Genome-wide identification and abiotic stress-responsive expression of MLP family genes in Brassica rapa

The major latex protein/ripening-related protein (MLP/RRP) subfamily plays a key role in the growth, development, and stress resistance of plants. Brassica rapa is an important oil crop in China but also represents a model species for studying plant evolution. The specific roles of the MLP gene family in the development of B. rapa have yet to be elucidated. Here, we identified 31 MLPs from B. rapa (BrMLPs) which could have belonged to 3 groups. Using bioinformatics tools, we investigated and compared the 31 MLPs with regards to gene exons, gene substructures, protein domains, and chromosomal location. Real-time quantitative polymerase chain reaction (RT-PCR) was then carried out to investigate the expression of the 31 BrMLPs, using Murashige and Skoog as contrast, with three types of processing conditions (NaCl), abscisic acid (ABA), and mannitol and over three time periods (1, 3, and 6 h). Our data showed that BrMLP1/6 plays a role in resistance to drought and salt resistance. Collectively, our findings provide a useful foundation or improving the resistance of B. rapa to period of drought and salty conditions.