Zhang Shumeng, Sun Fengli, Wang Weiwei, Yang Guoyu, Zhang Chao, Wang Yongfeng, Liu Shudong, Xi Yajun
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China.
Biotechnol Biofuels. 2019 Aug 5;12:193. doi: 10.1186/s13068-019-1534-4. eCollection 2019.
Switchgrass ( L.), a warm-season perennial C4 plant, can be used as a forage plant, a soil and water conservation plant, a windbreak plant, and as a good source of biofuels and alternative energy with low planting costs. However, switchgrass exhibits low rates of seedling development compared to other crops, which means it is typically out-competed by weeds. There is a large variation in seedling development rates among different plantlets in switchgrass, which limits its usefulness for large-scale cultivation. Little is currently known about the molecular reasons for slow seedling growth.
Characterization of the seedling development process via growth indices indicated a relatively stagnant growth stage in switchgrass. A total of 678 differentially expressed genes (DEGs) were identified from the comparison of transcriptomes from slowly developed (sd) and rapidly developed (rd) switchgrass seedlings. Gene ontology and pathway enrichment analysis showed that DEGs were enriched in diterpenoid biosynthesis, thiamine metabolism, and circadian rhythm. Transcription factor enrichment and expression analyses showed MYB-related, bHLH and NAC family genes were essential for seedling growth. The transcriptome results were consistent with those of quantitative real-time polymerase chain reaction. Then, the expression profiles of maize and switchgrass were compared during seedling leaf development. A total of 128 DEGs that play key roles in seedling growth were aligned to maize genes. Transcriptional information and physiological indices suggested that several genes involved in the circadian rhythm, thiamine metabolism, energy metabolism, gibberellic acid biosynthesis, and signal transduction played important roles in seedling development.
The seedling development process of switchgrass was characterized, and the molecular differences between slowly developed and rapidly developed seedlings were discussed. This study provides new insights into the reasons for slow seedling development in switchgrass and will be useful for the genetic improvement of switchgrass and other crops.
柳枝稷（Panicum virgatum L.）是一种暖季多年生C4植物，可作为饲料植物、水土保持植物、防风植物，也是生物燃料和替代能源的优质来源，种植成本低。然而，与其他作物相比，柳枝稷的幼苗发育速度较慢，这意味着它通常会被杂草竞争。柳枝稷不同植株间的幼苗发育速度差异很大，这限制了其大规模种植的实用性。目前对幼苗生长缓慢的分子原因知之甚少。
通过生长指标对幼苗发育过程进行表征，结果表明柳枝稷存在一个相对停滞的生长阶段。通过比较发育缓慢（sd）和发育迅速（rd）的柳枝稷幼苗的转录组，共鉴定出678个差异表达基因（DEG）。基因本体和通路富集分析表明，DEG在二萜生物合成、硫胺素代谢和昼夜节律中富集。转录因子富集和表达分析表明，MYB相关、bHLH和NAC家族基因对幼苗生长至关重要。转录组结果与定量实时聚合酶链反应结果一致。然后，比较了玉米和柳枝稷在幼苗叶片发育过程中的表达谱。共有128个在幼苗生长中起关键作用的DEG与玉米基因比对。转录信息和生理指标表明，一些参与昼夜节律、硫胺素代谢、能量代谢、赤霉素生物合成和信号转导的基因在幼苗发育中起重要作用。
对柳枝稷的幼苗发育过程进行了表征，并讨论了发育缓慢和发育迅速的幼苗之间的分子差异。本研究为柳枝稷幼苗发育缓慢的原因提供了新的见解，将有助于柳枝稷和其他作物的遗传改良。
