Blueberry cell wall polysaccharide composition of three distinct fruit firmness phenotypes

Authors: Trandel, Marlee; Johanningsmeier, Suzanne; OH, HEEDUK - North Carolina State University; IORIZZO, MASSIMO - North Carolina State University; PERKIS-VEAZIE, PENELOPE - North Carolina State University

Submitted to: ACS Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2023
Publication Date: 11/8/2023
Citation: Trandel-Hayes M, Johanningsmeier S., Oh H, Iorizzo M, and Perkins-Veazie P. 2023. Blueberry cell wall polysaccharide composition of three distinct fruit firmness phenotypes. ACS Food Science & Technology 3: 1920-1930. https://doi.org/10.1021/acsfoodscitech.3c00284.
DOI: https://doi.org/10.1021/acsfoodscitech.3c00284?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as

Interpretive Summary: Blueberry fruit exhibits changes and loss of tissue firmness in cultivars harvested from the same lot and within the same plant. Fruit firmness is a critical quality trait for consumer acceptance and marketability. Changes and subsequent losses of firmness have been related to the plant cell wall. However, previous cell wall research on blueberry is crude and does not entirely explain the firmness conundrum. In the present work, we assessed quantitative cell wall differences between the peel and pulp of three highbush blueberry cultivars with phenotypic differences in tissue firmness (crisp, firm and soft cultivars). Twelve neutral sugars and 45 cell wall linkage residues were quantified in peel and pulp samples, representing the most comprehensive cell wall assessment to date. The firm and crisp cultivar had highest amounts of specific hemicelluloses, arabinan and arabinogalactan. While the pulp of the crisp cultivar had highest amounts of hemicelluloses heteromannan and xyloglucan. The peel of the crisp cultivar had highest amounts of 2-deoxy-d-ribose, which is a new a novel finding in blueberry cell wall research. The increase of this monosaccharide, 2-deoxy-d-ribose, in the peel and hemicelluloses of heteromannan and xyloglucan in the pulp, are the likely contributing factors to blueberry crispness. Depending upon new cultivar development and desirable traits, upregulating cell wall markers contributing to increased hemicellulose and 2-d-d-ribose content can be focused on in future blueberry breeding programs.

Technical Abstract: Blueberry (Vaccinium corymbosum) cultivars exhibit inconsistencies in fruit quality, firmness and shelf-life. Cell wall polysaccharides of blueberry peel and pulp may reflect fruit firmness phenotypes. Fruit firmness and quantitative cell wall composition was determined for three cultivars of distinctive firmness types, Indigocrisp (crisp type), Emerald (firm, industry standard) and Jewel (soft). Four mechanical force parameters evaluating firmness in the epidermis (Fep), hypodermis (Fh), parenchyma (Fp), and inner pulp (Finner) were measured. ‘Indigocrisp’ had the highest values for all parameters, indicating a distinctive mechanical texture. Fh and Finner values were significantly different in all comparisons among cultivars, suggesting these parameters enable discernment between cultivars of varying firmness. Peel and pulp alcohol insoluble residues (AIRs) were prepared then reduced, hydrolyzed, methylated, acetylated, and quantified using GC-MS analysis for monosaccharide composition and polysaccharide linkage assembly. Monosaccharide composition (µg·mg-1) differed among cultivars by tissue type, where 2-deoxy-d-ribose (0.031) and glucuronic acid (22.23) were highest in the pulp of ‘Indigocrisp’; allose (2.55) was highest in the pulp of ‘Jewel’; mannose (11.86) and arabinose (38.73) were highest in peel of ‘Jewel’; and glucose (106.31) was highest in the pulp of ‘Emerald’. Peel and pulp differed, with xylose (94.89) highest in the pulp and fucose (0.65) highest in the peel. The degree of methylation was higher in the pulp compared to the peel. We report for the first time 45 cell wall linkages in blueberry, representing the most comprehensive linkage assembly to date. Polysaccharide classifications were estimated using cell wall linkage analysis. ‘Emerald’ and ‘Indigocrisp’ pulp had higher amounts of the hemicelluloses arabinan and arabinogalactan II. ‘Indigocrisp’ pulp had highest amounts of heteromannan, xyloglucan, and cellulose. Pectic polysaccharides of rhamnogalacturonan I and II were highest in the soft cultivar, Jewel. Pectins are known to depolymerize first in the plant cell wall, potentially leading to the decreased firmness in ‘Jewel’. The increased amounts of hemicelluloses in the pulp of the firm and crisp cultivars are likely the contributing factor to higher tissue firmness. Blueberry breeding programs may be able to utilize cell wall markers to increase these hemicelluloses in the pulp of blueberry cultivars selected for commercial production.