Marcin Rapacz

University of Agriculture in Krakow,

Department of Plant Physiology,

Podłużna 3, 30-239 Kraków, Poland

Ideotyp rośliny tolerującej suszę optymalny

dla polskiego rolnictwa

Basic strategies to survive drought Escape

Life cycle synchronized with periodic droughts

Short life cycle

To survive water shortage in the cells (drought resistant

plants/tissues)

To protect water balance and avoid damages (drought tolerant

plants)

Which mechanisms are desired in agricultural plants? – what

we should looking for?

Mechanisms of drought tolerance

Conservative

Inductible by moderate drought, in some cases together with

other signals

All of these mechanisms work in crops

and are in most cases inductible

(conservative mechanisms decrease

yielding when water is available).

Water conservation in the tissues

Reduced transpiration and evaporation – stomata (incl. CAM), waxes,

trichomes, phenolics in cell walls….

Water storage in special tissues

Water conservation in cells (osmotic adjustment)

Enhanced growth and water extraction ability of the root system

Root expansion

Aquaporins induction

Protection against damages

dehydrines

Antioxidants

Metabolic resilience

Basic mechanisms of drought tolerance

Resurection (poikilochlorophyllous) plants

Dehydrine’s induction

Sporobolus stapfianus – one of the 11 resurrection

grasses – most of them are desiccation resistant only

in some parts of the plant.

phot. M. Rapacz

Drought resistant plants

Best way to avoid but not in the case of agricultural systems

phot. M. Rapacz

A specific kind of metabolic resilience

Presents in almoust all grasses (reduction of leaf area,

senescence)

phot. M. Rapacz

Root system size and effectiveness

en.wikipedia.org

Tripsacum dactyloides (eastern gamagrass) - the deep roots which extend to

around 4.5 m to the underground, is the main key structure that allow

gamagrass to tolerate drought . Additionally adapted to heavy soils.

Basic responses to soil water deficit

ABA

Closing stomata Decrease in CO2 assimilation

pH

other signals

Decrease in cytokinins Increase in root expantion

Decrease in assimilates availability

for yielding

Basic responses to soil water deficit (2)

ABA

Cell water deficit

Other signals

Osmotic adjustment

Protection against damages

(eg. dehydrines)

Repair

Future drought scenarios for Poland

Different times, levels, and durations of drought required

different tolerance mechanisms.

The reliable scenarios for the future is the burning question.

Drought tolerant cereals in Poland

Why not? The effect of spring drought on plants density in July (Polanowice 2012)

Suweren Blask

Dehydrins -

HVA1 in drougt tolerance of barley

HVA1 – dehydrine, overexpression lead to enhanced drought tolerance in many plant

species

Expression triggered mostly by intact water deficit in the cells (Wójcik-Jagła et al. 2012,

Acta Physiol Plant 34:2069–2078)

Actine cytoskeleton may be involved

CAM/B1/CI Maresi Treatment (S-susza, K-kontrola)

S S K K S S K K

Latrunkuline + - + - + - + - Relative HVA1 transcript accumulation level

22.07 46.48 9.88 15.85 4.96 41.09 14.98 1

HVA1

Wójcik-Jagła et al. 2012, Acta Physiol Plant 34:2069–2078

Śniegowska et al. 2014, unpublished

Drought tolerant Syrian CAM/B1/CI

exhibit different drought adaptation pattern

that Polish tolerant cultivars, Maresi is

drought susceptible.

When genotype is drought-tolerant the

increse in HVA1 transcript accumulation

is stable during fast drying of the leaves

Rapacz et al. 2010, JACS 196: 9–19.

In the group of more tolerant malting cultivars, the

accumulation of HVA1 enable to maintain high photosynthetic

activity when stomata are open in drought

In less tolerant group stomata are in general closed (Suweren is

an exception) in drought – correlation is not observed

HVA1 expression in drought varied among Polish breeding materials

HVA1 expression correlated (negatively) with water content in feed-

type barleys only

HVA1 expression correlated with assimilation and stomata opening

(malt-type)

STH754

STH369 (Suweren)

Drought tolerant

plants:

Drought tolerance in spring wheat - CO2 net assimilation

rate (A)

Accession Drought Control

A SI N

Mean %%

CIMMYT 2 D 7.46

69.1 * 5

C 10.8 5

CIMMYT 3 D 0.33

2.9 * 5

C 11.36 5

CIMMYT 4 D 0.62

7.0 * 5

C 8.84 5

Harenda D 3.05

32.6 * 6

C 9.36 5

Ostka Smolicka

D 0.05 0.6 *

5

C 8.58 5

KWS Torridon

D 9.56 91.2 n.s.

