Molecular Plant Breeding, 2016, Vol.7, No.16, 1-7
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formation of female part instead of male part in family
cucurbitaceae, similarly in some plants species
ethylene promote flower induction while in others, it’s
otherwise.
In plants, all biotic and abiotic factors are elicited
ethylene synthesis. Regulation of ethylene synthesis is
highly influenced by various developmental signals
and hormones including auxin, cytokinins, and
gibberellin etc (Figure 2). This is also intensively
enhanced by environmental and biological factors
such as drought, salinity, cold, pathogens as well as
insect pests etc (Bleecker and Kende, 2000). This
shows the key role of ethylene in internal growth
coordination and even in defense mechanism for
survival against environmental confronts. Up-and-
coming evidences have unraveled that ethylene
sensitivity varies in diverse tissues and divergent
developmental stages in consequence of signaling
interactions with other plant hormones, metabolites
and environmental cues (Klee, 2004; Alonso and
Stepanova, 2004). Current studies in Arabidopsis
thaliana by developing its ethylene mutants have also
revealed an interconnection between early ovule
abortion and silique size (Guo and Ecker, 2004).
5 Role of Ethylene in Biotic Stresses in
Plants
Ethylene significant role in plant defense depicts its
association in multiple physiological processes by
stimulating necrosis and establishing hypersensitive
response in plants (Lund et al., 1998 and Ciardi et al.,
2001). Plant defense related dynamics including
phytoalexins induction, production pathogenesis
related proteins as well as cell wall modulations are
activated by ethylene (Tornero et al., 1997 and Fan et
al., 2000). Hence ethylene has been an object of
intensive study regarding resistance pathways and
mechanisms from last few decades. The role of
ethylene in resistance against pathogens had been
studied by Hoffman et al., (1999) by developing
soybean ethylene insensitive mutants. They observed
that ethylene helps in restricting the pathogen invasion
by leaf abscission when disease is aggravated. Similar
studies had been done on Arabidopsis thaliana and
Nicotiana tabacum (Knoester et al., 1998 and
Thomma et al., 1999) by developing their mutants to
explore the versatile role of ethylene in plant defense
against pathogens.
Immature phase to Mature phase transition
Figure 3 Ethylene Signaling pathway: a schematic diagram of
ethylene signaling transduction pathway depicting the signal
cascade controlling infantile to mature phase transition (Idea
taken from Schaller, E. G. 2012. Ethylene and the regulation
of plant development. BMC Biology, 10:9).
6 Ethylene Perception and Signaling Pathway
Plants have diverse mechanisms for modulating
themselves and showing elasticity against altering
internal and external environmental conditions.
Among these, ethylene signaling pathway is at
imperative status that plants have espoused for
regulating stress responses. The foremost elements in
ethylene signaling pathway comprise the ethylene
receptors, the Raf-like serine/threonine kinase, CTR1,
EIN2 (transmembrane protein), and the EIN3-like (EIL)
family of transcription factors (Alonso et al., 1999).
