The architecture of intra-organism mutation rate variation in plants
The architecture of intra-organism mutation rate variation in plants
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植物体内突变率变异的结构
DOI：
10.1371/journal.pbio.3000191
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发表时间：
2019-04-01
期刊：
影响因子：
9.8
通讯作者：
Tian, Dacheng
中科院分区：
文献类型：
--
作者：
Wang, Long;Ji, Yilun;Tian, Dacheng
考虑到体细胞组织的可处置性，选择可能有利于早期分离体细胞比种系细胞具有更高的突变率，正如在一些动物中所看到的那样。尽管在植物中，生物体内部的突变率异质性很难解决，但相同的选择论逻辑可以预测芽中的突变率低于根中的突变率，以及寿命较长的末端组织（例如叶）中的突变率低于个体发育相似的短寿命组织（例如花瓣）中的突变率，并且突变率异质性应该是确定性的，生物重复之间没有显着差异。为了满足这些期望，我们对来自 8 个植物物种的不同组织的 754 个基因组进行了测序。与选择论模型一致，在多年生植物中，茎尖分生组织中单位时间的突变积累率低于根尖组织中的突变积累率，其中茎中的大部分突变本身是可传播的，但一年生植物则不然，其中体细胞突变往往是不可传播的。类似地，同一植物的叶子中积累的突变数量通常低于花瓣中的突变数量，并且复制分支之间的积累率的异质性并不比偶然预期的多。我们认为，草莓匍匐茎中的高突变积累是证明这一规则的例外，因为突变传播模式表明，匍匐茎的种系受到限制。然而，我们还发现体外愈伤组织比野生生长的比较组织具有更高的突变率（每单位时间），表明非适应性突变“脆弱性”。由于突变脆弱性不能明显解释为什么茎-根差异随植物寿命而变化，因此我们得出结论，组织之间的某些突变率变化与选择论一致，但应考虑突变脆弱性的机制无效。
Given the disposability of somatic tissue, selection can favor a higher mutation rate in the early segregating soma than in germline, as seen in some animals. Although in plants intra-organismic mutation rate heterogeneity is poorly resolved, the same selectionist logic can predict a lower rate in shoot than in root and in longer-lived terminal tissues (e.g., leaves) than in ontogenetically similar short-lived ones (e.g., petals), and that mutation rate heterogeneity should be deterministic with no significant differences between biological replicates. To address these expectations, we sequenced 754 genomes from various tissues of eight plant species. Consistent with a selectionist model, the rate of mutation accumulation per unit time in shoot apical meristem is lower than that in root apical tissues in perennials, in which a high proportion of mutations in shoots are themselves transmissible, but not in annuals, in which somatic mutations tend not to be transmissible. Similarly, the number of mutations accumulated in leaves is commonly lower than that within a petal of the same plant, and there is no more heterogeneity in accumulation rates between replicate branches than expected by chance. High mutation accumulation in runners of strawberry is, we argue, the exception that proves the rule, as mutation transmission patterns indicate that runner has a restricted germline. However, we also find that in vitro callus tissue has a higher mutation rate (per unit time) than the wild-grown comparator, suggesting nonadaptive mutational “fragility”. As mutational fragility does not obviously explain why the shoot—root difference varies with plant longevity, we conclude that some mutation rate variation between tissues is consistent with selectionist theory but that a mechanistic null of mutational fragility should be considered.