Regulation and Subfunctionalization of Flowering Time Genes in the Allotetraploid Oil Crop Brassica napus

Abstract

Flowering is a vulnerable, but crucial phase in building crop yield. Proper timing of this period is therefore decisive in obtaining optimal yields. However, genetic regulation of flowering integrates many different environmental signals and is therefore extremely complex. This complexity increases in polyploid crops which carry two or more chromosome sets, like wheat, potato or rapeseed. Here, I summarize the current state of knowledge about flowering time gene copies in rapeseed (Brassica napus), an important oil crop with a complex polyploid history and a close relationship to Arabidopsis thaliana. The current data show a high demand for more targeted studies on flowering time genes in crops rather than in models, allowing better breeding designs and a deeper understanding of evolutionary principles. Over evolutionary time, some copies of rapeseed flowering time genes changed or lost their original role, resulting in subfunctionalization of the respective homologs. For useful applications in breeding, such patterns of subfunctionalization need to be identified and better understood.

Genetic and Physiological Responses to Heat Stress in Brassica napus

“…During flowering, energy demand spikes due to different processes, such as: formation of flowers, nitrogen use efficiency and reduced photosynthesis ( Schiessl, 2020 ). Such crucial physiological period has been found sensitive to various biotic and abiotic stress and particularly to heat, which has a pronounced effect on the timing of flowering, depending on its duration, frequency, and intensity ( Lohani et al, 2020b ).…”

“…However, environmental adaptation has led to the evolution of new FTi regulator genes with no functional equivalence in A. thaliana ( Blümel et al, 2015 ). Moreover, some FTi gene copy numbers were found to either change or lose functionality over evolutionary periods resulting in sub-functionalization ( Schiessl, 2020 ). As a result, it is difficult to functionally characterize crop FTi regulators and pathways based on inferences from this model species.…”

Predicting yield traits of individual field-grownBrassica napusplants from rosette-stage leaf gene expression

“…4 , n=29), five genes code for AGAMOUS-LIKE MADS-box transcription factors (best candidate A. thaliana orthologs and associated AGI codes are given between parentheses): BnaC05g17630D ( AtAGL104 / AT1G22130 ), BnaA02g15390D ( AtAGL12 / AT1G71692 ), BnaA02g00370D ( BnFLC.A2 , AtFLC / AT5G10140 ), BnaA01g02900D ( AtAGL16 / AT3G57230 ), and BnaA09g53680D ( AtAGL30 / AT2G03060 ). BnFLC.A2 is orthologous to A. thaliana FLOWERING LOCUS C ( AtFLC ), a key repressor of the floral transition (64, 65). Two AGAMOUS-LIKE genes feature in the combined set of top-10 RF predictors for yield phenotypes ( Additional File 2: Fig.…”

Heterosis Derived From Nonadditive Effects of the BnFLC Homologs Coordinates Early Flowering and High Yield in Rapeseed (Brassica napus L.)

“…This provides a reliable reference for FT in rapeseed ( Schiessl et al, 2014 ; Bouché et al, 2016 ). In rapeseed, many QTLs and peaks identified via genome-wide association studies have been colocalized with some of the annotated FT genes from the reference genome ( Schiessl, 2020 ), and the crucial genes, namely, BnFLC.A10 , BnFLC.A2 , and BnFLC.C2 , which participate in the vernalization pathway, have been characterized in rapeseed ( Chen L. et al, 2018 ; Yin et al, 2020 ).…”