Department of Genetics, Luiz de Queiros College of Agriculture (ESALQ), University of São Paulo (USP), Avenida Pádua Dias, 11, Pircacicaba, SP, 13400-970, Brazil.
FTS Sementes S.A., Avenida Newton Slaviero, Ponta Grossa, PR, 84043-560, Brazil.
BMC Plant Biol. 2018 Oct 10;18(1):223. doi: 10.1186/s12870-018-1450-y.
Rubber tree is cultivated in mainly Southeast Asia and is by far the most significant source of natural rubber production worldwide. However, the genetic architecture underlying the primary agronomic traits of this crop has not been widely characterized. This study aimed to identify quantitative trait loci (QTLs) associated with growth and latex production using a biparental population established in suboptimal growth conditions in Brazil.
A full-sib population composed of 251 individuals was developed from crossing two high-producing Asiatic rubber tree cultivars, PR 255 and PB 217. This mapping population was genotyped with microsatellite markers from enriched genomic libraries or transcriptome datasets and single-nucleotide polymorphism (SNP) markers, leading to construction of a saturated multipoint integrated genetic map containing 354 microsatellite and 151 SNP markers. Height and circumference measurements repeated over a six-year period and registration of cumulative latex production during six consecutive months on the same individuals allowed in-depth characterization of the genetic values of several growth traits and precocious latex production. Growth traits, circumference and height, were overall positively correlated, whereas latex production was not correlated or even negatively correlated with growth traits. A total of 86 distinct QTLs were identified, most of which were detected for only one trait. Among these QTLs, 15 were linked to more than one phenotypic trait (up to 4 traits simultaneously). Latex production and circumference increments during the last wintering period were associated with the highest numbers of identified QTLs (eleven and nine, respectively), jointly explaining the most significantly observed phenotypic variances (44.1% and 44.4%, respectively). The most important QTL for latex production, located on linkage group 16, had an additive effect of the male parent PB 217 and corresponded to a QTL at the same position detected in a previous study carried out in Thailand for the biparental population RRIM 600 x PB 217.
Our results identified a set of significant QTLs for rubber tree, showing that the performance of modern Asiatic cultivars can still be improved and paving the way for further marker-assisted selection, which could accelerate breeding programs.
橡胶树主要种植于东南亚，是目前全球天然橡胶生产的最重要来源。然而，该作物主要农艺性状的遗传结构尚未得到广泛描述。本研究旨在利用在巴西不利生长条件下建立的双亲群体，鉴定与生长和乳胶产量相关的数量性状位点（QTL）。
从两个高产品种，PR 255 和 PB 217 杂交，建立了一个全同胞群体，共 251 个个体。该作图群体用来自富集基因组文库或转录组数据集的微卫星标记和单核苷酸多态性（SNP）标记进行基因型分析，构建了一个饱和的多点综合遗传图谱，包含 354 个微卫星和 151 个 SNP 标记。对个体进行了六年的高度和周长测量，并在同一个体上连续六个月记录累计乳胶产量，从而深入了解了几个生长性状和早熟乳胶产量的遗传值。生长性状，周长和高度总体上呈正相关，而乳胶产量与生长性状不相关甚至负相关。共鉴定到 86 个不同的 QTL，其中大多数只检测到一个性状。在这些 QTL 中，有 15 个与不止一个表型性状相关（最多同时与 4 个性状相关）。最后一个冬季的乳胶产量和周长增量与鉴定到的最多数量的 QTL 相关（分别为 11 个和 9 个），共同解释了观察到的最大表型方差（分别为 44.1%和 44.4%）。与乳胶产量相关的最重要的 QTL 位于连锁群 16 上，其加性效应来自父本 PB 217，与之前在泰国对 RRIM 600 x PB 217 双亲群体进行的研究中在同一位置检测到的 QTL 相对应。
本研究鉴定到了一组橡胶树的重要 QTL，表明现代亚洲品种的表现仍可提高，并为进一步的标记辅助选择铺平道路，这将加速育种计划。
