Biology subjects

Myles, S.

Publications and source records attributed to Myles, S..

8 recordsLinked to original sources

bioRxiv2025

Differences in apple fruit shape are independent of fruit size

PremiseFruit quality is crucial in breeding new apple accessions. Before tasting, consumers assess freshness and flavour based on the physical appearance of fruit. Understanding how fruit quality traits such as shape and size vary across diverse apples provides a foundation for future breeding efforts. MethodsWe analyzed images of 5724 apples representing 743 different trees and 534 unique accessions from Canadas Apple Biodiversity Collection to quantify variation in fruit shape and size. To achieve this, we used a pseudo-landmarking approach paired with traditional linear measurements including length, width, area, solidity, and aspect ratio. We also incorporated previously collected fruit weight measurements from the same trees. ResultsUsing a comprehensive measure of shape, we determined that the primary source of variation in apple fruit shape was the width to length (aspect) ratio of the fruit. This variation was not significantly correlated with differences in fruit size from its area and harvest weight. ConclusionsOur findings indicate that two critical aspects of morphological variation in apple--fruit shape and size--are independent, suggesting it is possible to select for a diverse range of fruit shapes while maintaining a consistent and marketable size.

plant biology↗

bioRxiv2024

Comparing diploid and triploid apples from a diverse collection

Apples (Malus X. domestica Borkh.) are an economically important fruit species and the focus of continuing breeding efforts around the world. While most apple varieties are diploid, ploidy levels vary across the species, and triploids may be used in breeding despite poor fertility. The impact of ploidy on agricultural traits in apple is not well understood but is an important factor to consider when breeding new apple varieties. Here, we use mean heterozygosity values to categorize 970 apple accessions as diploid or triploid and then contrast apples of varying ploidy levels across 10 agriculturally important traits with sample sizes ranging from 427 to 928 accessions. After correction for multiple testing, we determine that triploids have significantly higher phenolic content. By examining historical release dates for apple varieties, our findings suggest that contemporary breeding programs are primarily releasing diploid varieties, and triploids tend to be older varieties. Ultimately, our results suggest that phenotypic differences between diploids and triploids are subtle and often insignificant indicating that triploids may not provide substantial benefit above diploids to apple breeding programs.

plant biology↗

bioRxiv2021

S-acylation is a positive regulator of FLS2-mediated plant immunity

Plant receptor kinases are key transducers of extracellular stimuli, such as the presence of beneficial or pathogenic microbes or secreted signalling molecules. Receptor kinases are regulated by numerous post-translational modifications. Here, using the immune receptor kinases FLS2 and EFR, we show that S-acylation at a cysteine conserved in all plant receptor kinases is crucial for function. S-acylation involves the addition of long-chain fatty acids to cysteine residues within proteins, altering their biophysical properties and behaviour within the membrane environment. We observe S-acylation of FLS2 at C-terminal kinase domain cysteine residues within minutes following perception of its ligand flg22, in a BAK1 co-receptor dependent manner. We demonstrate that S-acylation is essential for FLS2-mediated immune signalling and resistance to bacterial infection. Similarly, mutating the corresponding conserved cysteine residue in EFR supressed elf18 triggered signalling. Analysis of unstimulated and activated FLS2-containing complexes using microscopy, detergents and native membrane DIBMA nanodiscs indicates that S-acylation stabilises and promotes retention of activated receptor kinase complexes at the plasma membrane to increase signalling efficiency.

plant biology↗

bioRxiv2021

Phenotypic divergence between the cultivated apple (Malus domestica) and its primary wild progenitor (Malus sieversii)

An understanding of the relationship between the cultivated apple (Malus domestica) and its primary wild progenitor species (M. sieversii) not only provides an understanding of how apples have been improved in the past, but may be useful for apple improvement in the future. We measured 10 phenotypes in over 1000 unique apple accessions belonging to M. domestica and M. sieversii from Canadas Apple Biodiversity Collection. Using principal components analysis (PCA), we determined that M. domestica and M. sieversii differ significantly in phenotypic space and are nearly completely distinguishable as two separate groups. We found that M. domestica had a shorter juvenile phase than M. sieversii and that cultivated trees produced flowers and ripe fruit later than their wild progenitors. Cultivated apples were also 3.6 times heavier, 43% less acidic, and had 68% less phenolic content than wild apples. Using historical records, we found that apple breeding over the past 200 years has resulted in a trend towards apples that have higher soluble solids, are less bitter, and soften less during storage. Our results quantify the significant changes in phenotype that have taken place since apple domestication, and provide evidence that apple breeding has led to continued phenotypic divergence of the cultivated apple from its wild progenitor species.

