<p class="first" id="d4189141e85">Pecan ( Carya illinoinensis) is an important tree
nut throughout the world. The high
concentration of flavonoid in its kernels makes it an excellent food with health benefits.
However, the molecular basis of flavonoid biosynthesis in pecan remains unclear, which
hinders quality breeding in this plant. Therefore, in order to find the crucial genes
involved in flavonoid biosynthesis, the changes in flavonoid profiles and the transcriptomes
of pecan kernels at four developmental stages (late water, gel, dough, and mature
stages) were analyzed. As a result, the highest levels of total phenolic, condensed
tannin, and flavan-3-ols were observed at the "late water stage". Catechin was the
most abundant flavan-3-ol at different development stages. In total, 64 773 unigenes
were obtained, and 46 924 (72.44%) unigenes were annotated. After differentially expressed
gene (DEG) analysis, 12 750 unique DEGs were identified. Flavonoid-related DEGs of
36 structural genes and eight MYBs were obtained. The structural gene set contained
three PALs, three CHSs, two CHIs, one F3H, two F3'Hs, two F3'5'Hs, one DFR, one ANS,
two LARs, and two ANRs. The expression patterns of most of the structural genes were
consistent with the changes in flavonoid profiles during kernel development. We believe
that this RNA-Seq data set will provide valuable resources for unraveling the molecular
mechanism of flavonoid metabolism in pecan and will significantly promote genetic
studies and quality breeding in this plant.
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