A Genetic-Mitigation Strategy GV Subbarao · JIRCAS-NARO International Symposium on Agricultural Greenhouse Gas Mitigation, 31st August 2017, Tsukuba, Japan. A major portion (80%)

JIRCAS-NARO International Symposium on Agricultural Greenhouse Gas Mitigation,

31st August 2017, Tsukuba, Japan

Biological Nitrification Inhibition (BNI)-Technology Tackling Agricultural Greenhouse Gas Emissions

GV SubbaraoJIRCAS, Japan

Collaborators & PartnersCIAT

CIMMYTICRISAT

CCAF

A Genetic-Mitigation Strategy

BNIBiological Nitr i fication Inhibi t ion

Global GHG emissions Monetization of climate effects using “the best available science and economics”

*49 Gt of CO2 eq.yr-12004 data; Nature 2011



1 Gt = 1 billion tonsIWG = Interagency Working Group on Social cost of GHGCost of global damage from GHG is

$50 t-1 CO2**based on IWG recent estimate (Science 2017, 357:655)

Cost of Global damage from GHG emissions estimated at

$US 2450 billion y-1 ($US 2.45 trillion y-1)




A major portion (80%) of agricultural GHG emissions are associated with

Production and Use of N-fertilizers(based on life-cycle analysis, which is energy and carbon intensive)

Agriculture alone is responsible for 14 Gt CO2.eq.y-1About 24% of total GHG emissions

The social cost of 14 Gt of GHG emissions from agriculture is

$US 700 billion y-1


Why NUE is <30% in most agricultural systems?Uncontrolled rapid nitrification in

agricultural soils

Global food production has doubled from 1960 – 2000Nitrogen fertilizer consumption increased 10-fold

Nearly 70% of the N fertilizer applied is lost to the environment

Amounts to a direct annual economic loss of

US$ 90 billion*[*based on - a) world annual N fertilizer production is 150 million Mg; b) 0.45 US$ kg-1 urea]

Nitrogen fertilizer consumption worldwide in 2010

>120 Tg (million metric tons)

Energy cost of nitrogen fertilizer – 1.8 to 2 L diesel oil per kg N fertilizer

1.70 billion barrels of diesel oil (energy equivalent) is needed to produce this nitrogen

fertilizer


31st August 2017, Tsukuba, JapanBNIBiological Nitr i fication Inhibi t ion

Tillman et al. 2011PNAS 108:20260-20264

Based on Khalil and Rasmussen 1988Annals of Glaceology 10:73-79

N-fertilizer usage to

reach 250 Tg yr-1

N2O emissions

double from 2011 levels

Soil

OMOrganic N

NH4+

Microbial

N NO3-

>95% of the total soil inorganic N pool

Plant N uptake & Assimilation

Mineralization

Nitrification

Inorganic

N

Crop Residues

NFertilizer

Intensification of agricultural practices led to acceleration of nitrification in modern production

systems BNIBiological Nitr i fication Inhibi t ion

Nitrification(NH4….NO3

-)Nitrosomonas

ArchaeaNitrobacter

Aerobic process

Denitrification(NO3

-….N2)>15 groups of bacteria and fungi use NO3- as

source of energy Anaerobic process

N2ONO

Nitrification and denitrificationare the primary drivers for generation of

N2O>80% of global N2O

emissions is generated from Farming



How to achieve low-nitrifying agricultural soils?

Switch to low-nitrifying agricultural systems


BNI Concept

Ammonium(NH4

+)Nitrite(NO2

-)

Nitrate(NO3

-)Ammonia-oxidizing Bacteria Nitrite-oxidizing BacteriaBL

BL

BL BL

Microbial-N

Imm

obili

zatio

n

Min

eral

izat

ion

Nitrate leaching

Denitrification

N2O, NO and N2

N lost from agricultural system

N lost from agricultural system

Concept of Biological Nitrification Inhibition (BNI)

BNI-Mitigation Technology?


