Analysis of flooding-responsive proteins localized in the nucleus of soybean root tips

Flooding stress has negative impact on soybean cultivation as it severely impairs plant growth and development. To examine whether nuclear function is affected in soybean under flooding stress, abundance of nuclear proteins and their mRNA expression were analyzed. Two-day-old soybean seedlings were treated with flooding for 2 days, and nuclear proteins were purified from root tips. Gel-free proteomics analysis identified a total of 39 flooding-responsive proteins, of which abundance of 8 and 31 was increased and decreased, respectively, in soybean root tips. Among these differentially regulated proteins, the mRNA expression levels of five nuclear-localized proteins were further analyzed. The mRNA levels of four proteins, which are splicing factor PWI domain-containing protein, epsilon2-COP, beta-catenin, and clathrin heavy chain decreased under flooding stress, were also down-regulated. In addition, mRNA level of a receptor for activated protein kinase C1(RACK1) was down-regulated, though its protein was accumulated in the soybean nucleus in response to flooding stress. These results suggest that several nuclear-related proteins are decreased at both the protein and mRNA level in the root tips of soybean under flooding stress. Furthermore, RACK1 might have an important role with accumulation in the soybean nucleus under flooding-stress conditions.     

Determinants of coronary microvascular dysfunction in symptomatic hypertrophic cardiomyopathy

Impaired hyperemic myocardial blood flow (MBF) in hypertrophic cardiomyopathy (HCM), despite normal epicardial coronary arteries, results in microvascular dysfunction. The aim of the present study was to determine the relative contribution of extravascular compressive forces to microvascular dysfunction in HCM. Eighteen patients with symptomatic HCM and normal coronary arteries and 10 age-matched healthy volunteers were studied with PET to quantify resting and hyperemic MBF at a subendocardial and subepicardial level. In HCM patients, MRI was performed to determine left ventricular (LV) mass index (LVMI) and volumes, echocardiography to assess diastolic perfusion time, heart catheterization to measure LV outflow tract gradient (LVOTG) and LV pressures, and serum NH(2)-terminal pro-brain natriuretic peptide (NT-proBNP) as a biochemical marker of LV wall stress. Hyperemic MBF was blunted in HCM vs. controls (2.26 +/- 0.97 vs. 2.93 +/- 0.64 ml min(-1) g(-1), P < 0.05). In contrast to controls (1.38 +/- 0.15 to 1.25 +/- 0.19, P = not significant), the endocardial-to-epicardial MBF ratio decreased significantly in HCM during hyperemia (1.20 +/- 0.11 to 0.88 +/- 0.18, P < 0.01). This pattern was similar for hypertrophied septum and lateral wall. Hyperemic MBF was inversely correlated with LVOTG, NT-proBNP, left atrial volume index, and LVMI (all P < 0.01). Multivariate regression analysis, however, revealed that only LVMI and NT-proBNP were independently related to hyperemic MBF, with greater impact at the subendocardial myocardial layer. Hyperemic MBF is more severely impaired at the subendocardial level in HCM patients. The level of impairment is related to markers of increased hemodynamic LV loading conditions and LV mass. These observations suggest that, in addition to reduced capillary density caused by hypertrophy, extravascular compressive forces contribute to microvascular dysfunction in HCM patients.     

番茄多蛋白桥梁因子基因LeMBF1的克隆及抗病性分析

采用同源序列克隆法,从番茄中克隆了多蛋白桥梁因子基因LeMBF1,该基因包含一个完整的420 bp的开放阅读框,编码139个氨基酸,具有MBF1保守结构域.LeMBF1氨基酸序列与马铃薯StMBF1、烟草NtMBF1和葡萄VvMBF1的氨基酸序列相似度分别是99.3%、91.4%和84.2%.为了研究番茄多蛋白桥梁因子LeMBF1在植物抗病性中的作用,以LeMBF1超表达转基因番茄和野生型番茄为材料,对其进行接种病原细菌Pst.DC3000和尖孢镰刀菌Fusarium.oxysporum的生物胁迫实验.抗菌表型分析发现,LeMBF1超表达转基因番茄叶片上的菌斑数明显少于对照植株;实时定量PCR分析表明,LeMBF1超表达番茄植株中防卫基因PR1、PR6的表达水平明显增强.由此可见,LeMBF1可能通过激活部分PRs基因的表达提高了植物的抗病性.     

Heat-induced accumulation of protein synthesis elongation factor 1A implies an important role in heat tolerance in potato

Main conclusion

Potato eukaryotic elongation factor 1A comprises multiple isoforms, some of which are heat-inducible or heat-upregulated and might be important in alleviating adverse effects of heat stress on plant productivity. Heat stress substantially reduces crop productivity worldwide, and will become more severe due to global warming. Identification of proteins involved in heat stress response may help develop varieties for heat tolerance. Eukaryotic elongation factor 1A (eEF1A) is a cytosolic, multifunctional protein that plays a central role in the elongation phase of translation. Some of the non-canonical eEF1A activities might be important in developing plant heat-stress tolerance. In this study, we investigated effects of heat stress (HS) on eEF1A expression at the protein level in potato, a highly heat vulnerable crop. Our results from both the controlled environment and the field have shown that potato eEF1A is a heat-inducible protein of 49.2-kDa with multiple isoforms (5–8). Increase in eEF1A abundance under HS can be mainly attributed to 2–3 basic polypeptides/isoforms. A significant correlation between eEF1A abundance and the potato productivity in the field was observed in two extremely hot years 2011 and 2012. Genomic Southern blot analysis indicated the existence of multiple genes encoding eEF1A in potato. Identification, isolation and utilization of heat-inducible eEF1A genes might be helpful for the development of the heat-tolerant varieties.