Inheritance of reproductive phenology traits and related QTL identification in apricot

Abstract

Reproductive phenological traits of great agronomical interest in apricot species, including flowering date, ripening date and fruit development period, were studied during 3 years in two F 1 progenies derived from the crosses 'Bergeron' × 'Currot' (B × C) and 'Goldrich' × 'Currot' (G × C). Results showed great variability and segregation in each population, confirming the polygenic nature and quantitative inheritance of all the studied traits. Genetic linkage maps were constructed combining SSR and SNP markers, using 87 markers in the 'B × C' population and 89 markers in 'G × C'. The genetic linkage maps in both progenies show the eight linkage groups (LGs) of apricot, covering a distance of 394.9 cM in 'Bergeron' and of 414.3 cM in 'Currot'. The 'Goldrich' and 'Currot' maps were of 353.5 and 422.3 cM, respectively. The average distance obtained between markers was thus 7.59 cM in 'Bergeron' and 7.53 cM in 'Currot', whereas the 'Goldrich' and 'Currot' averages were 5.6 and 7.5 cM, respectively. According to the polygenic nature of the studied phenology traits, QTLs linked to flowering date, ripening date and the fruit development period were identified during the 3 years of the study in all LGs except for LG 8. Among the QTLs identified, major QTLs for flowering and ripening date and the fruit development period were identified in LG 4, especially important in the 'G × C' population.

Multiple-population QTL mapping of maturity and fruit-quality traits reveals LG4 region as a breeding target in sweet cherry (Prunus avium L.)

“…The high positive correlation between MD and FD time, observed herein for the first time in sweet cherry, has been previously observed in peach and apricot 4,5,27 . The results indicate that MD is highly dependent on FD time in sweet cherry, as has been previously observed in other Prunus species.…”

“…FD time has also been investigated in Prunus, but only in apricot and peach. A main QTL for FD time was found on the same LG4 genomic region where the MD QTL has been identified in these species 5,13,14 . In this region, NAC transcription factors have been reported as candidate genes for MD in peach 15 and other Rosaceae species like apple 16 .…”

“…Sweet cherry MD is related to bloom date and fruit development (FD), both of which vary between cultivars. In apricot and peach, it has been observed that FD and MD also display broad variability and a large positive correlation 4,5 . Early and late blooming are also breeding objectives for market and crop adaptation 6 .…”

Genetic Dissection of Bloom Time in Low Chilling Sweet Cherry (Prunus avium L.) Using a Multi-Family QTL Approach

“…However in our work, this QTL explained a smaller part of the variation (6.0%) ( Table 1) and was not detected all years. Several works indicated that the LG4 QTL had a larger effect on BT of high chill cultivars (Castède et al, 2014;Kitamura et al, 2018), while in low chill cultivars, as in this work, the variation in BT is more dependent in the QTL on LG1 (Fan et al, 2010;Sánchez-Pérez et al, 2012;Zhebentyayeva et al, 2014;Salazar et al, 2016). LG1 candidate genes (DAM1-6) are related to CR, and therefore these genes may have a larger contribution to BT of low chilling cultivars.…”

“…In sweet cherry, skewed segregation in F 1 populations towards high CR, but not late bloom, was also observed (Castède et al, 2014). This was also the case in almond, where Late bloom (Lb) is dominant (Ballester et al, 2001), and in Japanese plum and apricot F 1 populations from low CR cultivars (Campoy et al, 2011;Salazar et al, 2016;Kitamura et al, 2018). However, transgressive segregation toward both early and late blooming was observed in peach F 2 populations (Fan et al, 2010;Bielenberg et al, 2015).…”