苗期低温胁迫对不同棉花品种叶肉细胞超微结构的影响

以早熟、中熟、晚熟三种不同熟性的6个棉花品种幼苗为试材,分析4℃低温胁迫处理对叶肉细胞超微结构的影响。结果表明：4℃低温处理3 d后,中熟品种N177和N181及晚熟品种K-1和N203的细胞器均受到严重破坏,表现为叶绿体受损严重,部分类囊体解体,线粒体膜模糊,失去完整性,细胞核膜基本消失,染色质凝聚,淀粉粒的数量和体积增大,嗜锇颗粒增多;而早熟品种中50和N52受损较轻,叶绿体变化不明显,线粒体结构完整,细胞壁完整。说明早熟品种中50和N52具有与抗冷性相适应的结构特点,其抗冷性较强。     

水分胁迫下小麦叶肉细胞超微结构变化与抗旱性的关系

本文用电子显微镜观察研究了抗旱性不同的6个小麦品种在不同程度水分胁迫下叶肉细胞超微结构的变化。结果表明:轻度水分胁迫(-0.5MPa)对参试的6个小麦品种叶肉细胞超微结构几乎没有影响。中度(-1.0MPa)和严重(-1.5MPa)水分胁迫下的叶肉细胞超微结构发生了程度不同的变化,且这种变化与品种抗旱性相一致。抗旱性愈弱的品种,对水分胁迫反应愈敏感。但表现在叶肉细胞结构上的变化过程基本一致。胁迫导致叶肉细胞质壁分离,液泡膜破裂。叶绿体变成球形挤入细胞中央,类囊体肿胀。线粒体基质变稀,脊减少。最终叶绿体、线粒体解体。其它细胞器消失,细胞中出现大量的小泡。     

低温胁迫下西番莲叶片的生理反应及超微结构变化

以西番莲扦插苗为实验材料,比较预冷处理和常温处理(对照)情况下,西番莲叶片对-6℃低温胁迫的生理反应及叶肉细胞的超微结构变化,以探讨预冷处理对西番莲的抗寒作用及其机理。结果显示:(1)常温处理组在-6℃低温胁迫处理后,西番莲叶片的质膜相对透性、MDA含量随着低温处理时间的延长而逐渐增加,而预冷处理组这两个指标在处理期间都比常温处理组低;(2)常温处理组叶片H2O2含量在48h时达到峰值后出现下降,而预冷处理组的H2O2含量都低于对照,在48h时对照的H2O2含量比预冷锻炼的高1.14倍;(3)常温处理组的脯氨酸含量在24h内增加以后出现下降,而预冷处理组在处理期间逐渐增加且高于对照;(4)常温处理组的POD活性在12h时最高,CAT、SOD活性在24h时最高,以后出现下降。预冷处理组提高了3个酶的活性,其中POD在12h时是对照的2.73倍,CAT、SOD活性在24h时比对照分别提高18.7%和42.7%。(5)超微结构研究显示,预冷处理组在低温胁迫72h时虽出现叶绿体片层肿胀、核膜消失、质膜内陷等症状,但叶绿体伤害症状轻于常温处理。研究表明,低温预冷处理能够提高西番莲的抗寒性。     

盐胁迫下芦苇叶肉细胞超微结构的研究

对青藏高原柴达木盆地柯柯盐湖边盐碱地上生长的芦苇叶肉细胞的超微结构进行了研究,并以西宁地区非盐碱地上生长的芦苇作对照。结果表明：西宁地区的芦苇叶肉细胞的叶绿体呈椭圆形,其膜系统完整,基粒片层和基质片层发育良好。在盐碱地上生长的芦苇叶肉细胞的叶绿体呈圆形,叶绿体内出现较大的淀粉粒,并发现有线粒体嵌入叶绿体的现象。叶绿体的类囊体膨大,线粒体的嵴也有膨大的现象。在盐湖水中生长的芦苇叶肉细胞,叶绿体的类囊体排列紊乱、扭曲、松散。类囊体膜局部被破坏,部分类囊体膜解体,空泡化,甚至消失,一些溶解了的类囊体流进细胞质中。综上所述,芦苇叶肉细胞超微结构的变化是该植物适应柯柯盐湖地区盐渍、低温、低气压、强辐射等环境因子的结果。     

