Improving salinity tolerance in crop plants: a biotechnological view

Abstract

Salinity limits the production capabilities of agricultural soils in large areas of the world. Both breeding and screening germplasm for salt tolerance encounter the following limitations: (a) different phenotypic responses of plants at different growth stages, (b) different physiological mechanisms, (c) complicated genotype × environment interactions, and (d) variability of the salt-affected field in its chemical and physical soil composition. Plant molecular and physiological traits provide the bases for efficient germplasm screening procedures through traditional breeding, molecular breeding, and transgenic approaches. However, the quantitative nature of salinity stress tolerance and the problems associated with developing appropriate and replicable testing environments make it difficult to distinguish salt-tolerant lines from sensitive lines. In order to develop more efficient screening procedures for germplasm evaluation and improvement of salt tolerance, implementation of a rapid and reliable screening procedure is essential. Field selection for salinity tolerance is a laborious task; therefore, plant breeders are seeking reliable ways to assess the salt tolerance of plant germplasm. Salt tolerance in several plant species may operate at the cellular level, and glycophytes are believed to have special cellular mechanisms for salt tolerance. Ion exclusion, ion sequestration, osmotic adjustment, macromolecule protection, and membrane transport system adaptation to saline environments are important strategies that may confer salt tolerance to plants. Cell and tissue culture techniques have been used to obtain salt tolerant plants employing two in vitro culture approaches. The first approach is selection of mutant cell lines from cultured cells and plant regeneration from such cells (somaclones). In vitro screening of plant germplasm for salt tolerance is the second approach, and a successful employment of this method in durum wheat is presented here. Doubled haploid lines derived from pollen culture of F 1 hybrids of salt-tolerant parents are promising tools to further improve salt tolerance of plant cultivars. Enhancement of resistance against both hyper-osmotic stress and ion toxicity may also be achieved via molecular breeding of salt-tolerant plants using either molecular markers or genetic engineering.

The effect of salt stress on the germination of maize (Zea mays L.) seeds and photosynthetic pigments

“…Salinity due to the over-accumulation of NaCl is usually of great concern and is the most damaging factor in arid and semi-arid regions. Saline soils are widespread throughout the world, and their genesis may be natural or accelerated by irrigated agriculture, the intensive use of water resources combined with high evaporation rates and human activity (Lambers, 2003;Arzani, 2008). The osmotic adjustment, i.e.…”

The examination of Na-Ca effect on some qualitative and quantitative characters in durum wheat plants

“…Arzani (2008) found that the net photosynthesis rate and growth of plant reduced because of salinity. Misra et al (1997) and Munns et al (2002) also found that various parameters about photosynthesis, such as the potential of leaf moisture, the composition of pigment, the heat of leaf and the relative water content of leaf, were changed by salinity.…”

Review Paper on Approaches in Developing Inbred Lines in Cross-Pollinated Crops

“…These genotypes may have carried useful genes that would be expressed in other target environments. Owing to the gains in speeded up cultivar development and the creation of desirable genetic backgrounds, doubled haploids are widely utilized in breeding as well as in genetic studies of various crops and traits [16]; [17]; [18] and [19]. Overall, the DH technology allows for the creation of stable haploids after recombination of parents with broad genetic variation.…”