Multiple origins of allopolyploid <Emphasis Type="Italic">Aegilops triuncialis</Emphasis>

Polyploidization is a key component of plant evolution. The number of independent origins of polyploid species traditionally has been underestimated. The objective of this study was to ascertain the number of origins of a tetraploid Aegilops species. We screened 84 primer sets to identify genome-specific primer sets for the tetraploid wheat relative [Aegilops triuncialis (UUCC genome)] and its diploid progenitors [Ae. umbellulata (UU genome) and Ae. caudata (CC genome)]. Primer sets G12 and G43 were U genome-specific and D21 was a C genome-specific primer. DNA sequence comparison of the G43 locus was used to estimate the number of polyploidization events in the formation of Ae. triuncialis. Parsimony analysis of G43 data revealed at least two independent formations of Ae. triuncialis. In the chloroplast hotspot region, located between genes rbcL and petA, sequence analysis suggested that at least three polyploidization origins might have occurred independently. Ae. triuncialis appears to be a tetraploid derived from multiple origins with minimal genome change after its formation.     

中国特有属牛筋条属的花粉形态与其系统位置

从发育的角度研究了中国特有单种属DichotomanthesKurz及与其系统学研究有关的外类群Prinsepiautilis的花粉形态 ,扫描电镜观察显示Dichotomanthes花粉粒自脱离四分体胼胝质膜开始至成熟二核花粉粒不同发育时期 ,花粉形态和外壁纹饰未见变化 ,仅花粉体积随成熟度增加而有所增大。而Prinsepiautilis ,其花粉粒刚脱离四分体时形状和成熟花粉明显不同 ,成熟花粉极面观为三裂圆形 ,赤道面观为圆形 ,外壁具清晰的平行条纹 ,但幼嫩花粉粒的形状很特别 ,极面观为深三裂圆形 ,赤道面观亦见花粉在两条沟之间下陷而沟部外突 ,明显为角萌发孔花粉 ,且花粉体积较成熟者小 ,而外壁纹饰同成熟者相比无根本性差异。前述两种植物花粉在不同成熟期体积有明显差异 ,而外壁纹饰在不同成熟期不存在质的变化并相对稳定 ,说明花粉外壁纹饰这一性状在蔷薇科中具有较为重要的分类学意义。DichotomanthesKurz具典型Rosaceae花粉的三孔沟结构 ,外壁具条纹 -穴状纹饰。将其孢粉学特征同Rosaceae 4个亚科有关类群的同类资料相比较 ,并结合其它形态解剖与细胞学等研究结果 ,支持将Dichotoman thes置入Maloideae下而不赞同将其另立亚科或置于Prunoideae之下。此外 ,由于Prinsepiautilis的花粉在其发育初期具角萌发孔花粉 ,与Cunoniacea     

中国紫金牛属圆齿组花粉形态研究及其分类学意义

利用扫描电子显微镜对紫金牛属圆齿组20种1变种植物的花粉形态进行了研究,并比较分析了腋序组2种及锯齿组1种的花粉。经观察花粉为近球形或近扁球形,具3孔沟,除锯齿组的月月红外,其余种均形成合沟。外壁纹饰可分为四类:穴网状、细网状、皱波状及细颗粒状(带刺突)。结果显示,花粉形态特征可作为属下分组及组下分类处理的依据。     

中国苦苣苔科三特有属花粉形态研究

对中国苦苣苔科异片苣苔属、长檐苣苔属和报春苣苔属等3个特有属中3种代表植物的花粉形态进行了光镜和扫描电镜的观察。结果发现这些植物的花粉形状比较一致,均为长球形或近球形,表明花粉形状对苦苣苔科的系统与分类没有太大的参考价值。观察到两种类型的花粉外壁纹饰:细网状纹饰、粗网状纹饰;异片苣苔属具粗网状纹饰,长檐苣苔属和报春苣苔属具细网状纹饰。还讨论了一些花粉外壁纹饰特征在苦苣苔科的系统研究方面的潜在价值。     

