Biology subjects

Dardick, C. D.

Publications and source records attributed to Dardick, C. D..

2 recordsLinked to original sources

bioRxiv2023

Temporal Changes in The Proanthocyanidins to Anthocyanins Ratio During Dormancy Associate with Bloom Time Variations in Peach

This study provides a thorough exploration of the mechanisms regulating the onset of flowering in peach trees, a process principally governed by bud-dormancy. We applied untargeted metabolomics combined with a comprehensive series of molecular and biochemical experiments to scrutinize the variations in bloom times among different peach cultivars. The impact of exogenous chemical stimuli, specifically ethephon (ET) and abscisic acid (ABA), on bloom times was also evaluated. Our study revealed that the ET-induced delay in bloom time was associated with higher levels of proanthocyanidin (PA) compared to anthocyanins (ACNs) during endodormancy. Furthermore, fluctuations in the PA/ACNs ratio during dormancy demonstrated a strong correlation with the chill requirements and bloom dates of 12 distinct peach genotypes. The research further uncovers the crucial role of ABA in regulating the biosynthesis of PAs and ACNs during peach tree dormancy. Intriguingly, the exogenous application of ABA during endodormancy resulted in a reduction of PA content, leading to an earlier bloom time. We also observed variations in DAM gene expression between early- and late-blooming cultivars. The late-blooming cultivars exhibited higher transcript levels of DAM genes, elevated PA levels, and lower ABA levels compared to their early-blooming counterparts. Importantly, our study proposes PAs and ACNs as quantitative marker metabolites for endo- and ecodormancy phases. This innovative finding paves the way for developing more accurate chill and heat requirement models, thereby enabling a more precise understanding and projection of the impacts of global climate change on the phenology of tree fruit species.

developmental biology↗

bioRxiv2023

A single amino acid substitution in MdLAZY1A dominantly impairs shoot gravitropism in Malus

Plant architecture is one of the most important factors that determines crop yield potential and productivity. In apple (Malus), genetic improvement of tree architecture has been challenging due to a long juvenile phase and their growth as complex trees composed of a distinct scion and a rootstock. To better understand the genetic control of apple tree architecture, the dominant weeping growth phenotype was investigated. We report the identification of MdLAZY1A (MD13G1122400) as the genetic determinant underpinning the Weeping (W) locus that largely controls weeping growth in Malus. MdLAZY1A is one of the four paralogs in apple that are most closely related to AtLAZY1 involved in gravitropism in Arabidopsis. The weeping allele (MdLAZY1A-W) contains a single nucleotide mutation c.584T>C that leads to a leucine to proline (L195P) substitution within a predicted transmembrane domain that co-localizes with Region III, one of the five conserved regions in LAZY1-like proteins. Subcellular localization revealed that MdLAZY1A localizes to the plasma membrane and nucleus in plant cells. Over-expressing the weeping allele in apple cultivar Royal Gala (RG) with standard growth habit impaired its gravitropic response and altered the growth to weeping-like. Suppressing the standard allele (MdLAZY1A-S) by RNA interference (RNAi) in RG similarly changed the branch growth direction to downward. Overall, the L195P mutation in MdLAZY1A is genetically causal for weeping growth, underscoring not only the crucial roles of residue L195 and Region III in MdLAZY1A-mediated gravitropic response, but also a potential DNA base editing target for tree architecture improvement in Malus and other crops.

plant biology↗