The use of <i>Pisolithus albus</i> found in saline areas to improve the growth of <i>Eucalyptus</i> seedlings under high salinity conditions

Salinity is an abiotic factor limiting plant fitness and therefore forest crop productivity, and salt-affected areas have been expanding throughout the world. Ectomycorrhizal (ECM) fungi can improve the salt tolerance of woody plants, including <i>Eucalyptus</i> species To screen for salt-resistant <i>Pisolithus albus</i> (PA) isolates, 16 PA isolates were cultivated on modified Melin-Norkrans agar containing NaCl at concentrations of 0, 10, 20, and 30 dS m⁻¹. The <i>P. albus</i> isolate PA33 had the greatest salt resistance under 10 and 20 dS m⁻¹ NaCl, which are soil salinity levels in salt-affected areas of Thailand. We studied the effect of PA33 on <i>Eucalyptus camaldulensis</i> × <i>E. pellita</i> cuttings under salt stress (0 and 16 dS m⁻¹) for 1 month. PA enhanced the growth of the <i>Eucalyptus</i> seedlings, as indicated by higher relative growth rates in height and root collar diameter of inoculated seedlings compared with non-inoculated seedlings. Moreover, the inoculated seedlings had less cell damage from NaCl, as indicated by significantly lesser leaf thickness and electrolyte leakage than the controls. These findings could lead to practices conferring socioeconomic and environmental benefits, as abandoned salt-affected areas could be reclaimed using such <i>Eucalyptus</i> seedlings inoculated with salt-tolerant ECM fungi.

盐度是限制植物适合度、进而制约林木生产力的非生物因子，且全球盐渍化区域正持续扩张。外生菌根（ectomycorrhizal, ECM）真菌可提升木本植物的耐盐性，其中涵盖桉树（Eucalyptus）类物种。为筛选耐盐的白豆马勃（Pisolithus albus, PA）菌株，我们将16株PA菌株置于添加了0、10、20、30 dS·m⁻¹浓度氯化钠的改良梅林-诺克兰斯琼脂培养基中培养。在泰国盐渍化区域对应的土壤盐度水平（10和20 dS·m⁻¹氯化钠）下，PA33菌株展现出最优的耐盐性能。我们进一步研究了PA33在盐胁迫（0和16 dS·m⁻¹）条件下对赤桉（Eucalyptus camaldulensis）×细叶桉（E. pellita）插穗的影响，实验处理时长为1个月。与未接种的对照组幼苗相比，接种PA33的桉树幼苗的株高和根颈直径相对生长率更高，表明其生长得到显著促进。此外，接种组幼苗受氯化钠诱导的细胞损伤程度更低，具体表现为叶片厚度与电解质渗漏率均显著低于对照组。本研究结果可为盐渍化废弃区域的修复提供可行实践路径，通过使用接种耐盐外生菌根真菌的桉树幼苗，可同时获得社会经济与环境双重效益。