叢枝菌根植物的乾旱逆境抗性機制

Mechanism for the Drought Stress Resistance of Arbuscular Mycorrhizal Plants

叢枝菌根除了能幫助宿主植物吸收水分與礦物營養，促進生長與產量外，也能影響宿主植物的水分狀態，進而增加其耐旱性。其對乾旱逆境抗性的機制可能為：1.藉由根外菌絲增加宿主植物根部吸收面積；2.增加組織內水分運輸能力，因而有較大膨壓抗旱；3.影響宿主植物代謝物含量，藉由滲透調節來增加耐旱性；4.養分吸收的改變，進而促進宿主植物生長與耐旱性；5.調節宿主植物氣孔行為；6.影響宿主植物荷爾蒙變化等，以增加其耐旱性。 The effects of arbuscular mycorrhiza on the growth and development of host plants have been studied by many investigators. Arbuscular mycorrhizal fungi can also affect the water balance of both amply watered and desiccated host plants. This review summarizes these effects and possible casual mechanisms. There were five mechanisms involved: 1. More effective scavenging of soil water, possibly through improved soil and root contact, and contributions of soil hyphae to water absorption. 2. Water transport ability of host plants was increased. 3. Effect of osmotic adjustment by changing the content of metabolites. 4. The enhancement of the nutrient uptake of host plants resulted in good growth and increased drought resistance. 5. Adjustment of stomatal conductance and transpiration. 6. Modification of the hormonal level of host plants. However, the ideas about mycorrhizal mechanisms of drought resistance suggested by these studies are still being tested today.