Late Embryogenesis Abundant (LEA) Constitutes a Large and Diverse Family of Proteins Involved in Development and Abiotic Stress Responses in Sweet Orange (Citrus sinensis L. Osb.)

Abstract

Late Embryogenesis Abundant (LEA) proteins are an ubiquitous group of polypeptides that were first described to accumulate during plant seed dehydration, at the later stages of embryogenesis. Since then they have also been recorded in vegetative plant tissues experiencing water limitation and in anhydrobiotic bacteria and invertebrates and, thereby, correlated with the acquisition of desiccation tolerance. This study provides the first comprehensive study about the LEA gene family in sweet orange (Citrus sinensis L. Osb.), the most important and widely grown fruit crop around the world. A surprisingly high number (72) of genes encoding C. sinensis LEAs (CsLEAs) were identified and classified into seven groups (LEA_1, LEA_2, LEA_3 and LEA_4, LEA_5, DEHYDRIN and SMP) based on their predicted amino acid sequences and also on their phylogenetic relationships with the complete set of Arabidopsis thaliana LEA proteins (AtLEAs). Approximately 60% of the CsLEAs identified in this study belongs to the unusual LEA_2 group of more hydrophobic LEA proteins, while the other LEA groups contained a relatively small number of members typically hydrophilic. A correlation between gene structure and motif composition was observed within each LEA group. Investigation of their chromosomal localizations revealed that the CsLEAs were non-randomly distributed across all nine chromosomes and that 33% of all CsLEAs are segmentally or tandemly duplicated genes. Analysis of the upstream sequences required for transcription revealed the presence of various stress-responsive cis-acting regulatory elements in the promoter regions of CsLEAs, including ABRE, DRE/CRT, MYBS and LTRE. Expression analysis using both RNA-seq data and quantitative real-time RT-PCR (qPCR) revealed that the CsLEA genes are widely expressed in various tissues, and that many genes containing the ABRE promoter sequence are induced by drought, salt and PEG. These results provide a useful reference for further exploration of the CsLEAs functions and applications on crop improvement.

Distinctive Gene Expression Patterns Define Endodormancy to Ecodormancy Transition in Apricot and Peach

“…Similar to the CAP160, one LEA gene (Prupe.1G104900) was significantly downregulated during ecodormancy but increased during chill hour accumulation in endodormancy (Figure 4 and Supplementary Figure 11). The LEA protein family has been shown to respond to abiotic stress such as cold, drought and salt (Hara et al, 1999;Chandra Babu et al, 2004;Checker et al, 2012;Duan and Cai, 2012;Pedrosa et al, 2015). The LEA expression pattern in our experiments is consistent with previously observed LEA gene expression, which was induced by short photoperiod and downregulated as dormancy progressed (Jiménez et al, 2010a;Leida et al, 2012a).…”

“…Prupe.5G014900 is a glutathione S-transferase, many of which provide cellular detoxification and have been profiled in stress response in many plant species (Seppänen et al, 2000;Anderson and Davis, 2004;Jain et al, 2010). Prupe.1G104900 is a late embryogenesis abundant protein (LEA), a family known to be involved in cold and drought stress response (Pedrosa et al, 2015) and previously profiled in dormant apricot (Yamane et al, 2006) and oak buds (Ueno et al, 2013). The final RT-qPCR gene was DAM6 (ppa010714m) discussed above.…”

Genome-wide identification and comparative expression analysis of LEA genes in watermelon and melon genomes

“…Similar studies on genome wide identification of LEA family members in other plants revealed, 79 LEA genes in cucumber (Altunoglu et al2016), 53 LEA genes in poplar (Lan et al 2013), 51 LEA genes in Arabidopsis (Hundertmark and Hincha 2008), 36 LEA genes in soybean (Li et al 2011), 34 LEA genes in rice (Wang et al 2007), 32 LEA genes in maize (Li and Cao 2016), 29 LEA genes in potato (Charfeddine et al 2015), 27 LEA genes in tomato (Cao and Li 2015) and 72 genes in sweet orange (Pedrosa et al 2015). Accordingly, watermelon has the second highest number of LEA protein genes after cucumber enabling a lot more different types of searches in different databases and to include more plants for inquiry.…”

“…In these studies, chromosomal location and gene duplications, cis-elements, phylogenetic relationships and conserved domains of LEA proteins were determined. Also, expression patterns of this gene family under abiotic stress conditions were evaluated using publically open RNA seq data and quantitative PCR results (Wang et al 2007;Hundertmark and Hincha 2008;Li et al 2011;Lan et al 2013;Cao and Li 2015;Charfeddine et al 2015;Pedrosa et al 2015;Altunoglu et al 2016;Li and Cao 2016).…”

Native Plants to Arid Areas: A Genetic Reservoir for Drought-Tolerant Crops

“…Up to 242 LEA genes have been found in Gossypium hirsutum [57]. The LEA genes have several stress-responsive cis-acting regulatory elements in the promoter region such as ABRE, DRE/CRT, MYBS, and LTRE [59]. The expression of LEA proteins is associated with acquisition of drought stress tolerance [60,61].…”