Biodiversity of sweetpotato (iPomoea batatas,Convolvulaceae) in Southern Mexico

Between 1987 and 1992 the phytogeographic region of southern Mexico was explored during three collecting trips made in search of cultivated and wild germplasm of the sweetpotato (Ipomoea batatas). The first trip was made in 1987, when we collected wild species in Ipomoea section Batatas found in the southeastern and southwestern regions of Mexico. A second trip was made in 1990, when we collected accessions of the cultivated species as well as wild species in the southeast, southwest and northeast. The third and final trip was oriented at identification, characterization and collecting seeds in the ecological niches ofI.tabascana andI.umbraticola. As a result of the three trips we collected 165 accessions of cultivated and wild germplasm with populations dispersed in 147 localities in 15 states of the Mexican region: Veracruz, Tabasco, Campeche, Chiapas, Oaxaca, Yucatán, Guerrero, Michoacán, San Luis Potosí, Hidalgo, Querétaro, Tamaulipas, Guanajuato, Puebla and México. Of the total accessions some 64 (38.3%) were of the cultivated species including nine accessions of feral material, and 103 accessions (61.7%) were of wild species made up of 59 accessions of seven species in the section Batatas, 37 of other species in the family Convolvulaceae, and seven yet to be determined. We have identified the largest genetic biodiversity in six localities of five states: Tabasco, Oaxaca, Michoacán, San Luis Potosí, and Puebla. Biodiversity maintenance in this region is associated with the day-of-the-dead festivities.     

Changes in the West Indian operculina (Convolvulaceae)

Two West Indian names inOperculina are briefly discussed and compared with the Old WorldO. turpethum (L.) S. Manso. The conclusions are made thatO. triquetra (Vahl) H. Hallier is a taxonomic synonym ofO. turpethum and thatO. ventricosa (Bertero) Peter may best be considered a variety ofO. turpethum. Typification ofOperculina is discussed, and it is found that, although S. Manso had a mixed concept ofO. turpethum, this species must be the type of the genus.     

Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas,Convolvulaceae) complex

• Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa.
• Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy.
• 2C DNA content of hexaploid I. batatas ranged between 3.12–3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana, 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. ×leucantha, I. tiliacea, I. trifida and I. triloba, 2C DNA content was 1.01–1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea, were clearly different from the other diploid species, with 2C of 1.47–1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases.
• DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida, the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas.

     

Nomenclatural updates in Ipomoea (Convolvulaceae)

The lectotypification of Ipomoea fimbriosepala, I. horsfalliae, I. marcellia, I. subincana and I. tenera is proposed herein. In addition, we suggest to change one name, from I. tubata to I. sidifolia since I. sidifolia predate I. tubata and must replace it.     

Stictocardia tiliifolia (Convolvulaceae) re-evaluated

Stictocardia tiliifolia (Desr.) H. Hall. is accepted as the correct name for the type species ofStictocardia. An earlier name,Ipomoea campanulata L., regarded as a synonym of S.tiliifolia for the last 50 years, is found to be synonymous withIpomoea illustris (C. B. Clarke) Prain, a species occurring in coastal/tidal riverine habitats of South Asia. Material from interior habitats, calledI. campanulata by authors of Indian floras, is believed to represent a variety of trueI. campanulata or a closely related species.     

Caught in action: fine-scale plastome evolution in the parasitic plants of Cuscuta section Ceratophorae (Convolvulaceae)

Plant Molecular Biology - The mitochondrial metallochaperone COX19 influences iron and copper responses highlighting a role of mitochondria in modulating metal homeostasis in Arabidopsis. The...     

Effects of leaves of Ipomoea batatas (Convolvulaceae) on nest development and on respiratory metabolism of leaf-cutting ants Atta sexdens L. (Hym., Formicidae)

Abstract: Laboratory colonies of the leaf-cutting ants Atta sexdens feed daily with leaves of Ipomoea batatas s howed ant mortality and a significant decrease in the size of the fungal garden after the second week, with complete depletion of nests after 5 weeks of treatment. The mean oxygen consumption rate of these ants was higher than the control (ants collected from nests feed with leaves of Eucalyptus alba ), suggesting a physiological action of the leaves of I. batatas on the ants in addition to the effect of inhibiting the growth of the fungal garden.     

