Nitrogen-induced changes in morphological development and bacterial susceptibility of Belgian endive (Cichorium intybus L.) are genotype-dependent
Nitrogen-induced changes in morphological development and bacterial susceptibility of Belgian endive (Cichorium intybus L.) are genotype-dependent
复制标题
氮诱导的比利时菊苣（Cichorium intybus L.）形态发育和细菌敏感性的变化具有基因型依赖性
作者：
Céline Richard;S. Wuillème;Christina Scheel;P. Gresshoff;J. Morot;A. Limami
已知氮调节植物发育和对病原体的抗性。以菊苣（Cichorium intybusL.）在低浓度（0.6 mM）和高浓度（3 mM）NO− 3营养下生长，以研究N对三个性状表达的影响，即芽/根比、小孢子形态和对欧文氏菌引起的软腐病的抗性。对于所有的基因型，增加氮供应导致更高的冠/根比，从地上部生物量增加，但对根的生长没有影响。与此相反，氮对小孢子形态和对细菌的抗性的影响是基因型依赖的，我们根据它们的表型特征区分了两组品系。在NR 1和NR 2组成的组中，营养生长期增加NO-3供应使chicon形态从开放型转变为封闭型，而对细菌的抗性不受N供应的影响。在NS 1和Alg组中，N对纤毛形态的影响与NR 1-NR 2组相反，而NS 1和Alg对欧文氏菌表现出部分抗性，只有在供氮量达到3 mM时才表现软腐病。通过DNA扩增指纹（DNA amplification fingerprinting，RFLP）的表征允许产生110个多态性条带，并且证实了一方面是品系NR 1和NR 2，另一方面是品系NS 1和Alg，属于两个不同的遗传群。结果表明，该菌对欧文氏菌有一定的抗性。是复杂的性状，将服从数量性状基因座分析。菊苣的分裂生长阶段意味着在营养生长过程中与氮供应相关的任何chicon变化都是由根源信号介导的。根系碳含量在基因型和NO-3处理间无显著差异。相比之下，根氮含量的差异揭示了菊苣品系的相同分组，NR 1和NR 2系统地富含氨基酸和NO-3，而NS 1和Alg。然而，如果将所有基因型一起考虑，则氮化合物与小孢子形态或病理之间不存在相关性。因此，氮对植物发育和病理学的影响以及推定的识别信号可能是特定的基因型。我们的研究表明，在任何信号通路的研究中，考虑物种内的遗传变异是必要的。
Nitrogen is known to modulate plant development and resistance to pathogens. Four selected lines (Alg, NS1, NR1 and NR2) of chicory (Cichorium intybusL.) were grown on low (0.6 mM) and high (3 mM) NO−3nutrition in order to study the effect of N on the expression of three traits, namely, shoot/root ratio, chicon morphology and resistance to soft rot caused byErwiniasp. For all genotypes, increasing N supply led to a higher shoot/root ratio, resulting from an increased shoot biomass but with no effect on root growth. In contrast, the effect of N on chicon morphology and resistance to bacteria was genotype-dependent and we distinguished two groups of lines according to their phenotypic characteristics. In the group consisting of NR1 and NR2, increasing NO−3supply during the vegetative phase made the chicon morphology switch from an opened to a closed type while resistance to bacteria was not affected by N supply. In the NS1 and Alg group, the effect of N on chicon morphology was the opposite to that observed in the NR1-NR2 group while NS1 and Alg exhibited a partial resistance toErwiniasp., only expressing soft-rot disease when the N supply reached 3 mM. Characterization by DNA amplification fingerprinting (DAF) allowed the generation of 110 polymorphic bands and confirmed that the lines NR1 and NR2, on the one hand, and NS1 and Alg, on the other hand, belong to two distinct genetic groups. The DAF results indicate that chicon morphology and partial resistance toErwiniasp. are complex traits which would be amenable to quantitative trait loci analysis. The split growth phase of chicory means that any changes in chicon related to N supply during vegetative growth were mediated by a root-originating signal. No variation in root carbon content among genotypes and NO−3treatments was observed. In contrast, differences in root N content revealed the same grouping of the chicory lines, NR1 and NR2 being systematically richer in amino acids and NO−3than NS1 and Alg. However, no correlation existed between N compounds and chicon morphology or pathology if all genotypes were considered together. Thus, the effect of N on plant development and pathology as well as putative identified signals might be specific for a genotype. Our study indicates that it is necessary to consider the genetic variability within a species in any signalling-pathway research.