Chemistry Reference
In-Depth Information
SA was the best treatment to increase sugar translocation from leaves to fruits,
average fruit weight, and fruit yield, and decreased POX activity of greenhouse
grown pepper (Capsicum annuum L.) under salinity stress (Elwan and El-Hama-
hmy
2009
).
3.2.3 Ascorbate Content
In this study, decreased AA and high H
2
O
2
levels occurred in infected plants as a
response to phytoplasma stress in contrast to phytoplasma-free plants. Decreased
AA in infected plants could be associated with phytoplasma infection, since an AA
decline has been associated with TMV infection in tobacco (Fodor et al.
1997
). In
this work, all SA concentrations significantly increased AA levels, particularly at
30 DAT as a short term response, in opposition to the observed response as long
term effect, where a reduction of AA concentration was noticed respecting the
positive control (Fig.
5
a). At 90 DAT not only in short but also in long term AA
concentration increased respecting the positive control (Fig.
5
c).
In agreement with previous studies showing that suitable concentrations of
exogenous SA enhanced plant antioxidant system efficiency (Hayat et al.
2009
).
AA plays an important role in many cell processes, mainly as an antioxidant
(Smirnorf
1996
), and can increase resistance to abiotic (Shalata and Neumann
2001
) and biotic (Noctor and Foyer
1998
) stresses. Exogenous SA-induced aug-
mentation of AA concentrations in wheat (Asthir et al.
2009
), Oryza sativa
(Choudhury and Panda
2004
), carrot (Eraslan et al.
2007
), tobacco (Fodor et al.
1997
), Lycopersicon esculentum (He and Zhu
2008
), orange (Huang et al.
2008
),
and maize (Krantev et al.
2008
).
Greenhouse grown pepper treated with low SA concentrations under salinity
stress had high fruit vitamin C (AA) and carotenoid levels (Elwan and El-Ha-
mahmy
2009
), and SA-induced AA participates in alleviating biotic (Fodor et al.
1997
) and abiotic (Horváth et al.
2007
; He and Zhu
2008
; Huang et al.
2008
)
stresses. In our study, increased AA in SA-treated plants could be associated with
reduced symptoms in potato plants infected by phytoplasma, possibly via PR gene
expression because AA content can modulate PR gene expression (Foyer and
Noctor
2005
). Alterations in AA levels and/or redox state, as well as in their redox
enzyme activities are important during plant-pathogen interactions (De Gara et al.
2003
). The role of AA in plant growth is known (Pedreira et al.
2004
), and perhaps
SA-augmented AA contributed to increased tuber size and dry matter content. AA
controls growth and it is mediated by H
2
O
2
content (Pedreira et al.
2004
). Hence,
the significantly high H
2
O
2
content in the early stage might be a key condition for
the signaling response to reduce damage. SA can affect AA content either,
increasing (Choudhury and Panda
2004
; Eraslan et al.
2007
; He and Zhu
2008
)or
reducing (Saruhan et al.
2012
). Interestingly SA induced reduction of AA and
gluthation contents in sensible cultivars but enhanced AA concentration in the
tolerant (Saruhan et al.
2012
).
Search WWH ::
Custom Search