Selection-enriched genomic loci (SEGL) reveals genetic loci for environmental adaptation and photosynthetic productivity in Chlamydomonas reinhardtii
Selection-enriched genomic loci (SEGL) reveals genetic loci for environmental adaptation and photosynthetic productivity in Chlamydomonas reinhardtii
复制标题
DOI：
10.1016/j.algal.2022.102709
复制
发表时间：
2022-04-21
影响因子：
5.1
通讯作者：
Kramer，David M.
中科院分区：
文献类型：
--
作者：
Lucker，Ben F.;Temple，Joshua A.;Kramer，David M.
这项工作展示了一种方法，以生产和选择杂交藻株表现出增加光合生产力在多种环境条件下。这同时解决了改善藻类生物能源生产的两个主要障碍：1）产生具有改进性能的新遗传变体;以及2）解开有助于这些改进的遗传和生理因素之间的复杂相互作用。我们合并后代交配产生的两个环境分离株的绿色藻类衣原体reinhardtii和培养池在多种环境条件下。在与生物量生产有关的某些环境下，包括实验室条件以及高氧、波动的光照、高盐度和高温下，来自优胜竞争群体的菌株显示出比亲本系生产力显著增加（在某些情况下超过3倍）。结果表明，C. reinhardtii具有显著的，未开发的，定向进化的能力，可以利用育种和竞争的方法。在多个时间点对群体进行深度测序，以鉴定在群体中积累的“选择富集的基因组位点”（SEGL），从而可能在相应的环境条件下赋予增加的适应性。随着分辨率的提高，SEGL作图可以识别用于目标育种方法的等位基因组合，产生具有多种理想性状的精英藻类品系，以及进一步了解光合生产力的遗传和机制基础。在生物质生产过程中提高藻类的光合效率可能是经济上可持续的藻类生物燃料最关键的障碍。这提出了独特的挑战，因为设计用于增加光合作用的修饰通常会导致适应性降低，这是由于当光合作用未得到充分调节时产生有毒的活性氧。由于光合作用的复杂性质以及遗传、环境和生理因素之间的多方面相互作用，这些问题在自然和户外生产环境下加剧。在这里，我们展示了一种高通量的生物技术筛选方法，同时产生藻类菌株高度增加的自养生产力，并确定有助于这些改进的基因组位点。我们的研究结果表明，衣原体reinhardtii具有高定向进化能力，容易通过育种和选择。
This work demonstrates an approach to produce and select hybrid algal strains exhibiting increased photosynthetic productivity under multiple environmental conditions. This simultaneously addresses two major impediments to improving algal bioenergy production: 1) generating new genetic variants with improved performance; and 2) disentangling complex interactions between genetic and physiological factors contributing to these improvements. We pooled progeny generated from mating two environmental isolates of the green algaChlamydomonas reinhardtiiand cultured the pools under multiple environmental conditions. Strains from the outcompeting populations showed substantial (in some cases over 3 fold) increases in productivity over the parental lines under certain environments related to biomass production, including laboratory conditions as well as hyperoxia, fluctuating light, high salinity and high temperature. The results indicate thatC. reinhardtiihas remarkable, untapped, directed evolution capacity that may be harnessed using breeding and competition approaches. The populations were deep sequenced at multiple time points to identify “Selection-Enriched Genomic Loci” (SEGL) that accumulated in the populations, and thus likely confer increased fitness under the respective environmental conditions. With improved resolution, SEGL mapping can identify allelic combinations used for targeted breeding approaches, generating elite algal lines with multiple desirable traits, as well as to further understand the genetic and mechanistic bases of photosynthetic productivity.Increasing the photosynthetic efficiency of algae during biomass production is perhaps the most critical hurdle for economically sustainable algal based biofuels. This presents unique challenges because modifications designed to increase photosynthesis often result in decreased fitness, due to production of toxic reactive oxygen species when photosynthesis is not adequately regulated. These problems are exacerbated under natural and outdoor production environments because of the complex nature of photosynthesis and the multifaceted interactions between genetic, environmental and physiological factors. Here, we demonstrate a high throughput biotechnological screening approach that simultaneously produces algal strains with highly increased autotrophic productivity and identifies genomic loci contributing to these improvements. Our results demonstrate thatChlamydomonas reinhardtiiexhibits high directed evolutionary capacity readily accessed through breeding and selection.