The fertilization process in Lithocarpus dealbatus (Fagaceae) and its implication on the sexual reproduction evolution of Fagales

Kaiping Yao; Min Deng; Lin Lin; Jinjin Hu; Xiaorui Yang; Qiansheng Li; Zhuo Feng

doi:10.1007/s00425-023-04178-0

The fertilization process in Lithocarpus dealbatus (Fagaceae) and its implication on the sexual reproduction evolution of Fagales

Planta. 2023 Jun 21;258(2):23. doi: 10.1007/s00425-023-04178-0.

Authors

Kaiping Yao^#^{1

2

3}, Min Deng^#^{4

5

6}, Lin Lin^{1

2

3}, Jinjin Hu⁷, Xiaorui Yang⁸, Qiansheng Li⁹, Zhuo Feng¹⁰

Affiliations

¹ School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China.
² Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Institute of Biodiversity, Yunnan University, Kunming, 650504, Yunnan, China.
³ The Key Laboratory of Rare and Endangered Forest Plants of National Forestry and Grassland Administration and the Key Laboratory for Silviculture and Forest Resources Development of Yunnan Province, Yunnan, Academy of Forestry and Grassland, Kunming, 650201, Yunnan, China.
⁴ School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China. dengmin@ynu.edu.cn.
⁵ Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Institute of Biodiversity, Yunnan University, Kunming, 650504, Yunnan, China. dengmin@ynu.edu.cn.
⁶ The Key Laboratory of Rare and Endangered Forest Plants of National Forestry and Grassland Administration and the Key Laboratory for Silviculture and Forest Resources Development of Yunnan Province, Yunnan, Academy of Forestry and Grassland, Kunming, 650201, Yunnan, China. dengmin@ynu.edu.cn.
⁷ Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China.
⁸ Shanghai Chenshan Botanical Garden, Shanghai, 201602, China.
⁹ Atlanta Botanical Garden, Atlanta, GA, 30309, USA. qli@atlantabg.org.
¹⁰ Institute of Palaeontology, Yunnan Key Laboratory of Earth System Science, Yunnan Key Laboratory for Palaeobiology, MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, 650500, China. zhuofeng@ynu.edu.cn.

^# Contributed equally.

PMID: 37341801
DOI: 10.1007/s00425-023-04178-0

Abstract

The pistillate flowers of Lithocarpus dealbatus show two pollen tube (PT) arresting sites (the style-joining and micropyle) within the pistil during the postpollination-prezygotic stage. The PT, arrested at the pre-ovule stage, enhanced PT competition allowing the most compatible PTs to enter the ovary to ensure the highest fertilization success. During the shift from animal pollination to wind pollination, plants require a series of changes in reproductive traits. The mode of pollination is striking labile in Fagaceae. Lithocarpus is insect pollinated and is closely related to wind-pollinated Quercus. Little is known about the sexual reproduction of Lithocarpus. This study aimed to reveal the sexual reproduction of Lithocarpus dealbatus and to explore the evolutionary pattern of the key sexual reproduction traits to better understand their possible role in labile pollination. We found that after pollination, L. dealbatus PTs grew slowly in the style reaching style-joining in mid-January of the second year; then PT growth was arrested at style-joining for four months. Only two to three PTs resumed growth in mid-May to reach the micropyle, where PT growth ceased for one month before one PT resumed growth and passed through the micropyle to the embryo sac. Fagaceae showed a generalized mating system. Vast pollen production, small-sized pollen grains, long stigmatic receptive time, and reduced perianth were compatible with beetle pollination syndrome, representing the plesiomorphic status in Fagaceae. A large stigmatic surface and dry pollen grains linked to wind pollination might be independently derived several times in fagaceous lineages. Beetle pollination syndrome can cope with the uncertainty of pollinators to ensure conspecific pollen capture, which represents pre-adaptation status and has a selective advantage when conditions change, favouring wind pollination. The arrest of the PT at style-joining is a unique mechanism in later derived fagaceous lineages to enhance PT competition and promote outcrossing.

Keywords: Adaptation; Delayed fertilization; Pollen tube growth; Pollination mode; Trait evolution.

MeSH terms

Fagaceae*
Fagales
Fertilization
Flowers
Pollination
Reproduction

Abstract

MeSH terms

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