Crosstalk between phytohormones and secondary metabolites in the drought stress tolerance of crop plants: A review

Drought stress negatively affects crop performance and weakens global food security. It triggers the activation of downstream pathways, mainly through phytohormones homeostasis and their signaling networks, which further initiate the biosynthesis of secondary metabolites (SMs). Roots sense drought stress, the signal travels to the above-ground tissues to induce systemic phytohormones signaling. The systemic signals further trigger the biosynthesis of SMs and stomatal closure to prevent water loss. SMs primarily scavenge reactive oxygen species (ROS) to protect plants from lipid peroxidation and also perform additional defense-related functions. Moreover, drought-induced volatile SMs can alert the plant tissues to perform drought stress mitigating functions in plants. Other phytohormone-induced stress responses include cell wall and cuticle thickening, root and leaf morphology alteration, and anatomical changes of roots, stems, and leaves, which in turn minimize the oxidative stress, water loss, and other adverse effects of drought. Exogenous applications of phytohormones and genetic engineering of phytohormones signaling and biosynthesis pathways mitigate the drought stress effects. Direct modulation of the SMs biosynthetic pathway genes or indirect via phytohormones' regulation provides drought tolerance. Thus, phytohormones and SMs play key roles in plant development under the drought stress environment in crop plants.

Discovery of novel drug sensitivities in T-PLL by high-throughput ex vivo drug testing and mutation profiling

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells with an urgent need for rationally designed therapies to address its notoriously chemo-refractory behavior. The median survival of T-PLL patients is <2 years and clinical trials are difficult to execute. Here we systematically explored the diversity of drug responses in T-PLL patient samples using an ex vivo drug sensitivity and resistance testing platform and correlated the findings with somatic mutations and gene expression profiles. Intriguingly, all T-PLL samples were sensitive to the cyclin-dependent kinase inhibitor SNS-032, which overcame stromal-cell-mediated protection and elicited robust p53-activation and apoptosis. Across all patients, the most effective classes of compounds were histone deacetylase, phosphoinositide-3 kinase/AKT/mammalian target of rapamycin, heat-shock protein 90 and BH3-family protein inhibitors as well as p53 activators, indicating previously unexplored, novel targeted approaches for treating T-PLL. Although Janus-activated kinase-signal transducer and activator of transcription factor (JAK-STAT) pathway mutations were common in T-PLL (71% of patients), JAK-STAT inhibitor responses were not directly linked to those or other T-PLL-specific lesions. Overall, we found that genetic markers do not readily translate into novel effective therapeutic vulnerabilities. In conclusion, novel classes of compounds with high efficacy in T-PLL were discovered with the comprehensive ex vivo drug screening platform warranting further studies of synergisms and clinical testing.

Enhanced sensitivity to glucocorticoids in cytarabine-resistant AML

We sought to identify drugs that could counteract cytarabine resistance in acute myeloid leukemia (AML) by generating eight resistant variants from MOLM-13 and SHI-1 AML cell lines by long-term drug treatment. These cells were compared with 66 ex vivo chemorefractory samples from cytarabine-treated AML patients. The models and patient cells were subjected to genomic and transcriptomic profiling and high-throughput testing with 250 emerging and clinical oncology compounds. Genomic profiling uncovered deletion of the deoxycytidine kinase (DCK) gene in both MOLM-13- and SHI-1-derived cytarabine-resistant variants and in an AML patient sample. Cytarabine-resistant SHI-1 variants and a subset of chemorefractory AML patient samples showed increased sensitivity to glucocorticoids that are often used in treatment of lymphoid leukemia but not AML. Paired samples taken from AML patients before treatment and at relapse also showed acquisition of glucocorticoid sensitivity. Enhanced glucocorticoid sensitivity was only seen in AML patient samples that were negative for the FLT3 mutation (P=0.0006). Our study shows that development of cytarabine resistance is associated with increased sensitivity to glucocorticoids in a subset of AML, suggesting a new therapeutic strategy that should be explored in a clinical trial of chemorefractory AML patients carrying wild-type FLT3.

