Scavuzzo-Duggan Tess, Varoquaux Nelle, Madera Mary, Vogel John P, Dahlberg Jeffery, Hutmacher Robert, Belcher Michael, Ortega Jasmine, Coleman-Derr Devin, Lemaux Peggy, Purdom Elizabeth, Scheller Henrik V
Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, United States.
Joint BioEnergy Institute, Emeryville, CA, United States.
Front Plant Sci. 2021 Nov 12;12:747225. doi: 10.3389/fpls.2021.747225. eCollection 2021.
Renewable fuels are needed to replace fossil fuels in the immediate future. Lignocellulosic bioenergy crops provide a renewable alternative that sequesters atmospheric carbon. To prevent displacement of food crops, it would be advantageous to grow biofuel crops on marginal lands. These lands will likely face more frequent and extreme drought conditions than conventional agricultural land, so it is crucial to see how proposed bioenergy crops fare under these conditions and how that may affect lignocellulosic biomass composition and saccharification properties. We found that while drought impacts the plant cell wall of differently according to tissue and timing of drought induction, drought-induced cell wall compositional modifications are relatively minor and produce no negative effect on biomass conversion. This contrasts with the cell wall-related transcriptome, which had a varied range of highly variable genes (HVGs) within four cell wall-related GO categories, depending on the tissues surveyed and time of drought induction. Further, many HVGs had expression changes in which putative impacts were not seen in the physical cell wall or which were in opposition to their putative impacts. Interestingly, most pre-flowering drought-induced cell wall changes occurred in the leaf, with matrix and lignin compositional changes that did not persist after recovery from drought. Most measurable physical post-flowering cell wall changes occurred in the root, affecting mainly polysaccharide composition and cross-linking. This study couples transcriptomics to cell wall chemical analyses of a C4 grass experiencing progressive and differing drought stresses in the field. As such, we can analyze the cell wall-specific response to agriculturally relevant drought stresses on the transcriptomic level and see whether those changes translate to compositional or biomass conversion differences. Our results bolster the conclusion that drought stress does not substantially affect the cell wall composition of specific aerial and subterranean biomass nor impede enzymatic hydrolysis of leaf biomass, a positive result for biorefinery processes. Coupled with previously reported results on the root microbiome and rhizosphere and whole transcriptome analyses of this study, we can formulate and test hypotheses on individual gene candidates' function in mediating drought stress in the grass cell wall, as demonstrated in sorghum.
在不久的将来，需要可再生燃料来替代化石燃料。木质纤维素生物能源作物提供了一种可替代的可再生能源，能够封存大气中的碳。为防止粮食作物被替代，在边际土地上种植生物燃料作物将是有利的。与传统农田相比，这些土地可能面临更频繁和极端的干旱条件，因此了解拟种植的生物能源作物在这些条件下的表现以及这可能如何影响木质纤维素生物质的组成和糖化特性至关重要。我们发现，虽然干旱根据干旱诱导的组织和时间对植物细胞壁有不同影响，但干旱诱导的细胞壁组成变化相对较小，且对生物质转化没有负面影响。这与细胞壁相关的转录组形成对比，在四个与细胞壁相关的基因本体类别中，根据所调查的组织和干旱诱导时间，有一系列高度可变的基因（HVG）。此外，许多HVG的表达发生了变化，其假定的影响在物理细胞壁中未观察到，或者与它们的假定影响相反。有趣的是，大多数开花前干旱诱导的细胞壁变化发生在叶片中，基质和木质素组成的变化在干旱恢复后并未持续。大多数开花后可测量的物理细胞壁变化发生在根部，主要影响多糖组成和交联。本研究将转录组学与在田间经历渐进和不同干旱胁迫的C4禾本科植物的细胞壁化学分析相结合。因此，我们可以在转录组水平上分析对农业相关干旱胁迫的细胞壁特异性反应，并查看这些变化是否转化为组成或生物质转化差异。我们的结果支持了这样的结论，即干旱胁迫不会实质性影响特定地上和地下生物质的细胞壁组成，也不会阻碍叶片生物质的酶水解，这对生物精炼过程来说是一个积极的结果。结合本研究先前报道的关于根微生物组、根际和全转录组分析的结果，我们可以制定并测试关于单个基因候选物在介导禾本科植物细胞壁干旱胁迫中功能的假设，正如在高粱中所证明的那样。
