Xuelian Liu, Yu Qin, Dingding Cao, Jiao Deng, Songbiao Chen, Pingfang Yang, Zhongyuan Lin
Marine and Agricultural Biotechnology Laboratory, College of Geography and Oceanography, Minjiang University, Fuzhou, 350108, China.
State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430026, China.
BMC Plant Biol. 2024 Dec 18;24(1):1186. doi: 10.1186/s12870-024-05923-7.
Lotus (Nelumbo nucifera) is a significant aquatic ornamental genus widely utilized in horticulture for its decorative, culinary, medicinal, and other practical uses. It presents a variety of flower shapes, including few-petalled, semi-double-petalled, double-petalled and thousand-petalled flowers, making it an ideal candidate for studying the flower development of aquatic plants. However, the molecular mechanism of floral development in lotus remains elusive.
In this study, two APETALA2 (AP2) homologues, NnAP2a and NnAP2b, were identified in lotus. Interestingly, both NnAP2a and NnAP2b proteins contained two conserved AP2 domains and were verified to be located primarily in the nucleus. Both NnAP2a and NnAP2b showed high expression levels in the floral buds and petals. Ectopic expression of NnAP2a and NnAP2b in Arabidopsis led to an increase in the number of petals and sepals compared to the wild type (WT). Meanwhile, each of the two NnAP2 genes was able to rescue the sepal and petal defective phenotype of the ap2-6 mutant in Arabidopsis. Furthermore, protein-protein interaction assays indicated that NnAP2s could form a protein complex with other proteins involved in floral organ development, such as AP3, PISTILLATA (PI), and SEPALLATA3 (SEP3).
These results suggest that NnAP2s could influence sepal and petal development in N. nucifera. Our findings not only provide some insights into molecular mechanism underlying sepal and petal development and formation of lotus, but also might help its breeding in improving flower morphology.
莲花（Nelumbo nucifera）是一种重要的水生观赏植物属，因其装饰性、食用性、药用性及其他实际用途而在园艺中广泛应用。它呈现出多种花型，包括少瓣、半重瓣、重瓣和千瓣花，使其成为研究水生植物花发育的理想候选对象。然而，莲花花发育的分子机制仍不清楚。
在本研究中，在莲花中鉴定出两个APETALA2（AP2）同源基因，NnAP2a和NnAP2b。有趣的是，NnAP2a和NnAP2b蛋白均包含两个保守的AP2结构域，并被证实主要定位于细胞核中。NnAP2a和NnAP2b在花芽和花瓣中均表现出高表达水平。与野生型（WT）相比，NnAP2a和NnAP2b在拟南芥中的异位表达导致花瓣和萼片数量增加。同时，两个NnAP2基因中的每一个都能够挽救拟南芥ap2-6突变体的萼片和花瓣缺陷表型。此外，蛋白质-蛋白质相互作用分析表明，NnAP2s可以与参与花器官发育的其他蛋白质，如AP3、PISTILLATA（PI）和SEPALLATA3（SEP3）形成蛋白质复合物。
这些结果表明，NnAP2s可能影响莲的萼片和花瓣发育。我们的研究结果不仅为莲花萼片和花瓣发育及形成的分子机制提供了一些见解，也可能有助于其在改善花形态方面的育种。
