Research Article

Mechanisms of Salt Tolerance of Wheat Cultivars  

Hamdia M. Abd El Samad , Shaddad Shaddad M.A.K.
Botany and Microbiology Department, Faculty of Science, Minia University, El-Minia, Egypt
Author    Correspondence author
Triticeae Genomics and Genetics, 2016, Vol. 7, No. 2   doi: 10.5376/tgg.2016.07.0002
Received: 21 Oct., 2015    Accepted: 15 Dec., 2015    Published: 02 Jan., 2016
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This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:

Hamdia M. Abd El- Samad, and Shaddad M.A.K., 2016, Mechanisms of Salt Tolerance of Wheat Cultivars, Triticeae Genomics and Genetics, 7(02): 1-16 (doi: 10.5376/tgg.2016.07.0002)

Abstract

This work was carried out to study the effect of various salinization levels (0,20,50,,150and 300mM NaCl) through the whole life cycle of four wheat cultivars (Sakha94,Gimiza11,Gimiza10, and Giza 168). Accordingly the salt tolerance of four wheat cultivars during vegetative and crop yieldstages ranked according to dry matter and chemical constituents  as the following: cv. Sakha 94>cv. Gimiza 11>cv. Gimiza 10 > cv. Giza 168.The carbohydrate and protein contents varied between the four wheat cultivars and their different plant organs, generally the  soluble carbohydrate content remained more or less unchanged in cv. Sakha94 and to some extent in cv. Gimiza11 and troubled in cv. Gimiza10 and cv. Giza168.The amino acids were interesting because, they increased considerably in cv. Sakha 94 and cv. Gimiza11 accompanied with a great equilibration in protein content in the two sensitive cultivars Gimiza 10 and Giza 168.Proline content varied consequently among the four wheat cultivars and their plant organs.The results also revealed that, 23 protein bands were detected in cv. Sakha 94, 18 protein bands in cv. Gimiza 11, 16 protein bands in cv. Gimiza 10 and 18 protein bands in cv. Giza 168 in protein analysis by electrophoreses. The four cultivars possessed 17 common protein bands while they different from each other in 6 protein bands. The 14.1 KDa  is specific marker for both cutivars Sakha 94 and Giza 168. However, the 33.2 KDa is specific marker for  cv.  Sakha 94, cv. Gmiza 11 and Giza 168.The 32.3 KDa is specific marker for cv. Sakha 94 and cv. Gimiza 11. The results revealed that three bands at molecular weight 52.1 kDa is  induced under salinity stress in four tested cultivars  Sakha 94, Gimiza 11, Gimiza10 and Giza 168, as compared to the control treatment. It was induced at 50 mM, 150 mM in both cultivars Gimiza 11, Gimiza 10 and Giza 168 while, induced at 50 mM, 150 mM and 300 mM NaCl levels in cv. Sakha 94 as compared to control treatment. These results revealed that the 52.1 kDa protein band was commonly induced as a result of salinity treatment in the four cultivars.All the previous parameters supported  the differentiation of salt tolerance between the four cultivars and open the chance for crop selection to be cultivated in saline soil.

