The Cotton WRKY Transcription Factor GhWRKY17 Functions in Drought and Salt Stress in Transgenic Nicotiana benthamiana Through ABA Signaling and the Modulation of Reactive Oxygen Species Production

Abstract

Drought and high salinity are two major environmental factors that significantly limit the productivity of agricultural crops worldwide. WRKY transcription factors play essential roles in the adaptation of plants to abiotic stresses. However, WRKY genes involved in drought and salt tolerance in cotton (Gossypium hirsutum) are largely unknown. Here, a group IId WRKY gene, GhWRKY17, was isolated and characterized. GhWRKY17 was found to be induced after exposure to drought, salt, H2O2 and ABA. The constitutive expression of GhWRKY17 in Nicotiana benthamiana remarkably reduced plant tolerance to drought and salt stress, as determined through physiological analyses of the germination rate, root growth, survival rate, leaf water loss and Chl content. GhWRKY17 transgenic plants were observed to be more sensitive to ABA-mediated seed germination and root growth. However, overexpressing GhWRKY17 in N. benthamiana impaired ABA-induced stomatal closure. Furthermore, we found that GhWRKY17 modulated the increased sensitivity of plants to drought by reducing the level of ABA, and transcript levels of ABA-inducible genes, including AREB, DREB, NCED, ERD and LEA, were clearly repressed under drought and salt stress conditions. Consistent with the accumulation of reactive oxygen species (ROS), reduced proline contents and enzyme activities, elevated electrolyte leakage and malondialdehyde, and lower expression of ROS-scavenging genes, including APX, CAT and SOD, the GhWRKY17 transgenic plants exhibited reduced tolerance to oxidative stress compared with wild-type plants. These results therefore indicate that GhWRKY17 responds to drought and salt stress through ABA signaling and the regulation of cellular ROS production in plants.

Investigation of the ASR family in foxtail millet and the role of ASR1 in drought/oxidative stress tolerance

“…For drought treatment in soil, 2-week-old seedlings were not watered for 10 days and then re-watered for 20 days under the above conditions. Accumulation of H 2 O 2 and O 2-was detected using 3, 3 0 -diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) as previously described (Yan et al 2014). For oxidative treatment in soil, 2-week-old seedlings were watered with 10 lM MV for 10 days and then re-watered normally for 20 days.…”

“…7). MV is a herbicide that causes chlorophyll degradation and cell membrane leakage through ROS production (Yan et al 2014). In the MS medium supplemented with MV, germination of WT seeds was inhibited, whereas transgenic seeds continued to germinate (Fig.…”

Integration of Hormonal and Nutritional Cues Orchestrates Progressive Corolla Opening

“…The WRKY family is an enormous family that has 74 members in Arabidopsis and more than 90 members in rice (Oryza sativa; Ülker and Somssich, 2004). Previous studies indicate that WRKY TFs play important roles in stress responses (Ren et al, 2010;Qin et al, 2013;Yan et al, 2014). For example, rice WRKY13 regulates the cross talk between drought and disease-resistance signaling pathways by binding to different DNA sequence motifs (Xiao et al, 2013).…”

VvWRKY13 enhances ABA biosynthesis in Vitis vinifera

“…The cotton WRKY transcription factor, GhWRKY17, increased sensitivity of transgenic Nicotiana benthamiana to drought. It achieved this by reducing the level of ABA and transcript levels of ABA-inducible genes, including AREB, DREB, NCED, ERD, and LEA [18]. AtWRKY33 acted upstream of NCED3/ NCED5 to negatively regulate ABA biosynthesis in Arabidopsis [19].…”