Specific Physiological and Anatomical Traits Associated With Polyploidy and Better Detoxification Processes Contribute to Improved Huanglongbing Tolerance of the Persian Lime Compared With the Mexican Lime

International audienceHuanglongbing (HLB) is presently a major threat to the citrus industry. Because of this disease, millions of trees are currently dying worldwide. The putative causal agent is a motile bacteria belonging to Candidatus Liberibacter spp., which is transmitted by psyllids. The bacteria is responsible for the synthesis of callose at the phloem sieve plate, leading to the obstruction of the pores that provide connections between adjacent sieve elements, thus limiting the symplastic transport of the sugars and starches synthesized in leaves to the other plant organs. The Persian triploid lime ( Citrus latifolia ) is one of the most HLB-tolerant citrus varieties, but the determinants associated with the tolerance are still unknown. HLB-infected diploid Mexican lime ( Citrus aurantiifolia ) and Persian lime were investigated. The leaf petiole was analyzed using scanning electron microscopy (SEM) to observe callose deposition at the phloem sieve plate. Leaf starch contents and detoxification enzyme activities were investigated. In the field, Persian lime leaves present more limited symptoms due to HLB than the Mexican lime leaves do. Photosynthesis, stomatal conductance, and transpiration decreased compared with control plants, but values remained greater in the Persian than in the Mexican lime. Analysis of the petiole sieve plate in control petiole samples showed that pores were approximately 1.8-fold larger in the Persian than in the Mexican lime. SEM analyses of petiole samples of symptomatic leaves showed the important deposition of callose into pores of Mexican and Persian limes, whereas biochemical analyses revealed better detoxification in Persian limes than in Mexican limes. Moreover, SEM analyses of infected petiole samples of asymptomatic leaves showed much larger callose depositions into the Mexican lime pores than in the Persian lime pores, whereas biochemical traits revealed much better behavior in Persian limes than in Mexican limes. Our results reveal that polyploids present specific behaviors associated with important physiological and biochemical determinants that may explain the better tolerance of the Persian lime against HLB compared with the Mexican lime

Triploid lime is more tolerant to HLB than diploid lime because specific physiological and anatomical traits associated to better detoxification processes

International audienceConsidered a major issue in citrus growing, Huanglongbing (HLB), also known as Citrus Greening or yellow dragon disease, is a citrus bacterial disease. This disease is caused by the bacteria Candidatus Liberibacter spp that is spread by Diaphorina citri, also called citrus psylla. This stinging insect allows a rapid spread of tree disease trees by feeding on the leaf petiole. In the short term, the HLB causes a decline and the death of trees. In Brazil and Florida, the disease affects several million trees and thou-sands of hectares have had to be torn down. This disease affects the entire Caribbean basin including Guadeloupe and Martinique. After the bite leading to HLB infection, the reaction of the plant will result in the synthesis of callose in the pores of the phloem sieve cells thus leading to a stop of elaborated sap flow. Today, there is no pure resistance to HLB within the Citrus genus. However, the Tahiti limer (natu-ral triploid variety, 3x) is much less affected by the disease (Gomez, 2008), other diploid varieties (2x) being very sensitive. Our study was to decipher the potential traits of tolerance to HLB related to poly-ploidy. Diploid (2x, Citrus aurantiifolia) and triploid (3x, Citrus latifolia) limes grafted onto diploid citru-melo 4475 (Citrus paradisi × Poncirus trifoliata) rootstocks were investigated when naturally infected by HLB or infected by grafting. The plant physiology, the anatomy, of leaf petiole were analyzed using Scanning Electron Microscope to observe callose deposition at sieve plate of the phloem, as well leaf starch content and detoxification enzyme activities in 2x and 3x leaves were investigated. The results of these experiments seem to show that 3x are more tolerant than 2x

Better tolerance to Huanglongbing is conferred by tetraploid Swingle citrumelo rootstock and is influenced by the ploidy of the scion