Pollen differences between Stylisma and Bonamia (Convolvulaceae)

Although discounted in a monograph recognizingStylisma as distinct fromBonamia, pollen morphology is useful in distinguishing these genera, Light and scanning electron microscopy show that the pollen ofStylisma is characterized by an advanced 3-aggrecolpate aperture totaling 12 or 15 colpi, while pollen ofBonamia is typically of a primitive 3-colpate type.     

Morphological studies in Argyreia Lour. (Convolvulaceae)

A detailed anatomical study of two species of Argyreia, viz. A. nervosa Bojer and A. roxburghii Choisy, has been made. The structure of the cotyledonary and other nodes and internodes, including the developmental anatomy of the dominant axillary and accessory branches, the course and structure of medullary bundles, and the formation of successive rings of cambia along with the xylem and phloem, have been worked out. Two hitherto unknown types of saccate tracheidal and vessel elements are described. In the light of this work certain inaccuracies in observations and interpretations of some earlier workers are also corrected.     

Convolvulus grandiflorus Jacq. (Convolvulaceae) re-examined

Convolvulus grandiflorus Jacq. has been treated as a synonym ofOperculina ventricosa andStictocardia tiliifolia. It is here accepted as identifiable withIpomoea (sect.Calonyction)macrantha which is the correct name for Jacquin’s taxon. Full synonymies ofIpomoea macrantha andOperculina ventricosa are given, along with a comment about a variant occurring in Micronesia.     

金钟藤中酚类化合物的研究

从金钟藤(Merremia boisiana(Gagnep.)V.Ooststr.)的地上部分分离得到8个酚类化合物。通过光谱分析,分别鉴定为东莨菪内酯(1)、七叶内酯(2)、N-p-香豆酰酪胺(3)、3,5-二咖啡酰基奎尼酸甲酯(4)、3,4-二咖啡酰基奎尼酸甲酯(5)、3,4,5-三咖啡酰基奎尼酸甲酯(6)、槲皮素(7)以及山奈酚-3-β-D-半乳糖甙(8)。这些化合物均是首次从鱼黄草属(Merremia)植物中发现。     

Enlargement of fibrous roots inIpomoea sectionBatatas (Convolvulaceae)

The bank of sweet potato germplasm at the International Potato Center (CIP) in Lima, Peru, is made up of cultivated germplasm [Ipomoea batatas (L.) Lam.] and wild germplasm collected in Latin America and the Caribbean. In the wild germplasm sectionBatatas is included because of its genetic importance in relation to its phylogenetic affinity with the cultivated sweet potato. In our study we have included 11 wild species of the section to identify and determine the primary factors that influence the enlargement of fibrous roots under greenhouse conditions. Thus, the study was divided into two sequential phases: a) identification of wild species with thickened fibrous roots; b) determination of the primary factors that influence the thickening of fibrous roots. The first phase began between 197 and 593 days after planting the 11 species by using a visual evaluation of the roots according to the gradual scale: 0 = fibrous roots; 1 = slightly thickened; 2 = moderately thickened; 3 = thickened; 4 = very thick. As a result four species were identified in categories three and four (I. batatas, I. cordato-triloba, I. tiliacea, andI. ramosissima). The second phase was begun between 123 and 669 days after planting of nine species identified with some category of enlargement according to an evaluation with a gradual quantified scale: 0 = <1.45 mm; 1 = 1.45–3.99 m; 2 = 4.0–6.99 mm; 3 = 7.0–9.0 mm; 4 = >9.0 mm. In this phase, two physiological factors were identified (vegetative period and volume of substrate) and a genetic factor (level of ploidy), which directly influence the thickening of fibrous roots. Considering the four species identified with thickened fibrous roots in categories three and four in the two phases of the study [I. batatas (4x),I. tiliacea (4x),I. cordato-triloba (2x) andI. ramosissima (2x)], we propose a plan for the use of wild germplasm in a program of systematic genetic improvement of the sweet potato.     

