Abstract：
BACKGROUND: Species of the carnivorous family Lentibulariaceae exhibit the smallest genomes in flowering plants. We explored the hypothesis that their minute genomes result from the unique mitochondrial cytochrome c oxidase (COX) mutation. The mutation may boost mitochondrial efficiency, which is especially useful for suction-bladder traps of Utricularia, but also increase DNA-damaging reactive oxygen species, leading to genome shrinkage through deletion-biased DNA repair. We aimed to explore this mutation\'s impact on genome size, providing insights into genetic mutation roles in plant genome evolution under environmental pressures.
METHODS: We compiled and measured genome and mean chromosome sizes for 127 and 67 species, respectively, representing all three genera (Genlisea, Pinguicula, and Utricularia) of Lentibulariaceae. We also isolated and analyzed COX sequences to detect the mutation. Through phylogenetic regressions and Ornstein-Uhlenbeck models of trait evolution, we assessed the impact of the COX mutation on the genome and chromosome sizes across the family.
RESULTS: Our findings reveal significant correlations between the COX mutations and smaller genome and chromosome sizes. Specifically, species carrying the ancestral COX sequence exhibited larger genomes and chromosomes than those with the mutation. This evidence supports the notion that the COX mutation contributes to genome downsizing, with statistical analyses confirming a directional evolution towards smaller genomes in species harboring these mutations.
CONCLUSIONS: Our study confirms that the COX mutation in Lentibulariaceae is associated with genome downsizing, likely driven by increased reactive oxygen species production and subsequent DNA damage requiring deletion-biased repair mechanisms. While boosting mitochondrial energy output, this genetic mutation compromises genome integrity and may potentially affect recombination rates, illustrating a complex trade-off between evolutionary advantages and disadvantages. Our results highlight the intricate processes by which genetic mutations and environmental pressures shape genome size evolution in carnivorous plants.
METHODS: We compiled and measured genome and mean chromosome sizes for 127 and 67 species, respectively, representing all three genera (Genlisea, Pinguicula, and Utricularia) of Lentibulariaceae. We also isolated and analyzed COX sequences to detect the mutation. Through phylogenetic regressions and Ornstein-Uhlenbeck models of trait evolution, we assessed the impact of the COX mutation on the genome and chromosome sizes across the family.
RESULTS: Our findings reveal significant correlations between the COX mutations and smaller genome and chromosome sizes. Specifically, species carrying the ancestral COX sequence exhibited larger genomes and chromosomes than those with the mutation. This evidence supports the notion that the COX mutation contributes to genome downsizing, with statistical analyses confirming a directional evolution towards smaller genomes in species harboring these mutations.
CONCLUSIONS: Our study confirms that the COX mutation in Lentibulariaceae is associated with genome downsizing, likely driven by increased reactive oxygen species production and subsequent DNA damage requiring deletion-biased repair mechanisms. While boosting mitochondrial energy output, this genetic mutation compromises genome integrity and may potentially affect recombination rates, illustrating a complex trade-off between evolutionary advantages and disadvantages. Our results highlight the intricate processes by which genetic mutations and environmental pressures shape genome size evolution in carnivorous plants.
摘要：
背景：食肉科的种类在开花植物中表现出最小的基因组。我们探索了以下假设：它们的微小基因组是由独特的线粒体细胞色素c氧化酶（COX）突变引起的。突变可能会提高线粒体效率，这是特别有用的吸引膀胱的陷阱，而且还会增加破坏DNA的活性氧，通过缺失偏倚的DNA修复导致基因组收缩。我们旨在探索这种突变对基因组大小的影响，提供对环境压力下植物基因组进化中基因突变作用的见解。
方法：我们汇编并测量了127和67个物种的基因组和平均染色体大小，分别,代表所有三个属(Genlisea，腹股沟,和乌贼科）。我们还分离和分析COX序列以检测突变。通过系统发育回归和性状进化的Ornstein-Uhlenbeck模型，我们评估了COX突变对整个家族基因组和染色体大小的影响.
结果：我们的发现揭示了COX突变与较小的基因组和染色体大小之间的显著相关性。具体来说,携带祖先COX序列的物种比具有突变的物种表现出更大的基因组和染色体。这个证据支持COX突变有助于基因组缩小的观点，统计分析证实，在有这些突变的物种中，向较小的基因组方向进化。
结论：我们的研究证实，在龙舌兰科的COX突变与基因组缩小有关，可能是由活性氧产生增加和随后的DNA损伤驱动的，需要缺失偏倚的修复机制。在增加线粒体能量输出的同时，这种基因突变损害了基因组的完整性，并可能影响重组率，说明了进化利弊之间的复杂权衡。我们的结果强调了复杂的过程，基因突变和环境压力通过这些过程塑造了食肉植物的基因组大小进化。
方法：我们汇编并测量了127和67个物种的基因组和平均染色体大小，分别,代表所有三个属(Genlisea，腹股沟,和乌贼科）。我们还分离和分析COX序列以检测突变。通过系统发育回归和性状进化的Ornstein-Uhlenbeck模型，我们评估了COX突变对整个家族基因组和染色体大小的影响.
结果：我们的发现揭示了COX突变与较小的基因组和染色体大小之间的显著相关性。具体来说,携带祖先COX序列的物种比具有突变的物种表现出更大的基因组和染色体。这个证据支持COX突变有助于基因组缩小的观点，统计分析证实，在有这些突变的物种中，向较小的基因组方向进化。
结论：我们的研究证实，在龙舌兰科的COX突变与基因组缩小有关，可能是由活性氧产生增加和随后的DNA损伤驱动的，需要缺失偏倚的修复机制。在增加线粒体能量输出的同时，这种基因突变损害了基因组的完整性，并可能影响重组率，说明了进化利弊之间的复杂权衡。我们的结果强调了复杂的过程，基因突变和环境压力通过这些过程塑造了食肉植物的基因组大小进化。
