Abstract
Cadmium (Cd) is a toxic heavy metal element. It is relatively easily absorbed by plants and enters the food chain, resulting in human exposure to Cd. Italian ryegrass (Lolium multiflorum Lam.), an important forage cultivated widely in temperate regions worldwide, has the potential to be used in phytoremediation. However, genes regulating Cd translocation and accumulation in this species are not fully understood. Here, we optimized PacBio ISO-seq and integrated it with RNA-seq to construct a de novo full-length transcriptomic database for an un-sequenced autotetraploid species. With the database, we identified 2367 differentially expressed genes (DEGs) and profiled the molecular regulatory pathways of Italian ryegrass with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis in response to Cd stress. Overexpression of a DEG LmAUX1 in Arabidopsis thaliana significantly enhanced plant Cd concentration. We also unveiled the complexity of alternative splicing (AS) with a genome-free strategy. We reconstructed full-length UniTransModels using the reference transcriptome, and 29.76% of full-length models had more than one isoform. Taken together, the results enhanced our understanding of the genetic diversity and complexity of Italian ryegrass under Cd stress and provided valuable genetic resources for its gene identification and molecular breeding.
Highlights
The genus Lolium L., belonging to the Poaceae family, is native to Europe, North Africa, and temperate Asia and has been introduced to almost all temperate regions in the world [1]
Metal concentrations of Italian ryegrass roots were significant affected by Cd (Figure 1)
To profile the transcriptomic information, total RNA of Italian ryegrass roots was extracted after a six-hour treatment with Cd, and three control and three treated samples were combined into one sample in equal amounts
Summary
The genus Lolium L., belonging to the Poaceae family, is native to Europe, North Africa, and temperate Asia and has been introduced to almost all temperate regions in the world [1]. Italian ryegrass (L. multiflorum Lam.) and perennial ryegrass (L. perenne L.) are two important species, and both of them are valuable forage grasses. Because of their desirable characteristics, such as high yields, tolerance to grazing, rapid establishment, and high palatability and digestibility for ruminant animals, they have been cultivated through hybrid or molecular breeding in the last hundred years [2]. Molecular breeding has played an increasingly important role in breeding programs of late [3]. In many plants, it has shown promise in increasing yield as well as resistance to multiple biotic and abiotic stresses. Known as annual ryegrass, is used for turf, forage, and quick cover in the event of erosion [5], and it has some new uses, such as lignocellulosic ethanol conversion programs [6] and phytoremediation [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