Sulfur nutrition and its role in plant growth and development

Sulfur is one of the essential nutrients that is required for the adequate growth and development of plants. Sulfur is a structural component of protein disulfide bonds, amino acids, vitamins, and cofactors. Most of the sulfur in soil is present in organic matter and hence not accessible to the plants. Anionic form of sulfur (SO42-) is the primary source of sulfur for plants that are generally present in minimal amounts in the soil. It is water-soluble, so readily leaches out of the soil. Sulfur and sulfur-containing compounds act as signaling molecules in stress management as well as normal metabolic processes. They also take part in crosstalk of complex signaling network as a mediator molecule. Plants uptake sulfate directly from the soil by using their dedicated sulfate transporters. In addition, plants also use the sulfur transporter of a symbiotically associated organism like bacteria and fungi to uptake sulfur from the soil especially under sulfur depleted conditions. So, sulfur is a very important component of plant metabolism and its analysis with different dimensions is highly required to improve the overall well-being of plants, and dependent animals as well as human beings. The deficiency of sulfur leads to stunted growth of plants and ultimately loss of yield. In this review, we have focused on sulfur nutrition, uptake, transport, and inter-organismic transfer to host plants. Given the strong potential for agricultural use of sulfur sources and their applications, we cover what is known about sulfur impact on the plant health. We identify opportunities to expand our understanding of how the application of soil microbes like AMF or other root endophytic fungi affects plant sulfur uptake and in turn plant growth and development.

Anticancer compound ABT-263 accelerates apoptosis in virus-infected cells and imbalances cytokine production and lowers survival rates of infected mice

ABT-263 and its structural analogues ABT-199 and ABT-737 inhibit B-cell lymphoma 2 (Bcl-2), BCL2L1 long isoform (Bcl-xL) and BCL2L2 (Bcl-w) proteins and promote cancer cell death. Here, we show that at non-cytotoxic concentrations, these small molecules accelerate the deaths of non-cancerous cells infected with influenza A virus (IAV) or other viruses. In particular, we demonstrate that ABT-263 altered Bcl-xL interactions with Bcl-2 antagonist of cell death (Bad), Bcl-2-associated X protein (Bax), uveal autoantigen with coiled-coil domains and ankyrin repeats protein (UACA). ABT-263 thereby activated the caspase-9-mediated mitochondria-initiated apoptosis pathway, which, together with the IAV-initiated caspase-8-mediated apoptosis pathway, triggered the deaths of IAV-infected cells. Our results also indicate that Bcl-xL, Bcl-2 and Bcl-w interact with pattern recognition receptors (PRRs) that sense virus constituents to regulate cellular apoptosis. Importantly, premature killing of IAV-infected cells by ABT-263 attenuated the production of key pro-inflammatory and antiviral cytokines. The imbalance in cytokine production was also observed in ABT-263-treated IAV-infected mice, which resulted in an inability of the immune system to clear the virus and eventually lowered the survival rates of infected animals. Thus, the results suggest that the chemical inhibition of Bcl-xL, Bcl-2 and Bcl-w could potentially be hazardous for cancer patients with viral infections.

In Vitro Anticancer Activity of the Root, Stem and Leaves of Withania Somnifera against Various Human Cancer Cell Lines