Keywords
Mechanisms; Salt tolerance; Wheat

Introduction

Several environmental factors adversely affect plant growth and development and final yield performance of a crop (Ahmad et al., 2008, 2013; Hayat et al., 2012). Plants are frequently exposed to two main types of environmental stresses while grown in nature: a- Biotic stress (Kumar et al., 2009) while caused by infection and/or competition by other organism. b- Abiotic stress may be caused by numerous factors such as drought (Simova-Stoilova et al., 2009; Shaddad et al., 2011 a, b), cold (Van Kumar et al., 2009), high temperature (Reynolds-Henne et al., 2010), salinity (Wang et al., 2012), heavy metals (Abd El-Samad, 2014), alkalinity (Breusegm et al., 2001), air pollution, pesticides (Hong-Bo et al., 2008), ultraviolet radiation (Gao and Zhang, 2008) and is also affected with the fertility status of soil (Sogbedi et al., 2006). Moreover, daily sudden changes in the temperature and the presence of heavy metals, toxins, and oxidants due to human activities could result in extra stresses on plant (Vierling, 1991).Soil salinity, one of the most severe abiotic stresses, limits the production of about 6% of the world’s total land and 20% of irrigated land (17% of total cultivated areas) and negatively affects crop production worldwide. On the other hand, increased salinity of agricultural land is expected to have destructive global effects, resulting in up to 50% land loss by the next couple of decades. The adverse effects of salinity have been ascribed mainly to an increase in sodium (Na+) and chloride (Cl) ions and hence these ions produce the critical conditions for plant survival by intercepting different plant mechanisms (Hasanuzzaman et al., 2013). In saline environments, however, the difference in the water potential between soil and root cells is reduced or even inverted, leading to a reduction in water uptake or loss of water (Boursiacet al., 2005). Growth inhibition, and ultimately, serious tissue damages, are the consequences. According to the incapacity to grow on high salt medium, plants have been classified as glycophytes or halophytes. Most plants are glycophytes and cannot tolerate salt stress (Sairam and Tyagi, 2004). There are naturally occurring salt-tolerant trees (mangroves), shrubs, grasses and herbs. However, virtually none of our crop plants is able to tolerate even a quarter of seawater without loss of yield (Flowers and Flowers, 2005; Abd El-Samad and Shaddad, 2010, 2013 and, 2014).

 
Thus the aim of the present work was to describing salt-induced changes on the phenology of the four wheat cultivars (Sakha94, Gimiza11, Gimiza10, and Giza 168. The correlation between growth kinetics, dry matter production, carbohydrates, proteins amino acids andproline are in serving these toerance.
 
1 Results
1.1 Plant growth parameters
Dry matter yield
The data in Table 1 exhibited that salinity stress up to the level of 150mMNaCl, stimulated the production of dry matter of stems and leaves of wheat cultivar Sakha94.The percent of increase in dry matter yield approached 20% and 1.5- folds at the level of 150 mMNaCl in stems and leaves respectively. Dry matter of roots remained unchanged up to 150 mM NaCl then a highly significant reduction was recorded which was about 38.1% at the level of 300 mMNaCl. In spikes, There is a marked and progressive enhancement but not irregular in the production of spike in wheat cultivar Sakha94. The highest dry matter yield of spike was at the level of 150 mMNaCl more than 2 folds and the lowest accumulation of spike dry matter was at the highest salinity level used (about 16% over the control values).The data in Table 1 showed that the salinity stress stimulated the dry matter yield of stems up to 150 mMNaCl of wheat cultivar Gimiza 11. At this level the percent increase in dry matter of stem was about 29.6% in relation to the control. Then a highly significant reduction was obtained (about 25% below the control ). In leaves, the NaCl salinity induced insignificant changes in dry matter of leaves up to 150 mM NaCl, there after a marked and progressive reduction was obtained only at the level of 300 mMNaCl which was about (35% in relation to control).The dry matter of roots stimulated by salinity stress up to 50 mMNaCl by about 50% over those of control values, there after the dry matter of roots reduced sharply and suddenly, while the dry matter of roots stimulated by 50% at 50 mMNaCl, it on the other hand and surprisingly dropped by 22.3% at 150 mMNaCl and then continue to be reduced highly significantly up to the highest salinity level used 300 mMNaCl. At this level 300 mMNaCl the percent of reduction in root approached 80% in comparison to control. There is some irregular stimulation in the production of spikes in cv. Gimiza 11 up to the level of 150 mMNaCl. This stimulation fluctuated between 6% to 18% in relation to the control sample. However some inhibition was recorded only at 300 mMNaCl (about 19% in relation to control).

 

 

Table 1 Effect of various concentrations of NaCl on dry matter of roots, stems, leaves and spikes of cv. Sakha 94, cv. Gimiza11, cv. Gimiza10 and cv. Giza 168 wheat cultivar.

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