The potassium channel FaTPK1 plays a critical role in fruit quality formation in strawberry (Fragaria × ananassa)

Abstract

SummaryPotassium (K+), an abundant cation in plant cells, is important in fruit development and plant resistance. However, how cellular K+ is directed by potassium channels in fruit development and quality formation of strawberry (Fragaria × ananassa) is not yet fully clear. Here, a two‐pore K+ (TPK) channel gene in strawberry, FaTPK1, was cloned using reverse transcription–PCR. A green fluorescent protein subcellular localization analysis showed that FaTPK1 localized in the vacuole membrane. A transcription analysis indicated that the mRNA expression level of FaTPK1 increased rapidly and was maintained at a high level in ripened fruit, which was coupled with the fruit's red colour development, suggesting that FaTPK1 is related to fruit quality formation. The down‐ and up‐regulation of the FaTPK1 mRNA expression levels using RNA interference and overexpression, respectively, inhibited and promoted fruit ripening, respectively, as demonstrated by consistent changes in firmness and the contents of soluble sugars, anthocyanin and abscisic acid, as well as the transcript levels of ripening‐regulated genes PG1 (polygalacturonase), GAL6 (beta‐galactosidase), XYL2 (D‐xylulose reductase), SUT1 (sucrose transporter), CHS (chalcone synthase) and CHI (chalcone flavanone isomerase). Additionally, the regulatory changes influenced fruit resistance to Botrytis cinerea. An isothermal calorimetry analysis showed that the Escherichia coli‐expressed FaTPK1 recombinant protein could bind K+ with a binding constant of 2.1 × 10–3 m −1 and a dissociation constant of 476 μm. Thus, the strawberry TPK1 is a ubiquitously expressed, tonoplast‐localized two‐pore potassium channel that plays important roles in fruit ripening and quality formation.

GhNAC83 inhibits corm dormancy release by regulating ABA signaling and cytokinin biosynthesis inGladiolus hybridus

“…Virus-induced gene silencing (VIGS) is widely used in functional analysis of horticultural plants, such as rose, apple, strawberry, and Gladiolus (Zhong et al , 2014; Wu et al , 2016; Ma et al , 2017; S. Wang et al , 2018). Therefore, we investigated the role of GhPP2C1 in CDR using a VIGS approach.…”

Strawberry tonoplast transporter, FaVPT1, controls phosphate accumulation and fruit quality

“…A sample (3 g) of the fruit flesh was ground to powder in liquid nitrogen, and then, 2.5 mL of methanol (1% HCl) was added to 0.5 g of powder. The extraction, centrifugation, and measurement of anthocyanin content followed the methods of Wang et al (). Pelargonidin‐3‐O‐glucoside was used as a standard.…”

“…The vacuole, as the largest multifunctional organelle of fleshy fruits, plays a vital role in fruit development, ripening, and quality (Liu et al, ). In recent years, although a set of tonoplast transporters or channels has been identified in fleshy fruits (Cheng et al, ; Cheng et al, ; De, Angeli, et al, ; Francisco et al, ; Liu, Li, Qin, Zhang, & Tian, ; Merlaen, De, Keyser, & Van, Labeke, ; Ren et al, ; Snowden, Thomas, Baxter, Smith, & Sweetlove, ; Wang et al, ; Wang et al, ; Yang, Huang, Kuo, & Chiou, ), the tonoplast phosphate transporters in fleshy fruits remain unknown.…”

“…Biochemically, the vacuolar accumulation of these compounds across the tonoplast against a concentration gradient requires various transporters (De, Angeli, et al, ; Jung et al, ; Liu et al, ; Ren et al, ). In recent years, many tonoplast transporters or channels in fleshy fruits have been identified, such as grape vacuolar channel9 (ALMT9; De, Angeli, et al, ), tomato tonoplast Glu/Asp/GABA exchanger9 (SlCAT9; Snowden et al, ), tomato tonoplast dicarboxylate transporter (SlTDT; Liu et al, ), melon tonoplast sugar transporter2 (CmTST2; Cheng, Wen, et al, ), pear tonoplast monosaccharide transporter4 (PbTMT4; Cheng, Cheng, et al, ), watermelon tonoplast sugar transporter2 (ClTST2; Ren et al, ), strawberry tonoplast potassium channel (FaTPK1; Wang et al, ), and tonoplast intrinsic proteins (TIP; Merlaen et al, ). Although phosphate plays a vital role in fleshy fruit quality (Martuscelli, Stagnari, Speca, Pisante, & Mastrocola, ), the vacuole phosphate transporter in fleshy fruits, to our knowledge, remains to be identified.…”

FaPAO5 regulates Spm/Spd levels as a signaling during strawberry fruit ripening

“…To confirm that FaPAO5 is a negative regulator of strawberry fruit ripening, Agrobacterium tumefaciens (strain GV3101) cells con- (Wang et al, 2018) were separately injected into 20 DG fruits on plants at 18 DAA. The fruit phenotypes were examined at 4, 8, and 10 days after injection or at 22, 26, and 28 DAA.…”