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Iron is required for the Fe-S cluster assembly which occurs in chloroplasts, mitochondria, and cytosol and here we characterized 44 Fe-S cluster biosynthesis genes and investigated their expression profiles during different peach flowering stages. Quantitative real-time PCR analysis shows that the highest expression of most peach Fe-S cluster biosynthesis genes appeared in the full bloom stage. Also, the highest Fe accumulation occurred in the full bloom stage followed by beginning bloom, petal fall, and bud swell stages. Activities of nitrite reductase (NiR) and succinate dehydrogenase (SDH) were closely correlated to the flower Fe content, whereas the aconitase (ACO) activity kept steady during the whole flowering process. Moreover, shading treatment significantly reduced Fe accumulation and NiR, SDH, and ACO activities of the full blooming flowers. Seventeen Fe-S cluster biosynthesis genes were down-regulated in response to a shading treatment. In particular, plastid sulfur mobilization genes were sensitive to the shading treatment.

Potassium uptake and transport is facilitated by KT/HAK/KUP transporters. In this study, we identified 16 putative K+-uptake transporter genes in peach (Prunus persica). To investigate the role of PpeKUP in maintaing K+ uptake, transport, and homeostasis, we applied abiotic stresses to peach seedlings and analysed physiological reactions and transcriptional responses of PpeKUP genes. The peach seedlings were sensitive to polyethylene glycol (PEG), Pb, and Cd, as evidenced by impaired growth, K+ nutrition, and photosynthetic performance. However, the peach seedlings were tolerant to aluminum. K+ deficiency mainly increased, whereas K+ excess reduced the PpeKUP gene expression in roots. The Al treatments enhanced the PpeKUP transcription in shoots, whereas PEG, Pd, and Cd enhanced the PpeKUP transcription in all tissues. Our findings provided molecular basis for K+ uptake, transport, and homeostasis in the peach seedlings, and revealed potential candidate genes for further functional determination or breeding of peaches.

We used flowering branches at the budding stage of two peach cultivars Xiahui 6 and Xiacui with different cold resistance to explore the effect of exogenous salicylic acid (SA) on the freezing injury of peach floral organs and the molecular mechanism. Using water application as the negative control, the effects of spraying with SA at concentrations of 20 or 100 mg dm-3 on stigma receptivity, frost damage characteristics of floral organs, and the expressions of C-repeat-binding factor (PpCBF) gene family members were investigated at 0 °C. No significant frost damage was observed on petals in all treatments. No frost damage was seen in the ovary and style under 20 mg dm-3 SA treatment, but damage was substantial at the other two treatments. Cultivar Xiahui 6 was more susceptible to freezing than cv. Xiacui. The expression peaks of PpCBFs in the SA-pretreated floral organs occurred at 3 or 6 h after low temperature treatment, and peak time was closely related to peach cultivar, organ, and SA concentration. This indicates that appropriate concentration of exogenous SA may alleviate freezing damage to floral organs and enhance cold resistance by the regulated expression pattern of PpCBF.