Background

The present study was designed to investigate the inhibition role of two polyamine biosynthesis inhibitors, i.e., D-arginine (D-Arg) and DL-α-difluoromethylornithine (DFMO), in polyamine biosynthesis under chilling stress in different tissues of two maize inbred lines – Huang C (chilling-tolerance) and Mo17 (chilling-sensitive).

Results

The results showed that exposure to the lower concentration of polyamine biosynthesis inhibitors improved seedlings growth, such as the root length, root and shoot fresh weight, chlorophyll a (chl a). The effectiveness of 10 µM D-Arg treatments was more prominent than those of 10 µM DFMO. However, the higher concentration of inhibitors suppressed seedlings growth, and the exposure to 100 µM DFMO caused stronger decreases in the photosynthetic pigments, such as chlorophyll a (chl a), chlorophyll b (chl b), total chlorophyll and carotenoids, than the other treatments. Meanwhile, the inhibitor treatments caused the lower content of putrescine (Put) in roots, mesocotyls and coleoptiles in both maize inbred lines as compared with untreated plants. However, the lower concentration (10 µM) of polyamine biosynthetic inhibitors improved the Spd content, except 10 µM D-Arg in root of Huang C, and 10 µM DFMO in coleoptiles of both Mo17 and Huang C. The correlation analysis found that Spd was positively significantly correlated with root length and shoot fresh weight of seedling.

Conclusion

It was showed that the Spd played an important role in seedling growth improvement. At the same concentration of polyamine biosynthetic inhibitors, the Put contents in different tissues of the seedlings treated with DFMO were generally lower than those treated with D-Arg, except for Put contents in root of Mo17 with 10 µM treatment. Moreover, the treatments of 100 µM were more prominent than those of 10 µM treatments. Exposure to 100 µM D-Arg and 100 µM DFMO could each decrease the activities of Arginine decarboxylase (ADC), Ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) in all maize tissues. However, the decrease of the ADC activity was more prominent in 100 µM D-Arg-treated seedlings, while the decrease of SAMDC and ODC activities was prominent in 100 µM DFMO-treated seedlings. Genes involved in polyamine biosynthesis, such as ADC, ODC, SAMDC, and PAO, showed different expression patterns in response to chilling stress and polyamine biosynthesis inhibitors. This study suggested that Put was synthesized via both the ADC and ODC pathways after chilling stress, with the ODC pathway being the major one.

中文翻译：

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多胺生物合成途径及其与玉米幼苗耐寒性的关系

背景

本研究旨在研究两种玉米自交系不同组织在低温胁迫下D-精氨酸（D-Arg）和DL-α-二氟甲基鸟氨酸（DFMO）这两种多胺生物合成抑制剂在多胺生物合成中的抑制作用。 – Huang C（耐寒性）和Mo17（耐寒性）。

结果

结果表明，暴露于较低浓度的多胺生物合成抑制剂可改善幼苗的生长，例如根长，根和苗鲜重，叶绿素a（chla）。10 µM D-Arg处理的效果比10 µM DFMO的效果更为突出。但是，较高浓度的抑制剂会抑制幼苗的生长，暴露于100 µM DFMO会导致光合色素（如叶绿素a（chl a），叶绿素b（chl b），总叶绿素和类胡萝卜素）的下降更为强烈。治疗。同时，与未经处理的植物相比，抑制剂处理导致两种玉米近交系的根，中胚轴和胚芽鞘中腐胺的含量降低。但是，较低浓度（10 µM）的多胺生物合成抑制剂可提高Spd含量，

结论

结果表明，Spd在改善幼苗生长中起重要作用。在相同浓度的多胺生物合成抑制剂的条件下，用10 µM处理的Mo17根中的Put含量除外，用DFMO处理的幼苗不同组织中的Put含量通常低于使用D-Arg处理的幼苗。此外，100 µM的处理比10 µM的处理更为突出。暴露于100 µM D-Arg和100 µM DFMO可能会降低所有玉米组织中精氨酸脱羧酶（ADC），鸟氨酸脱羧酶（ODC）和S-腺苷甲硫氨酸脱羧酶（SAMDC）的活性。但是，在100 µM D-Arg处理过的幼苗中ADC活性的下降更为明显，而在100 µM DFMO处理过的幼苗中SAMDC和ODC活性的下降是明显的。涉及多胺生物合成的基因，例如ADC，ODC，SAMDC和PAO，响应于冷应激和多胺生物合成抑制剂而表现出不同的表达模式。这项研究表明，Put是在寒冷胁迫后通过ADC和ODC途径合成的，其中ODC途径是主要途径。