Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
Sci Rep. 2019 Jan 22;9(1):249. doi: 10.1038/s41598-018-36971-3.
We examined the effect of soil microbial communities on plant physiological responses to drought. Bouteloua gracilis seeds were planted in sterilized sand with (inoculated) and without (controls) soil microbial communities. After substantial growth, drought was imposed by completely withholding water. Before soil moisture declined to zero, inoculated plants germinated faster, were significantly taller, and maintained greater soil moisture than controls. The greater soil moisture of the inoculated plants allowed greater photosynthesis but also induced lower tissue drought tolerance (as indicated by turgor loss point) compared to controls. The inoculated plants were more susceptible to severe drought compared to control plants as indicated by significantly lower mean stomatal conductance, as well as marginally significantly greater mean wilting score, for the entire severe drought period after soil moisture declined to zero. Inoculated plants exhibited enhanced growth and photosynthesis and dampened drought stress over short timescales, but also increased susceptibility to drought over long timescales. This work demonstrates (1) an unexpected insight that microbes can have positive initial effects on plant performance, but negative impacts on plant performance during severe drought, and (2) that microbially altered effects on plant function during well-watered and moderate drought conditions can influence plant function under subsequent severe drought.
我们研究了土壤微生物群落对植物干旱生理响应的影响。将柳枝稷种子种植在经过消毒的沙土中，这些沙土中含有（接种的）或不含有（对照的）土壤微生物群落。在大量生长后，通过完全断水来施加干旱胁迫。在土壤湿度降至零之前，接种植物的发芽速度更快，明显更高，并且保持更高的土壤湿度。与对照相比，接种植物的土壤湿度更大，允许更大的光合作用，但也导致更低的组织耐旱性（如膨压损失点所示）。与对照植物相比，接种植物对严重干旱更敏感，这表现为在土壤湿度降至零后的整个严重干旱期间，平均气孔导度显著降低，以及平均萎蔫评分略有显著升高。接种植物在短时间内表现出增强的生长和光合作用，减轻干旱胁迫，但在长时间内也增加了对干旱的敏感性。这项工作表明：（1）一个意想不到的见解，即微生物最初可以对植物表现产生积极影响，但在严重干旱期间对植物表现产生负面影响；（2）在充分浇水和中度干旱条件下，微生物改变对植物功能的影响，可以影响随后严重干旱期间的植物功能。
