Agriculture Reference
In-Depth Information
ABA has been shown to play a broad role in the regulation of plant defence
responses. For example, ABA acts a positive regulator of the defence response
during pathogen invasion, whereas it acts as a negative regulator of the defence
response following pathogen invasion (Yasuda et al. 2008 ; Ton et al. 2009 ; Robert-
Seilaniantz et al. 2011 ). A recent study revealed that ABA deficiencies antagonise
the high-temperature inhibition of disease resistance by enhancing the nuclear
accumulation of the resistance proteins SNC1 and RPS4 in Arabidopsis (Mang
et al. 2012 ). Therefore, ABA and SA may act antagonistically to affect plant devel-
opment and the defence response, as well as the cold stress response (Fig. 17.2 e).
17.11 Conclusions
Cold acclimation is a complex physiological process that is affected by various
developmental and environmental factors, including growth stage, tissue type,
photoperiod, hydration status, and low temperatures. ABA has long been thought
to play an important role in mediating the cold response in plants, and accumula-
tion of ABA may indeed be required for full cold acclimation. However, the extent
of its role in vivo has been controversial. It appears that ABA biosynthesis is not
a major aspect of the early cold stress response but rather that it contributes to
the maximum induction of cold-responsive genes during later stages. It is also
possible that ABA plays diverse roles in the regulation of multiple physiological
processes that are affected by chilling or freezing stress. However, the majority of
the molecular mechanisms underlying how ABA affects freezing tolerance remain
to be investigated. In particular, elucidating whether the key components of ABA
signalling are involved in CBF-regulated cold acclimation should be a priority for
those studying the role of ABA in cold signalling. In addition, understanding the
signalling networks between ABA and the other relevant plant hormones during
the cold stress response will be crucial for determining any potential applications
for ABA in enhancing plant tolerance to cold stress.
References
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