Genome-wide identification and expression analysis of the GRAS family under low-temperature stress in bananas

GRAS, named after GAI, RGA, and SCR, is a class of plant-specific transcription factors family that plays a crucial role in growth and development, signal transduction, and various stress responses.

To understand the biological functions of the banana GRAS gene family, a genome-wide identification and bioinformatics analysis of the banana GRAS gene family was performed based on information from the M. acuminata, M. balbisiana, and M. itinerans genomic databases.

In the present study, we identified 73 MaGRAS, 59 MbGRAS, and 58 MiGRAS genes in bananas at the whole-genome scale, and 56 homologous genes were identified in the three banana genomes. Banana GRASs can be classified into 10 subfamilies, and their gene structures revealed that most banana GRAS gDNAs lack introns. The promoter sequences of GRASs had a large number of cis-acting elements related to plant growth and development, phytohormone, and adversity stress responsiveness. The expression pattern of seven key members of MaGRAS response to low-temperature stress and different tissues was also examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The microRNAs-MaGRASs target prediction showed perfect complementarity of seven GRAS genes with the five mac-miRNAs. The expression of all seven genes was lowest in roots, and the expression of five genes was highest in leaves during low-temperature stress. The expression of MaSCL27-2, MaSCL27-3, and MaSCL6-1 was significantly lower under low-temperature stress compared to the control, except for MaSCL27-2, which was slightly higher than the 28°C control at 4 h. The expression of MaSCL27-2, MaSCL27-3, and MaSCL6-1 dropped to the lowest levels at 24 h, 12 h, and 4 h, respectively. The MaSCL27-4 and MaSCL6-2 expression was intermittently upregulated, rising to the highest expression at 24h, while the expression of MaSCL22 was less variable, remaining at the control level with small changes.

In summary, it is tentatively hypothesized that the GRAS family has an important function in low-temperature stress in bananas. This study provides a theoretical basis for further analyzing the function of the banana GRAS gene and the resistance of bananas to cold temperatures.