2
|
Lux A, Lackovič A, Van Staden J, Lišková D, Kohanová J, Martinka M. Cadmium translocation by contractile roots differs from that in regular, non-contractile roots. Ann Bot 2015; 115:1149-54. [PMID: 25939652 PMCID: PMC4648461 DOI: 10.1093/aob/mcv051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/20/2015] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Contractile roots are known and studied mainly in connection with the process of shrinkage of their basal parts, which acts to pull the shoot of the plant deeper into the ground. Previous studies have shown that the specific structure of these roots results in more intensive water uptake at the base, which is in contrast to regular root types. The purpose of this study was to find out whether the basal parts of contractile roots are also more active in translocation of cadmium to the shoot. METHODS Plants of the South African ornamental species Tritonia gladiolaris were cultivated in vitro for 2 months, at which point they possessed well-developed contractile roots. They were then transferred to Petri dishes with horizontally separated compartments of agar containing 50 µmol Cd(NO3)2 in the region of the root base or the root apex. Seedlings of 4-d-old maize (Zea mays) plants, which do not possess contractile roots, were also transferred to similar Petri dishes. The concentrations of Cd in the leaves of the plants were compared after 10 d of cultivation. Anatomical analyses of Tritonia roots were performed using appropriately stained freehand cross-sections. KEY RESULTS The process of contraction required specific anatomical adaptation of the root base in Tritonia, with less lignified and less suberized tissues in comparison with the subapical part of the root. These unusual developmental characteristics were accompanied by more intensive translocation of Cd ions from the basal part of contractile roots to the leaves than from the apical-subapical root parts. The opposite effects were seen in the non-contractile roots of maize, with higher uptake and transport by the apical parts of the root and lower uptake and transport by the basal part. CONCLUSIONS The specific characteristics of contractile roots may have a significant impact on the uptake of ions, including toxic metals from the soil surface layers. This may be important for plant nutrition, for example in the uptake of nutrients from upper soil layers, which are richer in humus in otherwise nutrient-poor soils, and also has implications for the uptake of surface-soil pollutants.
Collapse
Affiliation(s)
- Alexander Lux
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic
| | - Andrej Lackovič
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic
| | - Johannes Van Staden
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic
| | - Desana Lišková
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic
| | - Jana Kohanová
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic
| | - Michal Martinka
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 38, Slovak Republic, Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa and Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 845 23, Slovak Republic
| |
Collapse
|
3
|
Anderson B, Ros P, Wiese TJ, Ellis AG. Intraspecific divergence and convergence of floral tube length in specialized pollination interactions. Proc Biol Sci 2014; 281:20141420. [PMID: 25274360 PMCID: PMC4213615 DOI: 10.1098/rspb.2014.1420] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 08/27/2014] [Indexed: 11/12/2022] Open
Abstract
Floral tubes are often thought to be a consequence of adaptive specialization towards pollinator morphology. We explore floral tube length evolution within Tritoniopsis revoluta (Iridaceae), a species with considerable geographical tube length variation. We ask whether tube lengths of T. revoluta populations are associated with pollinator proboscis lengths, whether floral divergence occurs in the presence of different pollinators and whether floral convergence occurs between distantly related populations pollinated by the same pollinator. Finally, we ask whether tube length evolution is directional. Shifts between morphologically different pollinators were always associated with shifts in floral morphology, even when populations were very closely related. Distantly related populations had similar tube lengths when they were pollinated by the same pollinator. Shifts in tube length tended to be from short to long, although reversals were not infrequent. After correcting for the population-level phylogeny, there was a strong positive, linear relationship between floral tube length and pollinator proboscis length, suggesting that plants are functionally specialized on different pollinators at different sites. However, because tube length evolution in this system can be a bidirectional process, specialization to the local pollinator fauna is unlikely to result in evolutionary or ecological dead-ends such as canalization or range limitation.
