Evolutionary relationships and expression analysis of EUL domain proteins in rice (Oryza sativa)

Abstract

Background: Lectins, defined as 'Proteins that can recognize and bind specific carbohydrate structures', are widespread among all kingdoms of life and play an important role in various biological processes in the cell. Most plant lectins are involved in stress signaling and/or defense. The family of Euonymus-related lectins (EULs) represents a group of stress-related lectins composed of one or two EUL domains. The latter protein domain is unique in that it is ubiquitous in land plants, suggesting an important role for these proteins. Results: Despite the availability of multiple completely sequenced rice genomes, little is known on the occurrence of lectins in rice. We identified 329 putative lectin genes in the genome of Oryza sativa subsp. japonica belonging to nine out of 12 plant lectin families. In this paper, an in-depth molecular characterization of the EUL family of rice was performed. In addition, analyses of the promoter sequences and investigation of the transcript levels for these EUL genes enabled retrieval of important information related to the function and stress responsiveness of these lectins. Finally, a comparative analysis between rice cultivars and several monocot and dicot species revealed a high degree of sequence conservation within the EUL domain as well as in the domain organization of these lectins.

130 years of Plant Lectin Research

“…Transgenic lines overexpressing Orysata demonstrated a higher germination rate and better growth after salt treatment in comparison with non-transformed control plants [ 102 ]. EUL proteins have been reported as drought, salt and abscisic acid responsive proteins in Arabidopsis, rice, wheat and barley [ 103 – 105 ]. Experiments with transgenic lines with reduced expression of the lectin receptor like kinases OsSIT1 and OsSIT2 revealed that these proteins play a role in the salt sensitivity as well as in plant development and productivity [ 106 ].…”

De novo transcriptome analysis and comparative expression profiling of genes associated with the taste-modifying protein neoculin in Curculigo latifolia and Curculigo capitulata fruits

“…latifolia and C. capitulata contain many neoculin-related genes, which are similar within and between species. This diversity of neoculinrelated genes is thought to result from gene duplication, which is known to contribute to plant evolution [41][42][43][44][45][46][47]. Such gene duplication might place some genes under the same transcriptional regulation.…”

“…Perhaps these physiological differences are due to mutation of the cis-elements in these genes. Ciselements, including promoters, enhancers, and silencers, are very important in regulation of gene expression [41,[55][56][57][58]. The different expression levels of related genes in C. latifolia vs. C. capitulata could be caused by mutations in their cis-elements.…”

“…capitulata that were categorized into each of the 12 lectin families to better understand the general outline of the GNA family genes in these species. To determine the number of lectin genes, we performed tBLASTn searches against all transcripts in each species using the sequences of 12 representative lectins as queries [41] (Table 4). In both species, the largest lectin family was the GNA family, including the neoculin (NBS and NAS) genes.…”

“…Identi cation of lectin gene transcripts in C. capitulata and C. latifolia fruits A tBLASTn search (E-value < 1e − 4 ; other options set to the default) was performed against all transcripts in C. capitulata and C. latifolia fruits with the following protein sequences as the queries, which represent each plant lectin family [41]…”