Wojtasik Wioleta, Kulma Anna, Namysł Katarzyna, Preisner Marta, Szopa Jan
Faculty of Biotechnology, University of Wrocław Wrocław, Poland.
Front Plant Sci. 2015 Apr 29;6:291. doi: 10.3389/fpls.2015.00291. eCollection 2015.
Flax crop yield is limited by various environmental stress factors, but the largest crop losses worldwide are caused by Fusarium infection. Polyamines are one of the many plant metabolites possibly involved in the plant response to infection. However, in flax plants the polyamine composition, genes involved in polyamine synthesis, and in particular their regulation, were previously unknown. The aim of this study was to investigate the polyamine synthesis pathway in flax and its involvement in response to pathogen infection. It is well established that polyamines are essential for the growth and development of both plants and fungi, but their role in pathogen infection still remains unknown. In our study we correlated the expression of genes involved in polyamine metabolism with the polyamine levels in plant tissues and compared the results for flax seedlings treated with two pathogenic and one non-pathogenic strains of Fusarium. We observed an increase in the expression of genes participating in polyamine synthesis after fungal infection, and it was reflected in an increase of polyamine content in the plant tissues. The highest level of mRNA was characteristic for ornithine decarboxylase during infection with all tested, pathogenic and non-pathogenic, Fusarium strains and the arginine decarboxylase gene during infection with the pathogenic strain of Fusarium culmorum. The main polyamine identified in the flax seedlings was putrescine, and its level changed the most during infection. Moreover, the considerable increase in the contents of cell wall-bound polyamines compared to the levels of free and conjugated polyamines may indicate that their main role during pathogen infection lies in strengthening of the cell wall. In vitro experiments showed that the polyamines inhibit Fusarium growth, which suggests that they play an important role in plant defense mechanisms. Furthermore, changes in metabolism and content of polyamines indicate different defense mechanisms activated in flax in response to infection by pathogenic and non-pathogenic Fusarium strains.
亚麻作物产量受到多种环境胁迫因素的限制，但全球范围内最大的作物损失是由镰刀菌感染造成的。多胺是众多可能参与植物对感染反应的植物代谢产物之一。然而，在亚麻植株中，多胺组成、参与多胺合成的基因，尤其是它们的调控，此前尚不清楚。本研究的目的是调查亚麻中的多胺合成途径及其在对病原体感染反应中的作用。众所周知，多胺对植物和真菌的生长发育都至关重要，但其在病原体感染中的作用仍然未知。在我们的研究中，我们将参与多胺代谢的基因表达与植物组织中的多胺水平相关联，并比较了用两种致病和一种非致病镰刀菌菌株处理的亚麻幼苗的结果。我们观察到真菌感染后参与多胺合成的基因表达增加，这反映在植物组织中多胺含量的增加上。在所有测试的致病和非致病镰刀菌菌株感染期间，鸟氨酸脱羧酶的mRNA水平最高，而在禾谷镰刀菌致病菌株感染期间，精氨酸脱羧酶基因的mRNA水平最高。在亚麻幼苗中鉴定出的主要多胺是腐胺，其水平在感染期间变化最大。此外，与游离和结合多胺水平相比，细胞壁结合多胺含量的显著增加可能表明它们在病原体感染期间的主要作用在于强化细胞壁。体外实验表明，多胺抑制镰刀菌生长，这表明它们在植物防御机制中发挥重要作用。此外，多胺代谢和含量的变化表明亚麻对致病和非致病镰刀菌菌株感染激活了不同的防御机制。
