Department of Plant Physiology, Poznań University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland.
Protoplasma. 2013 Feb;250(1):63-75. doi: 10.1007/s00709-012-0374-x. Epub 2012 Jan 25.
Ascochyta pisi is a necrotrophic pathogenic fungus, which mainly survives between seasons through infected seeds. Defence responses of pea embryo axes to A. pisi were investigated in the heterotrophic phase of seed germination and during the transition from the heterotrophic to the autotrophic phase. Germinated pea seeds, both non-inoculated and inoculated with A. pisi, were cultured in perlite for 96 h. Polarographic studies performed on intact embryo axes of germinating pea seeds infected with A. pisi showed a high respiratory intensity in time from 48 to 96 h after inoculation. Forty-eight-hour embryo axes of germinating pea seeds exhibited the highest respiration rate, which in infected axes was maintained at the following time points after inoculation. Moreover, at 72 and 96 h after inoculation, respiratory intensity was by 64% and 73% higher than in the control. Electron paramagnetic resonance analysis revealed a higher concentration of semiquinone free radicals with g values of g (||) = 2.0031 ± 0.0004 and g (⊥) = 2.0048 ± 0.0004 in infected axes than in the control. Generation of superoxide anion radical was also higher in infected axes than in the control but stronger at 72 and 96 h after inoculation. Starting from 72 h after infection, the level of Mn(2+) ions in infected axes decreased in relation to the control. At the same time, the highest activity of superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) was observed in 72-h infected axes. In turn, the activity of peroxidase (EC 1.11.1.7) up to 72 h after infection was lower than in the control. In 48-h infected embryo axes, a very high level of pterocarpan pisatin was observed. Infection of germinating pea seeds with A. pisi restricted mainly the growth of the epicotyl, but did not inhibit the increase in length and fresh weight of root embryo axes versus cultivation time. These results indicate that in pea during the stages of seed germination and early seedling growth, protective mechanisms are induced in embryo axes against A. pisi.
豌豆壳二孢菌是一种专性坏死性病原菌，主要通过感染的种子在季节间存活。在种子萌发的异养阶段和从异养向自养阶段过渡期间，研究了豌豆胚轴对豌豆壳二孢菌的防御反应。将接种和未接种豌豆壳二孢菌的萌发豌豆种子在珍珠岩中培养 96 小时。对感染豌豆壳二孢菌的萌发豌豆种子的完整胚轴进行的极谱研究表明，接种后 48 至 96 小时期间呼吸强度很高。48 小时的萌发豌豆种子胚轴表现出最高的呼吸速率，在接种后的以下时间点保持不变。此外，在接种后 72 和 96 小时，呼吸强度比对照高 64%和 73%。电子顺磁共振分析显示，感染轴中的半醌自由基浓度更高，g 值为 g (||) = 2.0031 ± 0.0004 和 g (⊥) = 2.0048 ± 0.0004，高于对照。感染轴中产生的超氧阴离子自由基也高于对照，但在接种后 72 和 96 小时更强。从感染后 72 小时开始，感染轴中的 Mn(2+)离子水平相对于对照降低。与此同时，在感染的 72 小时胚轴中观察到超氧化物歧化酶 (EC 1.15.1.1) 和过氧化氢酶 (EC 1.11.1.6) 的最高活性。相反，在感染后 72 小时之前，过氧化物酶 (EC 1.11.1.7) 的活性低于对照。在感染的 48 小时胚轴中，观察到非常高水平的蝶豆素 pisatin。豌豆壳二孢菌对萌发豌豆种子的感染主要限制了上胚轴的生长，但不抑制根胚轴相对于培养时间的长度和鲜重的增加。这些结果表明，在豌豆种子萌发和幼苗早期生长阶段，豌豆胚轴中诱导了针对豌豆壳二孢菌的保护机制。
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