Changes in Cell Ca²⁺ Distribution in Loquat Leaves and Its Effects on Cold Tolerance

Zheng, Guohua,Pan, Dongming,Niu, Xianqian,Wu, Hanwen,Zhang, Jinbiao Korean Society of Horticultural Science 2014 원예과학기술지 Vol.32 No.5

Calcium has been associated with improved cold tolerance in many crops. The aim of this study was to investigate the changes in leaf cell $Ca^{2+}$ distribution and cell organelle ultrastructure of loquat (Eriobotrya japonica Lindl.) plants in response to cold stress at $-3^{\circ}C$, using transmission electron microscopy (TEM). Two loquat accessions, Zaozhong 6 (a commercial cultivar) and oakleaf loquat (a wild relative) were used. Cold tolerance, as measured by leaf browning rate, was higher in oakleaf plants, and calcium treatment improved cold tolerance in both species. Cold stress first induced inward transport of $Ca^{2+}$ from the intracellular space. Then, the imported $Ca^{2+}$ was aggregated around the chloroplast membrane, finally entering the chloroplast. This pattern of $Ca^{2+}$ distribution in leaf cells occurred earlier in Zaozhong 6 than in the wild loquat. With increasing time of cold exposure, the chloroplast membranes of Zaozhong 6 leaves were damaged, blurred and even disappeared, while those of wild oakleaf loquat leaves maintained their structure longer. In Zaozhong 6, cold stress induced a clear cavity between poorly structured granal thylakoids and vesicles appearing inside the chloroplast, while in oakleaf leaves cold stress had little effect on the ultrastructure of chloroplasts (although chloroplast membranes looked blurred). Loquat leaves accumulated free calcium ions around chloroplasts in response to cold stress, with earlier calcium accumulation occurring in the cold-sensitive cultivar Zaozhong 6 than in wild oakleaf loquat. These results demonstrate that these two loquat species have differences in both cold tolerance and calcium accumulation dynamics.

Differential Frost Tolerance and Enzymatic Activities in the Leaves and Immature Fruits of Loquat (Eriobotrya japonica Lindl.)

Zheng, Guohua,Niu, Xianqian,Zhang, Jinbiao,Wu, Hanwen,Lin, Xiuxiang,Pan, Dongming Korean Society of Horticultural Science 2015 원예과학기술지 Vol.33 No.3

In this experiment, five commercial cultivars and one wild species of loquat were used to investigate frost tolerance and enzymatic activities in leaves and young fruits under cold stress at $-3^{\circ}C$. The frost injury, malondialdehyde (MDA) content, and oxygen-scavenging enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied. This results showed that the wild species 'Wild Oak-leaf' loquat was the most frost tolerant among accessions tested, followed by the cultivar 'Golden Block'. Other cultivars, 'Wu Gong Bai', 'Taicheng 4', 'Xiangzhong 11' and 'Zaozhong 6', were relatively weak in frost tolerance. The enzymatic activities of SOD, POD and CAT increased initially and then decreased as the exposure time increased. However, the enzymatic peak occurred later in the frost-tolerant accession than in the frost-sensitive accession. The correlation coefficients of MDA contents between leaves and immature fruits were from 0.93 to 0.99 in the five commercial loquat cultivars. For the 'Wild Oak-leaf' loquat, the correlation coefficients of MDA and POD were 0.98 and 0.95, respectively, but the coefficients for SOD, CAT and APX were relatively low. In general, there were good correlations between loquat leaves and immature fruits in MDA content and enzyme activities. These results indicate that analysis of these physiological and biochemical activities in loquat leaves could potentially be used to predict the cold tolerance in loquat at immature fruit stage and to accelerate breeding programs for cold tolerance in loquat.

Changes in Cell Ca 2+ Distribution in Loquat Leaves and Its Effects on Cold Tolerance

Guohua Zheng,Dongming Pan,Xianqian Niu,Hanwen Wu,Jinbiao Zhang 한국원예학회 2014 원예과학기술지 Vol.32 No.5

Calcium has been associated with improved cold tolerance in many crops. The aim of this study was to investigatethe changes in leaf cell Ca2+distribution and cell organelle ultrastructure of loquat (Eriobotrya japonica Lindl.) plants in responseto cold stress at -3°C, using transmission electron microscopy (TEM). Two loquat accessions, Zaozhong 6 (a commercial cultivar)and oakleaf loquat (a wild relative) were used. Cold tolerance, as measured by leaf browning rate, was higher in oakleaf plants,and calcium treatment improved cold tolerance in both species. Cold stress first induced inward transport of Ca2+from theintracellular space. Then, the imported Ca2+was aggregated around the chloroplast membrane, finally entering the chloroplast. This pattern of Ca2+distribution in leaf cells occurred earlier in Zaozhong 6 than in the wild loquat. With increasing time ofcold exposure, the chloroplast membranes of Zaozhong 6 leaves were damaged, blurred and even disappeared, while those ofwild oakleaf loquat leaves maintained their structure longer. In Zaozhong 6, cold stress induced a clear cavity between poorlystructured granal thylakoids and vesicles appearing inside the chloroplast, while in oakleaf leaves cold stress had little effecton the ultrastructure of chloroplasts (although chloroplast membranes looked blurred). Loquat leaves accumulated free calciumions around chloroplasts in response to cold stress, with earlier calcium accumulation occurring in the cold-sensitive cultivarZaozhong 6 than in wild oakleaf loquat. These results demonstrate that these two loquat species have differences in both coldtolerance and calcium accumulation dynamics.

