Corrigendum: Isolation, identification, biological characteristics, and antifungal efficacy of sodium bicarbonate combined with natamycin on Aspergillus niger from Shengzhou nane (Prunus salicina var. taoxingli) fruit.

[This corrects the article DOI: 10.3389/fmicb.2022.1075033.].

Isolation, identification, biological characteristics, and antifungal efficacy of sodium bicarbonate combined with natamycin on Aspergillus niger from Shengzhou nane (Prunus salicina var. taoxingli) fruit.

The fungi causing fruit rot were isolated from symptomatic Shengzhou nane (Prunus salicina var. taoxingli) fruit and were identified as Aspergillus niger by biological characteristics and molecular analysis of the internal transcribed spacer region (rDNA-ITS) and translation elongation factor-1α (TEF-1α) sequences. Optimal growth conditions for A. niger were 30°C, pH 5.0-6.0, and fructose and peptone as carbon and nitrogen sources. The effects of sodium bicarbonate (SBC), natamycin (NT), and combined treatments on A. niger inhibition were investigated. Treatment with 4.0 g/L sodium bicarbonate (SBC) + 5.0 mg/L natamycin (NT) inhibited mycelial growth and spore germination as completely as 12.0 mg/L SBC or 25.0 mg/L NT. SBC and NT treatments disrupted the structural integrity of cell and mitochondria membranes and decreased enzyme activities involved in the tricarboxylic acid (TCA) cycle, mitochondrial membrane potential (MMP), ATP production in mitochondria, and ergosterol content in the plasma membrane, thus leading to the inhibition of A. niger growth. Moreover, experimental results in vivo showed that the rot lesion diameter and decay rate of Shengzhou nane fruit treated with SBC and NT were significantly reduced compared with the control. The results suggest that the combination treatment of SBC and NT could be an alternative to synthetic fungicides for controlling postharvest Shengzhou nane decay caused by A. niger.

Auxin efflux carriers, MiPINs, are involved in adventitious root formation of mango cotyledon segments.

Adventitious roots form only at the proximal cut surface (PCS) but not at the distal cut surface (DCS) of mango cotyledon segments. In this study, mango embryos treated with indole-3-butyric acid (IBA) showed significantly increased adventitious root formation, while those treated with 2, 3, 5-triiodobenzoic acid (TIBA) demonstrated complete inhibition of adventitious rooting. Mango embryos treated with auxin influx inhibitors demonstrated lower inhibition of adventitious roots than those treated with TIBA. The endogenous indol-3-acetic acid (IAA) content on the PCS and DCS was similar at 0 h, then increased on both surfaces after 6 h, and IAA content on the PCS were always higher than those on the DCS. We cloned three genes encoding auxin efflux carriers (i.e., MiPIN2-4) and examined their temporal and spatial expression patterns under different treatments. Relative expression of all MiPINs studied was very low at 0 h but significantly increased on both PCS and DCS from 1 d to 10 d, to varying degrees. We overexpressed MiPIN1-4 in Arabidopsis plants and found a significant increase in adventitious root quantity in MiPIN1 and MiPIN3 transgenic lines. Immunofluorescence results showed that MiPIN1 and MiPIN3 are primarily localized in the vascular tissues and the cells adjacent to abaxial surface. In conclusion, we propose that in mango cotyledon segments, wounding stimulates IAA biosynthesis, the transcription levels of PIN genes were significantly increased in different magnitudes on the PCS and DCS, resulting in polar IAA transport from the DCS to PCS via the vascular tissues, thereby triggering adventitious root formation.