Biology subjects

Raines, D.

Publications and source records attributed to Raines, D..

2 recordsLinked to original sources

bioRxiv2024

Genome-Wide Associations within Diverse Wild Apple Germplasm for Postharvest Blue Mold Resistance to Penicillium expansum

Post-harvest disease caused by the blue mold fungus, Penicillium expansum, accounts for a substantial proportion of economic losses in United States apple industry. Multiple modes of entry in the apple supply chain, plus emerging fungicide resistance, limit the current and long-term viability of using chemical controls alone. Previous phenotypic screens of Malus accessions in the USDA-ARS apple germplasm have identified varying levels of blue mold disease resistance in some wild apple accessions and hybrids. These wild apple species contain reservoirs of genetic resistance that can be integrated into apple breeding programs to complement the previously identified qM-Pe3.1 marker from M. sieversii. We sought to identify these novel loci by combining historical phenotypes of the USDA-ARS wild apple germplasm with low-pass genomic sequencing to perform association mapping. Multi-locus mixed models identified five single nucleotide polymorphisms (SNPs) significantly associated with reduction of post-harvest rot under high concentration of P. expansum inoculum, and one SNP associated under low inoculum concentration. Within a 25,000 base pair window of these SNPs, we found candidate genes encoding proteins with known pathogen immune response and defense roles, such as a Cobra-like 7, flavin monooxygenase, LRR receptors, PR5-like receptor kinase, and a putative resistance protein RGA3. We present these loci as targets for identifying accessions with beneficial alleles that can be targeted for fine mapping and use in Malus breeding programs to achieve M. domestica lines with natural post-harvest rot resistance.

genetics↗

bioRxiv2024

Working smarter, not harder: silencing LAZY1 in Prunus domestica causes outward, wandering branch orientations with commercial and ornamental applications.

Controlling branch orientation is a central challenge in tree fruit production, as it impacts factors as diverse as light interception, pesticide use, fruit quality, yield, and labor costs. In an attempt to modify branch orientation, growers use many different management practices, including tying branches to wires or applying growth regulator sprays. However, these practices are often costly and ineffective. In contrast, altering the expression of genes that control branch angles and orientations would permanently optimize tree architecture with minimal management inputs. One gene implicated in branch angle control is LAZY1, which promotes upward branch growth in response to gravity. We used an antisense vector to silence LAZY1 in plum (Prunus domestica). We found that these LAZY1-silenced lines have significantly increased branch and petiole angles. In addition, they lack apical dominance and display a "wandering" or weeping branch trajectory. Given these phenotypes, we assessed whether the strength or stiffness of the branches were compromised. No differences were observed in new growth. While the wood of first-year LAZY1-silenced branches was more flexible and weaker than the control, the strength and stiffness of the branches were not decreased because branch diameter is increased. Finally, we evaluated the utility of LAZY1-silenced trees for two planar orchard systems, training them in super slender axe and espalier. LAZY1-silenced trees had more open canopies and were easier to constrain to the trellis height. This work illustrates the power of manipulating gene expression to optimize plant architecture for each horticultural application.

plant biology↗