Abscisic acid (ABA) is an important phytohormone regulating plant growth, development and stress responses. A multitude of key factors implicated in ABA signaling have been identified; however, the regulation network of these factors needs for further information. AtS40.4, a plant-specific DUF584 domain-containing protein, was identified previously as a senescence regulator in Arabidopsis . In this study, our finding showed that AtS40.4 was negatively involved in ABA signaling during seed germination and early seedling growth. AtS40.4 was highly expressed in seeds and seedlings, and the expression level was promoted by ABA. AtS40.4 was localized both in the nucleus and the cytoplasm. Moreover, the subcellular localization pattern of AtS40.4 was affected by ABA. The knockdown mutants of AtS40.4 exhibited an increased sensitivity to ABA, whereas the overexpression of AtS40.4 decreased the ABA response during seed germination and seedling growth of Arabidopsis . Furthermore, AtS40.4 was involved in ABRE-dependent ABA signaling and influenced the expression levels of ABA INSENTIVE ( ABI ) 1-5 and SnRK2.6 . Further genetic evidence demonstrated that AtS40.4 functioned upstream of ABI4. These findings support the notion that AtS40.4 is a novel negative regulator of the ABA response network during seed germination and early seedling growth.

植物学野外实习是植物学课程教学的重要环节,不仅有助于学生学习物种分类的基本原理并掌握标本采集制作方法,还能巩固植物学理论知识.为提高教学质量,重点从掌握理论知识,加强现代技术应用,合理推进教学进程和优化考核方式等方面探讨了野外实习教学模式的改进措施,为提升野外实习效果提供指导.

Summary In mammalians and yeast, the splicing factor U2AF65/Mud2p functions in precursor messenger RNA (pre‐mRNA) processing. Arabidopsis AtU2AF65b encodes a putative U2AF65 but its specific functions in plants are unknown. This paper examines the function of AtU2AF65b as a negative regulator of flowering time in Arabidopsis. We investigated the expression and function of AtU2AF65b in abscisic acid (ABA)‐regulated flowering as well as the transcript abundance and pre‐mRNA splicing of flowering‐related genes in the knock‐out mutants of AtU2AF65b. The atu2af65b mutants show early‐flowering phenotype under both long‐day and short‐day conditions. The transcript accumulation of the flowering repressor gene FLOWERING LOCUS C (FLC) is reduced in the shoot apex of atu2af65b, due to both increased intron retention and reduced transcription activation. Reduced transcription of FLC results, at least partially, from the abnormal splicing and reduced transcript abundance of ABSCISIC ACID‐INSENSITIVE 5 (ABI5), which encodes an activator of FLC in ABA‐regulated flowering signaling. Additionally, the expression of AtU2AF65b is promoted by ABA. Transition to flowering and splicing of FLC and ABI5 in the atu2af65b mutants are compromised during ABA‐induced flowering. ABA‐responsive AtU2AF65b functions in the pre‐mRNA splicing of FLC and ABI5 in shoot apex, whereby AtU2AF65b is involved in ABA‐mediated flowering transition in Arabidopsis.

Pre-mRNA splicing is an important step for gene expression regulation. Yeast Bud13p (bud-site selection protein 13) regulates the budding pattern and pre-mRNA splicing in yeast cells; however, no Bud13p homologs have been identified in plants. Here, we isolated two mutants that carry T-DNA insertions at the At1g31870 locus and shows early embryo lethality and seed abortion. At1g31870 encodes an Arabidopsis homolog of yeast Bud13p, AtBUD13. Although AtBUD13 homologs are widely distributed in eukaryotic organisms, phylogenetic analysis revealed that their protein domain organization is more complex in multicellular species. AtBUD13 is expressed throughout plant development including embryogenesis and AtBUD13 proteins is localized in the nucleus in Arabidopsis. RNA-seq analysis revealed that AtBUD13 mutation predominantly results in the intron retention, especially for shorter introns (<= 100 bases). Within this group of genes, we identified 52 genes involved in embryogenesis, out of which 22 are involved in nucleic acid metabolism. Our results demonstrate that AtBUD13 plays critical roles in early embryo development by effecting pre-mRNA splicing.

