Stripe rust is a continuous threat to wheat crop all over the world.  It causes considerable yield losses in wheat crop every year.  Continuous deployment of adult plant resistance (APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease.  Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm.  An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs.  Based on D´ measure, linkage disequilibrium (LD) exhibited between loci distant up to 45 cM.  Marker-trait associations (MTAs) were determined using mixed linear model (MLM).  Total 31 quantitative trait loci (QTLs) were observed on all 21 wheat chromosomes.  Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm.  The major QTLs were QYr.uaf.2AL and QYr.uaf.3BS (PVE, 11.9%).  Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop.

 

The identification of glyphosate-tolerant maize genotypes by field spraying with glyphosate is time-consuming, costly and requires treatment of a large area.  We report a potentially better technique of seed-soaking to identify glyphosate-tolerant maize genotypes.  The effects of soaking maize seeds in glyphosate solution under controlled conditions were studied on seed germination rate, seedling morphological indices, seedling growth and leaf chlorophyll content.  These responses were compared among a glyphosate-tolerant transgenic maize cultivar CC-2, glyphosate-susceptible inbred line Zheng 58 (the recurrent parent of CC-2) and hybrid cultivar Zhengdan 1002.  The results showed that the germination rate, seedling morphological indices and leaf chlorophyll content of glyphosate-tolerant CC-2 seeds did not change significantly among five different concentrations of glyphosate treatment (0 to 2%).  In contrast, germination rates, seedling morphological indices and leaf chlorophyll contents of Zheng 58 and Zhengdan 1002 seeds were significantly negatively affected by exposure to increasing concentrations of glyphosate.  The glyphosate-tolerant inbred line CC-2 displayed a strong tolerance to glyphosate after soaking in 0.1 to 2.0% glyphosate solutions, while both the inbred line Zheng 58 and hybrid Zhengdan 1002 were susceptible to glyphosate.  The accuracy of the glyphosate-soaking method for screening glyphosate-tolerant maize was confirmed using a field spraying trial.