A Genetic-Mitigation Strategy



Characterization of BNI function

Strength of BNIs production in crops/pasturesGenetic variability in BNI-traitChemical-identity of BNIsHow stable are BNIs?Soil conditions influence on BNIs functioningBNI concentration required in soil to be effectiveEffectiveness in tropics vs temperature environsRegulatory mechanisms for BNI release Mode of inhibitory actionNegative effects on soil microbial community

How to engineer a plant function into

Technology & Research Strategy


BNI activity added to the soil (AT g-1 soil)

0 5 10 15 20 25

NO

3 co

ncen

trat

ion

in so

il (p

pm)

0

50

100

150

200

250

Threshold

Releases about 200 to 400 ATU hydrophilic BNI d-1

55 d soil incubation

50% inhibition

90% inhibition


Release ratesStability

ED50Determines

Effectiveness of BNI function in the fieldBNIs can provide stable inhibitory effect on soil nitrification



Methyl p-coumarate Methyl ferulate

Methyl 3-(4-hydroxyphenyl)propionate

Root exudate

Root exudate

Root exudate

Root exudate

Root tissue Root tissue

Root tissue Root tissue

Sorgoleone

Sakuranetin

Brachialactone

Linoleic acidα-linoleic acid

BNIs isolated from sorghum BNIs isolated from B. humidicola

Plants produce a cocktail of BNIs to suppress nitrifying bacteriaNitrosomonas


AMO blocker

AMO & HAO blockerET disruptor

AMO & HAO blocker

AMO blocker

AMO & HAO blocker

How much BNI-activity is released from root systems of B. humidicola?An assessment

• Active root biomass in a long-term BH pasture being 1.5 Mg ha-1 •(Root mass up to 9.0 Mg ha-1 has been reported in BH pastures)

• BNI release rates can be 17 to 50 ATU g-1 root dry wt. d-1

• Estimated BNI activity release d-1 could be 2.6 x 106 to 7.5 x 106 ATU(CIAT 679) (CIAT 26159)

•1 ATU being equal to 0.6 µg of nitrapyrin

• This amounts to an inhibitory potential equivalent to the application of 6.2 to 18 kg of nitrapyrin application ha-1 yr-1

Does it work in the field?

BNIMitigation Technology

B. humidicola roots can release 2.6 to 7.5 million BNI activity d-1 ha-1




Can we breed for high-BNI capacity in food- and -feed crops?Developing low-nitrifying and low-N2O emitting systems

Cumulative N2O emissions (mg of N2O N per m2 per year) from field plots of tropical pasture grasses (monitored monthly over a 3-year period, from September 2004 to November 2007)

Subbarao G V et al. PNAS 2009;106:17302-17307©2009 by National Academy of Sciences

Brachiaria pastures suppressed N2O emissions from the fieldCan BNI function in plants be exploited to develop low-N2O emitting systems then?

BNI capacity in root systems – Field plots

No BNIcapacity

Highest BNIcapacity

BNI-Mitigation Technology




Nitrogen excreted (from urine) from grazing animals from managed grasslands (9 million km2) is estimated at

>120 Tg N y-1

1800 million livestock units; 182 to 392 g N excreted per animal d-1

Equal to synthetic Nitrogen fertilizer to global agricultural systemsSource: Saggar et al. 2005

Can BNI-enabled pastures help reducing N2O emissions from these grazing systems?



Sorghum-BNI characterization at a field site in ICRISAT, India

JIRCAS-ICRISAT Collaboration

Hydrophilic BNIs released from sorghum roots

Developing BNI-enabled crop/pasture varieties?

Mini-core Sorghum germplasm lines

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137139140141142143144145146147148149150151152153154155156157158159160161162163164165166167169170171172173174175176177178179180181182183184185186187188189190191192193194195197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231N.a.N.HSLs

Sorg

oleo

ne re

leas

ed (µ

g pl

ant-1

)

0

20

40

60

80

100

120

Sorgoleone phenotyping of mini-core sorghum germplasm (231 lines) - 2015

Highest sorgoleone producing germplasm

Germplasm lineCollected from Niger, WA

PVK 801

296-B


Breeding for high-sorgoleone producting sorghum cultivars - Feasible?

