Department of Horticultural Science and Microbial and Plant Genome Institute, University of Minnesota, Alderman Hall, 1970 Folwell Avenue, Saint Paul, MN, 55108, USA.
USDA/ARS Genetic Improvement of Fruit and Vegetables Laboratory, 10300 Baltimore Avenue, Beltsville, MD, 20705, USA.
Planta. 2019 Apr;249(4):1073-1085. doi: 10.1007/s00425-018-3061-0. Epub 2018 Dec 8.
Indole-3-acetylaspartate and indole-3-acetylglutamate are the stored auxin amino acid conjugates of the achene of the diploid strawberry and serve as sources of auxin during seedling growth. The edible part of the strawberry, a pseudocarp, has long been known to enlarge in response to auxin produced by the developing achenes, the botanical true fruit. Auxin homeostasis involves a complex interaction between biosynthesis, conjugate formation and hydrolysis, catabolism and transport. Strawberry tissues are capable of synthesizing auxin conjugates, and transcriptome data support the expression of genes involved in IAA conjugate formation and hydrolysis throughout embryo development and subsequent seedling growth. Using a highly sensitive and selective mass spectrometric method, we identified all the low molecular weight indole-auxin amino acid conjugates in achenes of F. vesca as consisting of indole-3-acetylaspartate (IAasp) and indole-3-acetylglutamate (IAglu). In contrast to what has been proposed to occur in Arabidopsis, we determined that IAasp and IAglu are hydrolyzed by seedlings to provide a source of free IAA for growth.
色氨酰基 - 天冬氨酸和色氨酰基 - 谷氨酸是二倍体草莓瘦果中储存的生长素氨基酸结合物，作为幼苗生长过程中生长素的来源。草莓的可食用部分，假果，长期以来一直被认为会响应由发育中的瘦果，即植物学上的真果，产生的生长素而增大。生长素稳态涉及生物合成、结合形成和水解、分解代谢和运输之间的复杂相互作用。草莓组织能够合成生长素结合物，转录组数据支持在胚胎发育和随后的幼苗生长过程中参与 IAA 结合物形成和水解的基因的表达。使用高度敏感和选择性的质谱方法，我们确定了 F. vesca 瘦果中所有低分子量吲哚-生长素氨基酸结合物均由色氨酰基 - 天冬氨酸（IAasp）和色氨酰基 - 谷氨酸（IAglu）组成。与拟南芥中提出的情况不同，我们确定 IAasp 和 IAglu 被幼苗水解，为生长提供游离 IAA 的来源。