Pollen Morphology of the Genus Malus and Its Taxonomic and Evolutionary Significance

The pollen morphology of 26 species and 5 hybrids of the genus Malus was investigated with aid of SEM. It is found that the pollen morphology of Malus is rather similar in shape, size, position and number of aperture and exine sculpture. The characters of polle morphology of sections and series are as follows: Sect. Malus Ser. Baccatae: Striae regular, parallel to colpi, and conjunct at pole; Ser. Pumilae: the same as in Ser. Baccatae, but more or less curved near pole. Sect. Docyniopes: Striae regular and parallel to colpi, but bent near pole. Sect. Chloromeles: Striae irregular, dense and interlock. Sect. Sorbormalus: Striae irregular, sparse and not interlock. Ser. Sieboldiance: pollen grains prolate, with perforation among striae, colpi narrow; Ser. Kansuenses: Pollen grains spheroidal, colpi wide in the middle but narrow at both ends, striae relatively dense and regular, mostly dichotomous, perforation present; Ser. Yunnanenses; Pollen grain spheroidae, colpi wide in the middle but narrow at both ends, striae obviously irregular, less dichotomous, perforation absent. The major evolutionary trend of exine sculpture of pollen may be from densely thin-striate to sparsely striate with perforation. Characters of the exine sculpture of hybrids can be used to recognize the rela-tionship between the parental species.     

Studies on the Pollen Morphology and Seed Coat of the Genus Cistanche (Orobanchaceae) in China

In the present paper pollen grains of 5 species and seed coat of 4 species of the genus Cistanche (Orobanchaceae) from China were examined by scanning electron microscope As a result, two types of the pollen exine sculpture are distinguished: (1) tuberculate, C. salsa and C. lanzhouensis; (2) rugulate or fine reticulation formed by the fusion of rugae, C. sinensis, C. deserticola and C. tubulosa. Chinese Cistanche was classified into two sections based on the gross morphology by the present author (Zhang, 1984). C. lanzhouensis and C. sinensis were included in one section. This classification is in conflict with the pollen type, which indicates that the characters of pollen grains and external morphology in this genus have evolved at different rates. The differences in pollen morphology of Chinese Cistanche can serve as characters for delimitating species. According to our abservation, C. lanzhouenis Z. Y. Zhang differs from the other members of Cistanche not only in external morphology but also in pollen morphology. Pollen grains are subprolate in this species, while prolate in the other four species, and exine sculpture is tuberculate. The present study provides the establishment of this new species (Zhang, 1984) with palynological evidence. The seed coat sculpture in Chinese Cistanche are constantly alveolate, but there are some slight differences, by which the sculpture can be divided into two types: (1) testa cells have or have not thickenings on the inner anticlinal walls; cavernulous sculpture is present on outer periclinal wall of some cells: C. sinensis; (2) testa cells have striate thickenings on the inner anticlinal walls: C. salsa, C. deserticola and C. tubulosa. The characters of seed coatof some significance for the delimitation of species.     

几个四倍体小麦-山羊草双二倍体及其部分亲本的抗小麦白粉病基因分析

用离体叶段接种方法鉴定了11个四倍体小麦一山羊草双二倍体、波斯小麦PS5、硬粒小麦DR147、5份山羊草、杂交高代材料Am9／莱州953*^2F5和(DR147／Ael4)／／莱州953*^2F4对20个具有不同毒力白粉菌株的抗谱。通过与含有已知抗病基因品种或品系的反应模式比较,推测Am9／莱州953*^2F5含有Pm4b,波斯小麦PS5含有Pm4b与一个未知抗病基因组合;(DR147／Ael4)／／莱州953*^2F4和硬粒小麦DR147含有Pm4a和一个未知抗病基因组合;尾状山羊草Ael4和小伞山羊草Y39抗所有白粉菌株,由于迄今还没有在尾状山羊草和小伞山羊草中鉴定出抗白粉病基因,推测这2份山羊草含有新的抗白粉病基因。除Am9外,在其它双二倍体中波斯小麦或硬粒小麦的抗性部分受到抑制。山羊草的抗性部分或完全量到抑制。     

