Different Rhizospheric pH Conditions Affect Nutrient Accumulations in Rice under Salinity Stress

• Main Authors: Mami Nampei, Kamonthip Jiadkong, Sumana Chuamnakthong, Thanakorn Wangsawang, Tanee Sreewongchai, Akihiro Ueda
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Plants
• Subjects: Na exclusion; nutrients accumulation; rice saline-alkaline tolerance
• Online Access: https://www.mdpi.com/2223-7747/10/7/1295

This study was conducted to determine the responses to saline-alkaline (SA) stress with regard to nutrient accumulation in two rice varieties having different tolerances to salt-stress. A salinity-tolerant landrace, Pokkali, and a salinity-sensitive variety, PTT1, were exposed to three levels of SA conditions, pH 7.0 (mild), pH 8.0 (moderate), and pH 9.0 (severe), under 50 mM Na stress. The results indicated that Pokkali had comparably greater SA tolerance than PTT1 owing to its higher biomass production. The maintenance of the lower Na/K ratio in Pokkali shoots was achieved by the higher expression of <i>OsHKT1;5</i> encoding a Na⁺ transporter in the shoots, <i>OsNHX1</i> encoding a tonoplast-localized Na⁺/H⁺ antiporter in the roots, and <i>OsHAK16</i> encoding a K⁺ transporter in the roots under SA conditions. We propose that the high expression of Fe deficiency-responsive genes, <i>OsIRT1</i>, <i>OsIRO2</i>, <i>OsYSL15</i>, <i>OsNAS1</i>, and <i>OsNAS2</i>, in both rice varieties under all SA conditions should contribute to Fe homeostasis in the shoots. In addition, SA treatment increased the concentrations of Ca, Mn, Zn, and Cu in the roots but decreased their concentrations in the shoots of both varieties. Overall, the results indicated that high rhizospheric pH influenced nutrient uptake and translocation from the roots to the shoots in rice.