IR64背景耐旱导入系“PD29”分蘖期的抗逆生理特征

以轮回亲本IR64(籼稻)及旱稻材料IRAT109为对照, 系统分析了“PD29”在灌溉(对照)与干旱(胁迫)条件下的相关生理性状特征。研究发现, 遭遇干旱胁迫后, “PD29”植株能够维持较高的相对含水量(RWC)且胁迫后复水2 h该株系的RWC迅速恢复到饱和状态, 表明其具有较强的御旱能力。干旱条件下, “PD29”的PS II最大光化学效率(F_v/F_m)、渗透势(Y)、脯氨酸含量(Pro)、活性氧清除系统活性(AOA)均显著高于IR64, 且相对于灌溉处理, 其RWC, F_v/F_m的降低幅度显著低于IR64, 净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)的降幅, Pro及AOA的增幅均高于IR64。与IRAT109比较, 干旱逆境下“PD29”的Pro含量显著偏高且AOA平均增幅较高。因此认为, “PD29”的优良耐旱性表现与其在逆境下脯氨酸含量及活性氧清除系统活性的显著增强有关。另外, 干旱环境下的P_n、G_s及T_r的显著降低, 表明“PD29”的光合性能可塑性较强, 其光合性能在有利生长环境下能高效表达, 而在土壤水有限的环境下, 能够迅速降低以减少水分的进一步损失。

Physiological Characteristics Related to Stress-Tolerance in Introgression Line "PD29" with IR64 Genetic Background at the Tillering Stage

Drought tolerance (DT) or water-saving is becoming one of the most important target traits in rice breeding community under ever-increasing severe drought situation all over the world. The introgression line “PD29” with IR64 genetic background has promising yield performance under both drought (stress) and irrigation (control) conditions. In the present study, the physiological characteristics related to stress tolerance of the “PD29” were analysised with recurrent parent, IR64, and upland rice variety IRAT109 as control varieties under both drought and irrigation conditions. The results showed that “PD29” not only had higher leaf relative water content (RWC) under stress but also could recover RWC to a fully turgid (hydrated) state 2 h after re-watering which indicated that “PD29” has higher DT ability than control varieties at the tillering stage. Further analysis showed that “PD29” not only had higher maximum photochemical of FPS II efficiency (F_v/F_m), osmotic potential (Y), proline content (Pro), and antioxidants activity (AOA) than IR64 under drought condition but also presented less decrease in the F_v/F_m and RWC and more decrease in net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s) and more increase in Pro and AOA. Furthermore, compared to IRAT109, “PD29” had higher Pro and more increase in the AOA under drought condition. Therefore, it was concluded that the promising DT-performance of “PD29” was related to the significant increase of AOA and proline under the drought. Moreover, the significant decrease of the P_n, G_s, and T_r under the drought condition indicated that “PD29”has strong plasticity in photosynthetic capacity which can keep the higher photosynthesis under the adaptive circumstance and decrease the water loss through transpiration under the stress condition.