Striga hermonthica reduces photosynthesis in sorghum: The importance of stomatal limitations and a potential role for ABA?
Striga hermonthica reduces photosynthesis in sorghum: The importance of stomatal limitations and a potential role for ABA?
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DOI：
10.1046/j.1365-3040.1997.d01-87.x
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发表时间：
1997-04-01
影响因子：
7.3
通讯作者：
Scholes, JD
中科院分区：
文献类型：
--
作者：
Frost, DL;Gurney, AL;Scholes, JD
我们报道了根半寄生物Striga hermonthica（Del，）Benth对两个高粱品种的生长和光合作用的影响：感病品种CSH-1和田间表现出一定抗性的Ochuti，在寄生虫附着寄主根部后4d内，两品种的植株均显著矮于对照，在55 d时，与未感染对照相比，两个品种的感染植物的地上部和根生物量显著减少，叶面积显著减小。在此阶段，附着于宿主根的S，hermonthica的干重不足以解释在竞争碳和氮库方面的生长下降，与对照相比，两个品种的感病植株的叶绿素和单位面积氮含量都增加，但感病CSH-1植株的幼叶光合作用和蒸腾作用随时间的推移而下降，在观察的整个时间过程中，感染的Ochuti植物中的速率与未感染的对照中的速率相似。在两个品种中，在光合诱导期间，在光合速率和气孔导度之间观察到强相关性，但是感染导致比对照慢得多的诱导。在CSH-1植物中，稳态光合作用和气孔导度均低于对照，而Ochuti叶片的稳态光合作用和气孔导度最终达到与对照叶片相同的值，来自A/C-i分析的结果以及来自C-i测定的结果13种同位素的区别与感染独脚金的植物叶片中光合作用的气孔限制一致，仅在感染的CSH-1植物的木质部汁液中测量植物生长调节剂脱落酸（阿坝）的浓度，并且发现是未感染植物的两倍，阿坝在决定寄主对S，hermonthica感染的反应中可能发挥的作用进行了讨论。
We report the effects of the root hemiparasite Striga hermonthica (Del,) Benth, on the growth and photosynthesis of two cultivars of sorghum: CSH-1, a susceptible variety, and Ochuti, which shows some tolerance to S, hermonthica in the field, Within 4 d of parasite attachment to the host roots, infected plants of both cultivars were significantly shorter than uninfected controls, At 55 d, infected plants of both cultivars had significantly less shoot and root biomass, and significantly smaller leaf areas than uninfected controls, The dry weight of S, hermonthica attached to host roots was insufficient at this stage to explain the decreased growth in terms of a competing sink for carbon and nitrogen, Leaf chlorophyll and nitrogen per unit area were greater in infected plants of both cultivars compared with control plants, However, whereas photosynthesis and transpiration in young leaves of infected CSH-1 plants declined with time when compared with controls, the rates in infected Ochuti plants were similar to those in uninfected controls throughout the time course of observation, In both cultivars, a strong correlation was observed between the rate of photosynthesis and stomatal conductance during photosynthetic induction, but infection resulted in a much slower induction than in controls, In CSH-1 plants, both steady-state photosynthesis and stomatal conductance were lower than in controls, whereas in leaves of Ochuti steady-state photosynthesis and stomatal conductance eventually reached the same values as in the control leaves, Results from A/C-i analysis and also from determination of C-13 isotope discrimination were consistent with a stomatal limitation to photosynthesis in the leaves of Striga-infected plants, The concentration of the plant growth regulator abscisic acid (ABA) was measured in the xylem sap of infected CSH-1 plants only, and was found to be twice that of uninfected plants, A possible role of ABA in determining host response to infection by S, hermonthica is discussed.