A new species of Ipomoea section Quamoclit (Convolvulaceae) from the Caribbean and a new combination for a Mexican species

Ipomoea praematura sp. nov. differs fromI. hederifolia L., its closest congener, in flower color and phenology, capsule shape, and seed shape and pubescence. Other distinguishing characteristics show some overlap with its more widespread and variable relative. The new species grows along the Caribbean coast of South America and on nearby islands. The recently described MexicanQuamoclit fissifolia McPherson is transferred asIpomoea fissifolia.     

Pollen evolution and its taxonomic significance in Cuscuta (dodders, Convolvulaceae)

The pollen morphology of 148 taxa (135 species and 13 varieties) of the parasitic plant genus Cuscuta (dodders, Convolvulaceae) was examined using scanning electron microscopy. Six quantitative characters were coded using the gap-weighting method and optimized onto a consensus tree constructed from three large-scale molecular phylogenies of the genus based on nuclear internal transcribed spacer (ITS) and plastid trn-LF sequences. The results indicate that 3-zonocolpate pollen is ancestral, while grains with more colpi (up to eight) have evolved only in two major lineages of Cuscuta (subg. Monogynella and clade O of subg. Grammica). Complex morphological intergradations occur between species when their tectum is described using the traditional qualitative types—imperforate, perforate, and microreticulate. This continuous variation is better expressed quantitatively as “percent perforation,” namely the proportion of perforated area (puncta or lumina) from the total tectum surface. Tectum imperforatum is likely the ancestral condition, while pollen grains with increasingly larger perforation areas have evolved multiple times. The reticulated tectum, unknown in other Convolvulaceae, has evolved in Cuscuta only in two lineages (subg. Monogynella, and clade O of subg. Grammica). Overall, the morphology of pollen supports Cuscuta as a sister to either the “bifid-style” Convolvulaceae clade (Dicranostyloideae) or to one of the members of this clade. Pollen characters alone are insufficient to reconstruct phylogenetic relationships; however, palynological information is useful for the species-level taxonomy of Cuscuta.     

Keraunea gen. nov. (Convolvulaceae) from Brazil

Keraunea Cheek & Simão‐Bianchini gen. nov. (Convolvulaceae) from Brazil is described and illustrated as the third known neuropeltoid genus. It appears allied to the Old World genera of Neuropeltis Wall and Neuropeltopsis Ooststr. in having wind‐dispersed fruits not by enlarged sepals, but subtended by an enlarged papery bract to which the pedicel is adnate, and flowers in which the bracteoles are absent or usually very inconspicuous. Keraunea brasiliensis, the single species thus far known, is here assessed as ‘Endangered’.     

New natural hybrids of Convolvulus (Convolvulaceae) from Turkey

The present study introduces two new nothospecies from Turkey, Convolvulus×pseudocompactus C. Aykurt & Sümbül (C. oleifolius Desr. var. deserti Pamp.×C. compactus Boiss.) and Convolvulus×peshmenii C. Aykurt & Sümbül (C. holosericeus Bieb. subsp. macrocalycinus Hausskn. & Bornm.×C. compactus Boiss.). Morphological differences and similarities between the hybrids and their parents are discussed; in addition, habit and sepals are illustrated as diagnostic characters, and the geographic distribution of the hybrids and their parents are mapped. Pollen characteristics of Convolvulus×pseudocompactus, Convolvulus×peshmenii and their parents were examined by means of light microscopy and SEM. Detailed morphological and palynological investigations have been performed for hybrid individuals and parental species. As a result of the palynological investigations, the rate of dehydrated pollen grains was established as an important criterion to determine the hybrid status of Convolvulus taxa.