Comparative analyses of American and Asian lotus genomes reveal insights into petal color, carpel thermogenesis and domestication

第一作者：Ping Zheng

第一单位：武汉植物园

通讯作者：Mei Yang

 Abstarct 

背景回顾：American lotus, which differs from Asian lotus morphologically, is one of the two remaining species in the basal eudicot family Nelumbonaceae. 

美洲莲与亚洲莲在形态上不同，是基础真双子叶植物莲科仅有的两个物种之一。

主要研究：Here, we assembled the 843-Mb genome of American lotus into eight pseudochromosomes containing 31,382 protein-coding genes. 

本文中，作者报道了美洲莲843Mb的基因组组装，并将基因组挂载到了8条拟染色体上，预测了31382个蛋白编码基因。

结果1-比较基因组：Comparative analyses revealed conserved synteny without large chromosomal rearrangements between the genomes of American and Asian lotus and identified 29,533 structural variants (SVs). 

比较基因组分析显示美洲莲和亚洲莲基因组之间较为保守，不存在大片段的染色体重组，共鉴定了29533个结构变异。

结果2-花瓣着色：Carotenoid and anthocyanin pigments determine the yellow and red petal colors of American and Asian lotus, respectively. The structural genes encoding enzymes of the carotenoid and anthocyanin biosynthesis pathways were conserved between two species, but differed in expression. We detected SVs caused by repetitive sequence expansion or contraction among the anthocyanin biosynthesis regulatory MYB genes. Further transient overexpression of candidate NnMYB5 induced anthocyanin accumulation in lotus petals. 

类胡萝卜素和花色苷分别是美洲莲和亚洲莲黄色和红色花瓣的着色色素。类胡萝卜素和花色苷生物合成通路上结构基因序列在美洲莲和亚洲莲之间比较保守，但是在表达量上存在差异。作者在花色苷生物合成基因调控因子MYBs基因检测到了由重复序列扩张或收缩所导致的结构变异。进一步对候选基因NnMYB5的过表达实验发现，其可以诱导莲花瓣中的花色苷积累。

结果3-心皮生热与雌蕊先熟：Alternative oxidase (AOX), uncoupling proteins (UCPs), and sugar metabolism and transportation contributed to carpel thermogenesis. Carpels produce heat with sugars transported from leaves as the main substrates because there is no TSTs activity, but highly expressed SWEETs during thermogenesis. Cell proliferation-related activities were particularly enhanced in the warmer carpels compared to stamens during the cold night before blooming, which suggested that thermogenesis plays an important role in flower protogyny.

交替氧化酶AOX、解偶联蛋白UCPs以及蔗糖代谢和转运作用于心皮的生热效应。心皮产热的主要底物是来自叶片的蔗糖，因为在生热作用过程中并未检测到TSTs活性，而检测到了SWEETs基因的高表达。与雄蕊相比，在开花前的寒冷夜晚，温暖的心皮中的细胞增殖相关活动得到增强，这表明生热效应在花雌蕊先熟中发挥重要作用。

结果4-驯化：Population genomic analyses revealed deep divergence between American and Asian lotus, and independent domestication affecting seed, rhizome, and flower traits. 

群体基因组分析显示美洲莲与亚洲莲存在明显的遗传分化，并且在影响种子、根茎和花性状方面存在独立的驯化。

结论：Our findings provide a high-quality reference genome of American lotus for exploring the genetic divergence and variation between two species and revealed possible genomic bases for petal color, carpel thermogenesis, and domestication in lotus.

本文的研究提供了一个高质量的美洲莲基因组，为进一步探索美洲莲和亚洲莲之间的遗传分化与变异提供了基础，同时也揭示了这两个物种之间在花瓣着色、心皮生热以及驯化方面的基因组基础。

（图片来源：百度百科）

** 杨美 **

doi: https://doi.org/10.1111/tpj.15753

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Journal: the plant journal

Published date:  April 01, 2022