Modulation of R-gene expression across environments.
Modulation of R-gene expression across environments.
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DOI：
10.1093/jxb/erv530
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发表时间：
2016-03
影响因子：
6.9
通讯作者：
Bergelson J
中科院分区：
文献类型：
--
作者：
MacQueen A;Bergelson J
r -基因表达强烈影响植物适应性和生物抗性，且随短期和历史环境的变化而显著变化，其模式与转录组不同，与选择驱动r -基因表达变化一致。有些环境比其他环境更有利于病原体的生长，因此，当病原体生长有利时，植物可能会在抗性方面投入更多。拟南芥抗性（R-）基因在不同环境下的基础表达差异较大。对r基因表达变化进行表征，探讨r基因表达是否在有利于病原体增殖的环境中上调，而在感染风险较低的环境中下调；如果在没有疾病的情况下，r基因的表达成本会对植物适应性产生负面影响，那么就会出现下调。采用定量逆转录- pcr方法对12份拟南芥材料8种环境条件下13个r基因位点的表达量进行了定量分析，发现环境对r基因表达的影响较大。令人惊讶的是，几乎环境的每一个变化——无论是生物还是非生物条件的变化——都会导致r基因表达的增加，这种反应与平均转录组反应和其他应激反应基因的反应不同。这些表达的变化是功能性的，因为感染前的环境变化影响了对丁香假单胞菌分离株的特定疾病抗性水平。此外，r基因的基础表达具有较强的纬度梯度，而r基因的表达可塑性则与干旱和高温相关。这些结果表明，不同环境中r基因表达的变化可能是由自然选择形成的，以降低r基因在宽松或可预测环境中表达的适应成本。
R-gene expression strongly affects plant fitness and biotic resistance and varies significantly, with short-term and historic environment in patterns distinct from the transcriptome, consistent with selection driving R-gene expression variation. Some environments are more conducive to pathogen growth than others, and, as a consequence, plants might be expected to invest more in resistance when pathogen growth is favored. Resistance (R-) genes in Arabidopsis thaliana have unusually extensive variation in basal expression when comparing the same R-gene among accessions collected from different environments. R-gene expression variation was characterized to explore whether R-gene expression is up-regulated in environments favoring pathogen proliferation and down-regulated when risks of infection are low; down-regulation would follow if costs of R-gene expression negatively impact plant fitness in the absence of disease. Quantitative reverse transcription–PCR was used to quantify the expression of 13 R-gene loci in plants grown in eight environmental conditions for each of 12 A. thaliana accessions, and large effects of the environment on R-gene expression were found. Surprisingly, almost every change in the environment—be it a change in biotic or abiotic conditions—led to an increase in R-gene expression, a response that was distinct from the average transcriptome response and from that of other stress response genes. These changes in expression are functional in that environmental change prior to infection affected levels of specific disease resistance to isolates of Pseudomonas syringae. In addition, there are strong latitudinal clines in basal R-gene expression and clines in R-gene expression plasticity correlated with drought and high temperatures. These results suggest that variation in R-gene expression across environments may be shaped by natural selection to reduce fitness costs of R-gene expression in permissive or predictable environments.