In Vitro Salt Stress Responses of Thai Oil Palm’s Embryogenic Callus Variety ‘SUP-PSU1’

Abstract

Evapotranspiration, which includes the evaporation of water from soils, may rise as a result of climate change and rising temperatures. The outcome is that water evaporates but salt stays in the soil, raising its saltiness. The growth and development of oil palm are also affected by salt stress, but decades of time frame are required with conventional breeding due to its reproductive biological reasons and its long-time life span. However, to facilitate stress tolerance evaluation at an early stage of plant material, the in vitro selection was considered, and the evaluation process was optimized for innovating variant selection out from calluses over abiotic stress. Thus, the objectives of this research were to study the effect of concentrations of sodium chloride (NaCl) on the growth rate, electrolyte leakage (EL) and proline content of embryogenic callus (EC) of oil palm ‘SUP-PSU1’. Was also, recovery of EC growth after treating with NaCl for further evaluation to set new variant tolerant line for breeding was established. EC was treated with different concentrations of NaCl in oil palm culture medium (OPCM) supplemented with 0.1 mg L–1 3,6-Dichloro-o-anisic acid (dicamba) and 200 mg L–1 ascorbic acid (AA) for 4 weeks. The results showed that inhibition concentration at 50 % (IC50) was 149.1 mM and NaCl at high concentrations increased EL and proline content. After transferring treated EC to solidified medium without NaCl for 4 weeks, The 200 mM condition’s EC turned yellowish-brown and couldn’t withstand higher (300 and 400 mM) NaCl concentrations. The lowest growth rate was obtained with NaCl at 300 and 400 mM, and the EC entirely turned brown. So, it was judged that NaCl concentration around 300 to 400 mM can be used as a selection agent for ‘SUP-PSU1’ new variant tolerant line in oil palm tissue culture breeding condition. HIGHLIGHTS The inhibition concentration that limits the growth of embryogenic callus of oil palm ‘SUP-PSU1’ at 50 % (IC50) was 149.1 mM NaCl at high concentration resulted in an increment of electrolyte leakage (EL) and proline content The embryogenic callus of oil palm ‘SUP-PSU1’can tolerate to NaCl up to 200 mM NaCl at concentrations of 300 and 400 mM can be used as a selection agent for ‘SUP-PSU1’ new variant tolerant line in oil palm tissue culture breeding condition GRAPHICAL ABSTRACT