Identification, Phylogeny, and Comparative Expression of the Lipoxygenase Gene Family of the Aquatic Duckweed, Spirodela polyrhiza, during Growth and in Response to Methyl Jasmonate and Salt

Abstract

Lipoxygenases (LOXs) (EC 1.13.11.12) catalyze the oxygenation of fatty acids and produce oxylipins, including the plant hormone jasmonic acid (JA) and its methyl ester, methyl jasmonate (MeJA). Little information is available about the LOX gene family in aquatic plants. We identified a novel LOX gene family comprising nine LOX genes in the aquatic plant Spirodela polyrhiza (greater duckweed). The reduced anatomy of S. polyrhiza did not lead to a reduction in LOX family genes. The 13-LOX subfamily, with seven genes, predominates, while the 9-LOX subfamily is reduced to two genes, an opposite trend from known LOX families of other plant species. As the 13-LOX subfamily is associated with the synthesis of JA/MeJA, its predominance in the Spirodela genome raises the possibility of a higher requirement for the hormone in the aquatic plant. JA-/MeJA-based feedback regulation during culture aging as well as the induction of LOX gene family members within 6 h of salt exposure are demonstrated.

Genomic analysis of the polyamine biosynthesis pathway in duckweed Spirodela polyrhiza L.: presence of the arginine decarboxylase pathway, absence of the ornithine decarboxylase pathway, and response to abiotic stresses

“…Two duckweed strains (S. polyrhiza, 7498 and 7003) were grown at room temperature (22 ± 2 °C) under white light (50-80 μmol/s 2 ) as previously described (Upadhyay et al 2020a). Three growth periods (14 ± 1 day, 21 ± 1 day and 28 ± 1 day) were chosen as previously described (Mattoo et al 1992).…”

“…Samples were taken at indicated timepoints, washed thrice with distilled water, frozen in liquid nitrogen and stored at − 70 °C until used. Transcript abundance of S. polyrhiza 7498 PA biosynthetic pathway genes in response to MeJA was carried out as previously described (Upadhyay et al 2020a). MeJA (Sigma, 95%) was diluted 1:10 with 95% ethanol, followed by a further dilution with sterile MilliQ water containing 0.1% Triton X-100, to a final concentration of 10 μM MeJA.…”

“…A minimum of 10-15 fronds were analyzed for each timepoint. Salinity stress involved treatment of 14-day-old S. polyrhiza 7498 plants with 200 mM salinity (Upadhyay et al 2020a). In total 100 fronds were transferred into flasks and a solution of 200 mM NaCl was added.…”

The CCCH zinc finger family of soybean (Glycine max L.): genome-wide identification, expression, domestication, GWAS and haplotype analysis

“…It is important to analyze new gene families with known established families during phylogenetic analyses. Therefore, to further characterize the zf_CCCH genes in soybean and its relationship with other legumes such as Medicago truncatula, Phaseolus vulgaris and Vigna unguiculata , the zf_CCCH proteins of Arabidopsis and rice were added to establish the phylogenetic relationship following the references of Rameneni, et al [ 28 ] and Upadhyay, et al [ 52 ]. The zf_CCCH protein sequences of the Medicago truncatula (50 zf_CCCHs ) , Phaseolus vulgaris (43 zf_CCCHs ) and Vigna unguiculata (49 zf_CCCHs ) were downloaded from the database of plant genomics resource Phytozome 12 using the tool of Biomart with the Pfam ID:PF00642 ( https://phytozome.jgi.doe.gov/biomart ).…”

Jasmonic Acid Pathway in Plants 2.0

“…Upadhyay et al [ 10 ] identified nine lipoxygenase (LOX) genes in aquatic plant, Spirodela polyrhiza . Plant LOXs catalyze hydroperoxidation at either the C-9 (9-LOX) or C-13 (13-LOX) residue of linoleic acid or linolenic acid, which are the major fatty acids in plant membrane lipid and are necessary for the biosynthesis of JA.…”