Withania Somnifera Dunal know as Ashwagandha belong Solanaceae family. It is extensively used in most of the Indian herbal pharmaceuticals and nutraceuticals. The current study, evaluate in vitro cytotoxicity in 50% ethanol extract of root, stem and leaves of Withania Somnifera against five human cancer cell lines of four different tissues i.e. PC-3, DU-145 (prostrate), HCT-15 (colon), A-549 (lung) and IMR-32 (neuroblastoma). Root, stem and leaves extracts showed cytotoxicity activity ranging 0-98% depending on the cell lines but maximum activity was found in 50% ethanol extract of leaves of Withania Somnifera. Ethanol extract of leaves obtained from treatments T2, T3, T4 and T5 showed strong activity against PC-3 and HCT-15 with 80-98% growth inhibition, while the 50% ethanol extract of leaves from T1 treatment showed a minimum of 39% and T3 treatment showed a maximum of 98% growth inhibition against HCT-15. This investigation is the first report of the anticancer activity in various parts of Withania Somnifera cultivated in fly ash amended soil.

Defining the content of individual physiotherapy and occupational therapy sessions for stroke patients in an inpatient rehabilitation setting. Development, validation and inter-rater reliability of a scoring list

Objective : To develop a valid and reliable scoring list to define the content of individual physiotherapy and occupational therapy sessions for stroke patients in inpatient rehabilitation.

Design : A list was developed based on previous lists, neurological textbooks and recorded therapy sessions. Content validity was verified and inter-rater reliability evaluated on videos of treatment sessions. In each of four rehabilitation centres, a researcher recorded and scored five physiotherapy and five occupational therapy sessions. These 40 treatment sessions were also scored by the first author. The scores of the researchers and first author were statistically compared.

Settings and subjects : Forty stroke patients in four European rehabilitation centres.

Results : The scoring list consists of 49 subcategories, divided into 12 categories: mobilization; selective movements; lying (balance); sitting (balance); standing (balance); sensory and visual perceptual training and cognition; transfers; ambulatory activities; personal activities of daily living; domestic activities of daily living; leisure- and work-related activities; and miscellaneous. Comparing the frequency of occurrence of the categories resulted in intraclass correlation coefficients, indicating high reliability for eight categories, good for one, and fair for two. One category was not observed. Spearman rank correlation coefficients were high to very high for 24 subcategories and moderate for four. Twenty-one subcategories contained too few observations to enable calculation of Spearman rank correlation coefficients. Average point-to-point percentage of agreement in time of the treatment sessions equalled 76.6 ± 16.2%.

Conclusions : The list is a valid and reliable tool for describing the content of physiotherapy and occupational therapy for stroke patients.

Flavanone glycosides from Alhagi pseudalhagi

Two new flavanone glycosides, alhagitin and alhagidin, have been isolated from the whole plant of Alhagi pseudalhagi and their structures established respectively as naringenin 5-methyl ether 4'-glucoside and hesperitin 7-galactosyl(1-->2)[rhamnosyl(1-->6)]glucoside by chemical and spectroscopic methods.

Plant mineral transport systems and the potential for crop improvement

Nutrient transporter genes could be a potential candidate for improving crop plants, with enhanced nutrient uptake leading to increased crop yield by providing tolerance against different biotic and abiotic stresses. The world's food supply is nearing a crisis in meeting the demands of an ever-growing global population, and an increase in both yield and nutrient value of major crops is vitally necessary to meet the increased population demand. Nutrients play an important role in plant metabolism as well as growth and development, and nutrient deficiency results in retarded plant growth and leads to reduced crop yield. A variety of cellular processes govern crop plant nutrient absorption from the soil. Among these, nutrient membrane transporters play an important role in the acquisition of nutrients from soil and transport of these nutrients to their target sites. In addition, as excess nutrient delivery has toxic effects on plant growth, these membrane transporters also play a significant role in the removal of excess nutrients in the crop plant. The key function provided by membrane transporters is the ability to supply the crop plant with an adequate level of tolerance against environmental stresses, such as soil acidity, alkalinity, salinity, drought, and pathogen attack. Membrane transporter genes have been utilized for the improvement of crop plants, with enhanced nutrient uptake leading to increased crop yield by providing tolerance against different biotic and abiotic stresses. Further understanding of the basic mechanisms of nutrient transport in crop plants could facilitate the advanced design of engineered plant crops to achieve increased yield and improve nutrient quality through the use of genetic technologies as well as molecular breeding. This review is focused on nutrient toxicity and tolerance mechanisms in crop plants to aid in understanding and addressing the anticipated global food demand.

