mycorrhiza Cortex Epidermis Soil mycelia 1. Ectomycorrhiza 2. Endomycorrhiza (includes ericoid and AM) Ectomycorrhizal fungi for trees, Basidiomycetes Ericoid mycorrhizal fungi for orchids, Ericaceae vesicule Arbuscular mycorrhizal fungi (AMF) Important for many plant species arbuscule

6 The role of mycorrhiza in transporting phosphorus from soil to plant roots Spore ( 胞子 ) of mycorrhizal fungi Solubilization of P into soil solution P containing mineral Diffusion of P to root Transportation of P through mycelium Root hair ( 根毛 ) P transported into root cell through mycelium Root colonized by mycorrhizalfungi Root not colonized by micorrhizal fungi (Matsunaka 2003, p. 215)

7 Mycorrhiza Definition : A mycorrhiza (pl. mycorrhizae) is a symbiotic (generally mutualistic, but occasionally weakly pathogenic) association between a fungus and the roots of a vascular plant. Fungi themselves are called as mycorrhizal fungi Mycorrhizal fungi receive carbohydrate from host plant and plants receive nutrients such as P (mainly), Zn, (Cu, Ca) and water. For the latter function, the mycelium of the mycorrhizal fungi are regarded as the fine, extended roots of plants.

8 AM measurement (1) : Per cent root infection Ultrasonic cleaning Dissecting roots to 2 3 cm Alkali treatment (heating) (To make root tissue transparent) Neutralizing (Usuki, personal communication)

9 Dying with trypan blue Fixation Mycorrhizal (count) Non mycorrhizal (no count) Roots are extended on petri dish with grid lines (Usuki, personal communication)

10 AM measurement (2) : Spore density in soil Washing the soil Suspend in sucrose solution with concentration gradient Sieving Centrifuge (Usuki, personal communication)

11 AM measurement (2) Spore density in soil Microscope observation and counting Intact and crushed spore (Usuki, personal communication)

12 Different infection % among plant species Legumes are the good mycorrhizal plants Non mycorrhizal plants (Thompson 1991)

13 Relative field mycorrhizal dependency index (Thompson 1991)

14 Effect of fallow on VAM and growth of the following crops These results have significant implications on the design of crop rotation including fallow period. (Thompson 1991)

15 Number of spores in the soil and the growth of the following crop (Thompson 1991)

16 Effect of the previous crops (Thompson 1991)

17 Effect of the previous crops on the growth of maize in Hokkaido, Japan

18 Case study example 2: Effect of the previous winter crops on the sunflower growth (summer crop) After bare soil After wheat After rapeseed Typical N deficiency symptoms Soybean was also affected as sunflower at the early growth stage, but recovered later. Similar effect wars observed in voluntary rapeseed (* Yasumoto, et al Plant Production Science 14: ) 18 (At a farmer s field in Tsukuba-mirai city in Ibaraki Prefecture, 11 Aug, 2005)

19 Factors affecting AM colonization Fallowing Previous crops Soil disturbance Soil ph Heating and fire Fungicides Waterlogging Fertilizers

20 Effect of soil disturbance on VAM (Thompson 1991)

21 Effect of summer green manure on the growth of following maize and the infection rate of AM Taken out Incorporated Dry weight of shoot Bare White Vetch Sunflower soil mustard Green manure crop AM infection rate (Karasawa et al. 2000)

22 Reduction in phosphorus fertilizer application to soybean after mycorrhizal plant Index of soybean yield After cabbage After maize Soybean growth was higher after mycorrhizal crop (maize) (MAFF 2009 Present situation and future issues for fertilizer management in upland farming in Hokkaido ) Amount of P applied (kg/10a) After non host crop (radish, buckwheat) After host crop (maize, sunflower) Amount of phosphate fertilizer can be reduced 15 5 (kg/10a)

23 2. ENDOPHYTIC NITROGEN FIXATION

24 Endophyte N fixing bacteria were tagged with the gfp gene encoding green fluorescent protein (GFP). (Elbeltagy et al. 2001)

25 Endophyte endo (within)+ phyte (plant) An endophyte is an symbiotic microbes in plant tissue, often a bacterium or fungus, that lives within a plant for at least part of its life without causing apparent disease. Endophytes are ubiquitous and have been found in all the species of plants studied to date.

26 Endophyte history Darnel (Lilium temulentum) was known from old age (mentioned in New Testament), but it was rather recent that the toxins were produced by fungus which colonizes in the plants, not by the plants.

27 Endophyte history Since 1970 s these were found to be the cause of the animals intoxication. In 1975 the cause of the fesucue toxicosis was found to be the endophytic fungi in tall fescue (Festuca arundinacea) in North America, and in 1979 ryegrass staggard was found to be caused by enophyte in perennial ryegrass (Lolium perenne). Tall fesucue Fesucue toxicosis (front cow) e/pests diseases and weeds/animaldiseases/beef and dairycows/perennial ryegrass toxicosis Perennial ryegrass

28 But Prestidge (1982) reported that endophytic perennial ryegrass is more tolerant to a kind of weevil ( ゾウムシ ) (Argentine stem weevil). Perrenial ryegrass affected by Crambus spp. ツトガ ) E+ Variety infected by endophyte : E Variety not infected by endophyte Power of endophyte (NHK video)

29 Nitrogen enrichment in sugarcane (pot experiment) (Boddey et al. 2003)

30 (Boddey et al. 2003) Endophytic N 2 fixation in sugarcane

31 Endophytic N fixation in Sugarcane * *BNF (biological nitrogen fixation) (Boddey et al. 1991)

32 Endophyte colonization in date palm (Gomez Vidal et al 2006)

33 Endophyte colonization in pineapple Fluorescence microscopy of GFP(green fluorescent protein) labelled diazotrophic enphytic bacterium Herbaspirillum seropedicae in pinapple plantlets 7 days after colonization, bacteria colonized epidermal cell walls junctions Leaf epiphytic colonization of bacteria at cell walls junctions (Baldotto et al. 2011)

34 Plants associated with N 2 fixing endophytes sugarcane rice palm (date, oil, etc.) sweet potato pineapple tea coffee and more? More easily ransmitted by vegetative propagation (Reis et al 2000) Associative and Endophytic Nitrogen fixing Bacteria and Cyanobacterial Associations (Nitrogen Fixation: Origins, Applications, and Research Progress) Claudine Elmerich (Editor), William E. Newton (Editor) 2010, Springer