Abstract
The LOX genes have been identified and characterized in many plant species, but studies on the banana LOX genes are very limited. In this study, we respectively identified 18 MaLOX, 11 MbLOX, and 12 MiLOX genes from the Musa acuminata, M. balbisiana and M. itinerans genome data, investigated their gene structures and characterized the physicochemical properties of their encoded proteins. Banana LOXs showed a preference for using and ending with G/C and their encoded proteins can be classified into 9-LOX, Type I 13-LOX and Type II 13-LOX subfamilies. The expansion of the MaLOXs might result from the combined actions of genome-wide, tandem, and segmental duplications. However, tandem and segmental duplications contribute to the expansion of MbLOXs. Transcriptome data based gene expression analysis showed that MaLOX1, 4, and 7 were highly expressed in fruit and their expression levels were significantly regulated by ethylene. And 11, 12 and 7 MaLOXs were found to be low temperature-, high temperature-, and Fusarium oxysporum f. sp. Cubense tropical race 4 (FocTR4)-responsive, respectively. MaLOX8, 9 and 13 are responsive to all the three stresses, MaLOX4 and MaLOX12 are high temperature- and FocTR4-responsive; MaLOX6 and MaLOX17 are significantly induced by low temperature and FocTR4; and the expression of MaLOX7 and MaLOX16 are only affected by high temperature. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression levels of several MaLOXs are regulated by MeJA and FocTR4, indicating that they can increase the resistance of banana by regulating the JA pathway. Additionally, the weighted gene co-expression network analysis (WGCNA) of MaLOXs revealed 3 models respectively for 5 (MaLOX7-11), 3 (MaLOX6, 13, and 17), and 1 (MaLOX12) MaLOX genes. Our findings can provide valuable information for the characterization, evolution, diversity and functionality of MaLOX, MbLOX and MiLOX genes and are helpful for understanding the roles of LOXs in banana growth and development and adaptations to different stresses.
Highlights
The LOX genes have been identified and characterized in many plant species, but studies on the banana LOX genes are very limited
LOX genes were identified from M. acuminata, M. balbisiana, and M. itinerans genome, respectively (Table 1, Supplementary Table S2)
The prediction of subcellular localization showed that MaLOX18, MbLOX18 and MiLOX18 were localized in the cytoplasm, while other Type II 13-LOX members were all localized in the chloroplast
Summary
The LOX genes have been identified and characterized in many plant species, but studies on the banana LOX genes are very limited. Our findings can provide valuable information for the characterization, evolution, diversity and functionality of MaLOX, MbLOX and MiLOX genes and are helpful for understanding the roles of LOXs in banana growth and development and adaptations to different stresses. The expression of Arabidopsis AtLOX1 was abscisic acid and JA inducible[14], and the rice OsLOX3 was MeJA and Magnaporthe Grisea inducible[15] Their diverse functions during plant growth and developmental and stress response processes have been experimentally confirmed in various plant species. Given that LOXs are vital for plant growth and stress resistance and different LOX members’ functions varied, it is of great importance to analyze the LOX gene family from whole genome level for the clarification of their diverse potentials in banana. Our preliminary results can extend the knowledge of banana LOX gene family and can provide insights into their roles in banana growth and development and stress responses
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