Morphology and Viability of Pollen from Three Hardy Water Lilies and Their Cross-Compatibility with Nymphaea hybrid

Huihui Zhang,Zunling Zhu,Qi Zhou,Huaiyan Wu,Qianqian Sheng

doi:10.3390/d14020092

Abstract

Owing to the wide variation in their morphological characteristics across diverse geographies, the identification and classification of plants in the Nymphaea genus are challenging. Therefore, the present study investigated the pollen morphological characteristics of hardy water lilies (N. ‘Rose Arey’, N. ‘Perry’s Fire Opal’, and N. ‘Peter Slocum’), their relationship with species classification and system evolution, and their cross-compatibility with three strains of Nymphaeahybrid (NH-1, NH-2, and NH-3), a tropical waterlily. Pollen of the hardy water lilies was single-grained, oblate, and 18.31–20.47 × 32.51–37.64 μm. The pollen apertures were of the ring-groove type, and the pollen exine ornamentation was rod- and tumour-shaped. Pollen grains of different species differed in size, the obviousness of tumour ornamentation, and the size and density of rod-like ornamentation; their germination rates also differed significantly. Viabilities of N. ‘Rose Arey’ and N. ‘Peter Slocum’ pollen were the highest and lowest, respectively. According to the artificial pollination results, all hybrid combinations except three (NH-1 × N. ‘Peter Slocum’, NH-2 × N. ‘Peter Slocum’, and NH-3 × N. ‘Peter Slocum’) bore seeds; combinations with NH-2 as the female parent and N. ‘Rose Arey’ as the male parent had the highest seed-setting rates.

Highlights

The water lily is a perennial aquatic plant of the genus Nymphaea in the familyNymphaeaceae; it has an early evolutionary origin and represents a rich plant resource
The results of this study showed that the pollen grains of the three hardy water lilies were oblate, triangular in the polar view, and oblong in the equatorial view; the pollen exine ornamentation was found to be rod-shaped and tumour-shaped, which was similar to the results of the study by Volkova et al on pollen from hardy water lilies [24] but was different from the results of the studies by Bodhipadma et al on N. nouchali var. versicolor [25], Coiro et al on N. caerulea and N. gigantea [26], Taylor et al on N. ondinea [21], and Zhang et al on N. hybrid [28] and pollen from other tropical water lilies
These differences among the varieties were evident. This showed that the morphology of pollen grains from different subgenera, populations, and varieties of plants in the genus Nymphaea exhibits a certain degree of difference

Summary

Introduction

The water lily is a perennial aquatic plant of the genus Nymphaea in the familyNymphaeaceae; it has an early evolutionary origin and represents a rich plant resource. It contains important active ingredients that can be used in food and beverages [2] and possesses antibacterial [3], antianxiety [4], and anti-hepatotoxicity [5] activities This plant is widely used in the fields of horticulture, ornamental botany, food science, and medicine. Plants from the genus Nymphaea are mainly identified according to the morphology of external parts, such as stems, leaves, flowers, and seeds, given that these are easy to observe. These plants can be divided into five subgenera: Nymphaea (northern temperatures), Brachyceras (pantropical), Anecphya (Australia), Hydrocallis (neotropics), and Lotos (palaeotropics) [6]. The former is mainly naturally distributed in subtropical and temperate areas, and the latter is mainly distributed in tropical areas

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Discussion

Conclusion