Regulatory and effector T cells changes in remission and resistant state of childhood nephrotic syndrome

Idiopathic minimal change disease is a disorder of T-cell dysfunction. The relative predominance of regulatory T cells (Tregs), Th1, and Th2 cells in nephrotic syndrome (NS) remains controversial. Imbalance in peripheral blood regulatory and effector T cells (Teff) are linked to cell mediated immune response and may be associated with steroid response in NS. Peripheral blood CD4 + CD25 + FoxP3 + (Tregs), CD4 + IFN-γ(+) (Th1), and CD4 + IL-4 + (Th2) lymphocytes were analyzed in 22 steroid-sensitive NS (SSNS) patients in sustained remission, 21 steroid-resistant NS (SRNS) and 14 healthy controls. The absolute percentage values and ratio of Th1/Tregs, Th2/Tregs, and Th1/Th2 were compared between SSNS, SRNS and control subjects. The percentage of Tregs was lower in SRNS patients (P = 0.001) compared with that of SSNS and healthy control. The percentage of Th1 cells was higher in SRNS (P = 0.001) compared to that of SSNS patients; however, it was similar to healthy controls (P = 1.00). The percentage of Th2 cells in SRNS (P = 0.001) was higher as compared to SSNS and controls. The ratio of Th1/Treg cells in SRNS (P = 0.001) was higher as compared to SSNS patients and controls. The ratio of Th2/Treg was also higher in SRNS as compared to SSNS and controls. The ratio of Th1/Th2 cells in SSNS, SRNS, and healthy controls were similar. The cytokines secretion complemented the change in different T-cell subtypes in SSNS, SRNS and healthy controls. However, the IFN-γ secretion in healthy controles was low inspite of similar percentage of Th1 cells among SRNS cases. We conclude that greater ratio of Tregs compared to that Th1 and Th2 favor steroid sensitivity and reverse ratio results in to SRNS. The difference in ratio is related to pathogenesis or it can be used as marker to predict steroid responsiveness needs further evaluation.

Novel drug candidates for blast phase chronic myeloid leukemia from high-throughput drug sensitivity and resistance testing

Chronic myeloid leukemia in blast crisis (CML BC) remains a challenging disease to treat despite the introduction and advances in tyrosine kinase inhibitor (TKI) therapy. In this study we set out to identify novel candidate drugs for CML BC by using an unbiased high-throughput drug testing platform. We used three CML cell lines representing different types of CML blast phases (K562, EM-2 and MOLM-1) and primary leukemic cells from three CML BC patients. Profiling of drug responses was performed with a drug sensitivity and resistance testing platform comprising 295 anticancer agents. Overall, drug sensitivity scores and the drug response profiles of cell line and primary cell samples correlated well and were distinct from other types of leukemia samples. The cell lines were highly sensitive to TKIs and the clinically TKI-resistant patient samples were also resistant ex vivo. Comparison of cell line and patient sample data identified new candidate drugs for CML BC, such as vascular endothelial growth factor receptor and nicotinamide phosphoribosyltransferase inhibitors. Our results indicate that these drugs in particular warrant further evaluation by analyzing a larger set of primary patient samples. The results also pave way for designing rational combination therapies.