International audienceHuanglongbing (HLB) is a disease that is responsible for the death of millions of trees worldwide. The bacterial causal agent belongs to Candidatus Liberibacter spp., which is transmitted by psyllids. The bacterium lead most of the time to a reaction of the tree associated with callose synthesis at the phloem sieve plate. Thus, the obstruction of pores providing connections between adjacent sieve elements will limit the symplastic transport of the sugars and starches synthesized through photosynthesis. In the present article, we investigated the impact of the use of tetraploid Swingle citrumelo ( Citrus paradisi Macfrad × Poncirus trifoliata [L.] Raf) rootstock on HLB tolerance, compared to its respective diploid. HLB-infected diploid and tetraploid rootstocks were investigated when grafted with Mexican and Persian limes. Secondary roots were anatomically studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to observe callose deposition at the phloem sieve plate and to evaluate the impact of the bacterium’s presence at the cellular level. Voltammetry of immobilized microparticles (VIMP) in roots was applied to determine the oxidative stress status of root samples. In the field, Mexican and Persian lime leaves of trees grafted onto tetraploid rootstock presented less symptoms of HLB. Anatomical analysis showed much stronger secondary root degradation in diploid rootstock, compared to tetraploid rootstock. Analysis of the root sieve plate in control root samples showed that pores were approximately 1.8-fold larger in tetraploid Swingle citrumelo than in its respective diploid. SEM analyses of root samples did not reveal any callose deposition into pores of diploid and tetraploid genotypes. VIMP showed limited oxidative stress in tetraploid samples, compared to diploid ones. These results were even strongly enhanced when rootstocks were grafted with Persian limes, compared to Mexican limes, which was corroborated by stronger polyphenol contents. TEM analysis showed that the bacteria was present in both ploidy root samples with no major impacts detected on cell walls or cell structures. These results reveal that tetraploid Swingle citrumelo rootstock confers better tolerance to HLB than diploid. Additionally, an even stronger tolerance is achieved when the triploid Persian lime scion is associated

Clinical Outcomes According to ECG Presentations in Infarct-Related Cardiogenic Shock in the Culprit Lesion Only PCI vs Multivessel PCI in Cardiogenic Shock Trial.

BACKGROUND The impact of ECG presentations of acute myocardial infarction (AMI) in cardiogenic shock is unknown. RESEARCH QUESTION In myocardial infarction with cardiogenic shock, is there a difference in the outcomes and effect of revascularization strategies between non-ST-segment elevation myocardial infarction (NSTEMI) and left bundle branch block myocardial infarction (LBBBMI) vs ST-segment elevation myocardial infarction (STEMI)? STUDY DESIGN AND METHODS Cardiogenic shock patients from the CULPRIT-SHOCK trial with NSTEMI or LBBBMI were compared with STEMI patients for 30-day and 1-year all-cause mortality. The interaction between ECG presentation and the effect of revascularization strategies on outcomes was evaluated. RESULTS Of 665 cardiogenic shock patients analyzed, 55.9% demonstrated STEMI, 29.3% demonstrated NSTEMI, and 14.7% demonstrated LBBBMI. Patients differed in mean age (68.0 years in STEMI patients, 71.0 years in NSTEMI patients, and 73.5 years in LBBBMI patients; P = .015), cardiovascular risk factors, and angiographic severity. No difference was found in the 30-day risk of death between NSTEMI and STEMI patients (48.7% vs 43.0%; adjusted OR [aOR], 1.05; 95% CI, 0.66-1.67; P = .85), nor between LBBBMI and STEMI patients (59.2% vs 43.0%; aOR, 1.31; 95% CI, 0.73-2.34; P = .36). Although the univariate risk of death by 1 year was higher in NSTEMI and LBBBMI patients compared with STEMI patients, ECG presentation was not an independent risk factor of mortality after adjustment (NSTEMI vs STEMI: 56.4% vs 46.8%; aOR, 1.21; 95% CI, 0.76-1.92; P = .42; LBBBMI vs STEMI: 69.4% vs 46.8%; aOR, 1.59; 95% CI, 0.89-2.84; P = .12). ECG presentation did not modify the effect of the revascularization strategy on 30-day and 1-year mortality (P = .91 and P = .97 for interaction). INTERPRETATION In patients with cardiogenic shock, NSTEMI and LBBBMI presentations reflect higher-risk profiles than STEMI presentations, but are not independent risk factors of mortality. ECG presentations did not modify the treatment effect, supporting culprit-lesion-only percutaneous coronary intervention as the preferred strategy across the AMI spectrum

PCI Strategies in Patients with Acute Myocardial Infarction and Cardiogenic Shock

