Role of an Abscisic Acid‐Activated Protein Kinase in Drought Response in Soybean Revealed by RNA‐Seq

Abstract

Glycine max (soybean) is the most important oilseed cereal crop, most widely grown in the world. It is the most important source of protein and oils for humans as well as for biodiesel production. Drought stress is the major environmental factor limiting the productivity of soybean. With the rapid growth of global population and environmental degradation, improving soybean yield is a crucial task to meet the human demand for food and energy. Soybean can survive drought stress if there is a robust and deep root system. Thus, there is a significant need for crop improvements that will increase stress tolerance. Abscisic acid is the essential hormone mediating abiotic stress responses in plants. We previously identified an abscisic acid‐activated protein kinase (AAPK) in broad bean and demonstrated that AAPK is a positive regulator that can enhance abscisic acid signaling. These results suggest that genetic engineering of the AAPK gene may have the potential to improve drought stress in crop plants. To this end, we have generated overexpression and RNAi lines of three AAPK homologous genes in soybean. We found an RNAi line of AAPK homologous gene a noticeable reduction in plant wilting in response to drought treatment. To understand the phenotype changes of this AAPK‐knockdown line, we conducted a genome‐wide transcriptomic analysis in roots of soybean at the early vegetative stage under drought stress. The analysis with an RNA‐Seq pipeline (using STAR aligner and edgeR analysis of differential gene expression) identified over 4000 gene transcripts that were differentially expressed as a response to drought stress in wild‐type samples and RNAi knockdown samples. Our ongoing study reveals the dynamic transcriptomic reconfiguration in soybean roots to acclimate drought stress and highlights the gene expression changes associated with signaling through AAPK. We expect that pathway analysis of the differentially expressed genes will reveal new signaling components associated with drought stress in soybean.Support or Funding InformationThis research was supported by MAFES (Mississippi Agricultural and Forestry Experiment Station) Special Research Initiative grants to Jiaxu Li and Vincent Klink. Saroj Sah is supported by a MAFES Director's Doctoral Fellowship awarded to Jiaxu Li and Raja Reddy. This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Hatch/Multi State project (Multistate No. NC1200; Project No. MIS‐153180) under Accession No. 232044. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.