Demodex canis targets TLRs to evade host immunity and induce canine demodicosis

Widespread incidence of Demodex mites throughout the mammalian class and occasional serious and fatal outcomes in dogs warrant an insight into the host-parasite interface especially. Therefore, this study was aimed to unravel the interplay between innate immune response and canine demodicosis. The dogs diagnosed to have natural clinical demodicosis were allocated into two groups; dogs with localized demodicosis (LD) and with generalized demodicosis (GD). The expression of toll-like receptors (TLRs) 2, 4 and 6 genes in peripheral blood mononuclear cells of these dogs was quantified by real-time PCR. Significantly increased TLR2 gene expression, while significantly diminished TLR4 and TLR6 gene expressions were observed in demodicosed dogs (LD and GD) as compared with the healthy ones. Even the expression of TLR2 gene was found to differ significantly between the dogs with LD and GD. Therefore, it can be inferred that clinical demodicosis in dogs is coupled with an up-regulation of TLR2 and down-regulation of TLR4 and TLR6 gene expressions. Overexpression of TLR2 gene might be responsible for Demodex-induced clinical manifestations, while TLR4 and TLR6 gene down-regulations could be the paramount strategy of Demodex mites to elude the host-immune interface.

Integrated omics approaches for flax improvement under abiotic and biotic stress: Current status and future prospects

Flax (Linum usitatissimum L.) or linseed is one of the important industrial crops grown all over the world for seed oil and fiber. Besides oil and fiber, flax offers a wide range of nutritional and therapeutic applications as a feed and food source owing to high amount of α-linolenic acid (omega-3 fatty acid), lignans, protein, minerals, and vitamins. Periodic losses caused by unpredictable environmental stresses such as drought, heat, salinity-alkalinity, and diseases pose a threat to meet the rising market demand. Furthermore, these abiotic and biotic stressors have a negative impact on biological diversity and quality of oil/fiber. Therefore, understanding the interaction of genetic and environmental factors in stress tolerance mechanism and identification of underlying genes for economically important traits is critical for flax improvement and sustainability. In recent technological era, numerous omics techniques such as genomics, transcriptomics, metabolomics, proteomics, phenomics, and ionomics have evolved. The advancements in sequencing technologies accelerated development of genomic resources which facilitated finer genetic mapping, quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and genomic selection in major cereal and oilseed crops including flax. Extensive studies in the area of genomics and transcriptomics have been conducted post flax genome sequencing. Interestingly, research has been focused more for abiotic stresses tolerance compared to disease resistance in flax through transcriptomics, while the other areas of omics such as metabolomics, proteomics, ionomics, and phenomics are in the initial stages in flax and several key questions remain unanswered. Little has been explored in the integration of omic-scale data to explain complex genetic, physiological and biochemical basis of stress tolerance in flax. In this review, the current status of various omics approaches for elucidation of molecular pathways underlying abiotic and biotic stress tolerance in flax have been presented and the importance of integrated omics technologies in future research and breeding have been emphasized to ensure sustainable yield in challenging environments.

Metal transporters in organelles and their roles in heavy metal transportation and sequestration mechanisms in plants

Heavy metal toxicity is one of the major concerns for agriculture and health. Accumulation of toxic heavy metals at high concentrations in edible parts of crop plants is the primary cause of disease in humans and cattle. A dramatic increase in industrialization, urbanization, and other high anthropogenic activities has led to the accumulation of heavy metals in agricultural soil, which has consequently disrupted soil conditions and affected crop yield. By now, plants have developed several mechanisms to cope with heavy metal stress. However, not all plants are equally effective in dealing with the toxicity of high heavy metal concentrations. Plants have modified their anatomy, morphophysiology, and molecular networks to survive under changing environmental conditions. Heavy metal sequestration is one of the essential processes evolved by some plants to deal with heavy metals' toxic concentration. Some plants even have the ability to accumulate metals in high quantities in the shoots/organelles without toxic effects. For intercellular and interorganeller metal transport, plants harbor spatially distributed various transporters which mainly help in uptake, translocation, and redistribution of metals. This review discusses different heavy metal transporters in different organelles and their roles in metal sequestration and redistribution to help plants cope with heavy metal stress. A good understanding of the processes at stake helps in developing more tolerant crops without affecting their productivity.

