Suppression of S-adenosylmethionine Decarboxylase Activity is a Major Cause for High-Temperature Inhibition of Pollen Germination and Tube Growth in Tomato (Lycopersicon esculentum Mill.)

Abstract

Possible involvement of impaired polyamine biosynthesis in the poor performance of tomato pollen (Lycopersicon esculentum Mill.) at high temperatures was investigated. Incubation of pollen at 38 degrees C suppressed the increase of S-adenosylmethionine decarboxylase (SAMDC) activity in germinating pollen with little influence on arginine decarboxylase activity. Consequently, spermidine and spermine content in the pollen did not increase at 38 degrees C, while putrescine content increased at both 25 degrees C and 38 degrees C. High-temperature inhibition of pollen germination was alleviated by the addition of spermidine or spermine but not of putrescine to the germination medium. Cycloheximide inhibited SAMDC activity in parallel with pollen germination at 25 degrees C, whereas actinomycin D had no effect on either of them, indicating that enhanced SAMDC activity is associated with de novo protein synthesis. Incubation of crude enzyme extracts at 40 degrees C for 1 h did not affect SAMDC. In addition, high temperatures did not enhance protease activity in germinating pollen. These results indicate that low activity of SAMDC, probably due to impaired protein synthesis or functional enzyme formation, is a major cause for the poor performance of tomato pollen at high temperatures.

Improvement of environmental stress tolerance of sweet potato by introduction of genes for spermidine synthase

“…After centrifugation, free polyamines in the supernatant were dansylated with dansyl chloride (10 mg ml Ϫ1 acetone) and quantified via HPLC with 1,6-hexanediamine as the internal standard, as described by Song et al (2002). Chlorophylls in leaves were extracted with 80% (v/v) acetone and quantified spectrophotometrically by the method of Arnon (1949).…”

cDNA Microarray Analysis of Rice Anther Genes under Chilling Stress at the Microsporogenesis Stage Revealed Two Genes with DNA TransposonCastawayin the 5′-Flanking Region

“…43) SAMDC is the key enzyme in PA biosynthesis that decarboxylates Sadenosylmethionine and supplies an aminopropyl moiety to putrescine and spermidine. 44) Low activity of SAMDC is a major cause of poor performance of tomato pollen germination at high temperatures. To our knowledge, no prior study has elucidated the relationship between PA and microspore development in the rice plant.…”

Identification of metabolites involved in heat stress response in different tomato genotypes

“…This observation suggested that heat stress decreased the level of polyamines. Indeed, an incubation of pollen at 38 °C during 4 h lowered the content of spermidine and spermine whereas the content of putrescine increased and these changes correlated with a decrease of pollen germination (Song et al 2002). Adding spermidine or spermine to the medium restored the level of pollen germination.…”

“…Therefore, pollen isolated in such a way needs to be considered as imbibed pollen (with analogy to seed). Although isolation in a solution is the most widespread method, isolation of dry mature pollen without solution is also found in literature (Song et al 2001, Song et al 2002. We called this isolation method flower vibrating with further pollen lyophilisation (VL).…”

“…This is often associated with aberrations occurring during pollen development such as premature degeneration of the tapetum and inhibition of anther dehiscence Matsui and Omasa 2002). In addition, the decrease in pollen viability upon heat stress is associated with a reduction of specific metabolites, such as carbohydrates and polyamines (Pressman et al 2002;Song et al 2002).…”