植物学是农业院校生物科学类专业及植物生产类专业的一门重要的专业基础课.植物学实验是植物学课程体系的一部分,是课堂教学内容的延伸,是农业院校重要的实践教学课程.本研究从合并课堂学时、丰富实验内容、调整实验课成绩考核办法等方面入手,对植物学实验课程进行了改革和探索.实践证明,教学改革调动了学生学习的积极性和主动性,学生实验课成绩明显提高,锻炼了学生的实验技能及科研创新能力,加深了植物学课堂理论知识学习效果.

During the opening and closing of stomata, guard cells undergo rapid and reversible changes in their volume and shape, which affects the adhesion of the plasma membrane (PM) to the cell wall (CW). The dynamics of actin filaments in guard cells are involved in stomatal movement by regulating structural changes and intracellular signaling. However, it is unclear whether actin dynamics regulate the adhesion of the PM to the CW. In this study, we investigated the relationship between actin dynamics and PM–CW adhesion by the hyperosmotic-induced plasmolysis of tobacco guard cells. We found that actin filaments in guard cells were depolymerized during mannitol-induced plasmolysis. The inhibition of actin dynamics by treatment with latrunculin B or jasplakinolide and the disruption of the adhesion between the PM and the CW by treatment with RGDS peptide (Arg-Gly-Asp-Ser) enhanced guard cell plasmolysis. However, treatment with latrunculin B alleviated the RGDS peptide-induced plasmolysis and endocytosis. Our results reveal that the actin depolymerization is involved in the regulation of the PW–CW adhesion during hyperosmotic-induced plasmolysis in tobacco guard cells.

Stomatal movement regulates photosynthesis and transpiration in plant,which plays a crucial role in plant growth,development and tolerance to abiotic stress.Guard cell perceives the intracellular and extracellular signals to regulate the stomata aperture.Therefore,guard cell has become a widely used model in signal transduction research in plant.Here,we review the functions of actin cytoskeleton and reactive oxygen species (ROS) in regulating stomatal movement and the interaction between cell wall and membrane regulated by actin dynamics.Finally,we propose the possible mechanism of microfilament regulating stomatal movement via ROS involved in the interaction between cell wall and membrane of guard cell.

Annexin is a highly conserved protein family binding to phospholipids in a calcium-dependent manner,while different annexins harbore various gene expression patterns and protein subcellular localizations.Eight arnexins in Arabidopsis thaliana (AnnAt) have been identified.These annexins play important roles in growth,development and responses to stress.Annexin 2 in Arabidopsis thaliana (AnnAt2) is involved in root secretion and auxin-mediated geotropism growth of root cells.However,the molecular mechanism remains undefined.The subcellular localization of proteins is a crucial cue to explore their biological functions and molecular mechanisms.In the current study,the subcellular localization of AnnAt2 was investigated with fusion protein expression and colocalization with green fluorescent protein (GFP) of organelles or specific fluorescence dyes,respectively.Our results revealed that AnnAt2 was localized simultaneously in cytosol,nuclei,Golgi apparatus and endoplasmic reticulums.These data indicates that the translation and transportation of AnnAt2 are complex.AnnAt2 was colocalized with actin filaments marked by GFP in transgenic ArmAt2-mCherry Arabidopsis lines,suggesting that AnnAt2 might be involved in cell secretion via dynamic regulation of microfilaments and microfilament-mediated vesicles transport in Arabidopsis.These data provide the experimental evidence for further studies of protein translation,transport pathways and the functions of AnnAt2.

The effect of drought stress on osmotic adjustment ability in the leaves of the ornamental grasses was studied with pot experiment in order to uncover the physiological mechanisms for drought tolerance.The results showed that the osmotic adjustment ability of the three ornamental grasses changed after drought stress treatment.The osmotic adjustment ability of the drought sensitive variety Curvedleaf Indian Lovegrass decreased gradually.In contrast,the osmotic adjustment ability of strong drought-resistant variety Selloa Pampasgrass changed slightly at early stage and significantly increased with the extension of the drought stress treatment.The osmotic adjustment ability of moderate drought-resistant variety Chinese Pennisetum was higher than that of Selloa Pampasgrass during drought stress,however decreased when the drought stress level and duration were increased.Furthermore,its osmotic adjustment ability decreased more than the others after rewatering.The main osmotic regulation substances were different among the three grass species.The inorganic ions such as K+,Na+,Ca2+,Mg2+ were involved in osmotic adjustment of ornamental grass,but K+ and Ca2+ played major role.

