TE7, AN INEFFICIENT SYMBIOTIC MUTANT OF MEDICAGO-TRUNCATULA GAERTN CV JEMALONG
TE7, AN INEFFICIENT SYMBIOTIC MUTANT OF MEDICAGO-TRUNCATULA GAERTN CV JEMALONG
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DOI：
10.1104/pp.107.1.53
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发表时间：
1995-01-01
期刊：
影响因子：
7.4
通讯作者：
HUGUET, T
中科院分区：
文献类型：
--
作者：
BENABEN, V;DUC, G;HUGUET, T
在蒺藜苜蓿 Gaertn cv Jemalong（一种一年生自交二倍体苜蓿）上使用甲基磺酸乙酯进行的诱变程序，允许分离出无法与苜蓿根瘤菌野生型菌株建立有效固氮共生的突变体（TE7）[Nod(+)Fix(-)]。突变表型的特征是感染过程改变，导致同一根系统上形成两种低效根瘤。一定比例的结节小、圆形、未感染，感染线仅限于外根皮层细胞。其他的则发育成正常的细长形状并被感染；发生细菌释放，但细菌不会分化为类菌体。侵入的结节与未侵入的结节的比率取决于所使用的细菌菌株。在整个感染过程中，可以观察到与植物对病原体的防御反应相关的某些事件：（a）与受感染细胞壁以及根皮层中感染线的某些部分相关的多酚化合物的存在； (b) 在感染早期阶段附着在感染丝壁上以及感染结节的中央组织内； (c) 含有释放细菌的植物细胞的自噬。遗传数据表明 TE7 的表型受到单基因和隐性控制；该基因被命名为 Mtsym1。
A mutagenesis program using ethylmethane sulfonate on Medicago truncatula Gaertn cv Jemalong, an annual, autogamous and diploid lucerne, permitted the isolation of a mutant (TE7) unable to establish an effective nitrogen-fixing symbiosis, [Nod(+)Fix(-)], with Rhizobium meliloti wild-type strains. The mutant phenotype is characterized by an altered infection process that leads to the formation of two kinds of inefficient nodules on the same root system. A certain proportion of the nodules are small, round, and uninfected, with infection threads limited to the outer root cortical cells. Others develop to a normal elongated shape and are infected; bacterial release occurs but the bacteria do not differentiate into bacteroids. The ratio of invaded to uninvaded nodules depends on the bacterial strain used. Throughout the infection process, certain events correlated with the plant defense response against pathogens can be observed: (a) the presence of polyphenolic compounds associated with the walls of infected cells and also with some parts of infection threads in the root cortex; (b) appositions on infection thread walls during the early stage of infection and also within the central tissue of infected nodules; and (c) autophagy of the plant cells that contain released bacteria. Genetic data suggest that the phenotype of TE7 is under monogenic and recessive control; this gene has been designated Mtsym1.