Rubber tree (Hevea brasiliensis) provides the sole commercial source of natural rubber, a crucial industrial raw material. Rubber yield and girth are widely considered as the most important agronomic traits of rubber tree. However, due to the delayed initiation of rubber tree research, the identification of quantitative trait loci (QTLs) and candidate genes for these traits remains limited. Here, QTL mapping analysis was conducted on the full-sibling progeny population derived from a cross between the clones of GT1 and CATAS8–79. Phenotypes of girth, dry rubber yield (DRY) and yield per centimeter girth (YCG) were measured annually for four consecutive years. Meanwhile, the resequencing of 238 offspring individuals identified 29,140,529 high-confidence SNPs, which resulted in the generation of 3147 non-redundant bin markers. Based on these bin markers, 18 high-density linkage groups were constructed, with an average genetic distance ranging from 1.49 to 4.96 cM. Subsequently, a total of 37 environmentally stable QTLs were identified comprising 8 for girth, 16 for DRY, and 13 for YCG. These QTLs explained phenotypic variances spanning from 0.32 % to 17.71 %. The two most reliable QTLs, namely QGirth-4 and QGirth-7.2, were further investigated and 21 candidate genes were identified. Based on transcriptome sequencing and homologous annotation, a gibberellin receptor gene (GIBBERELLIN-INSENSITIVE DWARF1, GID1) was determined as the promising candidate for QGirth-7.2. Overexpression of HbGID1 led to early flowering and increased rosette-leaf branches in Arabidopsis, implying its significant role in girth development. These findings provide valuable insights into QTLs and target genes for enhancing growth and rubber yield traits, thereby contributing to molecular breeding of elite latex-timber rubber tree clones.

中文翻译：

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基于重测序的全同胞橡胶树种群 GT1 × CATAS8-79 中周长和橡胶产量性状的 QTL 定位


橡胶树 （Hevea brasiliensis） 是天然橡胶的唯一商业来源，天然橡胶是一种重要的工业原料。橡胶产量和周长被广泛认为是橡胶树最重要的农艺性状。然而，由于橡胶树研究的延迟启动，数量性状位点 （QTL） 和这些性状的候选基因的鉴定仍然有限。在这里，对源自 GT1 和 CATAS8-79 克隆之间杂交的全兄弟姐妹后代群体进行了 QTL 定位分析。连续四年每年测量周长、干橡胶产量 （DRY） 和每厘米围产量 （YCG） 的表型。同时，对 238 个后代个体的重测序确定了 29,140,529 个高置信度 SNP，从而产生了 3147 个非冗余 bin 标记。基于这些 bin 标记，构建了 18 个高密度连锁组，平均遗传距离为 1.49 至 4.96 cM。随后，共鉴定出 37 个环境稳定的 QTL，其中周长 8 个，DRY 16 个，YCG 13 个。这些 QTL 解释了从 0.32 % 到 17.71 % 的表型变异。进一步研究了 QGirth-4 和 QGirth-7.2 这两个最可靠的 QTL，并鉴定了 21 个候选基因。基于转录组测序和同源注释，确定赤霉素受体基因 （GIBBERELLIN-INSENSITIVE DWARF1， GID1） 是 QGirth-7.2 的有前途的候选基因。过表达 HbGID1 导致拟南芥早开花和莲座叶枝条增加，表明其在周长发育中起重要作用。 这些发现为增强生长和橡胶产量性状的 QTL 和靶基因提供了有价值的见解，从而有助于优质乳胶-木材橡胶树克隆的分子育种。