Studies on the cold tolerance of ratoon 'Chaling' common wild rice

BACKGROUND: Rice is the staple food of many people around the world. However, most rice varieties, especially widely grown indica varieties and hybrids, are sensitive to cold stress. In order to provide a basis for the utilization of a common wild rice (CWR, Oryza rufipogon Griff.) named 'Chaling' CWR in cold-tolerant rice breeding and deepen the understanding of rice cold tolerance, the cold tolerance of ratoon 'Chaling' CWR was studied under the stress of the natural low temperature in winter in Changsha, Hunan province, China, especially under the stress of abnormal natural low temperature in Changsha in 2008, taking other ratoon CWR accessions and ratoon cultivated rice phenotypes as control. RESULTS: The results showed that ratoon 'Chaling' CWR can safely overwinter under the natural conditions in Changsha (28° 22' N), Hunan province, China, which is a further and colder northern place than its habitat, even if it suffers a long-term low temperature stress with ice and snow. In 2008, an extremely cold winter appeared in Changsha, i.e., the average daily mean temperature of 22 consecutive days from January 13 to February 3 was - 1.0 °C, and the extreme low temperature was - 4.7 °C. After subjected to this long-term cold stress, the overwinter survival rate of ratoon 'Chaling' CWR was 100%, equals to that of ratoon 'Dongxiang' CWR which is northernmost distribution in the word among wild rice populations, higher than those of ratoon 'Fusui' CWR, ratoon 'Jiangyong' CWR, and ratoon 'Liujiang' CWR (63.55-83.5%) as well as those of ratoon 'Hainan' CWR, ratoon 'Hepu' CWR, and all the ratoon cultivated rice phenotypes including 3 japonica ones, 3 javanica ones, and 5 indica ones (0.0%). CONCLUSIONS: The results indicate that ratoon 'Chaling' CWR possesses strong cold tolerance and certain freezing tolerance.

Deciphering the physiological and molecular mechanisms for copper tolerance in autotetraploid Arabidopsis.

KEY MESSAGE: Autotetraploid Arabidopsis line esd and 4COL exhibit enhanced tolerance to Cu stress by enhancing activation of antioxidative defenses, altering expression of genes related to Cu transport, chelation, and ABA-responsive. Autopolyploidy is ubiquitous among angiosperms and often results in better adaptation to stress conditions. Although copper (Cu) is an essential trace element, excess amounts can inhibit plant growth and even result in death. Here, we report that autotetraploid Arabidopsis thaliana esd and 4COL exhibit higher tolerance to Cu stress. Under such conditions, tetraploid plants had lower Cu contents and significantly more biomass compared with diploid plants. When exposed to excess Cu for 24 h, levels of superoxide anions, hydrogen peroxide, and malondialdehyde were lower in tetraploids than in diploids. Moreover, activities of the antioxidant enzymes superoxide dismutase and peroxidase were stimulated and glutathione content was maintained at a relative higher level in the tetraploids. The expression of genes related to Cu transport and chelation was altered in autotetraploid Arabidopsis under Cu stress, and several key genes involved in the response to abscisic acid (ABA) were significantly up-regulated. Our results indicate that tetraploid Arabidopsis esd and 4COL acquire improved tolerance to Cu stress through enhanced activation of antioxidative defense mechanisms, altered expression of genes related to Cu transport and chelation, and positive regulation of expression for ABA-responsive genes.

[Evaluation of the clinical and imaging examination in high-risk children with vesicoureteral reflux].

OBJECTIVE: To analyze the clinical data and result of voiding cystourethrography (VCUG) in high-risk children with vesicoureteral reflux (VUR) for better awareness of VUR, and to assess the usefulness of non-radioactive voiding ultrasonography (VUS) in the diagnosis of VUR. METHOD: Ninety-three high-risk children with VUR who were hospitalized from July 2007 to April 2010 were studied. The study included 58 cases of urinary tract infection (UTI) and 35 cases of fetal or postnatal hydronephrosis detected on a B ultrasound scan. The results of urinalysis, urine culture, renal function, B ultrasound and VCUG were evaluated. Part of patients underwent VUS followed by VCUG immediately. RESULT: (1) Sixty-two boys and 31 girls (aged 1 month to 11.5 years, mean age 2 years) were included. VUR was detected in 26 patients (28%) by VCUG. In terms of kidney-ureter units, VUR was detected in 36 of 186 kidney-ureter units, including 6 grade I, 3 grade II, 6 grade III, 15 grade IV and 6 grade V. (2) VUR was detected in 20 of 58 UTI patients (34.5%) by VCUG. The proportion of VUR in recurrent UTI group was 61.1%, much higher than that in first UTI group (22.5%). Thirteen of 20 VUR (65%) occurred in UTI patients under 1 year of age (M/F 10/3), with more bilateral VUR and severe grades of VUR than the older group. VUR was detected in 6 of 35 fetal or postnatal hydronephrosis patients (17.1%) by VCUG. (3) Twenty-two patients underwent both VUS and VCUG. VUR was detected in 4 patients and 6 kidney-ureter units by VCUG, while in 6 patients and 9 kidney-ureter units by VUS. Taking VCUG as the reference standard, VUS had a sensitivity of 100%, specificity of 92.1%, positive predictive value of 66.7%, and negative predictive value of 100%. There was a concordance rate of 93.2% between VUS and VCUG. CONCLUSION: It is important to early screen VUR in UTI, fetal or postnatal hydronephrosis patients. There are more VUR, especially more bilateral VUR and severe grades of VUR, occurred in UTI patients under 1 year of age compared to older children. The incidence of VUR in recurrent UTI group was much higher than that in first UTI group. VUS is an accurate, reliable and radiation-free technique for the detection of VUR. It could be used to screen high-risk children for VUR and do the evaluation in the follow-up of VUR.