Head to head comparison of adverse effects and efficacy between high dose deflazacort and high dose prednisolone in systemic lupus erythematosus: a prospective cohort study

BACKGROUND

Deflazacort (DFZ), an oxazoline derivative of prednisolone (PDN), has a dose equivalence of 1.2:1 (mg) to PDN. No study to date has compared adverse effects and efficacy of high doses of DFZ as against high-dose PDN in systemic lupus erythematosus (SLE).

OBJECTIVES

To compare adverse effects of high dose DFZ and PDN in SLE patients, especially in terms of cushingoid features and gain in body weight, 3 and 6 months after initiation of these agents.

METHODS

In both the steroid arms, the following outcome parameters were assessed at 3 and 6 months: (a) cushingoid features by Cushing's Severity Index (CSI) (b) hirsutism by modified Ferriman Gallwey score (c) weight gain by difference (Δ, delta) of weight (in kilograms).

RESULTS

Patients on PDN had 1.6 kg (3.2%) and 2 kg (5.1%) higher median weight gain as compared to those on DFZ at 3 and 6 months respectively ( p = 0.012 and 0.001). PDN caused 10% and 22.2% higher increment in median hirsutism scores as compared to DFZ at 3 months and 6 months follow-up, respectively ( p = 0.004 and 0.002). PDN caused 100% higher increase in median CSI scores than DFZ at 6 months ( p = 0.03). There was no significant difference by generalized estimation equation between the groups with respect to changes in SLEDAI, renal SLEDAI, anti-dsDNA titres and C3/C4 levels. There were two serious infections (requiring hospitalization/intravenous antibiotics) in the PDN group, while none in the DFZ group.

CONCLUSION

Comparable intake and tapering of high dose DFZ and PDN in active SLE revealed 2-fold less weight gain, 2.5-fold less hirsutism and 1.5-fold lower cushingoid severity index as well as lower glycaemic elevation in the DFZ group as compared to PDN group. Both had similar efficacy.

Need of Improvement in Emergency Medical Service in Urban Cities

Introduction: An effective Emergency Medical Service system does not exist in Nepal. For an effective EMS system to be developed the scale of the problem and the existing facilities need to be studied. Methods: Prospective observational study was carried out on 1964 patients attending Emergency Department at Patan Hospital during one month period of September 2006. The patients were specifically enquired on mode of transport used, place of origin and whether they called for an ambulance or not. Patients triage category at the time of triaging was also noted. Information on ambulance service were collected by direct interview with the service providers and the total number of patients attending Emergency Departments daily were collected from the major hospitals of the urban Lalitpur and Kathmandu. MS Excel and SPSS software were used for data entry, editing and analysis.Results: Total 9.9% patients arrived in ambulance whereas 53.6% came in a Taxi, 11.4% came in private vehicle, 13.5 % came by bus, 5.4% came by bike and the rest 6.2% came by other modes of transportation. Only 13.5% of triage category I patients took the ambulance. There were 31 service providers with 49 ambulances and 720 patients per day attend Emergency Departments in the surveyed area. Conclusions: Very less number of patients use the ambulance service for emergency services. The available ambulances are not properly equipped and do not have trained staff and as such are only a means of transportation to the hospitals of urban Lalitpur and Kathmandu.Key Words: ambulance, emergency medical service, para-medics, triage Need of Improvement in Emergency Medical Service in Urban Cities Gongal R,1Dhungana B,1Regmi S,1Nakarmi M,2Yadav B11Patan Hospital, Lalitpur, Nepal, 2Health Care Foundation, Kathmandu, NepalCorrespondence:Dr. Rajesh GongalDepartment of SurgeryPatan Hospital, Patan, Nepal.Email: rajgongal@yahoo.comORIGINAL ARTICLE J Nepal Med Assoc 2009;48(174):139-43INTRODUCTIONThe sophisticated Emergency Medical Service (EMS) is limited to developed country only. Many developing countries are now slowly developing such system although most services are localized to the urban areas.1-5 Although inadquate ambulance services are available in the capital city of Nepa

