Quigley, M. | Search bioRxiv

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↗

bioRxiv2021

Vitamin D modulation of mitochondrial oxidative metabolism and mTOR enforces stress tolerance and anti-cancer responses

The relationship between vitamin D and reactive oxygen species (ROS), two integral signaling and damaging molecules of the cell, is poorly understood. This is striking, given that both factors are involved in cancer cell regulation and metabolism. Mitochondria (mt) dysfunction is one of the main drivers of cancer, producing higher cellular energy and ROS that can enhance oxidative stress and stress tolerance responses. To study the effects of vitamin D on metabolic and mt dysfunction, we used the vitamin D receptor (VDR)-sensitive MG-63 osteosarcoma cell model. Using biochemical approaches, active vitamin D (1,25-dihydroxyvitamin D, 1,25(OH)2D3) decreased mt ROS levels, membrane potential ({Delta}{Psi}mt), biogenesis, and translation, while enforcing endoplasmic reticulum/mitohormetic stress tolerance responses. Using a mitochondria-focused transcriptomic approach, gene set enrichment and pathway analyses show that 1,25(OH)2D3 lowered mt fusion/fission and oxidative phosphorylation (OXPHOS). By contrast, mitophagy, ROS defense, and epigenetic gene regulation were enhanced after 1,25(OH)2D3 treatment, as well as key metabolic enzymes that regulate fluxes of substrates for cellular architecture and a shift toward non-oxidative energy metabolism. ATACseq revealed putative oxi-sensitive and tumor-suppressing transcription factors that may regulate important mt functional genes such as the mTORC1 inhibitor, DDIT4/REDD1. DDIT4/REDD1 was predominantly localized to the outer mt membrane in untreated MG-63 cells yet sequestered in the cytoplasm after 1,25(OH)2D3 and rotenone treatments, suggesting a level of control by membrane depolarization to facilitate its cytoplasmic mTORC1 inhibitory function. The results show that vitamin D activates distinct adaptive metabolic responses involving mitochondria to regain redox balance and control the growth of cancer cells.

cancer biology↗