Xu Jiahong, Zhou Mingming, Weng Qijie, Li Mei, Gan Siming
State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China.
Key Laboratory of State Forestry Administration on Tropical Forestry Research, Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou, China.
Front Plant Sci. 2025 Jun 3;16:1553819. doi: 10.3389/fpls.2025.1553819. eCollection 2025.
Clonal testing is crucial for estimating genetic parameters and selecting elite clones. However, few studies have tested clones over two or more rotations. In this study, a clonal trial of the sibs from a × cross was used for genetic parameter analyses and multitrait selection based on traits such as across-rotation growth, wood properties, coppicing ability, and coppice chlorophyll fluorescence. Clonal repeatability ( ) estimates for growth traits in the first rotation ranged from 0.73 (diameter at breast height at age 15) to 0.84 (single-tree volume at age 2.5) and were generally higher than those for growth traits in the second rotation (0.11-0.62). estimates for coppicing and chlorophyll fluorescence traits ranged from 0.35 to 0.57 and 0.03 to 0.53, respectively, indicating low to medium genetic control of these traits. Phenotypic correlations ( ) and additive genetic correlations ( ) were generally high among growth traits within a single rotation and among coppicing traits but varied considerably across other trait pairs. In particular, second-rotation volume at 2.5 years showed a very weak but a moderately positive with early-stage volumes from the first rotation. Multitrait selection index (SI) and multitrait genotype-idiotype distance index (MGIDI) methods were applied at a selection intensity of 15% under four scenarios, each combining two to five traits. Relative genetic gain () and selection efficiency () estimates were positive for all traits included in multitrait selection, indicating the usefulness of all selection scenarios. Compared to SI, the MGIDI method produced slightly lower and values for volumes at ages 8 and 15 years, but higher and values for wood basic density and cellulose content at age 8 in the first rotation. This study has important implications for eucalypt clonal breeding and management.
无性系测试对于估计遗传参数和选择优良无性系至关重要。然而，很少有研究对无性系进行两轮或更多轮的测试。在本研究中，利用一个杂交组合的同胞无性系试验进行遗传参数分析和基于跨轮生长、木材性质、萌蘖能力和萌蘖叶绿素荧光等性状的多性状选择。第一轮生长性状的无性系重复力估计值范围为0.73（15岁时的胸径）至0.84（2.5岁时的单株材积），通常高于第二轮生长性状的重复力估计值（0.11 - 0.62）。萌蘖和叶绿素荧光性状的重复力估计值分别为0.35至0.57和0.03至0.53，表明这些性状的遗传控制程度为低到中等。同一轮内生长性状之间以及萌蘖性状之间的表型相关性和加性遗传相关性通常较高，但在其他性状对之间差异很大。特别是，2.5岁时第二轮的材积与第一轮早期材积之间的表型相关性非常弱，但加性遗传相关性为中等正相关。在四种情况下，以15%的选择强度应用多性状选择指数（SI）和多性状基因型 - 个体型距离指数（MGIDI）方法，每种情况组合两到五个性状。多性状选择中所有包含性状的相对遗传增益和选择效率估计值均为正，表明所有选择方案都是有用的。与SI相比，MGIDI方法在第一轮中8岁和15岁时材积的相对遗传增益和选择效率值略低，但在8岁时木材基本密度和纤维素含量的相对遗传增益和选择效率值较高。本研究对桉树无性系育种和管理具有重要意义。
