Jasmonic Acid Plays a Pivotal Role in Pollen Development and Fertility Regulation in Different Types of P(T)GMS Rice Lines

Abstract

Two-line hybrid rice systems represent a new technical approach to utilizing the advantages of rice hybrids. However, the mechanism underlying the male sterile-line fertility transition in rice remains unclear. Peiai 64S (PA64S) is a photoperiod- and thermo-sensitive genic male sterile (PTGMS) line in which male sterility manifests at an average temperature above 23.5 °C under long-day (LD) conditions. Nongken 58S (NK58S) is a LD-sensitive genic male sterile (PGMS) rice that is sterile under LD conditions (above 13.75 h-day). In contrast, D52S is a short-day (SD)-PGMS line that manifests male sterility under SD conditions (below 13.5 h-day). In this study, we obtained fertile and sterile plants from all three lines and performed transcriptome analyses on the anthers of the plants. Gene ontology (GO) analysis suggested that the differentially expressed genes identified were significantly enriched in common terms involved in the response to jasmonic acid (JA) and in JA biosynthesis. On the basis of the biochemical and molecular validation of dynamic, tissue-specific changes in JA, indole-3-acetic acid (IAA) levels, gibberellin (GA) levels, and JA biosynthetic enzyme activities and expression, we proposed that JA could play a pivotal role in viable pollen production through its initial upregulation, constant fluctuation and leaf-spikelet signaling under certain fertility-inducing conditions. Furthermore, we also sprayed methyl jasmonate (MEJA) and salicylhydroxamic acid (SHAM) on the plants, thereby achieving fertility reversal in the PGMS lines NK58S and D52S, with 12.91–63.53% pollen fertility changes. Through qPCR and enzyme activity analyses, we identified two key enzymes—allene oxide synthase (AOS) and allene oxide cyclase (AOC)—that were produced and upregulated by 20–500-fold in PGMS in response to spraying; the activities of these enzymes reversed pollen fertility by influencing the JA biosynthetic pathway. These results provide a new understanding of hormone interactions and networks in male-sterile rice based on the role of JA that will help us to better understand the potential regulatory mechanisms of fertility development in rice in the future.

Combined analysis of transcriptome and metabolome reveals that sugar, lipid, and phenylpropane metabolism are essential for male fertility in temperature-induced male sterile rice

“…According to our previous research methods, representative mature rice plants and spikelets were selected for observation and photography using a stereomicroscope to develop I 2 -KI staining and seed setting rate statistics of rice ( He et al, 2021a ; Sun et al, 2022 ). Briefly, we picked the top florets that had initiated spikelets, pinched out the anthers with forceps, squeezed out the pollen grains into 1% I 2 -KI solution, and observed and counted them under a microscope.…”

Low Salicylic Acid Level Improves Pollen Development Under Long-Term Mild Heat Conditions in Tomato

“…Interestingly, 35S:nahG dampened the upregulation by LTMH of several JAZ genes, encoding repressors of the JA response ( Chini et al, 2017 ), raising the possibility that low JA signaling is causal to pollen LTMH damage and that increased JA signaling strength in 35S:nahG contributes to better pollen performance of this line. Indeed, Arabidopsis seedlings require JA signaling for heat tolerance, and heat-induced male sterility has been linked to reduced JA signal ( Clarke et al, 2009 ; Khan et al, 2020 ; He et al, 2021 ). It is likely, however, that both, the LTMH pollen phenotype in the wild type and the increased tolerance in the low-SA line involve interaction between multiple hormones.…”

OsSPLs Regulate Male Fertility in Response to Different Temperatures by Flavonoid Biosynthesis and Tapetum PCD in PTGMS Rice

“…The representative mature rice plants and spikelets were selected for observation according to our previous research methods [ 13 , 81 ]. The anthers of the top floret that had initiated heading were picked and stained with 1% I 2 -KI.…”