Increasing the oil content is a key objective in peanut breeding programs.  Accurate identification of quantitative trait loci (QTLs) with linked markers for oil content can facilitate marker-assisted selection for high-oil breeding.  In this study, a high-density bin map was constructed by resequencing a recombinant inbred line (RIL) population (ZH16×J11) consisting of 295 lines.  The bin map contained 4,212 loci and had a total length of 1,162.3 cM.  Ten QTLs for oil content were identified in six linkage groups.  Notably, two of these QTLs, qOCB03.1 and qOCB06.1, were consistently detected in a minimum of three environments and explained up to 13.62% of the phenotypic variation.  They have not been reported in previous studies and thus are novel QTLs.  The combination of favorable alleles from qOCB03.1 and qOCB06 in the RIL population could increase oil content across multiple environments from 1.50 to 2.46%.  Two insertions/deletions (InDels) markers linked to qOCB03.1 and qOCB06.1 were developed, and their association with oil content was validated in another RIL population (ZH10×ICG12625) with diverse phenotypes.  In addition, the high-resolution map allowed for the precise positioning of qOCB03.1 and qOCB06.1 within a 1.77 Mb interval on chromosome B03 and a 1.51 Mb interval on chromosome B06, respectively.  The annotation of genomic variants, analysis of transcriptome sequencing, and evaluation of the allelic effects in 292 peanut varieties revealed two candidate genes associated with oil content for each of the two QTLs.  The candidate genes identified in this study can enable the map-based cloning of key genes controlling oil content in peanut.  Furthermore, these novel and stable QTLs and their tightly linked markers are valuable for marker-assisted breeding for greater oil content in peanut.

Naturally colored cotton (NCC) represents a kind of eco-friendly and sustainable textile material. Limited colors and inferior yield and quality are the major obstacles to the wide application of NCCs.  The present work aimed to generate new colored cotton by synthesizing and accumulating anthocyanins in fibers.  Two anthocyanin regulatory genes Lc and GhPAP1D were fused and specifically expressed in fibers of the secondary cell wall (SCW) stage.  The transgenic fibers exhibited pronounced purplish-red color at 20 to 30 DPA (days post anthesis), and reddish-brown color at maturation.  Meanwhile, expressing Lc and GhPAP1D led to reduced elongation rate and impaired SCW deposition in fibers, finally decreased fiber strength and length, and low lint percentage at maturation.  Metabolomic and transcriptomic analyses indicated that the whole flavonoid pathway was significantly up-regulated, and multiple flavonoids, including anthocyanins, proanthocyanidins and flavonols, were accumulated in developing and mature fibers.  It was also found that lignin biosynthesis and accumulation were significantly increased in fibers of the SCW synthesis stage.  Our results provided a feasible strategy to promote anthocyanin synthesis and accumulation in cotton fibers, and also its side effects on fiber coloration and development, which laid the foundation for future NCC color innovation.