Genome-wide identification and characterization of the superoxide dismutase gene family in Musa acuminata cv. Tianbaojiao (AAA group).
BACKGROUND
Superoxide dismutase (SOD) is an essential enzyme of the plant antioxidant system that responds to oxidative stresses caused by adverse conditions. Banana is an important staple and economic crop in tropical and subtropical regions. However, its growth and yield are constantly affected by various abiotic stresses. To analyze the roles of distinct SOD genes under various stresses, a detailed characterization and analysis of the SOD gene family in Cavendish banana is indispensable.


METHODS
The presence and structure of the SOD family genes were experimentally verified using 5'/3' RACE-PCR, reverse transcription PCR and PCR. Then, their syntenic relationships, conserved motifs and phylogenetic relationships were analyzed using software. Cis-elements present in the promoters were predicted via PlantCARE. And the expression levels under abiotic and hormonal stresses were determined using real-time quantitative polymerase chain reaction.


RESULTS
In total, 25 'Tianbaojiao' SOD cDNAs (MaSODs), which encoded six Cu/ZnSODs, four MnSODs and two FeSODs, were cloned. The 12 MaSOD genes were divided into four groups based on their conserved motifs, which corroborated their classifications based on gene-structure patterns and subcellular localizations. Eleven MaSOD promoters were isolated and found to contain many cis-acting elements involved in stress responses. Gene expression analysis showed that 11 out of the 12 MaSODs were expressed in all tested tissues (leaf, pseudostem and root), whereas MaCSD2B was expressed only in leaves and roots. Specific MaSOD members exhibited different expression patterns under abiotic and hormonal treatments. Among the 12 MaSOD genes, MaCSD1D was the only one that responded to all eight treatments, suggesting that this gene plays a predominant role in reactive oxygen species scavenging caused by various stresses in banana.


CONCLUSIONS
A genome-wide analysis showed that the 'Tianbaojiao' banana harbored an expanded SOD gene family. Whole genome duplication, segmental duplication and complex transcriptional regulation contributed to the gene expansion and mRNA diversity of the MaSODs. The expression patterns of distinct MaSOD genes showed that they are important responses to different abiotic and hormonal stresses in banana.
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China. fengxin1506@163.com.
Xin
X
Feng
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China. laizx01@163.com.
Zhongxiong
Z
Lai
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China. 115635542@qq.com.
Yuling
Y
Lin
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China. 442441455@qq.com.
Gongti
G
Lai
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China. 770379183@qq.com.
Conglong
C
Lian
D000595:Amino Acid Sequence; D018506:Gene Expression Regulation, Plant; D005810:Multigene Family; D028521:Musa / Q000235:genetics*; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics*; D018517:Plant Roots / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics*
D010940:Plant Proteins; D013482:Superoxide Dismutase