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Evaluation Of Agro-morphology, Physio-biochemistry And Molecular Of The Most Important Wild Species And Some Cultivated Genotypes Of Almond (prunus Dulcis Mill.) In Iran  


Abstract Category: Other Categories
Course / Degree: Ph.D
Institution / University: Shahrekord University, Iran
Published in: 2012


Dissertation Abstract / Summary:

The currently research has been two section including physiobiochemical and molecular in wild and cultivated genotypes of almond. In wild species of almond (Prunus spp.), the activities of ascorbate peroxidase (APX), monodehy-droascorbate  reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), as well as the levels of ascorbate/glutathione pools and H2O2 were subjected to water deficit and shade conditions. After 60 days of water shortage, the species were subjected to a rewatering treatment. During water recovery, leaves exposed to sunlight and leaves under shade conditions of about 20–35% of environmental irradiance were sampled. After 70 days without irrigation, mean predawn leaf water potential of all the species fell from -0.32 to -2.30 MPa and marked decreases in CO2 uptake and transpiration occurred. The activities of APX, MDHAR, DHAR, and GR increased in relation to the severity of drought stress in all the wild species studied. Generally, APX, MDHAR, DHAR, and GR were down regulated during the rewatering phase and their activities decreased faster in shaded leaves than in sun exposed leaves. The levels in total ascorbate, glutathione, and H2O2 were directly related to the increase in drought stress and subsequently decreased during rewatering.

The antioxidant response of wild almond species to drought stress limits cellular damage caused by reactive oxygen species during periods of water deficit and may be of key importance for the selection of drought resistant rootstocks for cultivated almond. The effect of proline on antioxidative system in detached leaves of eight species of wild almond exposed to oxidative stress by H2O2 was studied. Proline (PRO) accumulation, accompanied by a decrease in ascorbate and glutathione content, was observed in leaves in plants subjected to H2O2 treatments. Inhibitory effects of H2O2 on antioxidant enzyme activities, MDA, and EL were found. Following two different treatments with PRO+H2O2, the activities of SOD and CAT decreased, while POD and APX activities increased if compared to leaves exposed only to H2O2.

PRO+H2O2 treatments also caused a decrease in cellular H2O2 content, MDA, and EL, while cellular concentration of PRO increased. The results showed that PRO and H2O2 could have a key role in oxidative stress injury of wild almond species. Finally, PRO might have direct positive effects on the regulation of antioxidant system and on the reduction of membrane oxidative damage. The effect of three different temperatures (10, 25, or 35 ºC), polyamines (putrescine, spermidine, and spermine) and polyamine synthesis inhibitor, methylglyoxals-bis (guanylhydrazone) (MGBG) on in vitro pollen germination and pollen tube growth were investigated in P. dulcis L. ‘Mamaei’. All temperatures and chemicals significantly affected both pollen germination percentage and pollen tube growth. In general, different polyamines stimulated the pollen germination percentage compared to the control at all temperatures, but increasing the temperature, particularly to 35 ºC, had demonstrated inhibitory effects on pollen germination. The present work also describes the changes in the activities of key antioxidant enzymes and the levels of some metabolites in relation to salt tolerance in eight wild almond species. All the species were exposed to four levels of NaCl (control, 40, 80 and 120 mM). Plant fresh biomass, α-, γ- and  -tocopherol, total soluble proteins, malondialdehyde (MDAeq), H2O2, total phenolics, and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were analyzed in leaves of salt-stressed and non-stressed plants of the eight almond species. In all the species, salt stress significantly enhanced the activities of SOD and POD, levels of total phenolics and c- and d-tocopherols. High levels of salt stress significantly depressed the levels of total soluble proteins, MDA and CAT activity, while salt stress did not significantly affect leaf H2O2 contents. A modified bilinear model best described the response to temperature of pollen germination and pollen tube length. Almond species variation was found for cardinal temperatures (Tmin, Topt and Tmax) of pollen germination percentage and pollen tube growth.

Mean cardinal temperatures averaged over eight almond species were 14.7, 24.2, and 43.7 º C for maximum percentage pollen germination and 14.48, 25.3, and 44.4 º C for maximum pollen tube length. Wild species from ‘Spartioides’ were less affected than ‘Lycioides’ and ‘Euamygdalus’. At the same level of water potential, sorbitol had lower adverse effects than PEG; the latter being severe. Prunus × sorbitol and Prunus × PEG interactions were significant. At 0.2 M sorbitol and 0.003 M PEG, ‘Spartioides’ produced significantly more roots with higher total root length and root volume, as well as root-dry weight than those of ‘Lycioides’ and ‘Euamygdalus.’ It is concluded that in vitro screening of native Iranian almond species under specific and limited water-stress conditions may provide a system for effectively differentiating the wild species of almond for their expected root mass production under field conditions. Finally, S-RNase and non-SRNase alleles
Self-incompatibility in some Iranian wild almond species using total length S-RNase PCR, IEF and sequencing identified. In addition, SFB and S-haplotype gene characterized.


Dissertation Keywords/Search Tags:
Prunus L. spp, Droughth, Salinity, SRNase, non-SRNase, SFB, S-Haplotyps

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Submission Details: Dissertation Abstract submitted by Karim Sorkheh from Iran on 09-Apr-2014 09:22.
Abstract has been viewed 2296 times (since 7 Mar 2010).

Karim Sorkheh Contact Details: Email: karimsorkheh@gmail.com



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