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Abstract：
Robustness is the reproducible development of a phenotype despite stochastic noise. It often involves tradeoffs with other performance metrics, but the mechanisms underlying such tradeoffs were largely unknown. An Arabidopsis flower robustly develops four sepals from four precisely positioned auxin maxima. The development related myb-like 1 (drmy1) mutant generates noise in auxin signaling that disrupts robustness in sepal initiation. Here, we find that increased expression of CUP-SHAPED COTYLEDON1 (CUC1), a boundary specification transcription factor, in drmy1 underlies this loss of robustness. CUC1 surrounds and amplifies stochastic auxin noise in drmy1 to form variably positioned auxin maxima and sepal primordia. Removing CUC1 from drmy1 provides time for noisy auxin signaling to resolve into four precisely positioned auxin maxima, restoring robust sepal initiation. However, removing CUC1 decreases the intensity of auxin maxima and slows down sepal initiation. Thus, CUC1 increases morphogenesis speed but impairs robustness against auxin noise. Further, using a computational model, we find that the observed phenotype can be explained by the effect of CUC1 in repolarizing PIN FORMED1 (PIN1), a polar auxin transporter. Lastly, our model predicts that reducing global growth rate improves developmental robustness, which we validate experimentally. Thus, our study illustrates a tradeoff between speed and robustness during development.
摘要：
稳健性是尽管有随机噪声但表型的可再现发展。它通常涉及与其他性能指标的权衡，但是这种权衡背后的机制在很大程度上是未知的。拟南芥花从四个精确定位的生长素最大值中强劲地发育出四个萼片。发育相关的myb样1（drmy1）突变体在生长素信号中产生噪声，破坏了萼片启动的鲁棒性。这里,我们发现CUP型COTYLEDON1（CUC1）的表达增加，边界规范转录因子，在drmy1中失去了这种鲁棒性。CUC1包围并放大drmy1中的随机生长素噪声，以形成不同位置的生长素最大值和萼片原基。从drmy1中删除CUC1为嘈杂的生长素信号提供了解析为四个精确定位的生长素最大值的时间，恢复健壮的萼片启动。然而,去除CUC1会降低生长素最大值的强度，并减慢萼片的启动。因此，CUC1增加了形态发生速度，但削弱了对生长素噪声的鲁棒性。Further,使用计算模型，我们发现观察到的表型可以通过CUC1在复极化PINFORMED1（PIN1）中的作用来解释，极地生长素运输机。最后,我们的模型预测，降低全球增长率会提高发展稳健性，我们通过实验验证了这一点。因此，我们的研究说明了开发过程中速度和鲁棒性之间的权衡。
