Abstract
The phenotype of the tomato mutant jasmonate-insensitive1-1 (jai1-1) mutated in the JA-Ile co-receptor COI1 demonstrates JA function in flower development, since it is female-sterile. In addition, jai1-1 exhibits a premature anther dehydration and pollen release, being in contrast to a delayed anther dehiscence in the JA-insensitive Arabidopsis mutant coi1-1. The double mutant jai1-1 Never ripe (jai1-1 Nr), which is in addition insensitive to ethylene (ET), showed a rescue of the jai1-1 phenotype regarding pollen release. This suggests that JA inhibits a premature rise in ET to prevent premature stamen desiccation. To elucidate the interplay of JA and ET in more detail, stamen development in jai1-1 Nr was compared to wild type, jai1-1 and Nr regarding water content, pollen vitality, hormone levels, and accumulation of phenylpropanoids and transcripts encoding known JA- and ET-regulated genes. For the latter, RT-qPCR based on nanofluidic arrays was employed. The data showed that additional prominent phenotypic features of jai1-1, such as diminished water content and pollen vitality, and accumulation of phenylpropanoids were at least partially rescued by the ET-insensitivity. Hormone levels and accumulation of transcripts were not affected. The data revealed that strictly JA-regulated processes cannot be rescued by ET-insensitivity, thereby emphasizing a rather minor role of ET in JA-regulated stamen development.
Highlights
Flower development is controlled by several plant hormones including their cross talk [1]
Any pre-mature function of ET is repressed by jasmonates. This is in strong contrast to Arabidopsis, where jasmonates serve as important regulators jasmonates
This is in strong contrast to Arabidopsis, where jasmonates serve as important regulators to trigger anther dehiscence visible in the delay of this process in the coi1 mutant [11]
Summary
Flower development is controlled by several plant hormones including their cross talk [1]. Among these hormones involved in regulation of flower development are jasmonic acid (JA) and its derivatives, commonly named jasmonates [2]. Jasmonates are lipid-derived compounds that ubiquitously occur in higher plants and act in the plant’s response to biotic and abiotic stress [2,3]. The main intermediate produced in plastids, cis-12-oxophytodienoc acid (OPDA), is converted within peroxisomes to JA, which is further metabolized into (+)-7-iso-jasmonoyl isoleucine (JA-Ile) in the cytosol [5]. JA-Ile represents the most biologically active form of jasmonates in higher plants [6]. JA-Ile mediates interaction of the co-receptor proteins CORONATINE INSENSITIVE1 (COI1) and JASMONATE ZIM DOMAIN (JAZ) [6,7,8,9], thereby mediating the proteasomal degradation of JAZ proteins and freeing transcription factors, such as MYC2, from repression to enable transcription of JA-induced genes [2,3,10]
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