Physio-Biochemical Insights into the Cold Resistance Variations among Nectarine (Prunus persica (L.) Batsch var. nectarina) Cultivars.

Simple Summary: In this study, the cold resistance of five main nectarine (Prunus persica (L.) Batsch, var nectarine) cultivars grown in Shanxi Province of China was evaluated and compared. To explore the physio-biochemical mechanism underlying their cold resistance variations, semi-lethal low temperature (LT50) and thirteen cold resistance related parameters at six timepoints during overwintering were determined and analyzed. Results showed that these five nectarine cultivars could be classified into high cold resistant (HR), moderate cold resistant (MR) and low cold resistant (LR) groups. The HR cultivars were of higher relative water (RW) and proline (PRO) contents and superoxide dismutase (SOD) activity, but much lower relative electric conductivity (RE), malondialdehyde (MDA) content and catalase (CAT) activity. Moreover, the increase of PRO and abscisic acid (ABA) contents and decrease of RW content in HR cultivars were greater than other cultivars. Additionally, redundancy analysis (RDA) revealed that these indexes were significantly correlated with the HR cultivars, indicating that they could be used as potential markers for the cold resistance evaluation of nectarine germplasm resources. Cold stress occurs in late winter and early spring threatens greatly the nectarine industry. In this study, the semi-lethal low temperature (LT50) and thirteen cold resistance related parameters of five nectarine cultivars, including 'Nonglehong little princess' (LP), 'Luyou No. 5' (LY), 'Nonglehong No. 6' (NL), 'Zhongyou No. 20' (ZY) and 'Qiuhongzhu' (QH), were determined. Based on these parameters, they were categorized into high—(HR, including NL and LP), moderate—(MR, including QH) and low-cold resistant (LR, including ZY and LY) groups. The relative water (RW), proline (PRO), soluble sucrose (SS) and soluble protein (SP) contents, and superoxide dismutase (SOD) and peroxidase (POD) activities of HR cultivars were higher while their relative electronic conductivity (RE), malondialdehyde (MDA) and gibberellin acid (GA3) contents and catalase (CAT) activity were lower than other cultivars during natural overwintering. Redundancy analysis revealed that the lowest temperature in a day (LT) and LT50 significantly explains 69.8% and 10.9% of these physiological variables, respectively. Moreover, GA3 and indoleacetic acid (IAA) contents and CAT activity were positively correlated, while PRO, SS, ABA and RW contents were negatively correlated with both LT and LT50. Our study will be helpful in understanding the cold resistance variations of nectarine germplasm resources. [ABSTRACT FROM AUTHOR]