盐胁迫对玉米叶片叶肉细胞生物膜超微结构的影响

研究了NaCl胁迫对玉米叶肉细胞生物膜超微结构的影响. 结果表明：NaCl胁迫破坏了玉米叶片叶肉细胞生物膜的正常结构,50 mmol·L^-1 NaCl处理胁迫下,玉米叶肉细胞核膜,线粒体膜,细胞膜,叶绿体膜,液泡膜都受到不同程度的破坏,叶绿体基粒类囊体膨胀,间质片层空间增大,片层紊乱。100 mmol·L^-1 NaCl处理胁迫下,质膜,液泡膜,线粒体,叶绿体都受到严重的破坏。细胞质膜破坏,破损的叶绿体充斥在细胞间隙中;叶绿体外膜破坏,甚至解体消失,叶肉细胞中充满膜结构,基粒排列方向改变,垛叠层数减少,基粒和基质片层界限模糊不清,有的基粒解体消失,甚至叶绿体完全解体;核膜破坏、解体,核中的染色质高度凝缩;线粒体的数量增多,线粒体膜破坏,脊的数量减少,甚至整个线粒体破损解体;液泡膜破坏;由于各种生物膜的破坏,使细胞内充满许多囊状小泡、多泡体或斑层小体;叶肉细胞发生严重的质壁分离,严重时发生细胞壁断裂;甚至整个细胞溶解。     

水分胁迫下玉米叶肉细胞超微结构的变化及其与膜脂过氧化伤害的关系

研究ＰＥＧ模拟水分胁迫条件对玉米叶肉细胞超微结构的影响,探讨了超微结构的变化与保护酶活性及膜酯过氧化伤害之间的关系。试验表明,在水分胁迫初期,叶肉细胞超微结构变化较小,此时,叶片的ＳＯＤ及过氧化氢酶活性明显升高,质膜相对透性和丙二醛含量增加缓慢,随着胁迫时间的延长,叶肉细胞超微结构破坏加重,且不同细胞对水分胁迫的敏感性相差很大,叶片ＣＡＴ性下降,质膜透性和ＭＤＡ含量急增;复水后,叶片超微结构,ＳＯ     

低温胁迫下董棕(Garyota urens L.)幼苗叶肉细胞内Ca~(2+)水平及细胞超微结构的变化

用焦锑酸钙沉淀的电镜细胞化学方法 ,研究了低温胁迫下董棕 (GaryotaurensL .)幼苗叶肉细胞内Ca2 + 水平的变化。研究结果表明 ,未经低温处理的董棕幼苗叶肉细胞 ,焦锑酸钙沉淀颗粒大量出现在液泡和细胞间隙中 ,细胞壁中也可见少量沉淀 ,而细胞基质中则看不到焦锑酸钙沉淀 ;经 2℃ 48h低温处理后 ,细胞基质和细胞膜上焦锑酸钙沉淀增加 ,而液泡和细胞间隙中的焦锑酸钙沉淀则显著减少 ,并且超微结构已初步显示出寒害的特征 ,叶绿体外膜部分破损 ,类囊体片层稀疏且排列不规则 ,光合速率明显下降等 ;经 2℃ 1 2 0h低温处理后 ,细胞间隙内的焦锑酸钙沉淀极少 ,有的也紧贴在细胞外壁上 ,而细胞基质和细胞膜上则分布有非常多的焦锑酸钙沉淀 ,在核基质和液泡中也可见到少量的焦锑酸钙沉淀 ,并且超微结构遭到了显著破坏 ,叶绿体结构完全被破坏 ,核膜与液泡膜严重破损 ,内部结构模糊 ,细胞只表现为呼吸作用 ,不进行光合作用。表明Ca2 + 的区域性分布的变化与植物抗寒性存在一定关系。     

