农学类英文文献

thereby decreasing the antioxidant status of the fruit.
Phenolic compounds are plant secondary metabolites involved in fruit quality (Tomás-Barberán,2001). These
Postharvest storage temperatures may also play a role in chilling susceptibility of lemon fruits. Lemon fruit were more chilling
tolerant when stored at −0.5℃ than when stored at 2 ℃、4.5 ℃.
The combined effect of temperature and postharvest chemical treatment with 10μM MJ plus 2 mM SA may have played a role in
cold acclimation against CI. Probably through inducing defense
Tomás-Barberán (2001) reported that POD and PPO are involved in the oxidation of antioxidants, the enzymes POD and PPO have been associated with tissue browning during plant stress (Martí nez-Téllez 1997).
3、Results and analysis
3.1 Effect of MJ and SA on CI of lemon fruit during cold storage Cold
3.2 Changes in electrolyte leakage in lemon flavedo of fruits inresponse to MJ and SA treatment and storage
New Venture Farm （Moderate subtropical zone ）
Tala Valley Citrus Estate （Warm temperate zone ） Sun Valley Estates （Cool subtropical zone）
Methods: soak
Storing lemon fruit at -0.5 ℃ may have led to suitable conditions for phenolic production, which could have been enhanced by
10μM MJ plus 2 mM SA treatment.
Fra Baidu bibliotek
3.7 Postharvest PPO activity in lemon flavedo of MJ and SA
4、Discussion and Conclusion
4.1 Discussion
In this study, both MJ and SA were used as postharvest
3.5 Postharvest metabolism of PAL in lemon flavedo of MJ and SAtreated lemon fruit
3.6 Postharvest POD activity in lemon flavedo of MJ and SA treatedlemon
Content
Introduction Experimental Materials and Methods Results and Analysis
Discussion and Conclusion
1、Introduction
1.1 Background
Chilling injury (CI), a physiological disorder disrupting normal cell metabolism, is one of the most significant
mechanisms involved in cold acclimation (phenolics and PAL activity) and inhibiting the accumulation of POD activity and membrane lipid peroxidation.
Citrus fruit contain antioxidants, such as phenolic compounds, that can mitigate cellular damage under chilling stress (Grace, 2000).
Phenylalanine ammonia-lyase (PAL) is the key
store（0、7、14、21、28 days ） room temperature
4 MJ and SA concentration ：0（Control）、 10 μM（MJ）、 2 mM （SA）、and 10 μM（MJ）+ 2 mM（ SA） 3 storage temperature ：−0.5 ℃、2 ℃、4.5℃
1996) and tomatoes (Ding et al.2002).
Preliminary results suggest that combined concentration of MJ and SA (10μM MJ+2 mM SA) may reduce CI in
lemon fruit (Siboza and Bertling, 2013).
treatments on lemon fruits to investigate whether they
play a role in maintaining fruit quality during cold storage by triggering the activity of phenolics and PAL.
3.3 The effect of postharvest treatments with MJ and SA in inhibiting MDA concentration in lemon flavedo
max
3.4 Postharvest phenolics concentration in lemon flavedo of MJ and SA treated lemon fruit
1、Determination of CI index：by Sala and Lafuente （0 = normal, 1
= slightpitting、2 = moderate pitting、3 = severe pitting）
2、Determination of membrane permeability ： Electrolyte leakage according to Cohen. 3、Determination of membrane lipid peroxidation：TCA 4、Extraction and assay of total phenolics ：determined using the method of Pérez-Tello et al. 5、Determination of PAL activity 6、Determination of POD activity 7、Determination of PPO activity
1.2 Objective
In this study, our objective was to determine
how MJ and SA promote accumulation of
phenolics and increased PAL activity ,while inhibiting enzymes oxidizing phenolic
enzyme at the entrypoint of the phenylpropanoid
pathway ,which is involved in defense and acclimation against chilling (Rivero, 2001). The
induction of PAL activity in response to stress has
Salicylic acid and methyl jasmonate improve chilling tolerance in cold stored lemon fruit Journal of Plant Physiology
（IF :2.77）
author:Xolani Irvin Sibozaa,∗, Isa Bertlinga
compounds, such as PPO and POD, which
may be one of the mechanisms of improved
chilling tolerance in cold stored lemon fruit .
2、Materials and Methods
Materials: ‘Eureka’ lemon fruits Materials source :
contributors to postharvest losses in citrus fruit
(Sala,2005) In citrus fruit, CI is manifested as pitting, rind staining,
red blotches and necrosis on the flavedo (Sala,1999).
3 materials source ：Tala Valley Citrus Estate、 New Venture Farm Sun Valley Estates Design: a randomized complete with five replications.
2.1 Experiment index and method
been considered a defense mechanism of fruit to withstand stress (Lafuente,1997), therefore chilling can affect PAL activity levels (Ballesta, 2000).
Phenolics and PAL are thought to be involved in the
alleviation of CI during cold storage. However, PPO and POD are believed to be antagonistic to the action of PAL.
(Raimbaultet. 2011).
The beneficial effect of plant hormones such as methyl
jasmonate (MJ) and salicylic acid (SA) in alleviating CI
has been demonstrated in zucchini squash (Wang and Buta, 1994), avocado, grapefruit, bell pepper (Meir et al.
compounds are powerful antioxidants (Grace, 2000)
capable of scavenging reactive oxygen species (González-Aguilar,2004). However, their physiological
functions have not been completely elucidated