plant biology↗

bioRxiv2019

Rootstock choice can dramatically affect grapevine growth

Grape growers use rootstocks to provide protection against pests and pathogens and to modulate viticulture performance such as shoot growth. Our study examined two grapevine scion varieties ( Chardonnay and Cabernet Sauvignon) grafted to 15 different rootstocks and determined the effect of rootstocks on eight traits important to viticulture. We assessed the vines across five years and identified both year and variety as contributing strongly to trait variation. The effect of rootstock was relatively consistent across years and varieties, explaining between 8.99% and 9.78% of the variation in growth-related traits including yield, pruning weight, berry weight, and Ravaz index (yield to pruning weight ratio). Increases in yield due to rootstock were generally the result of increases in berry weight, likely due to increased water uptake by vines grafted to a particular rootstock. We demonstrated a greater than 50% increase in yield, pruning weight, or Ravaz index by choosing the optimal rootstock, indicating that rootstock choice is crucial for grape growers looking to improve vine performance.

plant biology↗

bioRxiv2019

Allelic diversity of NAC18.1 is a major determinant of fruit firmness and harvest date in apple (Malus domestica)

Softening is a hallmark of ripening in fleshy fruits, and has both desirable and undesirable implications for texture and postharvest stability. Accordingly, the timing and extent of ripening and associated textural changes are key targets for improving fruit quality through breeding. Previously, we identified a large effect locus associated with harvest date and firmness in apple (Malus domestica) using genome-wide association studies (GWAS). Here, we present additional evidence that polymorphisms in or around a transcription factor gene, NAC18.1, may cause variation in these traits. First, we confirmed our previous findings with new phenotype and genotype data from [~]800 apple accessions. In this population, we compared a genetic marker within NAC18.1 to markers targeting three other firmness-related genes currently used by breeders (ACS1, ACO1, and PG1), and found that the NAC18.1 marker was the strongest predictor of both firmness at harvest and firmness after three months of cold storage. By sequencing NAC18.1 across 18 accessions, we revealed two predominant haplotypes containing the single nucleotide polymorphism (SNP) previously identified using GWAS, as well as dozens of additional SNPs and indels in both the coding and promoter sequences. NAC18.1 encodes a protein with high similarity to the NON-RIPENING (NOR) transcription factor, a regulator of ripening in tomato (Solanum lycopersicum). To test whether these genes are functionally orthologous, we introduced both NAC18.1 transgene haplotypes into the tomato nor mutant and showed that both haplotypes complement the nor ripening deficiency. Taken together, these results indicate that polymorphisms in NAC18.1 may underlie substantial variation in apple firmness through modulation of a conserved ripening program.

plant biology↗

bioRxiv2017

Persistent homology demarcates a leaf morphospace

Current morphometric methods that comprehensively measure shape cannot compare the disparate leaf shapes found in seed plants and are sensitive to processing artifacts. We explore the use of persistent homology, a topological method applied across the scales of a function, to overcome these limitations. The described method isolates subsets of shape features and measures the spatial relationship of neighboring pixel densities in a shape. We apply the method to the analysis of 182,707 leaves, both published and unpublished, representing 141 plant families collected from 75 sites throughout the world. By measuring leaves from throughout the seed plants using persistent homology, a defined morphospace comparing all leaves is demarcated. Clear differences in shape between major phylogenetic groups are detected and estimates of leaf shape diversity within plant families are made. This approach does not only predict plant family, but also the collection site, confirming phylogenetically invariant morphological features that characterize leaves from specific locations. The application of a persistent homology method to measure leaf shape allows for a unified morphometric framework to measure plant form, including shape and branching architectures.

plant biology↗

bioRxiv2017

Morphometrics Reveals Complex And Heritable Apple Leaf Shapes

Apple (Malus spp.) is a widely grown and valuable fruit crop. Leaf shape and size are important for flowering in apple and may also be early indicators for other agriculturally valuable traits. We examined 9,000 leaves from 869 unique apple accessions using linear measurements and comprehensive morphometric techniques. We identified allometric variation in the length-to-width aspect ratio between accessions and species of apple. The allometric variation was due to variation in the width of the leaf blade, not length. Aspect ratio was highly correlated with the primary axis of morphometric variation (PC1) quantified using elliptical Fourier descriptors (EFDs) and persistent homology (PH). While the primary source of variation was aspect ratio, subsequent PCs corresponded to complex shape variation not captured by linear measurements. After linking the morphometric information with over 122,000 genome-wide SNPs, we found high narrow-sense heritability values even at later PCs, indicating that comprehensive morphometrics can capture complex, heritable phenotypes. Thus, techniques such as EFDs and PH are capturing heritable biological variation that would be missed using linear measurements alone, and which could potentially be used to select for a hidden phenotype only detectable using comprehensive morphometrics.

plant biology↗