Abstract：
Drought stress affects plant photosynthesis, leading to a reduction in the quality and yield of crop production. Non-foliar organs play a complementary role in photosynthesis during plant growth and development and are important sources of energy. However, there are limited studies on the performance of non-foliar organs under drought stress. The photosynthetic-responsive differences of oat spikelet organs (glumes, lemmas and paleas) and flag leaves to drought stress during the grain-filling stage were examined. Under drought stress, photosynthetic performance of glume is more stable. Intercellular CO2 concentration (Ci), chlorophyll b, maximum photochemical efficiency of photosystem II. (Fv/Fm), and electron transport rate (ETR) were significantly higher in the glume compared to the flag leaf. The transcriptome data revealed that stable expression of the RCCR gene under drought stress was the main reason for maintaining higher chlorophyll content in the glume. Additionally, no differential expression genes (DEGs) related to Photosystem Ⅰ (PSI) reaction centers were found, and drought stress primarily affects the Photosystem II (PSII) reaction center. In spikelets, the CP43 and CP47 subunits of PSII and the AtpB subunit of ATP synthase were increased on the thylakoid membrane, contributing to photosynthetic stabilisation of spikelets as a means of supplementing the limited photosynthesis of the leaves under drought stress. The results enhanced understanding of the photosynthetic performance of oat spikelet during the grain-filling stage, and also provided an important basis on improving the photosynthetic capacity of non-foliar organs for the selection and breeding new oat varieties with high yield and better drought resistance.
摘要：
干旱胁迫影响植物光合作用,导致作物生产的质量和产量下降。非叶面器官在植物生长发育过程中的光合作用中起着互补作用，是重要的能量来源。然而,关于干旱胁迫下非叶面器官表现的研究有限。燕麦小穗器官的光合响应差异（glums，引理和古）和在灌浆阶段对干旱胁迫的旗叶进行了检查。在干旱胁迫下，颖的光合性能较为稳定。细胞间CO2浓度（Ci），叶绿素b,光系统的最大光化学效率II。（Fv/Fm），与旗叶相比，颖片中的电子传输速率（ETR）明显更高。转录组数据表明，RCCR基因在干旱胁迫下的稳定表达是维持颖片中较高叶绿素含量的主要原因。此外,未发现与光系统Ⅰ(PSI)反应中心相关的差异表达基因(DEGs),干旱胁迫主要影响光系统II（PSII）反应中心。在小穗中，PSII的CP43和CP47亚基以及ATP合酶的AtpB亚基在类囊体膜上增加，有助于小穗的光合稳定，以补充干旱胁迫下叶片有限的光合作用。结果增强了对籽粒灌浆期燕麦小穗光合性能的认识,为选育高产抗旱性好的燕麦新品种提供了提高非叶面器官光合能力的重要依据。