Sorgoleone-capacity in elite-breeding lines

00.20.40.60.8

11.21.41.61.8

2

200N 200N+Sorgoleone 200N+DCD

N2O

em

issi

on (u

g N

2O-N

)

Treatments

Integrated N2O emissiona

b

c

-8

-3

2

7

12

17

22

27

32

37

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

N2O

em

issi

on (n

g N

2O-N

(g d

ry so

il)-1

hr

-1 m

-2)

Days of incubation

N2O emission

200N

200N+Sorgoleone

200N+DCD

Sorgoleone additions to the soil suppressed N2O emissions


High-sorgoleone producing genetic stocks suppress N2O emissions better than low-sorgoleone producing genetic stocks?


High sorgoleone producing sorghum genetic stocks have low N2O emissions?

Sorghum germplasm linesIS 32087 IS 20762

Sorg

oleo

ne p

rodu

ctio

n (

g pl

ant-1

)

0

20

40

60

80

100

120

140

IS 32087 IS 20762

Germplasm line collected from

Yemen

Germplasm line collected from

USA

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Control DCD IS 32087 IS 20762

N2O

em

issi

on (µ

g N2O

-N m

-2 h-1

)

Treatment

Effect of sorghum genetic stocks on total N2O emission from incubated soil

IS 32087 IS 20762

High-sorgoleone germplasm line has 50% lower N2O emissions compared to

low-sorgoleone producing germplasm

O

O

OH

O

Breeding for high-sorgoleone production could a proxy to develop low-N2O emitting sorghum cultivars?

Nobeoka Chinese Spring

L. racemosus

Wild-wheat has high-BNI capacity

Leymus racemosus

Leymus does not release BNI when grown with NO3

--N where pH of RE-collection solution will be of >6.0

RE collection

pH 4.0

RE collection

pH 7.5

JIRCAS-CIMMYT partnership





Benefits from Genetic-Mitigation using BNI-Technology

Cost effective and Scalable Delivery of BNIs - precise and effective Cocktail of inhibitors from BNIs – more stable effect No negative environmental consequencesNo health issues on food or feed qualityImprove soil-N-retention and fertility




Portfolio of current technologies to reduce nitrification and N2O emissions

Synthetic nitrification inhibitorsUrease inhibitorsSlow-release nitrogen fertilizersPolythene-coated nitrogen fertilizersSplit-Nitrogen applicationsPrecision farming – ‘Green-seeker’ technologyAWD (alternate wetting and drying) for paddy rice systems

BNI-technology could become part of portfolio of technologies to address GHG emissions from agriculture




Developing novel Mitigation-technologies critical to reduce GHG emissions from agriculture

With substantial mitigation

Withoutadditionalmitigation

Change in average surface temperature (1986–2005 to 2081–2100)

Source: IPCC AR5 synthesis report BNIBiological Nitr i fication Inhibi t ion

Paris Climate Agreement signed in 2015 calls to hold the global average temperature to <2C above preindustrial levels by for 80% reduction in GHG

emissions from current levels by 2050

“ . . . holding the increase in the global average temperature to well below 2 °C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5 °C”

Paris-Climate Agreement Signed in 2015

Funding support for BNI ResearchMAFF

MOFA – CGIAR CollaboratorsCRP-WHEAT

JIRCAS-President’s special grantsJSPS Research Grants

The smart way to address climate change is through

Innovation

Reducing GHG emissions from Agriculture reduces N-pollution, N-fertilizer consumption, improve soil fertility and sustainability of production systems

Low N2O emission systems are a ‘WIN WIN’ situation for both environment and for Agriculture

Energy Production and Transport SectorsSolar-electricity, Hybrid Cars, Electric cars are some of the GHG reducing technologies

emerged recently


Arctic is melting fastTime for action

from Agricultural Scientific Community

JIRCAS


Thank You for the attention

Huge waterfall spouting from the ice edge of Brasvell Glacier – Getty image

https://www.treehugger.com/slideshows/clean-technology/7-terrifying-global-warming-pictures/page/9/

Documents

A Genetic-Mitigation Strategy GV Subbarao · JIRCAS-NARO International Symposium on Agricultural Greenhouse Gas Mitigation, 31st August 2017, Tsukuba, Japan. A major portion (80%)