Collapse
Affiliation(s)
- B Anderson
- Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
| | - P Ros
- Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
| | - T J Wiese
- Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
| | - A G Ellis
- Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
| |
Collapse
|
5
|
Sánchez JM, Ferrero V, Arroyo J, Navarro L. Patterns of style polymorphism in five species of the South African genus Nivenia (Iridaceae). Ann Bot 2010; 106:321-31. [PMID: 20576739 PMCID: PMC2908166 DOI: 10.1093/aob/mcq111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 04/08/2010] [Accepted: 04/20/2010] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Heterostylous plants have been characterized by the presence of two or three discrete morphs that differ in their sex organ position within populations. This polymorphism is widely distributed among the angiosperms, but detailed studies are limited to few taxonomic groups. Although a small representation, evolutionary meaningful variations of the heterostylous syndrome have been reported when precise measurements of the sexual whorls were taken. A thorough exploration of groups where heterostyly has been reported should offer new opportunities to further testing the evolutionary hypotheses explaining heterostyly. Here, the traits defining heterostyly were explored in half of the species in Nivenia, the only genus of Iridiaceae where heterostyly has been reported. METHODS Detailed morphometric analysis of the flower sexual whorls and some traits considered as ancillary are supplied to determine for each population (a) the kind of stylar polymorphism, (b) the morph ratio and (c) the degree of reciprocity between sexual whorls. Also the rates of assortative (within morph) versus disassortative (between morphs) pollen transfer were estimated by analysing pollen loads on stigmas. The association between floral phenotypic integration and the reciprocity between sexual whorls was estimated; both characteristics have been quoted as dependent on the accuracy of the fit between pollinators and flowers and therefore related to the efficiency of pollen transfer. KEY RESULTS Different types of polymorphism, differing in their degree of reciprocity, were found in Nivenia. Effective disassortative mating appears to be common, since (a) all dimorphic populations show equal morph-ratios (isoplethy), and (b) the pollen placed on the stigmas of each morph is likely to be coming from the other (complementary) morph. The most reciprocal populations of the heterostylous species have also the highest values of phenotypical integration. CONCLUSIONS Stigma height dimorphism, as opposed to distyly, is proven for the first time in Nivenia. The presence of different types of polymorphism within the genus is consistent with hypotheses of the evolution of heterostyly. The role of the pollinators as the leading force of the transition seems to be apparent, since floral integration is related to reciprocity.
Collapse
Affiliation(s)
- J M Sánchez
- Departamento de Biología Vegetal y Ciencia del Suelo, Universidad de Vigo, Spain.
| | | | | | | |
Collapse
|
6
|
Abstract
BACKGROUND Seventeen distinct pollination systems are known for genera of sub-Saharan African Iridaceae and recurrent shifts in pollination system have evolved in those with ten or more species. Pollination by long-tongued anthophorine bees foraging for nectar and coincidentally acquiring pollen on some part of their bodies is the inferred ancestral pollination strategy for most genera of the large subfamilies Iridoideae and Crocoideae and may be ancestral for the latter. Derived strategies include pollination by long-proboscid flies, large butterflies, night-flying hovering and settling moths, hopliine beetles and sunbirds. Bee pollination is diverse, with active pollen collection by female bees occurring in several genera, vibratile systems in a few and non-volatile oil as a reward in one species. Long-proboscid fly pollination, which is apparently restricted to southern Africa, includes four separate syndromes using different sets of flies and plant species in different parts of the subcontinent. Small numbers of species use bibionid flies, short-proboscid flies or wasps for their pollination; only about 2 % of species use multiple pollinators and can be described as generalists. SCOPE Using pollination observations for 375 species and based on repeated patterns of floral attractants and rewards, we infer pollination mechanisms for an additional 610 species. Matching pollination system to phylogeny or what is known about species relationships based on shared derived features, we infer repeated shifts in pollination system in some genera, as frequently as one shift for every five or six species of southern African Babiana or Gladiolus. Specialized systems using pollinators of one pollination group, or even a single pollinator species are the rule in the family. Shifts in pollination system are more frequent in genera of Crocoideae that have bilaterally symmetric flowers and a perianth tube, features that promote adaptive radiation by facilitating precise shifts in pollen placement, in conjunction with changes in flower colour, scent and tube length. CONCLUSIONS Diversity of pollination systems explains in part the huge species diversity of Iridaceae in sub-Saharan Africa, and permits species packing locally. Pollination shifts are, however, seen as playing a secondary role in speciation by promoting reproductive isolation in peripheral, ecologically distinct populations in areas of diverse topography, climate and soils. Pollination of Iridaceae in Eurasia and the New World, where the family is also well represented, is poorly studied but appears less diverse, although pollination by both pollen- and oil-collecting bees is frequent and bird pollination rare.
Collapse
Affiliation(s)
- Peter Goldblatt
- B. A. Krukoff Curator of African Botany, Missouri Botanical Garden, PO Box 299, St Louis, MO 63166, USA.
| | | |
Collapse
|