Pollen Morphology of the Genus Nomocharis and Its Delimitation with Lilium

In this work examined were pollen grains of 6 species of Nomocharis and 4 species of Lilium, all under LM and SEM, but Nomocharis saluenensis Balf. f. under TEM. The pollen grains are monocolpate (distal) in Nomocharis, monocolpate or 2-3-porate in the species of Lilium examined. Two types of pollen grains in Nomocharis are recognized based upon the exine stratification and sculpture. The pollen characters and gross morphology, and their evolutionary trends in both Nomocharis and Lilium are discussed. Our conclusions are as follows: 1. Lilium henrici Franch. 、L. souliei (Franch.) Sealy 、L. lophophorum (Bur. et Franch.) Franch. and L. nanum Klotz. et Garcke differ from Nomocharis in the aperture and sculpturing elements. Their pollen morphology supports their being placed in Lilium. 2. The pollen grains of both Lilium lophophorum (Bur. et Franch.) Franch. and L. nanum aggregate are monocolpate or 2-3-porate, which shows an evolutionary trend of aperture from monocolpate to porate, as suggested by Walker and others [Walker et al., (1975), and Chanda (1979)]. 3. In Balfour’s (1918) classification system of Nomocharis, N. pardanthina Franch. and N. meleagrina Franch. belong to Sect. Nomocharis, while N. forrestii and N. biluoensis are placed in Sect. Ecristata, but their pollen grains are all reticulate. They refer to type I (see Table 2). Thus, it does not seem reasonable placing in a single section, Sect. Ecristata, N. forrestii and N. biluoensis with the reticulate exine and N. saluenensis and N. aperta with the two-row-ritipilate exine. 4. Nomocharis saluenensis Balf. f. differs from Lilium in the exine sculpture, which seems to support placing it in Nomocharis. 5. Muri of N. forrestii Balf f. and N. biluoensis s.y. Liang show a tendency of connecting each other by heads of pili, and these two species are intergraded with the other species of the type I with respect to gross morphorlogical characters. It is thus considered that the reticulate pollen grains in Nomocharis is derived from ritipilate ones. This opinion is also held by Nair (1965). 6. Nomocharis differs from Lilium in the exine ornamentation, but some species of Nomocharis are very similar to Lilium in the gross morphology. It shows the close affinity between Nomocharis and Lilium.     

Analysis of HMW glutenin subunits and their coding sequences in two diploid Aegilops species

Considerable progress has been made in understanding the structure, function and genetic regulation of high-molecular-weight (HMW) glutenin subunits in hexaploid wheat. In contrast, less is known about these types of proteins in wheat related species. In this paper, we report the analysis of HMW glutenin subunits and their coding sequences in two diploid Aegilops species, Aegilops umbellulata (UU) and Aegilops caudata (CC). SDS-PAGE analysis demonstrated that, for each of the four Ae. umbellulata accessions, there were two HMW glutenin subunits (designated here as 1Ux and 1Uy) with electrophoretic mobilities comparable to those of the x- and y-type subunits encoded by the Glu-D1 locus, respectively. In our previous study involving multiple accessions of Ae. caudata, two HMW glutenin subunits (designated as 1Cx and 1Cy) with electrophoretic mobilities similar to those of the subunits controlled by the Glu-D1 locus were also detected. These results indicate that the U genome of Ae. umbellulata and the C genome of Ae. caudata encode HMW glutenin subunits that may be structurally similar to those specified by the D genome. The complete open reading frames (ORFs) coding for x- and y-type HMW glutenin subunits in the two diploid species were cloned and sequenced. Analysis of deduced amino acid sequences revealed that the primary structures of the x- and y-type HMW glutenin subunits of the two Aegilops species were similar to those of previously published HMW glutenin subunits. Bacterial expression of modified ORFs, in which the coding sequence for the signal peptide was removed, gave rise to proteins with electrophoretic mobilities identical to those of HMW glutenin subunits extracted from seeds, indicating that upon seed maturation the signal peptide is removed from the HMW glutenin subunit in the two species. Phylogenetic analysis showed that 1Ux and 1Cx subunits were most closely related to the 1Dx type subunit encoded by the Glu-D1 locus. The 1Uy subunit possessed a higher level of homology to the 1Dy-type subunit compared with the 1Cy subunit. In conclusion, our study suggests that the Glu-U1 locus of Ae. umbellulata and the Glu-C1 locus of Ae. caudata specify the expression of HMW glutenin subunits in a manner similar to the Glu-D1 locus. Consequently, HMW glutenin subunits from the two diploid species may have potential value in improving the processing properties of hexaploid wheat varieties.     

