Homolinear LOX gene analysis between <i>X</i>.<i>sorbifolium</i>, rice, <i>A</i>. <i>thaliana</i>, and <i>P</i>. <i>trichocarpa</i>.

A homology-based LOX gene analysis was performed among X.sorbifolium, rice, A. thaliana, and P. trichocarpa. The gray lines in the background indicated collinear blocks between X.sorbifolium, rice, A. thaliana, and P. trichocarpa, while the red line signified the collinear LOX gene pairs.</p

Phylogenetic relationships, conserved domain regions, gene structure, and motif patterns of LOX genes in yellow horn.

Clustal W and MEGA 7 were employed to realign the complete amino acid sequence and formulate the phylogenetic tree. The untranslated region (UTR), exons, and introns were depicted as green boxes, yellow boxes, and grey lines, respectively.</p

The differential expression levels of the <i>XsLOX</i> genes in response to low temperature treatment (LT), salt treatment (ST), and alkali treatment (AT).

The seedlings were treated with NaCl (150 mM) and Na2CO3 (150 mM) for 4 h and 24 h, low temperature (4°C) for 4 h, 12 h, and 24h. Red squares indicate increased abundance and blue squares indicate decreased quantity.</p

Phylogenetic tree of LOX genes with other plants.

The phylogenetic tree in the figure also distinguished the LOX genes of the various plants with distinct colors (9-LOX: purple, type I 13-LOX: orange, and type II 13-LOX: green). AtLOX: Arabidopsis thaliana. PtLOX: Populus trichocarpa. OsLOX: Oryza sativa.</p

Estimation of the Ka/Ks ratio of homologous gene pairs in yellow horn.

Estimation of the Ka/Ks ratio of homologous gene pairs in yellow horn.</p

Further illustrates the alignment of <i>XsLOX</i> genes in 5 chromosomes, expressing the gene arrangements in relative proportions.

Each line on the chromosome represents the fragment of a gene. The correlation between the two gene headers indicates that they are matched duplicates.</p

List of <i>XsLOX</i> genes identified.

Lipoxygenase (LOX) gene plays an essential role in plant growth, development, and stress response. 15 LOX genes were identified, which were unevenly distributed on chromosomes and divided into three subclasses in this study. In promoter region analysis, many cis-elements were identified in growth and development, abiotic stress response, hormonal response, and light response. qRT-PCR showed that the LOX gene showed tissue specificity in seven tissues, especially XsLOX1, 3, and 7 were relatively highly expressed in roots, stems, and axillary buds. The different expression patterns of LOX genes in response to abiotic stress and hormone treatment indicate that different XsLOX genes have different reactions to these stresses and play diversified roles. This study improves our understanding of the mechanism of LOX regulation in plant growth, development, and stress and lays a foundation for further analysis of biological functions.</div

Changes in expression analysis of eight randomly chosen <i>XsLOX</i> genes in seven tissues of mature plants by qRT-PCR.

All qRT-PCR data were normalized against that of the housekeeping gene. X-axis shows different tissues, and Y-axis shows the relative expression level. Error bars represent the mean ±SE of three biological replicates, and asterisks represent a significant difference from Duncan’s method (*p = 0.05, **p = 0.01, ***p = 0.001, ****p = 0.0001).</p

q-PCR primers.

Lipoxygenase (LOX) gene plays an essential role in plant growth, development, and stress response. 15 LOX genes were identified, which were unevenly distributed on chromosomes and divided into three subclasses in this study. In promoter region analysis, many cis-elements were identified in growth and development, abiotic stress response, hormonal response, and light response. qRT-PCR showed that the LOX gene showed tissue specificity in seven tissues, especially XsLOX1, 3, and 7 were relatively highly expressed in roots, stems, and axillary buds. The different expression patterns of LOX genes in response to abiotic stress and hormone treatment indicate that different XsLOX genes have different reactions to these stresses and play diversified roles. This study improves our understanding of the mechanism of LOX regulation in plant growth, development, and stress and lays a foundation for further analysis of biological functions.</div

Changes in expression analysis of eight randomly chosen <i>XsLOX</i> genes in response to 10% PEG 6000, 100 mM NaCl, 4°C low temperature, 100 μM ABA, 200 μM SA, and 100 μM GA stress for 24 h and dark for 48 h.

X-axis shows the different stress, and Y-axis shows the relative expression level. Error bars represent the mean ±SE of three biological replicates, and asterisks represent a significant difference from Duncan’s method (*p = 0.05, **p = 0.01, ***p = 0.001, ****p = 0.0001).</p