The Establishment of an Efficient Callus Induction System for Lotus (Nelumbo nucifera).

Xianbao Deng,Jing Li,Heyun Song,Yaqian Xiong,Junyu Ma,Yanling Liu,Mei Yang,Juan Liu,Heng Sun,Yunmeng Wang,Dong Yang

doi:10.3390/plants9111436

Abstract

The lotus (Nelumbo nucifera) is one of the most popular aquatic plants in Asia, and has emerged as a novel model for studying flower and rhizome development, and primary and secondary metabolite accumulation. Here, we developed a highly efficient callus induction system for the lotus by optimizing a series of key factors that affect callus formation. The highest efficient callus production was induced on immature cotyledon and embryo explants grown on Murashige and Skoog (MS) basal medium containing an optimized combination of 3 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/L 6-benzylaminopurine (6-BA). In addition, lotus callus induction was proven to be influenced by lotus genotypes, light conditions, the developmental stages of explants and the time of explant sampling. Collecting immature cotyledons from seeds of the genotype “Shilihe 1”, at 9 days post pollination, and to culture the explants in darkness, are proposed as the optimum conditions for lotus callus induction. Interestingly, highly efficient callus induction was also observed in explants of immature embryo derived aseptic seedlings; and a small amount of lotus benzylisoquinoline alkaloid (BIA) and obvious expression of BIA biosynthetic genes were detected in lotus callus.

Highlights

The Asian lotus (Nelumbo nucifera) is one of the only two extant species in the Nelumbonaceae family, cultivated throughout Asia for its high ornamental, edible and medicinal value [1]
Approximately 50% of leaf explants and 20% of shoot tip explants remained sterile after 4 days of culture on Murashige and Skoog (MS) medium, whereas over 95% of cotyledon and embryo explants were sterile
Immature cotyledons taken from seeds 9 days after pollination showed the earliest signs of callus formation at around 5 days post culture, followed by the sections of immature embryos taken from seeds 18 days after pollination, about 7 days after culture initiation

Summary

Introduction

The Asian lotus (Nelumbo nucifera) is one of the only two extant species in the Nelumbonaceae family, cultivated throughout Asia for its high ornamental, edible and medicinal value [1]. The rhizome lotus develops enlarged edible rhizomes, and a few flowers bloom in summertime. The flower lotus is cultivated primarily for ornamental purposes; it blooms dense and attractive flowers and produces a few seeds. The seed lotus develops numerous seed producing flowers, and is cultivated for harvesting fresh seedpods as fruits or mature seeds as food. The whole lotus plant is rich in bioactive benzylisoquinoline alkaloids (BIA) with significant medicinal properties, such as anti-obesity [3,4], anti-tumor [5,6], anti-diabetic [7] and anti-viral [8] activities

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Conclusion