zef ipads soil fertility management through microbial · “associative endophytic...
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ZEF‐IPADS Soil Fertility Management ‐7‐
Nutrient acquisition through microbial association
Department of Global Agricultural SciencesIPADS
Kensuke OKADA([email protected]‐tokyo.ac.jp)
1(Llanos Orientales in Colombia, photo by KO)
International Program in Agricultural Development Studies (IPADS)21 January 2016
Lecture outline
1. Mycorrhiza 2. Endophyte
1. MYCORRHIZA
Arbuscular Mycorrhiza (AM)
Spore Bar = 0.1 mm
(Ueda et al 1992)
V: vesicle A: arbuscule
Formerly it was called vesicular‐arbuscular mycorrhiza (VAM)
Three types of mycorrhizaEctomycorrhizal fungifor trees, Basidiomycetes
Ericoid mycorrhizal fungifor orchids, Ericaceae
Arbuscular mycorrhizal fungi (AMF)Important for many plant species
Soil
myceliaEpidermis
Cortex
vesicule
arbuscule
1. Ectomycorrhiza2. Endomycorrhiza
(includes ericoid and AM)
The role of mycorrhiza in transporting phosphorus from soil to plant roots
(Matsunaka 2003, p. 215)
Spore (胞子) of mycorrhizal fungi
Solubilization of P into soil solution
Diffusion of P to root
P containing mineral
Root not colonized by micorrhizal fungi
Transportation of P through mycelium
Root colonized by mycorrhizal fungi
P transported into root cell through mycelium
Root hair (根毛)
MycorrhizaDefinition : 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.
AM measurement (1) : Per cent root infection
(Usuki, personal communication)
Ultrasonic cleaning Dissecting roots to 2‐3 cm
NeutralizingAlkali treatment (heating)(To make root tissue transparent)
Mycorrhizal(count)
Non‐mycorrhizal(no count)
Dying with trypan blue Fixation
(Usuki, personal communication)
Roots are extended on petri dish with grid lines
AM measurement (2) : Spore density in soil
Sieving
(Usuki, personal communication)
Suspend in sucrose solution with concentration gradient
Washing the soil
Centrifuge
AM measurement (2) Spore density in soilMicroscopeobservation and counting
(Usuki, personal communication)
Intact and crushed spore
Different infection % among plant species
(Thompson1991)
Legumes are the good mycorrhizal plants
Non‐mycorrhizal plants
Relative field mycorrhizal dependency index
(Thompson 1991)
Effect of fallow on VAM and growth of the following crops
(Thompson 1991)
These results have significant implications on the design of crop rotation including fallow period.
Number of spores in the soil and the growth of the following crop
(Thompson 1991)
Effect of the previous crops(Thompson 1991)
Effect of the previous crops on the growth of maize in Hokkaido, Japan
Case study example 2: Effect of the previous winter crops on the sunflower growth (summer crop)
18
After bare soil After wheat After rapeseed
(At a farmer’s field in Tsukuba-mirai city in Ibaraki Prefecture, 11 Aug, 2005)
•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. 2011. Plant Production Science 14:339‐348)
Factors affecting AM colonization
• Fallowing• Previous crops• Soil disturbance• Soil pH• Heating and fire• Fungicides• Waterlogging• Fertilizers
Effect of soil disturbance on VAM
(Thompson 1991)
Effect of summer green‐manure on the growth of following maize and the infection rate of AM
(Karasawa et al. 2000)
Bare White Vetch Sunflowersoil mustard
Green manure crop
Taken outIncorporated
Dry weight o
f sho
ot
AM infection rate
Reduction in phosphorus fertilizer application to soybean after mycorrhizal plant
(MAFF 2009 “Present situation and future issues for fertilizer management in upland farming in Hokkaido”)
After cabbage After maizeSoybean growth was higher after mycorrhizal crop (maize)
Index of so
ybean yield
Amount of P applied (kg/10a)
After non‐host crop (radish, buckwheat)After host crop (maize, sunflower)
Amount of phosphate fertilizercan be reduced 15 → 5 (kg/10a)
2. ENDOPHYTIC NITROGEN FIXATION
Endophyte
N fixing bacteria were tagged with the gfp gene encoding green fluorescent protein (GFP).
(Elbeltagy et al. 2001)
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.
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.
Endophyte history
• Since 1970’s these were found to be the cause of the animals’ intoxication. In 1975 the cause of the fesucuetoxicosis 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)
Perennial ryegrass
http://www.youtube.com/watch?v=FQ3d2dFprdo
http://www.dpi.vic.gov.au/agriculture/pests‐diseases‐and‐weeds/animal‐diseases/beef‐and‐dairy‐cows/perennial‐ryegrass‐toxicosis
• 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)http://cgi4.nhk.or.jp/gendai/kiroku/detail.cgi?content_id=2958
Nitrogen enrichment in sugarcane (pot experiment)
(Boddey et al. 2003)
Endophytic N2 fixation in sugarcane
(Boddey et al. 2003)
Endophytic N fixation in Sugarcane
(Boddey et al. 1991)*BNF (biological nitrogen fixation)
*
Endophyte colonization in date palm
(Gomez‐Vidal et al 2006)
Endophyte colonization in pineapple
(Baldotto et al. 2011)
Fluorescence microscopy of GFP(green fluorescent protein)‐labelled diazotrophic enphytic bacterium Herbaspirillumseropedicae in pinapple plantlets
7 days after colonization, bacteria colonized epidermal cell walls junctions
Leaf epiphytic colonization of bacteria at cell walls junctions
Plants associated with N2‐fixing endophytes
• sugarcane• rice• palm (date, oil, etc.)• sweet potato• pineapple• tea• coffee• and more?
(Reis et al 2000)
“Associative and EndophyticNitrogen‐fixing Bacteria and Cyanobacterial Associations (Nitrogen Fixation: Origins, Applications, and Research Progress) “Claudine Elmerich (Editor), William E. Newton (Editor) 2010, Springer
“More easily ransmittedby vegetative propagation”