Blocked pollen release prevents fruit formation in the halophyte Elaeagnus angustifolia in non-saline habitats

Jianrong Guo,Baoshan Wang

doi:10.1016/j.envexpbot.2021.104566

Abstract

Anther development affects the reproduction of flowering plants. Halophyte Elaeagnus angustifolia can bear fruits when grown in saline soils. However, no fruits are born in non-saline soils. The possible reasons and differences in E. angustifolia under two growing conditions were elucidated. We examined features including pollen viability and germination, in situ pollen germination after natural and hand pollination, anthers after pollen release, and the transcriptome in anthers. No significant difference was observed in pollen viability or stigma receptivity in E. angustifolia in non-saline vs. saline habitats. However, no pollen tubes were present in styles, and pollen grains were abundant in E. angustifolia anthers under non-saline conditions. Notably, many pollen tubes formed in styles of E. angustifolia after hand pollination in the non-saline habitat. The differentially expressed genes in anthers from saline vs. non-saline habitats were mainly related to phytohormone, cell wall secondary thickening, transcription factors and ion transport. E. angustifolia fail to form fruits in non-saline habitats due to poor anther pollen release. The induction and coordinated upregulation of genes related to anther cell wall formation and JA biosynthesis likely contribute to anther dehiscence in E. angustifolia in saline habitats, whereas anther dehiscence is blocked in plants grown in non-saline habitats.

Highlights

Anther development affects the reproduction of flowering plants
The induction and coordinated upregulation of genes related to anther cell wall formation and jasmonic acid (JA) biosynthesis likely contribute to anther dehiscence in E. angustifolia in saline habitats, whereas anther dehiscence is blocked in plants grown in non-saline habitats
No significant difference in pollen viability or stigma receptivity between habitats To determine whether the lack of fruit in E. angustifolia in the non-saline habitat was caused by poor pollen vitality, we dyed pollen collected from E. angustifolia in both habitats with Alexander’s solution

Summary

Introduction

Halophyte Elaeagnus angustifolia can produce fruits when grown in saline soils. Elaeagnus angustifolia L., a member of the Elaeagnaceae family, can grow in a wide range of environmental conditions [10]. This tree is deciduous, with unique silver-gray scales covering the leaves, flowers, and newly grown branchlets. E. angustifolia fruit is edible and sweet, with a single seed [11], and the roots undergo nitrogen fixation [12]. Since this tree is resistant to salt and drought stress and is strongly adaptable, it is widely used for urban and road greening. Little is known about the reproductive development of E. angustifolia in saline environments, especially compared to non-saline environments

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Conclusion