Polyamine Homeostasis in Wild Type and Phenolamide Deficient Arabidopsis thaliana Stamens

Abstract

Polyamines (PAs) like putrescine, spermidine, and spermine are ubiquitous polycationic molecules that occur in all living cells and have a role in a wide variety of biological processes. High amounts of spermidine conjugated to hydroxycinnamic acids are detected in the tryphine of Arabidopsis thaliana pollen grains. Tapetum localized spermidine hydroxycinnamic acid transferase (SHT) is essential for the biosynthesis of these anther specific tris-conjugated spermidine derivatives. Sht knockout lines show a strong reduction of hydroxycinnamic acid amides (HCAAs). The effect of HCAA-deficient anthers on the level of free PAs was measured by a new sensitive and reproducible method using 9-fluorenylmethyl chloroformate (FMOC) and fluorescence detection by HPLC. PA concentrations can be accurately determined even when very limited amounts of plant material, as in the case of A. thaliana stamens, are available. Analysis of free PAs in wild type stamens compared to sht deficient mutants and transcript levels of key PA biosynthetic genes revealed a highly controlled regulation of PA homeostasis in A. thaliana anthers.

Biosynthesis, physiology, and functions of hydroxycinnamic acid amides in plants

“…Putrescine, spermidine, spermine were detected in tryphine of pollen grains (Fellenberg et al 2011) Plant Biotechnol Rep…”

Revealing insect herbivory‐induced phenolamide metabolism: from single genes to metabolic network plasticity analysis

“…Organ‐specific pools of phenolamides were originally thought to function only in developmental homeostasis. High levels of polyamine‐based phenolamides have long been known to be a characteristic feature of developing flower buds of many species, and floral organ‐specific phenolamide profiles are known to correlate with floral developmental stages (Fellenberg et al ., , , ,b; Grienenberger et al ., ; Matsuno et al ., ). Phenolamides appear to be absent from mutants that do not flower or produce abnormal flowers, suggesting that these metabolites fulfill important roles during normal flower development; however, the exact function of these metabolites in these tissues, including the pollen coat, where they may be particularly abundant, remains puzzling.…”

A MYB Triad Controls Primary and Phenylpropanoid Metabolites for Pollen Coat Patterning

“…During the tetrad stage of the developing pollen and after sporopollenin deposition, the tapetum undergoes programmed cell death, and following cellular degradation, all cell remnants are released within the anther locule (Blackmore et al, 2007). The tapetal degenerative debris form a sticky material, the tryphine, composed mostly of short-and long-fatty acids, hydroxycinnamic acid amides (HCAAs), a mixture of flavonoids and carotenoids (Jessen et al, 2011;Fellenberg et al, 2012b), and several types of proteins that take part in tapetal cell death (e.g. Cys proteases), pollen-stigma communication (e.g.…”