Litthauer, S. | Search bioRxiv

bioRxiv2022

EXORIBONUCLEASE4 integrates metabolic signals induced by osmotic stress into the circadian system

The circadian clock system acts as an endogenous timing reference that coordinates many metabolic and physiological processes in plants. Previous studies have shown that the application of osmotic stress delays circadian rhythms via 3-Phospho-Adenosine 5-Phosphate (PAP), a retrograde signalling metabolite that is produced in response to redox stress within organelles. PAP accumulation leads to the inhibition of EXORIBONUCLEASEs (XRNs), which are responsible for RNA degradation. Interestingly, we are now able to demonstrate that post-transcriptional processing is crucial for the circadian response to osmotic stress. Our data show that degradation of specific circadian clock transcripts is modulated by osmotic stress, suggesting that RNA metabolism plays a vital role in circadian clock coordination during drought. Inactivation of XRN4 is sufficient to extend circadian rhythms, with LWD1, LWD2, and PRR7 identified as specific XRN4 targets that are post-transcriptionally regulated to delay circadian progression. One Sentence SummaryPost-transcriptional regulation of specific transcripts enables the circadian system to respond to osmotic stress.

plant biology↗

bioRxiv2022

Epistatic Modifiers Influence the Expression of Continual Flowering in Strawberry

O_LIPrevious work within the community led to the identification of a single dominant allele that controls the everbearing trait. However, frequent observations have indicated that crosses do not segregate in a Mendelian fashion, as would be expected for a trait controlled by a single dominant gene. Therefore, it was hypothesised that one or more unidentified epistatic alleles interact with the major gene. C_LIO_LIA GWAS was conducted on 587 June-bearers and 207 everbearers to assess the genetic components associated with flowering habit. The segregation ratios of parental strawberry lines with known phenotypes were used to validate the identified alleles. C_LIO_LIThree loci including the known, major FaPFRU locus and two epistatic modifiers were identified. These modifiers function as enhancers of the everbearing trait in individuals containing a single copy of the FaPFRU everbearing allele and appear to be functionally redundant. Principally, heterozygous individuals required the presence of two modifying alleles in order to allow expression of the everbearing trait. C_LIO_LIInclusion of the epistatic alleles improved the prediction of everbearing segregation ratios, beyond that of a single allele model, however, a large proportion of the variation remained unexplained. Future work should identify the additional repressor and enhancer modifiers not identified here. Discovering the genetic components controlling the everbearing trait can enable genetic informed strawberry improvement. C_LI Society Impact StatementUntil the 1970s, the majority of commercial strawberry varieties produced a single bloom of flowers. However, continuously flowering, everbearing strawberries are now routinely cultivated and use is increasing. Indeed, introgression of the everbearing flowering trait can lead to economic benefits for growers through the production of a continual crop from the same plant. Utilising genetic guided improvement has the power to streamline everbearing generation. As such, utilising the genetic markers reported here, can help to identify everbearing individuals at an early time point in the breeding process. Furthermore, these markers can help to improve the predictions of progeny segregation ratios.

plant biology↗