Identification of microRNAs regulated by miR-168a-mediated Argonaute1 in
response to potassium deficiency stress in tomatoes
Abstract
Potassium (K+) is an essential macronutrient involved in regulating
plant growth and development. K+ homeostasis in plant cells is modulated
to facilitate plant adaptation to K+-deficiency stress. Argonaute1
(AGO1) interacts with miR-168a to modulate the small RNA regulatory
pathway in tomatoes. However, the roles of AGO1 and miR-168a in
modulating K+ deficiency stress in tomatoes have not been elucidated.
Accordingly, in this study, we examined the interactions between AGO1
and miR-168a in mediating low-K+ stress in tomato plants. SlmiR-168a and
its target SlAGO1 were differentially expressed between low-K+ tolerant
JZ34 and low-K+ sensitive JZ18 tomato plants. Transgenic tomato plants
constitutively expressing SlmiR-168a and rSlAGO1 (SlmiR-168a-resistant)
showed different root hair development, leaf phenotypes, and K+ contents
in roots under K+-deficiency stress. Sequencing analyses showed that 446
microRNAs (miRNAs) and 541 miRNAs were differentially expressed in
35S:SlmiR-168a compared with wild-type (WT) tomatoes and in 35S:rSlAGO1
compared with WT tomatoes, respectively. Twelve miRNA/mRNA pairs were
identified, and the root growth and cytokinin (CTK)/abscisic acid (ABA)
pathways were shown to be involved in SlmiR-168a-mediated SlAGO1
regulatory network in response to K+-deficiency stress. Thus, SlAGO1
regulated by SlmiR-168a may influence downstream miRNA pathways in
response to low-K+ stress though modulating root growth and CTK/ABA
pathways.