Mineral Content and Biochemical Variables of Aloe vera L. under Salt Stress

Abstract

Despite the proven economic importance of Aloe vera, studies of saline stress and its effects on the biochemistry and mineral content in tissues of this plant are scarce. The objective of this study was to grow Aloe under NaCl stress of 0, 30, 60, 90 and 120 mM and compare: (1) proline, total protein, and enzyme phosphoenolpyruvate carboxylase (PEP-case) in chlorenchyma and parenchyma tissues, and (2) ion content (Na, K, Ca, Mg, Cl, Fe, P. N, Zn, B, Mn, and Cu) in roots, stems, leaves and sprouts. Proline and PEP-case increased as salinity increased in both parenchyma and chlorenchyma, while total protein increased in parenchyma and decreased in chlorenchyma, although at similar salt concentrations total protein was always higher in chlorenchyma. As salinity increased Na and Cl ions increased in roots, stems, leaves, while K decreased only significantly in sprouts. Salinity increases typically caused mineral content in tissue to decrease, or not change significantly. In roots, as salinity increased Mg decreased, while all other minerals failed to show a specific trend. In stems, the mineral concentrations that changed were Fe and P which increased with salinity while Cu decreased. In leaves, Mg, Mn, N, and B decreased with salinity, while Cu increased. In sprouts, the minerals that decreased with increasing salinity were Mg, Mn, and Cu. Zinc did not exhibit a trend in any of the tissues. The increase in protein, proline and PEP-case activity, as well as the absorption and accumulation of cations under moderate NaCl stress caused osmotic adjustment which kept the plant healthy. These results suggest that Aloe may be a viable crop for soil irrigated with hard water or affected by salinity at least at concentrations used in the present study.

Aloe veralong-term saline irrigation increases contents of hydrogen peroxide, lipid peroxidation and phenolic compounds

“…Similar to the previous reports with Aloe Murillo-Amador et al 2014), in the present study, the stressed plants maintained a K/Na ratio significantly lower than those of control plants.…”

Moderate salt stress on the physiological and morphological traits of Aloe vera L.

“…Although water use effi cient in Aloe vera during relatively mild water defi cit, plants become stressed at severe water shortage, this species are generally considered most drought and salt-tolerant compared with other Aloe species such as Aloe saponarea (Sun et al, 2003). This salt tolerance in Aloe vera could be related to high calcium and chloride content in their tissues (Ranganathan, 1970) or due to osmotic adjustment caused by the increase in protein, proline and PEP-case activity, as well as the absorption and accumulation of cations under NaCl stress (Murillo-Amador et al, 2014). Other studies have shown that non-halophytic succulent plants with crassulacean acid metabolism such as Aloe vera, shows diurnal variation in acid content and can synthetize more amino acids when they are subjected to mild salt concentration by metabolizing transaminases and inhibiting production of malate dehydrogenase (Karmarkar and Ranganathan, 1971).…”

Propagation Techniques and Agronomic Requirements for the Cultivation of Barbados Aloe (Aloe vera (L.) Burm. F.)—A Review

“…Murillo-Amador et al (2014) reported that Na and Cl ions accumulated in the cells of roots, stems, leaves and sprouts, thus showing higher Na and Cl contents in sprouts followed by leaves, stems and roots.…”

“…Proline and PEP-case increased as salinity increased in both parenchyma and chlorenchyma of aloe under NaCl stress of 0, 30, 60, 90, and 120 mM, while total protein increased in parenchyma and decreased in chlorenchyma. The increase in protein, proline and PEP-case activity, as well as the absorption and accumulation of cations under moderate NaCl stress caused osmotic adjustment, which kept the plant healthy (Murillo-Amador et al, 2014). …”