Genome-Wide Identification and Expression Profiles of Late Embryogenesis-Abundant (LEA) Genes during Grain Maturation in Wheat (Triticum aestivum L.)

Abstract

Late embryogenesis-abundant (LEA) genes play important roles in plant growth and development, especially the cellular dehydration tolerance during seed maturation. In order to comprehensively understand the roles of LEA family members in wheat, we carried out a series of analyses based on the latest genome sequence of the bread wheat Chinese Spring. 121 Triticum aestivum L. LEA (TaLEA) genes, classified as 8 groups, were identified and characterized. TaLEA genes are distributed in all chromosomes, most of them with a low number of introns (≤3). Expression profiles showed that most TaLEA genes expressed specifically in grains. By qRT-PCR analysis, we confirmed that 12 genes among them showed high expression levels during late stage grain maturation in two spring wheat cultivars, Yangmai16 and Yangmai15. For most genes, the peak of expression appeared earlier in Yangmai16. Statistical analysis indicated that expression level of 8 genes in Yangmai 16 were significantly higher than Yangmai 15 at 25 days after anthesis. Taken together, our results provide more knowledge for future functional analysis and potential utilization of TaLEA genes in wheat breeding.

Keywords: genome-wide identification; grain maturation; late embryogenesis-abundant gene; wheat (Triticum aestivum L.).

Figure 1

Phylogenetic analysis of wheat Late Embryogenesis-abundant (LEA) proteins. The LEA1, LEA2, LEA3, LEA4, LEA5, LEA6, Dehydrin, and seed maturation protein (SMP) groups are presented in blue, pink, light green, bright purple, orange, light blue, purple, and red, respectively.

Figure 2

Exon-intron structures of TaLEA genes. Exon-intron are indicated by wide color bar and black line, respectively.

Figure 3

Conserved motifs (left) and their distributions (right) of TaLEA genes predicted by the MEME (Multiple Expectation Maximization for Motif Elicitation) online tool. Each motif is represented by a different colored box with corresponding number. The domain of each subfamily is represented by a different colored thick line below.

Figure 4

Distribution of TaLEA gene family members on wheat chromosomes. TaLEA1, TaLEA2, TaLEA3, TaLEA4, TaLEA5, TaLEA6, TaDehydrin and TaSMP subfamily are presented in orange, light green, red, purple, black, dark green, pink, and blue.

Figure 5

Expression profiling of TaLEA genes in different tissues. RNA-seq date downloaded from Wheat Expression Browser was used to analysis expression pattern. The heat map was drawn in Log₁₀ (tpm + 0.0001)-transformed expression values. Color scale on the right represent relative expression levels: red represents high level and blue represent low level.

Figure 6

Expression profiles of 12 wheat LEA genes during grain filling and maturation. Purple and light purple columns indicate Yangmai16 and Yangmai 15, respectively. Values represent means ± standard deviation of three replicates. Asterisks reveal the gene significantly higher or lower in Yangmai 16 than in Yangmai 15 by t-test (* p < 0.05, ** p < 0.01).

Figure 7

Phenotypic character of grain maturation in Yangmai 15 and Yangmai 16. (A), comparison of grain dry weight. (B), comparison of grain moisture content. (C), appearance of grains during maturation progress; Bar = 4 cm.