Evolutionary significance of imbalanced nuclear ratios within heterokaryons of the basidiomycete fungus Heterobasidion parviporum
Evolutionary significance of imbalanced nuclear ratios within heterokaryons of the basidiomycete fungus Heterobasidion parviporum
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DOI：
10.1111/j.1558-5646.2008.00462.x
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发表时间：
2008-09-01
期刊：
影响因子：
3.3
通讯作者：
Johannesson, Hanna
中科院分区：
文献类型：
--
作者：
James, Timothy Y.;Stenlid, Jan;Johannesson, Hanna
许多真菌具有异源性的生命阶段，其中遗传上不同的细胞核居住在同一个细胞中。在担子菌中，异核体是交配的产物，代表了一个与二倍体叶状体非常相似的基因组联合，但未融合的核的维持表明两个基因组相对于二倍体的更复杂的关联。在每个异源细胞具有可变数目的核的物种中，由于核竞争，菌丝体内的核比率可能变得不平衡（不同于1：1）。本研究以异担子（Heterobasidion parviporum）为材料，探讨营养菌丝核比例与基因型及环境的关系。数据显示，核比率经常不平衡，一般稳定，随着时间的推移，和遗传决定。核比受环境的影响，但观察到的核比并不遵循预期的强选择作用于一个人口的核。相反，这些比率主要是由遗传效应和表观遗传效应驱动的。最后，数据表明，核比例失衡也影响基因转录和生长速率，这意味着异源担子菌在功能上不等同于二倍体个体，并具有更高的基因型和表型变异的潜力。
Many fungi have heterokaryotic life stages in which genetically different nuclei inhabit the same cell. In basidiomycetes, the heterokaryon is the product of mating and represents a genomic union very similar to a diploid thallus, yet the maintenance of unfused nuclei suggests a more complex association of the two genomes relative to diploidy. In species with variable numbers of nuclei per heterokaryotic cell, nuclear ratios within a mycelium may possibly become imbalanced (differ from 1:1) due to nuclear competition. In this study, heterokaryons of the basidiomycete Heterobasidion parviporum were examined to determine the effects of genotype and environment on nuclear ratios within vegetative mycelia. The data reveal that nuclear ratios are frequently imbalanced, generally stable over time, and genetically determined. The nuclear ratios were affected by environment, but the observed nuclear ratios did not follow the expectations of strong selection acting on a population of nuclei. Instead, these ratios were largely driven by genetic effects and epigenetic effects. Finally, the data suggest that nuclear ratio imbalance also affects both gene transcription and growth rate, implying that heterokaryotic basidiomycetes are not functionally equivalent to diploid individuals and have a higher potential for genotypic and phenotypic variation.