Identification of Two Auxin-Regulated Potassium Transporters Involved in Seed Maturation

Abstract

The seed is the most important plant reproductive unit responsible for the evolutionary success of flowering plants. Aside from its essential function in the sexual reproduction of plants, the seed also represents the most economically important agricultural product worldwide, providing energy, nutrients, and raw materials for human nutrition, livestock feed, and countless manufactured goods. Hence, improvements in seed quality or size are highly valuable, due to their economic potential in agriculture. Recently, the importance of indolic compounds in regulating these traits has been reported for Arabidopsis thaliana. The transcriptional and physiological mechanisms involved, however, remain largely undisclosed. Potassium transporters have been suggested as possible mediators of embryo cell size, controlling turgor pressure during seed maturation. In addition, it has been demonstrated that the expression of K+ transporters is effectively regulated by auxin. Here, we provide evidence for the identification of two Arabidopsis K+ transporters, HAK/KT12 (At1g60160) and KUP4 (At4g23640), that are likely to be implicated in determining seed size during seed maturation and, at the same time, show a differential regulation by indole-3-acetic acid and indole-3-acetamide.

Close Temporal Relationship between Oscillating Cytosolic K+ and Growth in Root Hairs of Arabidopsis

“…All plant material employed in this study were Arabidopsis Col-0 wild-type plants or mutants in the Col-0 background. Transgenic marker lines and K + transporters mutants were as follows: YC3.6 [ 24 ], Lifeact–Venus [ 52 ], kup4-2 (SALK_071644) [ 53 ], akt1 (SALK_071803) [ 49 ], atkc1 (SALK_140579) [ 54 ], and hak5 (SALK_005604) [ 55 ], which have been described previously. Surface-sterilized seeds were sown on half-strength Murashige and Skoog (½ MS) medium (2.2 g/L MS salts, 15 g/L sucrose, pH 5.7–5.8, and 1 g/L phytagel) and germinated at 22 °C with a 16 L/8 D illumination cycle after imbibition.…”

Genome-Wide Survey and Expression Analysis of the KT/HAK/KUP Family in Brassica napus and Its Potential Roles in the Response to K+ Deficiency

“…Remarkably, more genes in groups II, III, and IV have been reported to be associated with various plant developmental processes. For instance, AtKUP4 (II) is crucial for both gravitropic responses and root hair formation by mediating auxin efflux [ 30 ]; AtKUP2 , AtKUP6 , AtKUP8 [ 4 ], and CnHAK1 [ 23 ] in group II are involved in K + -dependent cell expansion and mediate K + efflux in roots, which negatively regulate plant growth and cell size; AtKUP4 and OsHAK10 in group II play a role in seed maturation and reproductive processes, respectively [ 14 , 52 ]; AtKUP9 in group III can maintain root growth and meristem activity by regulating K + and auxin homeostasis under low-K + stress [ 27 ]; the cotton GhKT1 in group III plays a role in fiber elongation [ 53 ]; and LjKUP in group IV from Lotus japonicus is involved in nodulation development [ 54 ]. As mentioned above, group IV is absent in Brassicaceae [ 38 ].…”

Disruption ofAtHAK/KT/KUP9enhances plant cesium accumulation under low potassium supply

“…T-DNA insertion was checked and homozygous lines were identified using combination of T-DNA border primers and gene specific primers as outlined in the online protocol “Screening SALK T-DNA mutagenesis lines” (University of Wisconsin, Madison Knockout Facility and Ohio State University, Arabidopsis Biological Resource Center https://www.mcdb.ucla.edu/Research/Goldberg/HC70AL_S06/pdf/Expt6protocol.pdf). In the following, the SALK_108080C mutant line with T-DNA insertion located in exon 9 and the SAIL_211_E04 mutant line with T-DNA insertion located in intron 2 are named respectively kup9-1 (Tenorio-Berrío et al, 2018) and kup9-3 ( Fig. 1 ).…”