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Heteromorphic incompatibility and efficiency of pollination in two distylous Pentanisia species (Rubiaceae).
Ann Bot 2005; 95(3):389-99AB

Abstract

BACKGROUND AND AIMS

Distyly has been hypothesized to promote cross-pollination by reducing intrafloral and geitonogamous self-pollination, and enhancing intermorph pollination. Distylous plants typically display both reciprocal herkogamy and a heteromorphic incompatibility system, which allows mating only between morphs. Distyly and its pollination consequences were examined in two Pentanisia species with long-tubed flowers which are pollinated almost exclusively by butterflies.

METHODS

Anther and stigma heights were measured to quantify reciprocal herkogamy. The type of incompatibility system was determined by observing pollen tubes and seed production following controlled hand pollination. Pollen loads on pollinators and stigmas were also examined to assess the efficiency of intermorph pollen flow.

KEY RESULTS

Pentanisia prunelloides and P. angustifolia exhibit reciprocal herkogamy and a host of ancillary dimorphisms, including pollen colour, exine sculpturing, stigmatic papilla shape and floral-tube pubescence. Controlled hand-pollinations revealed the presence of a strong heteromorphic incompatibility system in both species. The site of incompatibility differed between the morphs; intramorph pollen tubes were blocked in the style of the short-styled morph and on the stigmatic surface of the long-styled morph. Butterflies carried pollen from the short- and long-styled morphs primarily on their head and proboscis, respectively. Natural pollination resulted in a higher proportion of pollen transfer from long- to short-styled plants than vice versa. Nevertheless, fruit set did not differ between morphs.

CONCLUSIONS

Both Pentanisia species are fully distylous. Reciprocal herkogamy results in pollen from the two morphs being carried on different locations on pollinators' bodies, which in turn promotes intermorph pollination. Intramorph pollination does not result in fertilization, because of an effective heteromorphic incompatibility system.

Authors+Show Affiliations

School of Botany and Zoology, University of Kwazulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15596454

Citation

Massinga, Paulo H., et al. "Heteromorphic Incompatibility and Efficiency of Pollination in Two Distylous Pentanisia Species (Rubiaceae)." Annals of Botany, vol. 95, no. 3, 2005, pp. 389-99.
Massinga PH, Johnson SD, Harder LD. Heteromorphic incompatibility and efficiency of pollination in two distylous Pentanisia species (Rubiaceae). Ann Bot. 2005;95(3):389-99.
Massinga, P. H., Johnson, S. D., & Harder, L. D. (2005). Heteromorphic incompatibility and efficiency of pollination in two distylous Pentanisia species (Rubiaceae). Annals of Botany, 95(3), pp. 389-99.
Massinga PH, Johnson SD, Harder LD. Heteromorphic Incompatibility and Efficiency of Pollination in Two Distylous Pentanisia Species (Rubiaceae). Ann Bot. 2005;95(3):389-99. PubMed PMID: 15596454.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Heteromorphic incompatibility and efficiency of pollination in two distylous Pentanisia species (Rubiaceae). AU - Massinga,Paulo H, AU - Johnson,Steven D, AU - Harder,Lawrence D, Y1 - 2004/12/13/ PY - 2004/12/15/pubmed PY - 2005/3/24/medline PY - 2004/12/15/entrez SP - 389 EP - 99 JF - Annals of botany JO - Ann. Bot. VL - 95 IS - 3 N2 - BACKGROUND AND AIMS: Distyly has been hypothesized to promote cross-pollination by reducing intrafloral and geitonogamous self-pollination, and enhancing intermorph pollination. Distylous plants typically display both reciprocal herkogamy and a heteromorphic incompatibility system, which allows mating only between morphs. Distyly and its pollination consequences were examined in two Pentanisia species with long-tubed flowers which are pollinated almost exclusively by butterflies. METHODS: Anther and stigma heights were measured to quantify reciprocal herkogamy. The type of incompatibility system was determined by observing pollen tubes and seed production following controlled hand pollination. Pollen loads on pollinators and stigmas were also examined to assess the efficiency of intermorph pollen flow. KEY RESULTS: Pentanisia prunelloides and P. angustifolia exhibit reciprocal herkogamy and a host of ancillary dimorphisms, including pollen colour, exine sculpturing, stigmatic papilla shape and floral-tube pubescence. Controlled hand-pollinations revealed the presence of a strong heteromorphic incompatibility system in both species. The site of incompatibility differed between the morphs; intramorph pollen tubes were blocked in the style of the short-styled morph and on the stigmatic surface of the long-styled morph. Butterflies carried pollen from the short- and long-styled morphs primarily on their head and proboscis, respectively. Natural pollination resulted in a higher proportion of pollen transfer from long- to short-styled plants than vice versa. Nevertheless, fruit set did not differ between morphs. CONCLUSIONS: Both Pentanisia species are fully distylous. Reciprocal herkogamy results in pollen from the two morphs being carried on different locations on pollinators' bodies, which in turn promotes intermorph pollination. Intramorph pollination does not result in fertilization, because of an effective heteromorphic incompatibility system. SN - 0305-7364 UR - https://www.unboundmedicine.com/medline/citation/15596454/Heteromorphic_incompatibility_and_efficiency_of_pollination_in_two_distylous_Pentanisia_species__Rubiaceae__ L2 - https://academic.oup.com/aob/article-lookup/doi/10.1093/aob/mci040 DB - PRIME DP - Unbound Medicine ER -