低温胁迫下董棕（Garyota urens L.）幼苗叶肉细胞内Ca2+水平及细胞超微结构的变化

用焦锑酸钙沉淀的电镜细胞化学方法,研究了低温胁迫下董棕（Garyota urensL.） 幼苗叶肉细胞内Ca2+水平的变化。研究结果表明,未经低温处理的董棕幼苗叶肉细胞,焦锑 酸钙沉淀颗粒大量出现在液泡和细胞间隙中,细胞壁中也可见少量沉淀,而细胞基质中则看 不到焦锑酸钙沉淀;经2 ℃ 48 h低温处理后,细胞基质和细胞膜上焦锑酸钙沉淀增加,而液泡和细胞间隙中的焦锑酸钙沉淀则显著减少,并且超微结构已初步显示出寒害的特征,叶绿体外膜部分破损,类囊体片层稀疏且排列不规则,光合速率明显下降等;经2℃ 120 h低温处理后,细胞间隙内的焦锑酸钙沉淀极少,有的也紧贴在细胞外壁上,而细胞基质和细胞膜上则分布有非常多的焦锑酸钙沉淀,在核基质和液泡中也可见到少量的焦锑酸钙沉淀,并且超微结构遭到了显著破坏,叶绿体结构完全被破坏,核膜与液泡膜严重破损,内部结构模糊,细胞只表现为呼吸作用,不进行光合作用。表明Ca2+的区域性分布的变化与植物抗寒性存在一定关系。     

低温胁迫下董棕（Garyota urens L.）幼苗叶肉细胞内Ca^2＋水平及细胞超微结构的变化

用焦锑酸钙沉淀的电镜细胞化学方法,研究了低温胁迫下董棕(Caryota urens L.)幼苗叶肉细胞内Ca^2 水平的变化。研究结果表明,未经低温处理的董棕幼苗叶肉细胞,焦锑酸钙沉淀颗粒大量出现在液泡和细胞间隙中,细胞壁中也可见少量沉淀,而细胞基质中则看不到焦锑酸钙沉淀;经2℃ 48h低温处理后,细胞基质和细胞膜上焦锑酸钙沉淀增加,而液泡和细胞间隙中的焦锑酸钙沉淀则显著减少,并且超微结构已初步显示出寒害的特征,叶绿体外膜部分破损,类囊体片层稀疏且排列不规则,光合速率明显下降等;经2℃ 120h低温处理后,细胞间隙内的焦锑酸钙沉淀极少,有的也紧贴在细胞外壁上,而细胞基质和细胞膜上则分布有非常多的焦锑酸钙沉淀,在核基质和液泡中也可见到少量的焦锑酸钙沉淀,并且超微结构遭到了显著破坏,叶绿体结构完全被破坏,核膜与液泡膜严重破损,内部结构模糊,细胞只表现为呼吸作用,不进行光合作用。表明Ca^2 的区域性分布的变化与植物抗寒性存在一定关系。     

低温下的绿豆下胚轴细胞超微结构变化

采用透射电子显微镜观察经10℃低温处理2d的绿豆下胚轴细胞超微结构变化的结果表明,细胞受到不同程度的伤害,其中大部分细胞的损伤是可逆的而非致死性的,如内质网膜模糊和呈颗粒状;线粒体呈现不同程度的膨胀,其数量增加,且聚集分布在内质网和高尔基体附近,核糖体聚集成为多聚核糖体等。也有小部分细胞受到的伤害是致死性的,如细胞质电子密度显著升高,质体中淀粉粒过度积累,内质网和高尔基体膨胀和解体,小液泡频繁吞噬细胞质和细胞器,细胞自溶死亡等。     

Identification of effective pollinators of Primula sieboldii E. Morren in a wild habitat in Hiroshima,Japan

Primula sieboldii E. Morren is a heterostylous clonal herb that is widely distributed in Japan but in danger of extinction in the wild. The existence of pollinators in each habitat is imperative for its long-term survival, because seeds can be produced only by insect cross-pollination between different flower morphs. In this study, we identified the pollinators of P. sieboldii in a wild habitat in Hiroshima as those insects that we observed to (a) put the proboscis into a corolla tube, (b) deposit pollen grains on the proboscis, and (c) have a proboscis of appropriate length and width. Effective pollinators were identified from their contribution to pollination. In 2015 and 2016, the flower visitations of 232 and 558 insects, respectively, were recorded and 85 and 13 insects were captured. Two Bombylius species, B. major L. and B. shibakawae Matsumura, accounted for 90% of flower-visiting insects in both years. All 14 species that we captured were considered pollinators of P. sieboldii, because they had proboscises that were long enough to reach pollen and that had pollen grains deposited on them. The total visitation rate of “Bombyliidae” was the highest among all pollinator categories. The results of potential pollen transport per flower per hour, which was based on total pollen number and total visitation rate of each pollinator category, indicated that “Bombyliidae” species were the most effective pollinators of P. sieboldii in this habitat.     

