Plant root architecture is highly plastic during development and can adapt to many environmental stresses. The proper distribution of roots within the soil under various conditions such as salinity, water deficit, and nutrient deficiency greatly affects plant survival.
Each and every plant species differ in their sensitivity or tolerance to salts and other abiotic stress conditions. However, there must be some selective cell type present in root epidermic tissue which is controlling the uptake of mineral nutrition. Apart from this, In my research, I have found fine root turnover which is proposed by Marschner, 1995 (Marschner, H. 1995. Mineral Nutrition of Higher Plants. London: Academic Press.) and that is also one of the wonderful adaption by plants.
Hi, Hery, salinity can be considering as abiotic stress. You can look for the SIMR model, perhaps, this will help you to link salinity with root architecture.http://www.sciencedirect.com/science/article/pii/S1360138507000179
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2008.01908.x/full
Good luck!
At the lateral root primordium initiation level, it has been shown that salinity is associated with lateral root primordium arrest. In other words, the root system adopts to the condition by limiting the number of lateral roots that emerge and develop. The response can vary within cultivated varieties for a crop species and can be used to select for more salt tolerant cultivars. There are several excellent papers out there in crop species; an example report in model systems: http://www.ncbi.nlm.nih.gov/pubmed/22738204
Dear Arthur,
I am little bit disagree with your comment ... because the main function of lateral roots is to gives mineral nutrition and water to plant. Therefore plant cannot stop producing lateral roots. Apart from this one theory said that when level of salt reach to excess level in the cell then plant transfer this additional salt into lateral roots then disassociate the lateral roots from tap roots...... may be due to that one can find less amount of lateral roots.....
Dear Ashish:
Lateral root emergence and development is subject to internal and external cues. As I mentioned in my previous response, the knowledge base is tremendous and continues to expand. As you well know, the root system is extremely plastic and responds to the soil environment. Lateral root development is the main method wherein the root system manifests plasticity. If you clicked on the reference that I shared, and search for "lateral root development" and "environmental cues", you will find a whole new meaning to "the hidden half." Have you measured lateral root development in your system? The understanding of arrested lateral root primordia offer an excellent conceptual platform to incorporate ABA-related responses as well. Cheers!
Thnx... I will go through it .... then back to you.....
Apart from this during our experiment in plastic bag with saline condition applied. We found that lot of dead lateral roots in dark black color. Then we have checked their Na content in atomic absorption spectrometer and compared those results with attached lateral roots and the results was surprising we have found almost 3 fold greater Na in black lateral roots.
Do you have any idea about this.....
Cheers
If the experimental treatment is in excess of physiological levels for that species, then I would imagine some turn over for existing lateral roots. However, did you check for arrested lateral root primordia in "stressed" plants vs. the control? This can be verified by examining developing tap roots (I am assuming your system is a dicot species), specifically a few mm from the root cap. If your roots are tetrarch, you can look at the control treatment, count the lateral roots and establish the baseline number; then you would expected lower lateral root density in stressed roots because some lateral root primordia are arrested.
Yes, I have checked for all stress conditions and found almost similar results. Please find attached herewith the research paper but I didn't put that data in my research paper.
Did you check for arrested lateral root primordia? How many protoxylem poles are in your roots? How many lateral roots per cm in the control? These are some fundamental considerations when looking at root system architecture. Cheers!
Interesting discussion...
Plants use different strategies to deal with high soil salinity. One strategy is activation of pathways that allow the plant to export or compartmentalise salt. Relying on their phenotypic plasticity, plants can also adjust their root system architecture (RSA) and the direction of root growth to avoid locally high salt concentrations. Here, we highlight RSA responses to salt and osmotic stress and the underlying mechanisms. A model is presented that describes how salinity affects auxin distribution in the root. Possible intracellular signalling pathways linking salinity to root development and direction of root growth are discussed. These involve perception of high cytosolic Na+ concentrations in the root, activation of lipid signalling and protein kinase activity and modulation of endocytic pathways. Source : Curr Opin Plant Biol. 2011 Jun;14(3):296-302. doi: 10.1016/j.pbi.2011.03.019. Epub 2011 Apr 20.
Roots respond first to edaphic stresses, yet little is known about root response to stress in mature, soil-grown plants. We investigated the effects of salinity and phytophthora root rot on root growth and senescence in tomato (Lycopersicon esculentum Mill.). Using minirhizotron- and rhizotron-based methodologies, we quantified intraspecific differences in root-system response to salinity and inoculation. Genotype susceptibility to salt-induced disease was related to root vulnerability to salt. ‘UC82B’ was vulnerable to infection by Phytophthora parasitica when subjected to salt stress and produced thinner roots and ≈50% higher root-senescence rates compared to the phytophthora root rot-resistant ‘CX8303’. Root growth at the peripheral regions of the ‘CX8303’ root system was inhibited by salinity, but otherwise root dynamics were not affected by salinity or inoculation. Overall, roots from the central root system and roots from the periphery responded differently to salt stress. Monitoring the diameters of new initiated roots indicated the vulnerability of a stressed root system to disease and early senescence. Source : J. AMER. SOC. HORT. SCI. 119(3):458–463. 1994.
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