El Hage Fadi, Virlouvet Laetitia, Lopez-Marnet Paul-Louis, Griveau Yves, Jacquemot Marie-Pierre, Coursol Sylvie, Méchin Valérie, Reymond Matthieu
Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France.
Ecole Doctorale n° 567: Science du Végétal: Du gène à l'écosystème, Université Paris-Saclay, Orsay, France.
Front Plant Sci. 2021 Feb 26;12:628960. doi: 10.3389/fpls.2021.628960. eCollection 2021.
Maize feeding value is strongly linked to plant digestibility. Cell wall composition and structure can partly explain cell wall digestibility variations, and we recently showed that tissue lignification and lignin spatial distribution also contribute to cell wall digestibility variations. Although the genetic determinism of digestibility and cell wall composition has been studied for more than 20 years, little is available concerning that of tissue lignification. Moreover, maize yield is negatively impacted by water deficit, and we newly highlighted the impact of water deficit on cell wall digestibility and composition together with tissue lignification. Consequently, the aim of this study was to explore the genetic mechanisms of lignin distribution in link with cell wall composition and digestibility under contrasted water regimes. Maize internodes from a recombinant inbred line (RIL) population grown in field trials with contrasting irrigation scenarios were biochemically and histologically quantified. Results obtained showed that biochemical and histological traits have different response thresholds to water deficit. Histological profiles were therefore only modified under pronounced water deficit, while most of the biochemical traits responded whatever the strength of the water deficit. Three main clusters of quantitative trait locus (QTL) for histological traits were detected. Interestingly, overlap between the biochemical and histological clusters is rare, and one noted especially colocalizations between histological QTL/clusters and QTL for -coumaric acid content. These findings reinforce the suspected role of tissue p-coumaroylation for both the agronomic properties of plants as well as their digestibility.
玉米的饲用价值与植株的消化率密切相关。细胞壁的组成和结构可以部分解释细胞壁消化率的差异，并且我们最近发现组织木质化和木质素的空间分布也会导致细胞壁消化率的差异。尽管对消化率和细胞壁组成的遗传决定因素已经研究了20多年，但关于组织木质化的研究却很少。此外，水分亏缺会对玉米产量产生负面影响，并且我们最近强调了水分亏缺对细胞壁消化率、组成以及组织木质化的影响。因此，本研究的目的是探索在不同水分条件下，与细胞壁组成和消化率相关的木质素分布的遗传机制。对在田间试验中采用不同灌溉方案种植的重组自交系（RIL）群体的玉米节间进行了生化和组织学定量分析。结果表明，生化和组织学性状对水分亏缺具有不同的响应阈值。因此，组织学特征仅在明显的水分亏缺条件下才会发生改变，而大多数生化性状无论水分亏缺的程度如何都会产生响应。检测到了三个主要的组织学性状数量性状位点（QTL）簇。有趣的是，生化和组织学簇之间很少重叠，特别值得注意的是组织学QTL/簇与对香豆酸含量的QTL之间的共定位。这些发现进一步证实了组织对香豆酰化在植物农艺特性及其消化率方面所起的作用。
