Root system adaptations represent untapped opportunities for forest tree seedling improvement
Root system adaptations represent untapped opportunities for forest tree seedling improvement
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DOI：
10.1007/s11056-022-09917-x
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发表时间：
2022-04
期刊：
影响因子：
2.2
通讯作者：
E. Moler;Andrei Toca;D. Jacobs;A. Nelson
中科院分区：
文献类型：
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作者：
E. Moler;Andrei Toca;D. Jacobs;A. Nelson
我们回顾了结合遗传和文化工具的方法，以解决与改善树苗根系以提高生存和生长相关的挑战。关于根性状变异来源、根性状与幼苗生长和存活之间的关系以及已发表研究的根性状遗传力估计的文献被用来说明结合多种方法来提高树苗改良计划效率的效用。我们发现：（1）证据表明许多根性状存在遗传变异，（2）根性状平均具有中等遗传力，（3）证据支持利用母体效应至少暂时改变根性状的可能性。在11项研究的8个根性状中，根直径、根数、根生物量、根茎干生物量之比和预计根面积的中位家族狭义遗传力估计值（h2）为中等（0.25≤h2≤0.50），根长度、比根长度和地下总干生物量比为低（h2< 0.25）。本次综述的结果表明，可以优化植物改良管道，以利用遗传、母体效应和苗圃文化制度造成的根性状变异。然而，文献中出现的以下相关空白成为了进展的根本障碍：根系对应激调理处理的反应持续时间是多长？哪些根性状与幼苗存活最相关，因此应优先改进？是否有可能可靠地利用母体效应导致的根性状变异？
We reviewed approaches for combining genetic and cultural tools to solve challenges associated with the improvement of tree seedling root systems for enhanced survival and growth. Literature regarding sources of variation in root traits, relationships between root traits and seedling growth and survival, and root trait heritability estimates from published studies were used to illustrate the utility of combining myriad approaches to enhance the efficiency of tree seedling improvement programs. We found that: (1) evidence exists for genetic variation in numerous root traits, (2) root traits tend to have intermediate heritability on average, and (3) evidence supports the possibility of harnessing maternal effects to modify root traits at least temporarily. Across eight root traits from 11 studies, median family narrow-sense heritability estimates (h2) were intermediate (0.25 ≤h2≤ 0.50) for root diameter, root count, root biomass, the ratio of root-to-stem dry biomass, and projected root area, and low (h2< 0.25) for root length, specific root length, and the ratio of total belowground-to-aboveground dry biomass. Findings from this review suggest that plant improvement pipelines can be optimized to harness root trait variation due to genetics, maternal effects, and nursery cultural regimes. However, the following related gaps in the literature emerged as fundamental obstacles to progress: What is the duration of root system responses to stress conditioning treatments? Which root traits correlate best with seedling survival and thus should be prioritized for improvement? Is it possible to reliably harness variation in root traits resulting from maternal effects?