Genome-wide identification and expression analysis of tomato ADK gene family during development and stress

Abstract

Background: Adenylate kinase (ADK) is widely distributed in organisms and plays an important role in cellular energy homeostasis. In plants, ADK has important functions in plant growth and development regulation as well as adaptation to the environment. However, little information is available about the ADK genes in tomato (Solanum lycopersicum), an important economic crop.Results: To investigate the characteristics and functions of ADK genes in tomato, a total of 11 ADK genes were identified and named according to their chromosomal locations. The ADK family was divided into five groups and motif analysis revealed that each SlADK protein contained five to eight conserved motifs. Sequence analysis revealed 4-19 exons in all SlADKs and most members possessed four. The 11 SlADKs were randomly distributed on nine of the 12 tomato chromosomes. A cis-element analysis inferred that several stress response elements were found on the promoters of SlADKs. The online TomExpress platform prediction revealed that SlADKs were expressed in various tissues and organs, basically consistent with the data obtained from real-time quantitative PCR (qPCR). The qPCR verification was also used to determine the expression level of SlADKs and demonstrated that the genes responded to multiple abiotic stresses, such as drought, salt and cold. For example, almost all SlADKs contained two expression peaks at 9 and 48 h following salt treatment. The qPCR results showed that SlADK transcription was responsive to most of the applied hormone treatment: methyl jasmonate, ethylene, salicylic acid, indole 3-acetic acid and abscisic acid. Notably, SlADK2 and 4 exhibited significant changes under multiple stress treatments.Conclusions: These results provide valuable information for clarifying the evolutionary relationship of the tomato ADK family and in aiding functional characterization of SlADKs in further research.