Conson André R O, Taniguti Cristiane H, Amadeu Rodrigo R, Andreotti Isabela A A, de Souza Livia M, Dos Santos Luciano H B, Rosa João R B F, Mantello Camila C, da Silva Carla C, José Scaloppi Junior Erivaldo, Ribeiro Rafael V, Le Guen Vincent, Garcia Antonio A F, Gonçalves Paulo de Souza, de Souza Anete P
Molecular Biology and Genetic Engineering Center, University of Campinas, Campinas, Brazil.
Department of Genetics, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil.
Front Plant Sci. 2018 Aug 24;9:1255. doi: 10.3389/fpls.2018.01255. eCollection 2018.
Rubber tree () cultivation is the main source of natural rubber worldwide and has been extended to areas with suboptimal climates and lengthy drought periods; this transition affects growth and latex production. High-density genetic maps with reliable markers support precise mapping of quantitative trait loci (QTL), which can help reveal the complex genome of the species, provide tools to enhance molecular breeding, and shorten the breeding cycle. In this study, QTL mapping of the stem diameter, tree height, and number of whorls was performed for a full-sibling population derived from a GT1 and RRIM701 cross. A total of 225 simple sequence repeats (SSRs) and 186 single-nucleotide polymorphism (SNP) markers were used to construct a base map with 18 linkage groups and to anchor 671 SNPs from genotyping by sequencing (GBS) to produce a very dense linkage map with small intervals between loci. The final map was composed of 1,079 markers, spanned 3,779.7 cM with an average marker density of 3.5 cM, and showed collinearity between markers from previous studies. Significant variation in phenotypic characteristics was found over a 59-month evaluation period with a total of 38 QTLs being identified through a composite interval mapping method. Linkage group 4 showed the greatest number of QTLs (7), with phenotypic explained values varying from 7.67 to 14.07%. Additionally, we estimated segregation patterns, dominance, and additive effects for each QTL. A total of 53 significant effects for stem diameter were observed, and these effects were mostly related to additivity in the GT1 clone. Associating accurate genome assemblies and genetic maps represents a promising strategy for identifying the genetic basis of phenotypic traits in rubber trees. Then, further research can benefit from the QTLs identified herein, providing a better understanding of the key determinant genes associated with growth of under limiting water conditions.
橡胶树（）种植是全球天然橡胶的主要来源，并且已扩展到气候条件欠佳和干旱期较长的地区；这种转变会影响橡胶树的生长和乳胶产量。具有可靠标记的高密度遗传图谱有助于对数量性状基因座（QTL）进行精确作图，这有助于揭示该物种复杂的基因组，提供增强分子育种的工具，并缩短育种周期。在本研究中，对由GT1和RRIM701杂交产生的全同胞群体进行了茎直径、树高和轮数的QTL作图。总共使用了225个简单序列重复（SSR）和186个单核苷酸多态性（SNP）标记构建了一个具有18个连锁群的基础图谱，并通过测序基因分型（GBS）将671个SNP锚定，以产生一个位点间间隔很小的非常密集的连锁图谱。最终图谱由1079个标记组成，跨度为3779.7 cM，平均标记密度为3.5 cM，并且显示出与先前研究中的标记具有共线性。在为期59个月的评估期内发现表型特征存在显著差异，通过复合区间作图法共鉴定出38个QTL。连锁群4显示的QTL数量最多（7个），表型解释值在7.67%至14.07%之间。此外，我们估计了每个QTL的分离模式、显性和加性效应。总共观察到53个对茎直径有显著影响的效应，这些效应大多与GT1克隆中的加性有关。将准确的基因组组装与遗传图谱相结合是确定橡胶树表型性状遗传基础的一种有前景的策略。然后，进一步的研究可以受益于本文鉴定出的QTL，从而更好地理解与水分受限条件下橡胶树生长相关的关键决定基因。
