Anatomical changes in stem and root of soybean plants submitted to salt stress

Abstract

The soybean is a legume that is widely cultivated in many countries due to the high levels of protein and oil contained in its seed, and is used for human and animal nutrition. However, salinity affects more than 800 million hectares worldwide, limiting global agricultural production. • The aim of this research was to evaluate the structural behaviour of the roots and stems under progressive salt stress, detailing the possible anatomical modifications to these organs in soybean plants during this stress. The plants were randomized into five treatments (0, 50, 100, 150 and 200 mM NaCl). • All the root regions studied and exposed to 100 mM Na + exhibited increases in the epidermis and endodermis and formation of lysogenic aerenchyma with increasing salinity, revealing the protective roles of these structures in reducing Na + influx. In the stem, increases in the cortex and pith in the first internode subject to 100 mM Na + suggest anatomical responses that aim to minimize oxidative stress. • Soybean plants subjected to progressive salt stress (>50 mM Na +) avoided cavitation and loss of function linked to vessel elements, reducing the metaxylem in all the root and stem regions analysed. Finally, our results confirm anatomical changes to the roots and stems.

Root plasticity under abiotic stress

“…This process also releases nutrients to the surrounding cells and is prevalent in older roots that are no longer taking up water efficiently. The formation of lysigenous aerenchyma is also stimulated under salt stress ( Silva et al, 2021 ).…”

Comparative de novo transcriptome analysis identifies salinity stress responsive genes and metabolic pathways in sugarcane and its wild relative Erianthus arundinaceus [Retzius] Jeswiet

“…2 b). Similar changes in the root cellular structure under drought and salinity stress in the tolerant genotypes are attributed to be an adaptive mechanism of resistant genotypes 32 , 33 .

Figure 2 Root anatomical changes in responses of IND99-907 and Co 97010 under salinity stress ( A ) Root anatomical images showing the vacuolization of cortex and thickening of metaxylem vessels in Co 97010 as compared to no significant changes in IND99-907.

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Salt Stress Responses and Tolerance in Soybean

“…One of the obvious effects of salt stress in soybean is the reduction of plant growth, which is reported in many plant studies [28,35,36]. As salt stress inhibits water and nutrient uptake and translocation, it is obvious that this hampers the normal cell growth and development and hence, growth is retarded.…”

“…Salt stress also hampers the plant's anatomy and impairs the normal growth of plants. As salt stress allows the entry of high Na + into plants roots, this reduces the elongation rate and disturbs root architecture [35,36,39]. It is evident that plants sometimes thicken the epidermis and endodermis root cells as a preventive measure of Na + influx.…”