Comparative transcriptome analysis of the regulation of ABA signaling genes in different rootstock grafted tomato seedlings under drought stress

Grafting cultivation could enhance the resistance to many biotic and abiotic stresses in tomato grafted seedlings. In order to further study the molecular mechanism of ABA signaling regulation in tomatoes grafted onto different rootstocks under drought stress, the different drought-resistance tomato varieties named drought-tolerant genotypes (T) and drought-sensitive genotypes (S), were selected for grafting with each other as rootstock or scion, and the response to drought stress were tested. And then whole transcriptome sequencing performed with the leaves and roots of S/T and S/S grafted tomato seedlings under drought stress. The results showed that, compared with seedlings grafted with S, the growth rate and stomatal aperture of seedlings grafted onto T were not significantly inhibited by drought and the ABA content increased after 15 days of drought stress. The roots had more DEGs in the functional category associated with plant hormone signal transduction than the leaves, and most of the genes were upregulated in S/T vs. S/S. The DEGs involved in ABA biosynthesis and ABA signaling both had impact on the drought resistance of grafted tomato with different rootstocks. Compared with ABA biosynthesis, there were more DEGs related to ABA signal transduction in different grafting treatments. They together regulated ABA content and stomatal aperture of the plant and allow it adapt to drought stress in time.