Prospective blood pressure measurement in renal transplant recipients

Blood pressure (BP) control at home is difficult when managed only with office blood pressure monitoring (OBPM). In this prospective study, the reliability of BP measurements in renal transplant patients with OBPM and home blood pressure monitoring (HBPM) was compared with ambulatory blood pressure monitoring (ABPM) as the gold standard. Adult patients who had living-related renal transplantation from March 2007 to February 2008 had BP measured by two methods; OBPM and ABPM at pretransplantation, 2^nd, 4^th, 6^th, and 9^th months and all the three methods: OBPM, ABPM, and HBPM at 6 months after transplantation. A total of 49 patients, age 35 ± 11 years, on prednisolone, tacrolimus, and mycophenolate were evaluated. A total of 39 were males (79.6%). Systolic BP (SBP) and diastolic BP (DBP) measured by OBPM were higher than HBPM when compared with ABPM. When assessed using OBPM and awake ABPM, both SBP and DBP were significantly overestimated by OBPM with mean difference of 3-12 mm Hg by office SBP and 6-8 mm Hg for office DBP. When HBPM was compared with mean ABPM at 6 months both the SBP and DBP were overestimated by and 7 mm Hg respectively. At 6 months post transplantation, when compared with ABPM, OBPM was more specific than HBPM in diagnosing hypertension (98% specificity, Kappa: 0.88 vs. 89% specificity, Kappa: 0.71). HBPM was superior to OBPM in identifying patients achieving goal BP (89% specificity, Kappa: 0.71 vs. 50% specificity Kappa: 0.54). In the absence of a gold standard for comparison the latent class model analysis still showed that ABPM was the best tool for diagnosing hypertension and monitoring patients reaching targeted control. OBPM remains an important tool for the diagnosis and management of hypertension in renal transplant recipients. HBPM and ABPM could be used to achieve BP control.

The mechanism and inheritance of adult plant leaf rust resistance in 12 wheat lines

Twelve lines of wheat (Triticum aestivum L.) were developed that had susceptible infection types to leaf rust (Puccinia recondita Rob. ex Desm. f.sp. tritici) race UN 15 in the seedling stage but were resistant in the adult plant stage in the field. The lines were developed from four crosses, each involving four parents (eight in total) that had originally been selected for adult plant or field resistance to stem rust (Puccinia graminis Pers. f.sp. tritici Eriks, and Henn.). The objectives of the present study were to determine the mechanism of resistance to leaf rust and its inheritance in the 12 lines. The 12 lines were grown in an artificially inoculated field nursery in Saskatoon, coefficients of infection (CI) were determined at four dates, and the areas under the disease progress curve (AUDPC) were calculated. Four representative lines were grown in a growth chamber to measure the latent period and pustule size at the two-leaf and flag-leaf stages. Eight lines were crossed and backcrossed to a susceptible check and the parents, F1, F2, F3, and BC1F2 generations were grown in a field nursery. The 12 lines showed wide ranges in CI and AUDPC but all were significantly more resistant than the susceptible check. The four lines studied in the growth chamber had longer latent periods and smaller pustules than the susceptible check at both stages. The differences tended to be greater at the flag-leaf stage. The inheritance studied showed that resistance was recessive or partially recessive and was controlled by two or more genes in each line of the eight lines. In three of the eight lines, Lr34 may be one of the genes and in the other five both Lr13 and Lr34 could be present. However, additional genes are clearly involved. A single gene by itself had only a small effect, but in two and three gene combinations the effects appeared to be greater. This type of resistance appears to occur frequently and may be durable because its complex inheritance may make it more difficult for the rust fungus to overcome. It should be used in breeding wheat for areas where leaf rust is a major problem.