Pollen morphology ofPyrola and its taxonomic significance

Pollen from 152 collections representing 16Pyrola species was examined with LM, SEM and TEM. The genusPyrola is stenopalynous in having tetrads and 3-colporoidate grains. However, a continuous and serial variation in the exine sculpture and the tetrad diameter (D) was revealed within the genus. Křísa's system ofPyrola (1971) was re-examined in the light of these palynological characters which may have a taxonomic significance, as well as the external morphology. P. minor (only member of the subgenusAmelia), which is characterized by having small (D=30–35 μm) pollen tetrads with verrucate sculpture must best be placed near sectionPyrola of the subgenusPyrola. P. faurieana must be segregated from sectionChlorantha and together withP. media placed intermediate between the subgenusAmelia and sectionPyrola of the subgenusPyrola based on their larger (D=ca. 40 μm) pollen tetrads with verrucate sculpture. Two series of sectionChlorantha excludingP. faurieana are differentiated in the exine sculpture. Therefore, they are regarded as the distinct taxonomic groups. SectionScotophylla is characterized by having psilate sculptured pollen tetrads, which indicates that its sectional rank is sufficiently asserted. The evolutionary trend in the exine sculpture from verrucate through rugulate to psilate is suggested withinPyrola.     

Studies on the Pollen Morphology of the Genus Brassica (Cruciferae) in China

The present paper reports the pollen morphology of 36 species and varieties of Brassica L. in China mostly for the first time. They were examined both under LM and SEM. Pollen grains of Brassica L. in China are long-spheroidal, subspheroidal, spheriodal, oblate, rarely reniformis or subsquare. According to the aperture characters pollen grains may be divided into four types: 2,3,4-colpate, 3-colpate, 3,4-colpate, 3,4-colporate. The exine sculpture may also be divided into three types: 1, reticulate, 2, cerebroid-reticulate, 3, foveolatereticulate. Detailed characters of pollen grains for each taxon are presented in Table 1. The 2,3,4-colpate type of pollen grains may be considered as primitive one and the 3,4-colpate or 3,4-colporate type of pollen grains is the most advanced in Brassica. The tricolpate aperture and reticulate exine have been reported by the previous authors, whereas, 3,4-colporate and cerebroid-reticulate or foveolate-reticulate pollen grains are newly reported.     

Pollen Morphology of Parnassia L. （Parnassiaceae） and Its Systematic Implications

The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type I, with foveolate-reticulate sculpture; (ii) type II, with a finely reticulate sculpture; and (iii) type III, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect.Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China,with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassiafaberi Oliv.) colpi,implying that Southwest China is the center of diversification of the genus.     

Pollen morphology,ultrastructure and taphonomy of the Neuradaceae with special reference to Neurada procumbens L. and Grielum humifusum E.Mey. ex Harv. et Sond.

