brief explanation about one of the plant stress known as cold stress

1. Plant StreSS:
Cold

2. Stress ： Environmental damage to plants
◇ Biotic stress Abiotic stress◇
Resistance ： The adaptability of plants to adverse environment
◇Stress avoidance Stress tolerance◇
Stress Physiology ： adversity makes an impact on plant life
activities, resistance of plants to adversities

3. TypesTypes ooff SStresstress
Biotic stress
◇ pathogen stress
Abiotic stress
◇ chilling stress
◇ freezing stress
◇ heat stress
◇ wet stress
◇ flood stress
◇ drought stress
◇ salt stress
temperatures stress
water stress

4. TypesTypes ooff ResistanceResistance
stress avoidance
In the whole growth process does not meet with the face of
adversity
stress tolerance
Plant has a capacity of environmental stress defense, and a variety
of physiological processes remain normal

5. Cold stress
~67% landmass has annual temps <0°C
~50% has temps < – 20°C (Larcher 2001)

6. Cold stress: complex!
Plants can be damaged in different ways by:
Low day/night air temps
Low day/night soil temps
Differences in plant tissue sensitivity.
Species differ in their sensitivity to temp., depending on
their origin:
Cool-season
Warm-season

7. Damage from cold
 Depends on many factors:
1. Developmental stage
2. Duration/severity of frost
3. Rates of cooling, rewarming
4. Ice formation:
 Intracellular: disintegrate cell membrane.
 Extracellular in intercellular spaces.

8. Low temperature stress
Effects of low temperature
Dehydration of cells/tissues when cellular water freezes
Beck et al. 2004

9. Cold acclimation
Acclimation involves
Synthesis of cryoprotectant molecules such as:
o Soluble sugars
o Sugar alcohols
o Low molecular weight nitrogenous compounds.
– Upregulation of genes for
» Dehydrins
» Cold regulated proteins (COR)
» HSPs
Janska et al. 2010

10. They are stress proteins with a high number of charged amino acids that
belong to the Group II Late Embryogenesis Abundant (LEA) family”. DHNs are
primarily found in the cytoplasm and nucleus but more recently, they have
been found in other organelles, like mitochondria and chloroplasts. DHNs are
characterized by the presence of Glycine and other polar amino acids. All
DHNs contain at least one copy of a consensus 15-amino acid sequence. The
“K segment, The K segment is a Lysine-rich 15-amino acid consensus
sequence (EKKGIMDKIKEKPLG) that is highly conserved in all plants”
Dehydrins

11. COLD ACCLIMATION
Synthesis of cryoprotectant
molecules
Soluble sugars
Sugar alcohols
Low molecular weight
nitrogenous compounds
Upregulation of genes for
Dehydrins
Cold regulated
proteins (COR)
HSPs
Janska et al. 2010

12. Contd...
Change in membrane lipid composition.
Suppression of phospholipase D.
Synthesis of antifreeze proteins.
An altered ratio of ABA to GA.
Janska et al. 2010

13. Proteins in cold tolerance
COR proteins (Cold regulated proteins)
LEA proteins (Late embryogenesis abundant proteins)
HSP proteins (Heat shock proteins)
PR proteins (Pathogenesis-related proteins)
Janska et al. 2010

14. PROTEINS IN
COLD TOLERANCE
COR
proteins
LEA
proteins
HSP
proteins
PR
proteins
Janska et al. 2010

15. Enzymatic and metabolic responses
Upregulation of galactinol synthase
Induction of SPS gene
Upregulation of proline synthesis
Upregulation of Glutamate decarboxylase genes
Suppression of lipid metabolism
Increase in biosynthesis of anthocyanins and flavonoids
Janska et al. 2010

16. ENZYMATIC AND
METABOLIC RESPONSES
Induction of
SPS gene
Upregulation
of
galactinol
synthase
Increase in
Anthocyanins
and
flavonoids
Upregulation
of
proline synthesis
Upregulation
of
GAD genes
Suppression
of
lipid metabolism
Janska et al. 2010

17. Sandve et al. 2011

18. Cold sensing and signaling
Potential sensors include
Ca2+
influx channels
Two component histidine kinase
Receptors associated with G-proteins
Change in cytoskeletal elements
Plasma membrane rigidity
Janska et al. 2010

19. Fig: Scheme illustrating the molecular response of plants to low-temperature stress,
realised as changes in transcriptome, proteome, metabolome and phenotype.
Janska et al. 2010