Genome-wide survey of the seagrass Zostera muelleri suggests modification of the ethylene signalling network

Abstract

HighlightAn aquatic life genome sequencing suggests a complete loss of genes for ethylene biosynthesis and signalling pathways in the seagrasses, Zostera muelleri and Zostera marina, a new model for hormone studies.

The Genome of a Southern Hemisphere Seagrass Species (Zostera muelleri)

“…Previous analyses demonstrated the loss of multiple ethylene biosynthesis and signaling genes in Z. muelleri and Z. marina (Golicz et al, 2015;Olsen et al, 2016). The overrepresentation of gene families encoding 1-aminocyclopropane-1-carboxylic acid synthase, 1-aminocyclopropane-1-carboxylic acid oxidase, ethylene receptors, and ethylene-activated transcription factors in AMOS, and the absence of these genes in seagrass-specific families, support these previous findings.…”

“…Genes involved in starch catabolic (GO:0005983) and biosynthetic (GO:0019252) processes, which were found previously to be lost or heavily modified in Z. muelleri reads (Golicz et al, 2015) and Z. marina (Olsen et al, 2016), also were significantly enriched in AMOS families (Table V). Genes responsible for the biosynthesis of secondary metabolites that were reduced in Z. marina (Olsen et al, 2016) also are found in AMOS (ath01110 ; Table VI).…”

“…This suggests that the methylesterification level of pectin is tightly controlled in seagrass, possibly to maintain marine osmoregulation. Pectin degradation is partly regulated by ethylene (De Paepe et al, 2004;Onkokesung et al, 2010), and it is unknown whether the modified pectin in seagrass is associated with the loss of ethylene signaling in seagrass (Golicz et al, 2015). This expansion of pectin catabolic genes also is observed in Z. marina (Olsen et al, 2016).…”

“…A comparative genomics approach was applied to characterize gene conservation and loss in seagrass in comparison with four terrestrial plants and one aquatic plant using unassembled whole-genome shotgun sequence data of Zostera muelleri (Golicz et al, 2015). Genes associated with ethylene synthesis and signaling pathways were found to be lost, suggesting that seagrasses have evolved to survive and grow without this important plant hormone, and this loss was confirmed recently in the genome assembly of Z. marina (Olsen et al, 2016).…”

The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea

“…Those unique to Z. marina include the absence of all the genes involved in stomatal differentiation (Fig. 3a, Extended Data Table 1 and Supplementary Note 5.1) and the disappearance of genes comprising entire pathways encoding volatiles synthesis and sensing (Supplementary Note 6.1), such as those for ethylene 15 (Fig. 3b, Extended Data Table 2).…”