Pollen morphology and sporoderm ultrastructure of modern Neurada procumbens L. and Grielum humifusum E.Mey. ex Harv. et Sond. were studied using light (LM) and electron (SEM and TEM) microscopy. Additionally late Holocene pollen of the Grielum-type was studied using LM. Systematic and ecological aspects have been discussed for the family Neuradaceae. The pollen grains of the studied species are characterized by similarities in size, shape, aperture type and differences in exine sculpture (reticulate semitectate exine in Neurada and finely reticulate to foveolate in Grielum) and sporoderm ultrastructure. The cavea in the exine is situated between the ectexine and endexine which are connected near the aperture region only. A combination of the palynological characters of the Neuradaceae (semitectate exine, rather loose columellae, interrupted foot layer, the cavea in the exine) increases the pollen plasticity, allowing considerable changes of the pollen grain volume but still remains insufficient to survive sharp fluctuations in hydration level.     

Links between morphology and function of the pollen wall: an experimental approach

The wall of pollen grains exhibits morphological variation in many features including apertures, ornamentation and thickness, but the function of these characters remains to be clarified. It has been suggested that they are involved in the accommodation of volume changes (harmomegathy). To investigate this further, we developed a protocol that induces a controlled hydration of the pollen without affecting its metabolism and we applied it to six species differing in their pollen wall morphology. The entry of water caused pollen swelling and volume increase leading to breakage of the wall and/or of the plasma membrane, such that the per cent of intact grains was negatively correlated with the level of hydration. Qualitative and quantitative differences were observed between the species. Breakage of the exine was observed only in pollen lacking apertures and with thin exine. Variation in the exine ornamentation and thickness could explain the interspecific differences observed for the rates of breakage of the plasma membrane. Our results suggest that pollen wall morphology matters for survival and maintenance of pollen integrity further to volume increase due to hydration. We propose a rationale for future studies that should allow disentangling the contribution of different pollen morphological and physiological features to harmomegathy.     

Pollen Morphology of Parnassia L. (Parnassiaceae) and Its Systematic Implications

The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type Ⅰ, with foveolate-reticulate sculpture; (ii) type Ⅱ, with a finely reticulate sculpture; and (iii) type Ⅲ, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect.Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China,with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassia faberi Oliv.) colpi,implying that Southwest China is the center of diversification of the genus.     

Pollen Morphology of Eight Genera of the Subtribe Mutisiinae Less. sensu Bremer (Compositae) from Asia

The pollen morphology of 28 species and one variety representing eight genera of the subtribe Mutisiinae Less. sensu Bremer (Compositae) was investigated by scanning electron microscopy (SEM) and light microscopy. The pollen grains are usually radically symmetrical, isopolar, and tricolporate. The shape varies from spheroidal to subprolate in equatorial view and is three-lobed circular in polar view. Based on exine sculpturing observed under SEM, the pollen grains can be divided into three types: (i) type Ⅰ, with macrogranulate sculpture; (ii) type Ⅱ, with a finely granulate sculpture; and (iii) type Ⅲ, with spiny sculpture.The palynological data showed that the Macroclinidium Maxim. was remarkably distinguished from those of the other seven genera. The variation of pollen characteristics within the Mutisiinae in Asia is little at species level, but it proves some useful information for studying the relationships among genera and it has an important significance in further understanding the evolutionary history of Mutisiinae.     

Unraveling salinity stress responses in ancestral and neglected wheat species at early growth stage: A baseline for utilization in future wheat improvement programs