Presence of putative Cycas necrotic stunt virus RNAs in Japanese primrose (Primula sieboldii E. Morren)

The study screened the putative viral RNA sequences in the cDNA library of Japanese primrose, and conducted a molecular approach in determining its presence in selected Primula sieboldii accessions showing characteristic viral symptoms. Three putatively viral non-homologous sequence groups of RNA were identified; however, coding for different proteins representing a complete virus structure, it was determined to be singly originating from Cycas necrotic stunt virus (CNSV). Subsequently, sequence-specific primers were customised based from the non-homologous-sequence groups; however, amplification data showed no association between the presence of the putative viral RNA sequences and the identified characteristic virus symptoms. Despite this, amplification of the three non-homologous sequences is fully correlated. Thus, Japanese primrose was potentially identified as an alternate host of CNSV.     

Spatial genetic structure among and within populations of Primula sieboldii growing beside separate streams

We investigated the hierarchical genetic structure of SSR (simple sequence repeats) and cpDNA (chloroplast DNA) polymorphisms among and within populations of Primula sieboldii, a heterostylous clonal herb. Seven out of eight populations at the study site, located in a mountainous region of Nagano Prefecture, had each developed alongside a different stream, and the other occurred on a flat area 70 m from the nearest stream. The magnitude of genetic differentiation among streamside populations in maternally inherited cpDNA (Phi = 0.341) was much higher than that in biparentally inherited SSRs (Phi = 0.011). This result suggests that seed dispersal among streams was restricted, and pollen was the primary agent of gene flow among streamside populations. In contrast, genetic differentiation among subpopulations within streams were low at both markers (Phi = 0.053 for cpDNA, Phi = 0.025 for SSR). This low differentiation among subpopulations in cpDNA compared with that among streamside populations suggest that seed dispersal occur along the stream probably during flooding. This hypothesis was supported by the fact that in cpDNA haplotypes, no clear genetic structure was detected within the streamside population, while a significant genetic structure was found within 20 m in the nonstreamside population. Furthermore, within the streamside populations, two pairs of ramets with identical multilocus genotypes for eight SSR loci were distantly (> 50 m) distributed along the same streamside, suggesting dispersal of clonal propagule. Our study showed that the heterogeneity of the landscape can influence gene flow and hence spatial genetic structure.     

Development of 120 microsatellite markers for Primula sieboldii E. Morren for linkage mapping

Primula sieblodii E. Morren is a perennial herb, classified as ‘Near Threatened’ in the Japanese Red List. Using the magnetic enrichment method, we have developed 120 microsatellite markers and screened polymorphisms within the species as a whole as well as within a single population. At the species level, the average number of alleles per locus, and the average observed and expected heterozygosities were 7.06, 0.48, and 0.74, respectively; at the level of the single population these values were 5.53, 0.52, and 0.64, respectively. The microsatellite markers presented here will be valuable research tools in forthcoming projects, such as QTL mapping as well as for association studies of P. sieboldii.     

Importance of Queen Bumble Bees as Pollinators Facilitating Inter-morph Crossing in Primula sieboldii

Abstract Flower-visiting insects, the distribution of pollen on an insect's body, and fruit and seed sets of Primula sieboldiiE. Morren were investigated in a maritime deciduous forest habitat of the Hidaka region in Hokkaido. Queens of Bombus diversus tersatus Smith (Hymenoptera: Apidae), Bombus schrencki albidopleuralis Skorikov, and Bombus deuteronymus deuteronymus Schulz were observed to visit the flowers of the species. Bumblebee claw marks were found on the flower petals of 68% of the flowering ramets of the species. Scanning-electronmicroscopy revealed that pin and thrum pollens of P. sieboldii were deposited in different positions along the proboscis of a B. diversus tersatus queen (n=38400 grains). On the glossa, all the observed pollen was of the pin type, while more than half of the pollen grains observed on the upper part of the proboscis, galea, stipes, and maxillary palpus were of the thrum type. In the field, high fruit and seed sets were recorded for both pin and thrum morphs, indicating the occurrence of sufficient legitimate pollination during the flowering season. In addition to the effectiveness of queen bumblebees as pollinators for P. sieboldii suggested in this study, phenological and morphological matches, i.e., early spring flowering during the queen bee emergence season and the similar lengths of the corolla tube and the bee proboscis, also support the inference that queen bumble bees play an important role in legitimate pollination of P. sieboldii.