The effect of drought stress on water state,relative electric conductance rate,osmotic regulation matter and protective enzyme activity in Curvedleaf Indian Lovegrass,Selloa Pampasgrass and Chinese Pennisetum were studied with pot control water method.The results showed that the relative water content and water potential in Curvedleaf Indian Lovegrass were declined sharply,cell membrane was harmed badly,which was sensitive to water stress.There were no significant differences in drought resistance between Selloa Pampasgrass and Chinese Pennisetum;the drought resistance of Selloa Pampasgrass was stronger than Chinese Pennisetum under heavy water stress.

芍药花药一般由4个花粉囊组成,偶尔可见5个或6个花粉囊.花药壁发育属基本型.花药壁由6～8层细胞组成,外中层宿存.绒毡层为腺质型.胞质分裂为同时型,小孢子四分体多为四面体型,少数为左右对称型.生殖细胞刚形成时有呈PAS正反应的拱形壁,游离在营养细胞质中后,壁消失,且被脂体冠包围.花粉成熟时,包围生殖细胞的脂体消失,生殖细胞与营养核贴近,构成雄性生殖单位(MGU).成熟花粉为二胞型.

利用14C示踪方法研究胁迫后复水对14C-光合产物从苹果结果树叶片的输出及其在体内的分配影响.结果表明,胁迫期间14C-光合产物合成和输出量均减少,同化物向枝、干的分配率增加,向新梢(幼叶)和果实的分配率下降;胁迫后复水,同化物的合成和输出均较胁迫条件下改善,但仍未完全恢复到充分供水的水平,同化物优先运往新梢(幼叶),果实未获得较多的同化物.

The nuclear vacuoles are present in Prophase I, they maybe digest or transfer the disintegration of nucleus. Cytoplasmic reorganization takes place during microsporogenesis and development of male gametophyte. It expressed in the falling in ribosome number and structural simplification of plastids and mitochondria in Prophase I; and increasing in ribosome number in Telophase I, and there is a organelles band between two new nucleus from this stage to Prophase II, organelles spread out at the stage of tetrad, plastids and mitochondria retain normal structure. From vacuolation stage of uninucleate microspore to the stage of two-cell pollen grain, the other cytoplasm reorganization takes place, expressing as the same as the first one. The generative cell has cell wall at early two-cell pollen grain stage, then the cell wall disappeared during it detaching from the vegetative cell wall, it has no plastid all along. The mature generative cell has no wall and is connect closely to the vegetative cell, thus they form a male germ unit (MGU).

Theh male gametophyte development in Paeonia lactiflora Pall. was investigated with transmission electron-microscopy. The results shows that the microspore mother cell has an organelle band at the stage of prophase II and the cytokinesis conforms to simultaneous type. The generative cell newly formed shows a PAS positive arched wall. The wall disappears, lipids in vegetative cell are distributed regularly along the paired plasma membranes, forming a lipid band, when the generative cell hasn^t completely departed from the pollen wall. The lipid band, referred to as lipid corone, surrounds the generative cell at late 2-celled pollen stage. At the mature pollen stage the lipid corone disappears and the generative cell connects closely with the vegetative nucleus, thus they compose a male germ unit. The mature pollen is 2-celled.

The microsporogenesis and the formation of male gametophyte on Paeonia suffruticosa Andr acre investigated the main results showed that:the anther wall development follows the basic type The anther wall comprises 6-7 layercells,its outter middle layer is persistent and has fibrous bands There are amoeboid tapetum and glandular tapetum in different anthers Simultaneous cytokinesis in the microspore mother cell follows meiosis,and the microspore tetrads are tetrahedral The generative cell displays a PAS positive wall at early two-celled pollen stage While the generative cell is detached from the intine of pollen grain,the generative cell is surounded by the lipid bodies which had been called the corona of them Pollen grains are two-celled when mature,the mature generative cell,which has no wall,associates with the vegetative nucleus ,and may form a male germ unit