Inflorescence and fruit structure in Maclura pomifera (Moraceae): study of its parthenogenesis

Subject Areas : Developmental biology of plants and animals , development and differentiation in microorganisms

Roza Arab ¹ , Farkhondeh Rezanejad ²

1 - Department of Biology, Islamic Azad University of Bam, Kerman, Iran
2 - Department of Biology, Shahid Bahonar university of Kerman, Kerman, Iran

Received: 2023-06-27 Accepted : 2023-07-31 Published : 2024-01-21

Keywords: Pollination, Moraceae, Maclura pomifera, souda plant, parthenogenesi,

Abstract :

Maclura pomifera (Moraceae), known as souda or American mulberry, is dioecious, about 5-8 meters long that its fruits have a very sticky sap. In different areas of Kerman city, no male tree was observed and all distributed plants were female. Interestingly, these female trees, produced seeds. It has been reported that some species Moraceae produce fruits and seeds without fertilization, a phenomenon called parthenogenesis. In this study, the structure of inflorescences and flowers were investigated. Further, some flowers were covered with wax paper bags to prevent pollination. The presence of pollen in pistil tissues was studied with a fluorescent microscopy. The dense and spherical female inflorescence has about 60-70 flowers with a single- whorled perianth similar to the sepals. The sepals were tetrameric and pink at young first and become fleshy and green during growth. The pistil and perianth (sepals) surrounding it together developed to a drupe like fruit. The pistil was unicarpellate and long style. The drupe-like fruits form each inflorescence formed accessory fruit, atypical fruit, with pomaceous view. No pollen grains were observed on pistil tissues (stigma, style and ovary) by aniline blue staining. The fruits of both closed (by wax paper bags) and open inflorescences produced about 8-18 seeds. The seeds was viable and during germination produced seedlings in perlite media without any chemical or physical treatment. Seed formation without pollination and fertilization in this species confirms the parthenogenesis phenomenon; this study is the first report about the occurrence of parthenogenesis in M. pomifera.