In this study, we analyzed the behavior of several neglected, ancestral, and domesticated wheat genotypes, including Ae. triuncialis, Ae. neglecta, Ae. caudata, Ae. umbellulata, Ae. tauschii, Ae. speltoides, T. boeoticum, T. urartu, T. durum, and T. aestivum under control and salinity stress to assess the mechanisms involved in salinity tolerance. Physiological and biochemical traits including root/shoot biomasses, root/shoot ion concentrations, activity of antioxidant enzymes APX, SOD, and GXP, and the relative expression of TaHKT1;5, TaSOS1, APX, GXP, and MnSOD genes were measured. Analysis of variance (ANOVA) revealed significant effects of the salinity treatments and genotypes for all evaluated traits. Salinity stress (350 mM NaCl) significantly decreased root/shoot biomasses, K+ concentration in root/shoot, and root/shoot K+/Na+ ratios. In contrast, salinity stress significantly increased Na+ concentration in root and shoot, activity of antioxidant enzymes (APX, SOD, and GPX) and relative expression of salt tolerance-related genes (TaHKT1;5, TaSOS1, APX, GPX, and MnSOD). Based on heat map and principal component analysis, the relationships among physiological traits and relative expression of salt-responsive genes were investigated. Remarkably, we observed a significant association between the relative expression of TaHKT1;5 with root K+ concentration and K+/Na+ ratio and with TaSOS1. Taken together, our study revealed that two neglected (Ae. triuncialis) and ancestral (Ae. tauschii) wheat genotypes responded better to salinity stress than other genotypes. Further molecular tasks are therefore essential to specify the pathways linked with salinity tolerance in these genotypes.     

Palynological survey of the subtribe Elephantopinae (Asteraceae, Vernonieae)

Despite the taxonomic value of pollen morphology within the tribe Vernonieae, a detailed study of the pollen of the subtribe Elephantopinae is still lacking. The pollen morphology of ten species, representing three of the four genera of the subtribe, Elephantopus, Pseudoelephantopus and Orthopappus, was studied with LM, SEM, and TEM. The pollen of all the species studied was found to be echinolophate, although the differences in aperture features and both sculpture and exine structure allowed recognizing two pollen types. The species of Elephantopus (except for E. elongatus) and Pseudoelephantopus share the regular or more or less regular ridges pattern, the colporate condition but with the ectoapertures little developed, and the acaveate exine structure. From the sculpture and the apertures, the pollen of Caatinganthus harleyi was found to be similar to that of Elephantopus and Pseudoelephantopus. The pollen morphology of the monotypic Orthopappus, which is shared with that of E. elongatus, was further investigated for the first time. We found that it differs from that of the other species in having an irregular pattern of ridges, colporate condition but with a well-developed ectoapertures, and caveate exine. Additional studies of the exine structure and apertures features, coupled with molecular phylogeny, are needed to understand the evolution of pollen characters and re-evaluate the intergeneric relationships within the tribe.     

Pollen morphology of the tribe Rhinantheae (Orobanchaceae) and its systematic significances

Pollen morphology of 36 species representing 14 genera within the tribe Rhinantheae in the family Orobanchaceae was studied and illustrated with light microscopy (LM) and scanning electron microscopy (SEM). Five major pollen types were recognized on the basis of exine ornamentation. Within these major types, minor types (subtypes) were distinguished based on exine surface pattern, size, shape, amb form, colpi and colpus membrane. These types and subtypes are as follows: type I. retipilate: subtype Ia. regular retipilate: (1) pollen size < 27 μm, (2) pollen size > 27 μm, subtype Ib. irregular retipilate; type II. verrucate: subtype IIa. macro-verrucate, subtype IIb. verrucate, subtype IIc. sparse verrucate; type III. retirugulate; type IV. granulate; type V. micro-reticulate. A key to pollen morphology of genera studied within the Rhinantheae was made based on pollen morphology from our study and earlier work. Combining with other sources of information on the Rhinantheae, the systematic relationships of this tribe are discussed. Rhinantheae pollen displays considerable variation between genera and species, with taxonomically significant characters at genus and species level. Palynological characteristics provide evidence for interpreting the conflicting views concerning the “Pterygiella Complex”. The evolutionary trend in exine sculpture of Rhinantheae could be proposed, namely that retipilate sculpturing which is the most widespread type is more primitive than the other types (such as foveolate, granulate, regulate, reticulate, retirugulate and verrucate). The pollen data in present study and the view of Hong (1986), as well as the molecular data from Bennett and Mathews (2006) indicated that Asia and related regions were likely to the origin centre of the tribe Rhinantheae.