BACKGROUND: In patients who have acute myocardial infarction with cardiogenic shock, early revascularization of the culprit artery by means of percutaneous coronary intervention (PCI) improves outcomes. However, the majority of patients with cardiogenic shock have multivessel disease, and whether PCI should be performed immediately for stenoses in nonculprit arteries is controversial. METHODS: In this multicenter trial, we randomly assigned 706 patients who had multivessel disease, acute myocardial infarction, and cardiogenic shock to one of two initial revascularization strategies: either PCI of the culprit lesion only, with the option of staged revascularization of nonculprit lesions, or immediate multivessel PCI. The primary end point was a composite of death or severe renal failure leading to renal-replacement therapy within 30 days after randomization. Safety end points included bleeding and stroke. RESULTS: At 30 days, the composite primary end point of death or renal-replacement therapy had occurred in 158 of the 344 patients (45.9%) in the culprit-lesion-only PCI group and in 189 of the 341 patients (55.4%) in the multivessel PCI group (relative risk, 0.83; 95% confidence interval [CI], 0.71 to 0.96; P=0.01). The relative risk of death in the culprit-lesion-only PCI group as compared with the multivessel PCI group was 0.84 (95% CI, 0.72 to 0.98; P=0.03), and the relative risk of renal-replacement therapy was 0.71 (95% CI, 0.49 to 1.03; P=0.07). The time to hemodynamic stabilization, the risk of catecholamine therapy and the duration of such therapy, the levels of troponin T and creatine kinase, and the rates of bleeding and stroke did not differ significantly between the two groups. CONCLUSIONS: Among patients who had multivessel coronary artery disease and acute myocardial infarction with cardiogenic shock, the 30-day risk of a composite of death or severe renal failure leading to renal-replacement therapy was lower among those who initially underwent PCI of the culprit lesion only than among those who underwent immediate multivessel PCI. (Funded by the European Union 7th Framework Program and others; CULPRIT-SHOCK ClinicalTrials.gov number, NCT01927549 .)

Clinical Outcomes According to ECG Presentations in Infarct-Related Cardiogenic Shock in the Culprit Lesion Only PCI vs Multivessel PCI in Cardiogenic Shock Trial

Background: The impact of ECG presentations of acute myocardial infarction (AMI) in cardiogenic shock is unknown. Research Question: In myocardial infarction with cardiogenic shock, is there a difference in the outcomes and effect of revascularization strategies between non-ST-segment elevation myocardial infarction (NSTEMI) and left bundle branch block myocardial infarction (LBBBMI) vs ST-segment elevation myocardial infarction (STEMI)? Study Design and Methods: Cardiogenic shock patients from the CULPRIT-SHOCK trial with NSTEMI or LBBBMI were compared with STEMI patients for 30-day and 1-year all-cause mortality. The interaction between ECG presentation and the effect of revascularization strategies on outcomes was evaluated. Results: Of 665 cardiogenic shock patients analyzed, 55.9% demonstrated STEMI, 29.3% demonstrated NSTEMI, and 14.7% demonstrated LBBBMI. Patients differed in mean age (68.0 years in STEMI patients, 71.0 years in NSTEMI patients, and 73.5 years in LBBBMI patients; P =.015), cardiovascular risk factors, and angiographic severity. No difference was found in the 30-day risk of death between NSTEMI and STEMI patients (48.7% vs 43.0%; adjusted OR [aOR], 1.05; 95% CI, 0.66-1.67; P =.85), nor between LBBBMI and STEMI patients (59.2% vs 43.0%; aOR, 1.31; 95% CI, 0.73-2.34; P =.36). Although the univariate risk of death by 1 year was higher in NSTEMI and LBBBMI patients compared with STEMI patients, ECG presentation was not an independent risk factor of mortality after adjustment (NSTEMI vs STEMI: 56.4% vs 46.8%; aOR, 1.21; 95% CI, 0.76-1.92; P =.42; LBBBMI vs STEMI: 69.4% vs 46.8%; aOR, 1.59; 95% CI, 0.89-2.84; P =.12). ECG presentation did not modify the effect of the revascularization strategy on 30-day and 1-year mortality (P =.91 and P =.97 for interaction). Interpretation: In patients with cardiogenic shock, NSTEMI and LBBBMI presentations reflect higher-risk profiles than STEMI presentations, but are not independent risk factors of mortality. ECG presentations did not modify the treatment effect, supporting culprit-lesion-only percutaneous coronary intervention as the preferred strategy across the AMI spectrum