5

C 10.48 5

Kościelniak et al., unpublished

Drought tolerance in spring wheat – stomatal conductance

(gs)

Accession Drought Control

gs SI N

Mean %%

CIMMYT 2 D 26.6

38.3 * 5

C 69.4 5

CIMMYT 3 D 3.2

4.3 * 5

C 75.0 5

CIMMYT 4 D 1.4

2.5 * 5

C 55.6 5

Harenda D 8.8

14.8 * 6

C 59.6 5

Ostka Smolicka

D 1.4 2.5 *

5

C 57.0 5

KWS Torridon

D 40.0 61.5 *

5

C 65.0 5

Kościelniak et al., unpublished

Drought tolerance in spring wheat – relative water

contents (leaves)

genotyp C/D RWC SI N

Mean %%

CIMMYT 2 D 80.2

82.4 * 5

C 97.3 5

CIMMYT 3 D 78.3

81.4 * 5

C 96.2 5

CIMMYT 4 D 71.1

74.0 * 5

C 96.1 5

Harenda D 71.3

73.8 * 6

C 96.6 5

Ostka Smolicka

D 64.2 66.8 *

5

C 96.2 5

KWS Torridon

D 88.6 92.5 n.s.

5

C 95.7 5

Kościelniak et al., unpublished

Field drought tolerance Yielding (% standard), Data from COBORU and IUNG (drought).

2011 2012 2013

Spring drought Spring drought -

KWS Toridon a1 102 103 99

KWS Torridon a2 102 103 100

Suweren a1 103 102 96

Suweren a2 102 102 96

a1 sustainable farming system

a2 intensive farming system

Good carboxylation in drought may be not sufficient when

drought is prolonged

(Lolium multiflorum/Festuca arundinacea introgression forms)

(Perlikowski et al. 2014; Plant Biology 16(2):385-394)

Gs (mmol m-2 s-1) E (mmol (H20) m-2 s-1) A (µmol (CO2) m-2 s-1)

drought control drought control drought control Tur 32.0 c 186.5 a 0.890 d 4.632 a 5.74 f 12.81 a 164/34/27 31.7 c 139.4 b 0.935 d 3.387 bc 6.30 ef 11.70 ab 164/34/37 27.6 c 133.2 b 0.748 d 3.256 bc 6.30 ef 11.48 b 164/34/40 27.8 c 141.8 b 0.824 d 3.481 b 6.58 e 11.48 b 164/34/66 30.0 c 121.7 b 0.858 d 3.024 c 7.42 d 11.01 c

2 4 6 8 10 12 14 16

A [ mol(CO ) m s ] 2-2 -1

020406080

100120140160180200220240

drought

control

g (

mm

ol m

s)

s-2

-1

In this group of plants (like in the

group of less tolerant fodder

barleys) CO2 assimilation in

drought (11th day) wasn’t

limited by stomata.

Genotype 66 is still good.

Good carboxylation in drought may be not

sufficient when drought is prolonged

(Perlikowski et al. 2014; Plant Biology 16(2):385-394)

The effect of 14-weeks

drought (rain shelters).

0

20

40

60

80

100

120

27 37 40 66

Fre

sh w

eigh

t [g]

Plant number

drought 1st rep drought 2nd repdrought 3rd rep control

Which mechanisms are desired in

agricultural plants? – what we should

looking for?

Depends on local conditions

In Poland for improving barley drought tolerance we should

look for high yielding plants with relative high carboxylation

rate under moderate drought AND efficient dehydratation

tolerance mechanism (eg. HVA1 highly expressed)

Summary

The problem of water shortage in the environment were

solved by the plants in many different ways

Some of them are advantageous for agricultural plants

Which traits are desired - depends on local conditions

The variation in these traits is very large in agricultural plants

which makes the selection of more drought tolerant plants

possible

Thank you for your attention