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Floral Biology and Embryological Studies are Important for Conservation of Threatened Plants Having Reproductive Bottlenecks:A Case Study of Illicium griffithii Hook. f. & Thomson


Affiliations
1 Department of Botany, Centre of Advanced Studies in Botany, North Eastern Hill University, Shillong 793 022, India
2 Centre for Biodiversity Studies, Baba Ghulam Shah Badshah University, Rajouri 185 234, India
3 Department of Forest Products, Dr Y.S. Parmar University of Horticulture and Forestry, Solan 173 23, India
 

Information on reproductive biology of threatened plant species could be useful for conservation, particularly when the species fails to perpetuate in nature due to regeneration failure. In flowering plants, the domain of reproductive biology includes structural details of reproductive units such as flower or inflorescence, formation of viable gametes, pollination dynamics, role of pollinators, pollen–pistil interactions as determined through compatibility, breeding system and mating strategies, fertilization and embryogeny, seed development, dispersal and germination. The importance of reproductive biology in species conservation has been demonstrated through a case study of Illicium griffithii Hook f. & Thomson, a threatened plant species from Arunachal Pradesh. I. griffithii (Illiciaceae) is a member of the ANITA clade and a representative taxon of the three most basal angiosperms. The flowers of I. griffithii are obligate xenogamous, and hence compatible pollen grains only germinate on the stigmatic papillae. Esterase and phosphatase enzymatic activities are absent in most stigmatic surfaces. Therefore, stigmatic receptivity is absent in many carpels. The ovules are anatropous and bitegmic with a four-celled/four-nucleate structure of embryo sac at maturity. Antipodals and filiform apparatus are absent. Presence of mucilage cells in the embryo sac facilitates the entry of pollen tubes into it. Embryolike organization of the endosperm is present, with one pole globular having smaller cells and the other pole roughly filamentous with larger cells resembling that of a suspensor. Extragynoecial compitum is not observed in I. griffithii. The flowers are brooding sites for the midges and the young ovules are eaten by larvae of the midges. Only 10% of the flowers mature into 13-seeded fruits and the carpels of the remaining 90% of the flowers have seeds ranging from 1 to 5. The seedling survival rate is only 7%. In addition to the above-mentioned reproductive bottlenecks, the species is also being over-harvested. It is now categorized as endangered. The findings of the present study on reproductive biology of I. griffithii should help in improving its conservation status.

Keywords

Embryological Studies, Floral Biology, Illicium griffithii, Reproductive Bottlenecks, Threatened Species Conservation.
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  • Floral Biology and Embryological Studies are Important for Conservation of Threatened Plants Having Reproductive Bottlenecks:A Case Study of Illicium griffithii Hook. f. & Thomson

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Authors

E. J. Marbaniang
Department of Botany, Centre of Advanced Studies in Botany, North Eastern Hill University, Shillong 793 022, India
N. Venugopal
Department of Botany, Centre of Advanced Studies in Botany, North Eastern Hill University, Shillong 793 022, India
Susheel Verma
Centre for Biodiversity Studies, Baba Ghulam Shah Badshah University, Rajouri 185 234, India
Ravinder Raina
Department of Forest Products, Dr Y.S. Parmar University of Horticulture and Forestry, Solan 173 23, India
Ankush Khajuria
Centre for Biodiversity Studies, Baba Ghulam Shah Badshah University, Rajouri 185 234, India
Kamini Gautam
Department of Forest Products, Dr Y.S. Parmar University of Horticulture and Forestry, Solan 173 23, India

Abstract


Information on reproductive biology of threatened plant species could be useful for conservation, particularly when the species fails to perpetuate in nature due to regeneration failure. In flowering plants, the domain of reproductive biology includes structural details of reproductive units such as flower or inflorescence, formation of viable gametes, pollination dynamics, role of pollinators, pollen–pistil interactions as determined through compatibility, breeding system and mating strategies, fertilization and embryogeny, seed development, dispersal and germination. The importance of reproductive biology in species conservation has been demonstrated through a case study of Illicium griffithii Hook f. & Thomson, a threatened plant species from Arunachal Pradesh. I. griffithii (Illiciaceae) is a member of the ANITA clade and a representative taxon of the three most basal angiosperms. The flowers of I. griffithii are obligate xenogamous, and hence compatible pollen grains only germinate on the stigmatic papillae. Esterase and phosphatase enzymatic activities are absent in most stigmatic surfaces. Therefore, stigmatic receptivity is absent in many carpels. The ovules are anatropous and bitegmic with a four-celled/four-nucleate structure of embryo sac at maturity. Antipodals and filiform apparatus are absent. Presence of mucilage cells in the embryo sac facilitates the entry of pollen tubes into it. Embryolike organization of the endosperm is present, with one pole globular having smaller cells and the other pole roughly filamentous with larger cells resembling that of a suspensor. Extragynoecial compitum is not observed in I. griffithii. The flowers are brooding sites for the midges and the young ovules are eaten by larvae of the midges. Only 10% of the flowers mature into 13-seeded fruits and the carpels of the remaining 90% of the flowers have seeds ranging from 1 to 5. The seedling survival rate is only 7%. In addition to the above-mentioned reproductive bottlenecks, the species is also being over-harvested. It is now categorized as endangered. The findings of the present study on reproductive biology of I. griffithii should help in improving its conservation status.

Keywords


Embryological Studies, Floral Biology, Illicium griffithii, Reproductive Bottlenecks, Threatened Species Conservation.

References





DOI: https://doi.org/10.18520/cs%2Fv114%2Fi03%2F576-587