Residual effect of defeated stripe rust resistance genes/QTLs in bread wheat against prevalent pathotypes of Puccinia striiformis f. sp. tritici

Abstract

The periodic breakdowns of stripe rust resistance due to emergence of new virulent and more aggressive pathotypes of Puccinia striiformis f. sp. tritici have resulted in severe epidemics in India. This necessitates the search for new and more durable resistance sources against stripe rust. The three bread wheat cultivars PBW 343 (carries Yr9 and Yr27), PBW 621 (carries Yr17) and HD 2967 (gene not known) were highly popular among the farmers after their release in 2011. But presently all three cultivars are highly susceptible to stripe rust at seedling as well as at adult plant stages as their resistance has been broken down due to emergence of new pathotypes of the pathogen (110S119, 238S119). In previous study, the crosses of PBW 621 with PBW 343 and HD 2967 and evaluation of further generations (up to F4) against pathotype 78S84 resulted in resistant segregants. In the present study, the F5 and F6 RIL populations have been evaluated against new pathotypes of Pst. The RILs categorized based on the disease severity on the P (Penultimate leaf) and F (flag) leaf into three categories i.e., high, moderate and low level of APR (adult plant resistance) having 1–200, 201–400 and >400 values of AUDPC, respectively, upon infection with stripe rust. The various APR components (latent period, lesion growth rate, spore production and uredial density) were studied on each category, i.e., resistant, moderately resistant and susceptible. The values of APR parameters decreased as the level of resistance increased. Based on molecular analysis, the lines (representing different categories of cross PBW 621 X PBW 343) containing the genes Yr9 and Yr17 due to their interactive effect provide resistance. Based on BSA using 35k SNPs and KASP markers association with phenotypic data of the RIL population (PBW 621 X HD 2967) showed the presence of two QTLs (Q.Pst.pau-6B, Q.Pst.pau-5B) responsible for the residual resistance and two SNPs AX-94891670 and AX-94454107 were found to be associated with the trait of interest on chromosome 6B and 5B respectively. The present study concludes that in the population of both the crosses (PBW 621 X PBW 343 and PBW 621 X HD 2967) major defeated gene contributed towards residual resistance by interacting with minor gene/QTLs.

Quantifying microcyte and macrocyte percentages in archived red blood cell volume histogram images

“…13 Non-hematology medical research and biology studies used the same application to measure irregular areas in images. [14][15][16][17] In preliminary studies using this application, we demonstrated that measurements of percentage areas of segments under a computer-generated normal distribution curve were accurate and precise. 18 To explore potential hematology research applicability of this method, we measured areas of archived AHA RBC volume histogram images that correspond to microcytes and macrocytes in women with previously untreated iron-deficiency anemia (IDA) and women with previously untreated hemochromatosis.…”

“…We developed a method to quantify microcyte and macrocyte percentages in archived AHA RBC volume histogram images using an on‐line application of Gauss' area formula, also known as the “shoelace” formula 13 . Non‐hematology medical research and biology studies used the same application to measure irregular areas in images 14–17 . In preliminary studies using this application, we demonstrated that measurements of percentage areas of segments under a computer‐generated normal distribution curve were accurate and precise 18 …”

Integrated genome-wide association and transcriptomic analysis to identify receptor kinase genes to stripe rust resistance in wheat germplasm from southwestern China

“…Up to now, 86 officially designated stripe rust resistance genes, 71 temporarily designated genes and 363 quantitative trait loci (QTLs) with different names have been reported in wheat. The 86 officially designated stripe rust resistance genes include 22 APR genes and 6 HTAP resistance genes [ 5 , 6 ]. Nine Yr genes have been cloned.…”