Dissecting the genetic basis of bioactive metabolites and fruit quality traits in blueberries (Vaccinium corymbosum L.)

Abstract

Blueberry is well-recognized as a healthy fruit with functionality derived largely from anthocyanin and chlorogenic acid. Despite their importance, no study to date has evaluated the genetic basis of these bioactives in blueberries and their relationship with fruit quality traits. Hence, to fill this gap, a mapping population including 196 F1 individuals was phenotyped for anthocyanin and chlorogenic acid concentration and fruit quality traits (titratable acidity, pH, and total soluble solids) over 3 years and data were used for QTL mapping and correlation analysis. Total soluble solids and chlorogenic acid were positively correlated with glycosylated anthocyanin and total anthocyanin, respectively, indicating that parallel selection for these traits is possible. Across all the traits, a total of 188 QTLs were identified on chromosomes 1, 2, 4, 8, 9, 11 and 12. Notably, four major regions with overlapping major-effect QTLs were identified on chromosomes 1, 2, 4 and 8, and were responsible for acylation and glycosylation of anthocyanins in a substrate and sugar donor specific manner. Through comparative transcriptome analysis, multiple candidate genes were identified for these QTLs, including glucosyltransferases and acyltransferases. Overall, the study provides the first insights into the genetic basis controlling anthocyanins accumulation and composition, chlorogenic acid and fruit quality traits, and establishes a framework to advance genetic studies and molecular breeding for anthocyanins in blueberry.

Trait Mapping of Phenolic Acids in an Interspecific (Vaccinium corymbosum var. caesariense × V. darrowii) Diploid Blueberry Population

“…The present study identifies a strong QTL for the tested phenolic acids, and its overlap with the QTL region identified by Mengist et al [ 46 ] lends credence to our finding. However, the lack of independent populations in which markers could be tested means that any genetic selection, such as in a breeding program, would require using an individual or parent from the BNJ16-4 population as the donor.…”

“…Comparing the results of trait mapping presented here with the previous findings of Mengist et al [ 46 ] showcases the mapping power of the interspecific population. While Mengist et al [ 46 ] used a population of 196 individuals and found QTL for CGA with LOD scores of 5.9–6.9, the present study used a comparable number of individuals and identified QTL for CGA with LOD scores of ~16.0. This difference is likely partially explained by the larger difference between the parents in the present study.…”

“…Two gene models in the significant region have BLAST hits on UGCT identified from poplar ( Populus spp.). Unfortunately, while Mengist et al [ 46 ] mapped CGA content and produced transcriptomes in tetraploid blueberry, they did not make a comparison between genotypes with varying levels of CGA and as yet, there is no searchable database with expression data in different tissues (J. L. Humann, personal communication).…”

“…This difference is likely partially explained by the larger difference between the parents in the present study. While the parents in Mengist et al [ 46 ] population, the cultivars Jewel and Draper-44392, differed by ~25mg/100g FW, BNJ05-237-8 and BNJ05-218-9 differed by ~110mg/100g FW. It is unlikely, however, that this would explain the 10-magnitude difference in probabilities.…”

“…Other minor and specialty crops have seen great advances in the availability of genetic resources over the past decade. However, blueberry has lagged behind, with only a few published genome sequences [ 44 , 45 , 46 ] and a limited number of genotyped mapping populations [ 46 , 47 , 48 , 49 ], all of which were constructed through crosses between tetraploid cultivars of V. corymbosum . The development of mapping populations in blueberry is complicated by long generation time and partial self-sterility but is of exceeding importance to crop improvement efforts, as the identification of genetic markers and trait loci can increase the speed at which new varieties can be developed, and aid in understanding the mechanisms of compound biosynthesis.…”