Page 215 - PC2019 Program & Proceedings

PLANT CANADA 2019

P3. Effects of exogenous melatonin on improving the drought resistance of oat seedlings
Chen, S.
Southwest Minzu University

Drought is one of the severe constraints in oat production. The effects of exogenous melatonin on
improving the drought resistance of oat seedlings were studied, which were subjected to water stress (-
0.9MPa) induced by polyethylene glycol 6000. The roots of oat plants were pretreated with 0.1mmol
melatonin for 7 days before water stress was implemented for 14 days in a growth chamber. The results
showed that the exogenous melatonin effectively alleviated the damage effects from drought stress, as
demonstrated by higher relative water content, chlorophyll content, soluble sugar content, free proline
content, root vigor and antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase, and
-
ascorbate peroxidase), lower O2 generation rate, relative electronic conductivity, H2O2 and
malondialdehyde content as compared to untreated plants. The accumulation of endogenous melatonin
and abscisic acid were elevated, while the accumulation of indole-3-acetic acid (IAA) and gibberellin A3
(GA3) were decreased in oat seedlings under drought stress. The application of exogenous melatonin
resulted in increased the endogenous melatonin and IAA contents, which also induced the synthesis of
GA3 and inhibit the synthesis of abscisic acid. These results suggest that ameliorating drought stress
through exogenously applied melatonin may be associated with increased antioxidant protection
capability and after a longer stress treatment with changed IAA and GA3 accumulation level on account
of improved endogenous melatonin content.

Shiyong Chen (chengshi8827@163.com)

P4. Wounding induces tomato Ve1 R-gene expression
2
1
1
Nazar, R. ; C. Castroverde ; X. Xu ; A. Kurosky ; E. Robb
1
1
1 University of Guelph
University of Texas Medical Branch
2
In tomato, Verticillium fungal resistance is determined by the Ve-gene locus, which encodes two leucine-
rich repeat receptor-like proteins (Ve1, Ve2). The gene encoding Ve1 protein has two functional alleles;
Ve1, encoding a resistance protein, and ve1, with a premature stop codon encoding a truncated product. In
both resistant and susceptible plants, Ve1 is induced differentially while Ve2 is constitutively expressed
throughout disease development. Contrary to their putative role in Verticillium resistance, these profiles
have been observed even during compatible Verticillium interactions, colonization by some bacterial
pathogens, and growth of transgenic tomato expressing the fungal Ave1 effector, suggesting broader roles
in disease and/or stress. Here we have examined further Ve-gene expression in resistant and susceptible
plants under abiotic stress, including drought, salinity and physical damage. Using qRT-PCR and label-
free LC-MS methods, chnges have been evaluated at both the mRNA and protein levels. The results
indicate that Ve1gene expression responds specifically to physical damage or plant wounding, resulting in
a defense/stress cascade that resembles observations during Verticillium colonization. In addition,
changes in Ve1 or Ve2 function also result in responses that occur with wilt pathogen and are consistent
with an antagonistic relationship between the two genes. Mutational analyses also indicate the plant
wounding hormone, systemin, is not required, while jasmonic acid appears to play a direct role in Ve1
induction.

Christian Danve Castroverde (danve.online@gmail.com)

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