Pereira Allan Silva, de Almeida Alex-Alan Furtado, Branco Márcia Christina da Silva, Costa Marcio Gilberto Cardoso, Ahnert Dario
Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Campus Soane Nazaré de Andrade, Rod. Jorge Amado, Ilhéus, BA, Brasil.
Centro de Pesquisas do Cacau, Comissão Executiva do Plano da Lavoura Cacaueira (CEPEC/CEPLAC). Rod. Jorge Amado, Ilhéus, BA, Brasil.
PLoS One. 2017 Jun 19;12(6):e0178790. doi: 10.1371/journal.pone.0178790. eCollection 2017.
Selecting parents and evaluating progenies is a very important step in breeding programs and involves approaches such as understanding the initial stages of growth and characterizing the variability among genotypes for different parameters, such as physiological, growth, biomass partitioning and nutrient translocation to the aerial part. In these cases, facilitating tools can be used to understand the involved gene dynamics, such as diallel crosses and genetic and phenotypic correlations. Our main hypothesis is that the contrasting phenotypes of these parental genotypes of cocoa used are due to genetic factors, and progenies derived from crosses of these parental genotypes are useful for breeding programs related to plant architecture, physiological parameters and translocation of mineral nutrients. We aimed to evaluate the combining abilities in progenies of cacao (Theobroma cacao L) originating from contrasting parents for canopy vigor. Emphasis was given to the evaluation of morphological and physiological parameters and the phenotypic and genotypic correlations to understand the dynamics of the action of the genes involved, as well as in expression profile from genes of gibberellins biosynthesis pathway in the parents. Fifteen F1 progenies were obtained from crosses of six clones (IMC 67, P4B, PUCALA, SCA 6, SCA 24 and SJ 02) that were evaluated in a randomized complete block design with four replicates of 12 plants per progeny, in a balanced half table diallel scheme. It is possible to identify and select plants and progenies of low, medium and high height, as there is expressive genetic variability for the evaluated parameters, some of these on higher additive effects, others on larger nonadditive effects and others under a balance of these effects. Most physiological parameters evaluated show that for selection of plants with the desired performance, no complex breeding methods would be necessary due to the high and medium heritability observed. Strong genetic components were observed from many of the correlations, which indicate the possibility to formulate selection indices for multi-traits, such as dwarfism or semidwarfism, tolerance to increase of leaf sodium concentrations and maintenance of the photosynthetic apparatus integrity under these conditions. Additionally, plants with higher carbon fixation, better water use, higher carboxylation efficiency and greater magnesium accumulation in leaves can be selected.
选择亲本并评估子代是育种计划中非常重要的一步，涉及多种方法，如了解生长的初始阶段以及表征不同参数（如生理、生长、生物量分配和向地上部分的养分转运）在基因型间的变异性。在这些情况下，可使用辅助工具来理解相关的基因动态，如双列杂交以及遗传和表型相关性。我们的主要假设是，所使用的这些可可亲本基因型的对比表型是由遗传因素导致的，并且这些亲本基因型杂交产生的子代对于与植株形态、生理参数和矿质养分转运相关的育种计划是有用的。我们旨在评估源自对比亲本的可可（Theobroma cacao L）子代在树冠活力方面的配合力。重点在于评估形态和生理参数以及表型和基因型相关性，以了解所涉及基因的作用动态，以及亲本中赤霉素生物合成途径基因的表达谱。通过六个克隆（IMC 67、P4B、PUCALA、SCA 6、SCA 24和SJ 02）杂交获得了15个F1子代，这些子代按照平衡半双列杂交设计，以随机完全区组设计进行评估，每个子代有4次重复，每次重复12株植物。由于所评估参数存在显著的遗传变异性，其中一些具有较高的加性效应，另一些具有较大的非加性效应，还有一些处于这些效应的平衡状态，因此有可能识别和选择矮、中、高不同高度的植株和子代。大多数评估的生理参数表明，由于观察到的高和中度遗传力，对于选择具有所需性能的植株，无需复杂的育种方法。从许多相关性中观察到了强大的遗传成分，这表明有可能制定多性状选择指数，如矮化或半矮化、对叶片钠浓度增加的耐受性以及在这些条件下维持光合器官完整性。此外，可以选择具有更高碳固定、更好水分利用、更高羧化效率以及叶片中更多镁积累的植株。
