Metabolome Profiling of Heat Priming Effects, Senescence, and Acclimation of Bread Wheat Induced by High Temperatures at Different Growth Stages.

Our previous study described stage-specific responses of 'Norin 61' bread wheat to high temperatures from seedling to tillering (GS1), tillering to flowering (GS2), flowering to full maturity stage (GS3), and seedling to full maturity stage (GS1-3). The grain development phase lengthened in GS1 plants; source tissue decreased in GS2 plants; rapid senescence occurred in GS3 plants; all these effects occurred in GS1-3 plants. The present study quantified 69 flag leaf metabolites during early grain development to reveal the effects of stage-specific high-temperature stress and identify markers that predict grain weight. Heat stresses during GS2 and GS3 showed the largest shifts in metabolite contents compared with the control, followed by GS1-3 and GS1. The GS3 plants accumulated nucleosides related to the nucleotide salvage pathway, beta-alanine, and serotonin. Accumulation of these compounds in GS1 plants was significantly lower than in the control, suggesting that the reduction related to the high-temperature priming effect observed in the phenotype (i.e., inhibition of senescence). The GS2 plants accumulated a large quantity of free amino acids, indicating residual effects of the previous high-temperature treatment and recovery from stress. However, levels in GS1-3 plants tended to be close to those in the control, indicating an acclimation response. Beta-alanine, serotonin, tryptophan, proline, and putrescine are potential molecular markers that predict grain weight due to their correlation with agronomic traits.

Stage-Specific Characterization of Physiological Response to Heat Stress in the Wheat Cultivar Norin 61.

Bread wheat (Triticum aestivum) is less adaptable to high temperatures than other major cereals. Previous studies of the effects of high temperature on wheat focused on the reproductive stage. There are few reports on yield after high temperatures at other growth stages. Understanding growth-stage-specific responses to heat stress will contribute to the development of tolerant lines suited to high temperatures at various stages. We exposed wheat cultivar "Norin 61" to high temperature at three growth stages: seedling-tillering (GS1), tillering-flowering (GS2), and flowering-maturity (GS3). We compared each condition based on agronomical traits, seed maturity, and photosynthesis results. Heat at GS2 reduced plant height and number of grains, and heat at GS3 reduced the grain formation period and grain weight. However, heat at GS1 reduced senescence and prolonged grain formation, increasing grain weight without reducing yield. These data provide fundamental insights into the biochemical and molecular adaptations of bread wheat to high-temperature stresses and have implications for the development of wheat lines that can respond to high temperatures at various times of the year.

[Diagnostic Ability of Natriuretic Peptides for Heart Failure According to eGFR Level: Comparison between Brain Natriuretic Peptide and Amino-Terminal Probrain Natriuretic Peptide].

Although the influence of reduced kidney function on natriuretic peptides (B-type natriuretic peptide [BNP] and amino terminal probrain natriuretic peptide [NT]) is clear, effect of kidney function on the difference of diagnostic ability for heart failure by these peptides is not obvious. The aim of this study was to examine the relationship between natriuretic peptide concentrations and echocardiographic findings according to eGFR level of the patients. In addition, we compared diagnostic ability of BNP with that of NT according to eGFR level. The eGFR levels were classified by based on CKD stage (≥ 60, 45-59, 30-44, 15-29, < 15 and on maintenance HD). Patients who underwent the measurements of BNP, NT and serum creatinine concentrations, as well as echocardiography between March and October in 2011 were enrolled (n = 1,297). The left ventricular mass index was greater in patients with eGFR < 60 than in those with eGFR ≥ 60, but EF (%) was not different among eGFR level (except eGFR30-44). The percentage of patients with heart failure in those with eGFR < 60 (16.0%) was more than eGFR ≥ 60 (5.8%). Median BNP and NT concentrations were elevated in association with decreasing eGFR level. Using receiver-operator characteristic (ROC) analysis, the area under the ROC curve for BNP and NT that stratified subjects with or without heart failure was not different among eGFR level. In conclusion, BNP and NT levels are elevated depend on decreasing eGFR level, BNP and NT are comparable in the accuracy for diagnosing heart failure at every eGFR level. The cut-off value of BNP and NT should be established according to the eGFR level.

Metabolic and physiological responses to progressive drought stress in bread wheat.

Wheat (Tritium aestivum) is vulnerable to future climate change because it is predominantly grown under rain-fed conditions in drought-prone areas. Thus, in-depth understanding of drought effect on wheat metabolism is essential for developing drought-tolerant wheat varieties. Here, we exposed wheat 'Norin 61' plants to progressive drought stress [0 (before drought), 2, 4, 6, 8, and 10 days after withholding water] during the flowering stage to investigate physiological and metabolomic responses. Transcriptional analyses of key abscisic acid-responsive genes indicated that abscisic acid signalling played a major role in the adaptation of wheat to water deficit. Carbon isotope composition had a higher value than the control while canopy temperature (CT) increased under drought stress. The CT depression was tightly correlated with soil water potential (SWP). Additionally, SWP at - 517 kPa was identified as the critical point for increasing CT and inducing reactive oxygen species. Metabolome analysis identified four potential drought-responsive biomarkers, the enhancement of nitrogen recycling through purine and pyrimidine metabolism, drought-induced senescence based on 1-aminocyclopropane-1-carboxylic acid and Asn accumulation, and an anti-senescence response through serotonin accumulation under severe drought stress. Our findings provide in-depth insight into molecular, physiological and metabolite changes involved in drought response which are useful for wheat breeding programs to develop drought-tolerant wheat varieties.