Cyperus esculentus (yellow nutsedge or tiger nut), a representative species of Cyperaceae(the third largest family of monocots), is a unique plant with notably high oil accumulation in its mature tubers，containing up to 20% to 30% oil. In contrast, its congener Cyperus rotundus accumulates more starch in its tubers and has very little oil content. However, the key genes and regulatory networks responsible for the difference in oil accumulation between the tubers of these two plants remain unclear.
In order to explore the mechanism of oil accumulation in nutrient organs, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) used high-oil, medium-oil Acorus calamus and Cyperus rotundus tubers as research materials, and compared the differences in gene transcription through comparative genomics and transcriptomics analysis.
The researchers sequenced and assembled the genome of C. esculentus at the contig level, obtaining the first relatively complete genome sequence of this species as the reference genome.They subsequently obtained two full-length transcriptomes of C. esculentus and its close relative C. rotundus, through a combination of second- and third-generation sequencing technologies.
They then compared high-quality transcriptomes in 36 tissues among high-oil, medium-oil, and low-oil C. esculentus and low-oil C. rotundus to identify potential genes and regulatory networks associated with tuber oil accumulation.
They identified tuber-specific genes in two C. esculentus cultivars. Through the trend analysis of tuber development, it was found that auxin-related genes gradually downregulated with the development of three types of tubers.Genes involved in fatty acid (FA) biosynthesis, triacylglycerol synthesis, and TAG packaging presented increased activity in the later stages of tuber development. The expression levels of these genes in high-oil C. esculentus tubers were higher than those in medium-oil ones, while they were lowly expressed or not expressed in C. rotundus.
Through exogenous hormone treatment, they found that treating C. esculentus leaves with ethephon significantly increased the oil content of its tubers. A lack of an important fatty acid (FA) biosynthesis rate-limiting enzyme encoding gene was found in C. rotundus transcripts, which may have implications for its oil accumulation capacity.
“Our study provides important information for understanding the mechanisms of efficient oil accumulation in plant nutritional organs and offering new ideas for future genetic engineering to increase plant oil yield.,” said TANG Mingyong of XTBG.
The study, supported by the Key Deployment Program of the Chinese Academy of Sciences, was published in Plant Science.
Contact
TANG Mingyong Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail: tangmingyong@xtbg.ac.cn
First published: 16 August 2024
