recognized by the plant receptors (such as PRR), and the first response which is
observed is the change in V m and generation of fast electrical signal (Maffei et al.
2007a, b). Further the activity of channels and transporters is triggered, such as Ca
2+ -
channels leading to spiking of Ca
2+ in the form of repetitive oscillation (Evans et al.
2001; Tian et al. 2020); the period of frequency, sinusoidal or square shape wave,
and amplitude specify the stimulus specificity (Kosuta et al. 2008). These repetitive
oscillations and spiking of Ca
2+ form the code called as “Ca
2+ signature” (Dodd et al.
2010; Webb et al. 1996; Mithöfer et al. 2009). Ca
2+ signature reveals the nature and
intensity of the stimulus and specific information of stress. In Phaseolus lunatus,
Spodoptera littoralis larvae start feeding on their leaf, which results in sharp spike of
Ca
2+ (Maffei et al. 2004, 2006). This highly evoked Ca
2+ levels during herbivore
attack help in transmitting the attack message. This change in cytosolic free calcium
is perceived and decoded by a myriad of Ca
2+ -sensor proteins, which stimulates a
conformational change and assists their interaction with downstream effector
molecules. Ca
2+ -sensor proteins either work as relay sensor (CaM, CML, CBL) or
as relay responders (CDPKs). CaM is known to interact with target proteins and
modulate their activity. CMLs are closely related to CaM family and have been
deciphered only in plants. CBLs and CDPKs are also plant specific proteins and an
important component of Ca
2+ signalling. At present, specific function of most of the
Ca
2+ -sensors remains unknown, but recent studies have highlighted their contribution in development, biotic and abiotic stresses (Aldon et al. 2018). This activation of
Ca
2+ signalling as well as ROS and MAPK signalling together stimulates JA-Ile
formation, which binds to SCF
COI1 complex, which degrades JAZ repressors, and
triggers the transcription factors to upregulate the production of defence-related
proteins and secondary metabolites.
16.2 Generation of Calcium Signatures During Plant–Herbivore
Interaction
Plants recognition of herbivores attack occurs initially when herbivores start
crawling (crawling pattern) in leaf and also by chewing of the leaf (chewing
behaviour) which release oral secretion (OS) (Zebelo and Maffei 2015). OS
possesses elicitors such as herbivore-associated molecular patterns (HAMPs) and
damage associated molecular pattern (DAMP), (Acevedo et al. 2015). Herbivory
introduces these insect-derived elicitors that trigger a cascade of signals. Among
them Ca
2+ due to its smaller ionic size (231 pm) responds rapidly to the herbivore
attack and travels throughout the cell to convey signal. Ca
2+ transported to the
cytosol through various Ca
2+ specific channels and ions. The Ca
2+ ions are not
directly involved in membrane depolarization proved by pdko3 plasmodesmatal
protein in Arabidopsis (Bricchi et al. 2010). Ca
2+ signalling was visualized in vivo
by using Ca
2+ sensitive like fluorescent probes or the bioluminescence based
aequorin technology (Kanchiswamy et al. 2010).
In a study, it was revealed that when lepidopteran larvae fed on plants, V m
depolarization occurred in the vicinity of wounding zone, which was followed by
16 Role of Calcium Signalling During Plant–Herbivore Interaction
493
observed is the change in V m and generation of fast electrical signal (Maffei et al.
2007a, b). Further the activity of channels and transporters is triggered, such as Ca
2+ -
channels leading to spiking of Ca
2+ in the form of repetitive oscillation (Evans et al.
2001; Tian et al. 2020); the period of frequency, sinusoidal or square shape wave,
and amplitude specify the stimulus specificity (Kosuta et al. 2008). These repetitive
oscillations and spiking of Ca
2+ form the code called as “Ca
2+ signature” (Dodd et al.
2010; Webb et al. 1996; Mithöfer et al. 2009). Ca
2+ signature reveals the nature and
intensity of the stimulus and specific information of stress. In Phaseolus lunatus,
Spodoptera littoralis larvae start feeding on their leaf, which results in sharp spike of
Ca
2+ (Maffei et al. 2004, 2006). This highly evoked Ca
2+ levels during herbivore
attack help in transmitting the attack message. This change in cytosolic free calcium
is perceived and decoded by a myriad of Ca
2+ -sensor proteins, which stimulates a
conformational change and assists their interaction with downstream effector
molecules. Ca
2+ -sensor proteins either work as relay sensor (CaM, CML, CBL) or
as relay responders (CDPKs). CaM is known to interact with target proteins and
modulate their activity. CMLs are closely related to CaM family and have been
deciphered only in plants. CBLs and CDPKs are also plant specific proteins and an
important component of Ca
2+ signalling. At present, specific function of most of the
Ca
2+ -sensors remains unknown, but recent studies have highlighted their contribution in development, biotic and abiotic stresses (Aldon et al. 2018). This activation of
Ca
2+ signalling as well as ROS and MAPK signalling together stimulates JA-Ile
formation, which binds to SCF
COI1 complex, which degrades JAZ repressors, and
triggers the transcription factors to upregulate the production of defence-related
proteins and secondary metabolites.
16.2 Generation of Calcium Signatures During Plant–Herbivore
Interaction
Plants recognition of herbivores attack occurs initially when herbivores start
crawling (crawling pattern) in leaf and also by chewing of the leaf (chewing
behaviour) which release oral secretion (OS) (Zebelo and Maffei 2015). OS
possesses elicitors such as herbivore-associated molecular patterns (HAMPs) and
damage associated molecular pattern (DAMP), (Acevedo et al. 2015). Herbivory
introduces these insect-derived elicitors that trigger a cascade of signals. Among
them Ca
2+ due to its smaller ionic size (231 pm) responds rapidly to the herbivore
attack and travels throughout the cell to convey signal. Ca
2+ transported to the
cytosol through various Ca
2+ specific channels and ions. The Ca
2+ ions are not
directly involved in membrane depolarization proved by pdko3 plasmodesmatal
protein in Arabidopsis (Bricchi et al. 2010). Ca
2+ signalling was visualized in vivo
by using Ca
2+ sensitive like fluorescent probes or the bioluminescence based
aequorin technology (Kanchiswamy et al. 2010).
In a study, it was revealed that when lepidopteran larvae fed on plants, V m
depolarization occurred in the vicinity of wounding zone, which was followed by
16 Role of Calcium Signalling During Plant–Herbivore Interaction
493