背景回顾：Deleterious genetic variation is maintained in populations at low frequencies. Under a model of stabilizing selection, rare (and presumably deleterious) genetic variants are associated with increase or decrease in gene expression from some intermediate optimum. 

主要研究：We investigate this phenomenon in a population of largely O. sativa ssp. indica rice landraces under normal unstressed wet and stressful drought field conditions. 

结果1：We include single nucleotide polymorphisms, insertion/deletion mutations and structural variants in our analysis and find a stronger association between rare variants and gene expression outliers under the stress condition. 

结果2：We also show an association of the strength of this rare variant effect with linkage, gene expression levels, network connectivity, local recombination rate, and fitness consequence scores, consistent with the stabilizing selection model of gene expression.

有害遗传变异在种群中保持在较低的频率。在一个稳定选择模型下，罕见的（可能是有害的）遗传变异与某些处于中间类型最优基因表达的增加或减少有关。作者基于一个籼稻地方品种种群调查了该现象，该种群一半处于正常的非胁迫湿润条件下，另外一半处于干旱胁迫的田间条件下。作者在分析中包含了单核苷酸多态性、插入/缺失突变和结构变异，结果发现在胁迫条件下罕见变异和基因表达异常之间存在更强的关联。作者还发现这种罕见变异效应的强度与连锁、基因表达水平、网络连通性、局部区域重组率以及适应度结果得分之间存在关联，这与基因表达的稳定选择模型一致。

p.s. Stabilizing selection，稳定选择：处于中间类型的性状特征得以保留，而处于两个极端的性状特征更易被淘汰。

** Michael D. Purugganan **