Differential Frost Tolerance and Enzymatic Activities in the Leaves and Immature Fruits of Loquat (Eriobotrya japonica Lindl.)

Guohua Zheng,Xianqian Niu,Jinbiao Zhang,Hanwen Wu,Xiuxiang Lin,Dongming Pan 한국원예학회 2015 원예과학기술지 Vol.33 No.3

In this experiment, five commercial cultivars and one wild species of loquat were used to investigate frost tolerance and enzymatic activities in leaves and young fruits under cold stress at -3℃. The frost injury, malondialdehyde (MDA) content, and oxygen-scavenging enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied. This results showed that the wild species ‘Wild Oak-leaf’ loquat was the most frost tolerant among accessions tested, followed by the cultivar ‘Golden Block’. Other cultivars, ‘Wu Gong Bai’, ‘Taicheng 4’, ‘Xiangzhong 11’ and ‘Zaozhong 6’, were relatively weak in frost tolerance. The enzymatic activities of SOD, POD and CAT increased initially and then decreased as the exposure time increased. However, the enzymatic peak occurred later in the frost-tolerant accession than in the frost-sensitive accession. The correlation coefficients of MDA contents between leaves and immature fruits were from 0.93 to 0.99 in the five commercial loquat cultivars. For the ‘Wild Oak-leaf’ loquat, the correlation coefficients of MDA and POD were 0.98 and 0.95, respectively, but the coefficients for SOD, CAT and APX were relatively low. In general, there were good correlations between loquat leaves and immature fruits in MDA content and enzyme activities. These results indicate that analysis of these physiological and biochemical activities in loquat leaves could potentially be used to predict the cold tolerance in loquat at immature fruit stage and to accelerate breeding programs for cold tolerance in loquat.

Changes in Cell Ca<SUP>2+</SUP> Distribution in Loquat Leaves and Its Effects on Cold Tolerance

Guohua Zheng,Dongming Pan,Xianqian Niu,Hanwen Wu,Jinbiao Zhang 한국원예학회 2014 원예과학기술지 Vol.32 No.5

Calcium has been associated with improved cold tolerance in many crops. The aim of this study was to investigate the changes in leaf cell Ca<SUP>2+</SUP> distribution and cell organelle ultrastructure of loquat (Eriobotrya japonica Lindl.) plants in response to cold stress at -3℃, using transmission electron microscopy (TEM). Two loquat accessions, Zaozhong 6 (a commercial cultivar) and oakleaf loquat (a wild relative) were used. Cold tolerance, as measured by leaf browning rate, was higher in oakleaf plants, and calcium treatment improved cold tolerance in both species. Cold stress first induced inward transport of Ca<SUP>2+</SUP> from the intracellular space. Then, the imported Ca<SUP>2+</SUP> was aggregated around the chloroplast membrane, finally entering the chloroplast. This pattern of Ca<SUP>2+</SUP> distribution in leaf cells occurred earlier in Zaozhong 6 than in the wild loquat. With increasing time of cold exposure, the chloroplast membranes of Zaozhong 6 leaves were damaged, blurred and even disappeared, while those of wild oakleaf loquat leaves maintained their structure longer. In Zaozhong 6, cold stress induced a clear cavity between poorly structured granal thylakoids and vesicles appearing inside the chloroplast, while in oakleaf leaves cold stress had little effect on the ultrastructure of chloroplasts (although chloroplast membranes looked blurred). Loquat leaves accumulated free calcium ions around chloroplasts in response to cold stress, with earlier calcium accumulation occurring in the cold-sensitive cultivar Zaozhong 6 than in wild oakleaf loquat. These results demonstrate that these two loquat species have differences in both cold tolerance and calcium accumulation dynamics.

Electrophysiologic Characteristics of Nitrous-Oxide-Associated Peripheral Neuropathy: A Retrospective Study of 76 Patients

Xiuying Fang,Miao Yu,Dongming Zheng,Han Gao,Weishuai Li,Ying Ma 대한신경과학회 2023 Journal of Clinical Neurology Vol.19 No.1

Background and Purpose The electrophysiologic characteristics of peripheral neuropathy secondary to nitrous oxide (N2O) abuse remain unclear. The paper therefore aimed to summarize the electrophysiologic characteristics of N2O-associated peripheral neuropathy and identify the risk factors of severe nerve injury. Methods The electrophysiologic results and clinical data of patients with peripheral neuropathy secondary to N2O abuse at our hospital between 2018 and 2020 were analyzed retrospectively, and their electrophysiologic changes were summarized. Results Most patients exhibited decreased sensory and motor nerve conduction velocities (75% and 76%), decreased sensory nerve and compound motor action potentials (57% and 59%), and prolonged distal motor latency (59%), while a response was absent in 36%. These findings indicate that N2O abuse can result in generalized injury to sensory and motor nerves. Electrophysiologic results indicated axonal neuropathy in 37 cases (49%), demyelinating peripheral neuropathy in 4 (5%), and mixed neuropathy in 12 (16%). Peripheral nerve injury was more common in the lower limbs (72%) than in the upper limbs (42%, p<0.0001). The upper and lower limbs were primarily affected by sensory nerve demyelination (35%) and motor axonal injury (67%), respectively. Subgroup analysis indicated that longer N2O exposure and longer disease course were associated with more-severe motor axonal injury in the lower limbs. Conclusions N2O-associated peripheral neuropathy can lead to sensory and motor nerve injury, with axonal injury being the most common. Injuries were more severe in the lower limbs. Prolonged N2O exposure and disease course increased the severity of motor axonal injury in the lower limbs.