Raju, S. K. K. | bioRxiv Science

bioRxiv2023

From buds to shoots: Insights into grapevine development from the Witch's Broom bud sport

Premise of StudyDevelopment is relatively understudied in woody vines, such as grapevine (Vitis vinifera). We used the Witchs Broom bud sport in grapevine to understand the developmental trajectories of the bud sports, as well as the potential genetic basis of the bud sport. MethodsWe phenotyped shoots, buds, and leaves of two independent cases of the Witchs Broom bud sport, in the Dakapo and Merlot varieties of grapevine, alongside wild-type counterparts of the same variety. We also performed Illumina and Oxford Nanopore sequencing on the two independent cases and two wild-type counterparts of the same variety. Key ResultsThe Dakapo and Merlot cases of Witchs Broom displayed severe developmental defects, with no fruit/clusters formed and dwarf vegetative features. However, the Dakapo and Merlot cases of Witchs Broom studied were also phenotypically different from one another, with distinct differences in bud and leaf development. We were able to identify unique genetic mutations in our two Witchs Broom cases that are strong candidates for the genetic basis of the bud sports. ConclusionsThe Witchs Broom bud sport in grapevine serves as a useful natural mutant in which to study grapevine development. The Witchs Broom bud sports in both varieties studied had dwarf phenotypes, but the two instances studied were also vastly different from one another. Future work on Witchs Broom bud sports in grapevine could provide more insight into development and the genetic pathways involved in grapevine.

plant biology↗

bioRxiv2022

Regulatory dynamics distinguishing desiccation tolerance strategies within resurrection grasses

Desiccation tolerance has evolved recurrently in grasses using two unique strategies to mitigate photooxidative damage under anhydrobiosis. The grass Oropetium thomaeum protects and retains chlorophyll, thylakoids, and the photosynthetic apparatus during desiccation (Homoiochlorophyly), while Eragrostis nindensis degrades and resynthesizes these components under desiccation and rehydration (Poikilochlorophyly). Here, we surveyed chromatin architecture and gene expression during desiccation in these two closely related species to identify regulatory dynamics underlying the distinct desiccation tolerance strategies in grasses. In both grasses, we observed a strong association between nearby chromatin accessibility and gene expression in desiccated tissues compared to well-watered, reflecting an unusual chromatin stability under anhydrobiosis. Integration of chromatin accessibility (ATACseq) and expression data (RNAseq) revealed a core desiccation response across these two grasses including many genes with binding sites for the core seed development transcription factor ABI5. O. thomaeum had a unique set of desiccation induced genes and regulatory elements associated with photoprotection, pigment biosynthesis, and response to high light, reflecting its adaptation of homoiochlorophyly. A tandem array of early light induced proteins (ELIPs) had massive shifts in gene expression and chromatin openness under desiccation in only O. thomaeum, and ELIPs acquired a novel desiccation related cis-regulatory motif, reflecting regulatory neofunctionalization during the evolution of desiccation tolerance. Together, our results highlight the complex regulatory and expression dynamics underlying desiccation tolerance in grasses.

plant biology↗