Differentially Expressed Genes Shared by Two Distinct Cytoplasmic Male Sterility (CMS) Types of Silene vulgaris Suggest the Importance of Oxidative Stress in Pollen Abortion

Cytoplasmic male sterility (CMS), encoded by the interacting mitochondrial and nuclear genes, causes pollen abortion or non-viability. CMS is widely used in agriculture and extensively studied in crops. Much less is known about CMS in wild species. We performed a comparative transcriptomic analysis of male sterile and fertile individuals of Silene vulgaris, a model plant for the study of gynodioecy, to reveal the genes responsible for pollen abortion in this species. We used RNA-seq datasets previously employed for the analysis of mitochondrial and plastid transcriptomes of female and hermaphrodite flower buds, making it possible to compare the transcriptomes derived from three genomes in the same RNA specimen. We assembled de novo transcriptomes for two haplotypes of S. vulgaris and identified differentially expressed genes between the females and hermaphrodites, associated with stress response or pollen development. The gene for alternative oxidase was downregulated in females. The genetic pathways controlling CMS in S. vulgaris are similar to those in crops. The high number of the differentially expressed nuclear genes contrasts with the uniformity of organellar transcriptomes across genders, which suggests these pathways are evolutionarily conserved and that selective mechanisms may shield organellar transcription against changes in the cytoplasmic transcriptome

The FLOWERING LOCUS T LIKE 2-1 gene of Chenopodium triggers precocious flowering in Arabidopsis seedlings

The FLOWERING LOCUS T (FT) gene is the essential integrator of flowering regulatory pathways in angiosperms. The paralogs of the FT gene may perform antagonistic functions, as exemplified by BvFT1, that suppresses flowering in Beta vulgaris, unlike the paralogous activator BvFT2. The roles of FT genes in other amaranths were less investigated. Here, we transformed Arabidopsis thaliana with the FLOWERING LOCUS T like (FTL) genes of Chenopodium ficifolium and found that both CfFTL1 and CfFTL2–1 accelerated flowering, despite having been the homologs of the Beta vulgaris floral promoter and suppressor, respectively. The floral promotive effect of CfFTL2–1 was so strong that it caused lethality when overexpressed under the 35S promoter. CfFTL2–1 placed in an inducible cassette accelerated flowering after induction with methoxyphenozide. The spontaneous induction of CfFTL2–1 led to precocious flowering in some primary transformants even without chemical induction. The CqFT2–1 homolog from Chenopodium quinoa had the same impact on viability and flowering as CfFTL2–1 when transferred to A. thaliana. After the FTL gene duplication in Amaranthaceae, the FTL1 copy maintained the role of floral activator. The second copy FTL2 underwent subsequent duplication and functional diversification, which enabled it to control the onset of flowering in amaranths to adapt to variable environments