Laboratory of Plant Cell Biology, Department of Botany, Institute of Biosciences, University of São Paulo, Rua do Matão, São Paulo, Brazil.
Tree Physiol. 2017 Jan 31;37(1):116-130. doi: 10.1093/treephys/tpw107.
Polyamines (PAs), such as spermidine and spermine, as well as amino acids that are substrates for their biosynthesis, are known to be essential for plant development. However, little is known about the gene expression and metabolic switches associated with the ornithine/arginine and PA biosynthetic pathway during seed development in conifers. To understand these metabolic switches, the enzyme activity of arginine decarboxylase and ornithine decarboxylase, as well as the contents of PAs and amino acids were evaluated in three Araucaria angustifolia (Bertol. Kuntze) seed developmental stages in combination with expression profile analyses of genes associated with the ornithine/arginine and PA biosynthetic pathway. Twelve genes were selected for further analysis and it was shown that the expression profiles of AaADC and AaSAMDC were up-regulated during zygotic embryo development. Polyamines and amino acids were found to accumulate differently in embryos and megagametophytes, and the transition from the globular to the cotyledonary stage was marked by an increase in free and conjugated spermidine and spermine contents. Putrescine is made from arginine, which was present at low content at the late embryogenesis stage, when high content of citrulline was observed. Differences in amino acids, PAs and gene expression profiles of biosynthetic genes at specific seed stages and at each seed transition stage were investigated, providing insights into molecular and physiological aspects of conifer embryogenesis for use in future both basic and applied studies.
多胺（PAs），如亚精胺和精胺，以及它们生物合成的氨基酸底物，被认为是植物发育所必需的。然而，关于松柏类植物种子发育过程中与鸟氨酸/精氨酸和 PA 生物合成途径相关的基因表达和代谢转换知之甚少。为了了解这些代谢转换，我们评估了三种南洋杉种子发育阶段的精氨酸脱羧酶和鸟氨酸脱羧酶的酶活性，以及 PAs 和氨基酸的含量，并结合与鸟氨酸/精氨酸和 PA 生物合成途径相关的基因表达谱分析。选择了 12 个基因进行进一步分析，结果表明 AaADC 和 AaSAMDC 的表达谱在合子胚发育过程中上调。多胺和氨基酸在胚胎和大配子体中的积累方式不同，从球形到子叶期的转变以游离和结合态亚精胺和精胺含量的增加为标志。腐胺由精氨酸合成，在胚胎后期含量较低，此时观察到瓜氨酸含量较高。我们研究了特定种子阶段和每个种子转换阶段的生物合成基因的氨基酸、PAs 和基因表达谱的差异，为松柏类植物胚胎发生的分子和生理方面提供了见解，可用于未来的基础和应用研究。
