背景:Festucakryloviana是青海湖地区重要的本地草种,出苗率低是限制耕地成功建立的主要因素。该地区干旱和低降雨的气候特征导致地表土壤水分含量降低。尽管人们认识到水的可用性对植物生长的影响,水分在幼苗发育中的具体作用仍未完全阐明。本研究的目的是研究不同水分条件下的F.kryloviana种子的发芽率和幼苗生长速度。并整合这些条件下幼苗的生理和转录组学分析,以揭示水分影响幼苗发育的机制。
结果:F.kryloviana幼苗的出苗率表现出初始增加,然后随着水分含量的增加而降低。出现率最高,达到75%,在20%的土壤湿度条件下观察到。到实验的第八天,在最佳出现率(满水,FW)分别为21.82%和10.87%,分别,比背景调查期间与土壤水分含量紧密匹配的那些(压力水,软件)。在不同的水分条件下,幼苗的发育差异归因于种子内的糖代谢和脱落酸(ABA)的积累。在FW条件下,增强糖代谢,为幼苗发育产生更多的能量,由较高的α-淀粉酶活性促进,蔗糖合成酶,和海藻糖-6-磷酸合酶与SW条件相比。这反映在转录组水平上,α-淀粉酶(AMY2)基因和海藻糖-6-磷酸合酶(TPS6)的表达上调,而与ABA信号和转导相关的基因下调。此外,在FW条件下,叶绿体类囊体光系统相关基因的表达,如光系统II(PSII)和光系统I(PSI),被上调,提高幼苗的光捕获能力和光合效率,从而提高他们的自养能力。此外,FW处理增强非酶抗氧化系统的表达,促进种子内的新陈代谢。相比之下,SW处理增加酶促抗氧化系统的活性,包括过氧化物酶(POD),超氧化物歧化酶(SOD),和过氧化氢酶(CAT),以应对水的压力。
结论:我们的实验系统地评估了水分条件对F.kryloviana幼苗生长发育的影响。生理和转录组数据共同表明,充足的水(20%)供应通过降低ABA水平和增加种子内α-淀粉酶活性来促进幼苗生长和发育。从而促进糖代谢,促进幼苗生长,这反过来又提高了出苗率。在未来的栽培实践中考虑水的管理可能是增强在草地生态系统中成功建立F.kryloviana的关键策略。
BACKGROUND: Festuca kryloviana is a significant native grass species in the Qinghai Lake region, and its low emergence rate is a primary factor limiting the successful establishment of cultivated grasslands. The region\'s arid and low-rainfall climate characteristics result in reduced soil moisture content at the surface. Despite the recognized impact of water availability on plant growth, the specific role of moisture in seedling development remains not fully elucidated. This study aims to investigate the germination rate and seedling growth velocity of F. kryloviana seeds under varying moisture conditions, and to integrate physiological and transcriptomic analyses of seedlings under these conditions to reveal the mechanisms by which water influences seedling development.
RESULTS: The emergence rate of F. kryloviana seedlings exhibited an initial increase followed by a decrease with increasing moisture content. The highest emergence rate, reaching 75%, was observed under 20% soil moisture conditions. By the eighth day of the experiment, the lengths of the plumules and radicles under the optimal emergence rate (full water, FW) were 21.82% and 10.87% longer, respectively, than those under closely matching the soil moisture content during the background survey (stress water, SW). The differential development of seedlings under varying moisture regimes is attributed to sugar metabolism within the seeds and the accumulation of abscisic acid (ABA). At FW conditions, enhanced sugar metabolism, which generates more energy for seedling development, is facilitated by higher activities of α-amylase, sucrose synthase, and trehalose-6-phosphate synthase compared to SW conditions. This is reflected at the transcriptomic level with upregulated expression of the α-amylase (AMY2) gene and trehalose-6-phosphate synthase (TPS6), while genes associated with ABA signaling and transduction are downregulated. Additionally, under FW conditions, the expression of genes related to the chloroplast thylakoid photosystems, such as photosystem II (PSII) and photosystem I (PSI), is upregulated, enhancing the seedlings\' light-capturing ability and photosynthetic efficiency, thereby improving their autotrophic capacity. Furthermore, FW treatment enhances the expression of the non-enzymatic antioxidant system, promoting metabolism within the seeds. In contrast, SW treatment increases the activity of the enzymatic antioxidant system, including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), to cope with water stress.
CONCLUSIONS: Our experiment systematically evaluated the impact of moisture conditions on the growth and development of F. kryloviana seedlings. Physiological and transcriptomic data collectively indicate that adequate water (20%) supply enhances seedling growth and development by reducing ABA levels and increasing α-amylase activity within seeds, thereby boosting sugar metabolism and promoting the growth of seedling, which in turn leads to an improved emergence rate. Considering water management in future cultivation practices may be a crucial strategy for enhancing the successful establishment of F. kryloviana in grassland ecosystems.