Data from: Gene expression differs in codominant prairie grasses under drought

Grasslands of the Central US are expected to experience severe droughts
and other climate extremes in the future, yet we know little about how
these grasses will respond in terms of gene expression. We compared gene
expression in Andropogon gerardii and Sorghastrum nutans, two closely
related co-dominant C4 grasses responsible for the majority of ecosystem
function, using RNA-seq. We compared Trinity assemblies within
each species to determine annotated functions of transcripts responding to
drought. Subsequently, we compared homologous annotated gene-groups across
the two species using cross-species meta-level analysis and functional
clustering based on key terms. The majority of variation was found between
species, as opposed to between drought and watered treatments. However,
there is evidence for differential responses; Andropogon allocated gene
expression differently compared to Sorghastrum, suggesting Andropogon
focuses on stress alleviation (such as oxygen radical scavenging) rather
than prevention. In contrast, Sorghastrum may employ a drought
avoidance strategy by modulating osmotic response, especially with
hormonal regulation. We found Sorghastrum tended to be more sensitive
within 10 key gene-groups related to stress, abscisic acid, and trichomes,
suggesting gene expression may mechanistically parallel sensitivity at the
physiological level. Our findings corroborate phenotypic and physiological
differences in the field and may help explain the phenotypic mechanisms of
these two species in the tallgrass prairie community under future drought
scenarios.

美国中部草原未来预计将经历严重干旱及其他气候极端事件，但我们对这些草本植物在基因表达层面的响应机制知之甚少。我们采用RNA测序（RNA-seq）技术，比较了须芒草（Andropogon gerardii）和黄假高粱（Sorghastrum nutans）这两种亲缘关系密切、共占优势的C4草本植物的基因表达模式；二者是该区域生态系统功能的主要贡献者。通过比较每个物种内部的Trinity组装结果，我们确定了响应干旱的转录本的注释功能。随后，我们利用跨物种元水平分析及基于关键术语的功能聚类，对两个物种间的同源注释基因群进行了比较。研究发现，大部分变异存在于物种间，而非干旱与水分充足处理组之间。然而，存在差异响应的证据：须芒草的基因表达分配模式与黄假高粱不同，表明须芒草更侧重于胁迫缓解（如氧自由基清除）而非预防。相比之下，黄假高粱可能通过调节渗透响应（尤其是激素调控）来采用干旱规避策略。我们发现，在与胁迫、脱落酸及毛状体相关的10个关键基因群中，黄假高粱表现出更高的敏感性，这表明基因表达在机制上可能与生理层面的敏感性平行。我们的研究结果验证了野外观察到的表型及生理差异，并可能有助于解释未来干旱情景下这两种物种在高草草原群落中的表型机制。