First ever probable oats (Avena sativa) QTLs mapped on chromosome 1 and 7 for pyrenophora leaf spot resistance in India

An experiment was conducted during 2021–22 at Punjab Agricultural University, Ludhiana, Punjab for the development of linkage map and identification of QTLs for pyrenophora or Helminthosporium leaf spot resistance in oats (Avena sativa L.). A total of 96 F2 plants were used which was derived from the cross EC/0007662 (resistant source) and EC/0131291 (susceptible source). Linkage map was constructed for genotypic data of 96 population lines with 24 polymorphic SSR markers using QTL cartographer. A total of 7 linkage groups (LGs) had been generated from this data. But out of 7 LGs, 5 LGs remained individually at 0 position (unlinked) i.e. belonged to different group each and LG1 and LG7 were grouped. First LG included ABAM232, ABAM493 and ABAM077 from 0 to 66.5 cM. Similarly, 7th LG had two marker position i.e. ABAM342 and ABAM425. Maximum distance between the two markers was found to be 33.4 cM (between the marker interval of ABAM232 and ABAM497. Further QTL analysis was done using cartographer with composite interval mapping to identify the QTLs associated with disease resistance by comparing the phenotypic data of F2 population for disease and genotypic data of the population. The work reported here constitutes a major step toward identification of genetic regions responsible for disease resistance. However, the utility of QTL for marker assisted selection requires that QTLs are localized in a narrow region tightly linked with associated markers. The result of the experiment can be used for marker assisted breeding to transfer such genes identified as part of our research in order to reduce disease severity and yield losses in oats

Towards mapping of Helminthosporium leaf blight/Pyrenophora leaf spot resistance genes/QTLs in oats

The oat crop has been neglected due to its use in limitation as a forage crop rather than a staple food in most of the countries throughout the world. Also it is more prone to foliar diseases, especially Helminthosporium leaf blight (HLB, syn Pyrenophora leaf spot) disease in the Punjab, especially Ludhiana region. It emerged as a new disease that can infect over 70% of the field resulting in up to forage yield losses of 50 per cent throughout. Hence, this study was conducted to evaluate the 167 germplasm lines for disease severity and its infection based on 1–9 scale through artificial inoculation of fungal spores. These lines were classified under four different clusters based upon infection with majority falling under cluster 2 and cluster 3 with infection of more than 50%. Lines ranged from being highly susceptible (more than 75% infection) to moderately resistant (22% infection). These contrasting lines were used in disease progression studies and also in hybridization programme to develop populations for future mapping studies. The contrasting lines were analysed for polymorphism using 220 SSR markers, of which 47 markers were polymorphic. Also the mapping for HLB resistance genes/QTLs is being carried out under the current ongoing research project, which will be the first research to map the resistance genes/QTLs in the oats throughout India and the world. Identified lines also can be used in future breeding programme to develop resistant cultivars

Meta‐analysis of the quantitative trait loci associated with agronomic traits, fertility restoration, disease resistance, and seed quality traits in pigeonpea (Cajanus cajan L.)

Abstract A meta‐analysis of quantitative trait loci (QTLs), associated with agronomic traits, fertility restoration, disease resistance, and seed quality traits was conducted for the first time in pigeonpea (Cajanus cajan L.). Data on 498 QTLs was collected from 9 linkage mapping studies (involving 21 biparental populations). Of these 498, 203 QTLs were projected onto “PigeonPea_ConsensusMap_2022,” saturated with 10,522 markers, which resulted in the prediction of 34 meta‐QTLs (MQTLs). The average confidence interval (CI) of these MQTLs (2.54 cM) was 3.37 times lower than the CI of the initial QTLs (8.56 cM). Of the 34 MQTLs, 12 high‐confidence MQTLs with CI (≤5 cM) and a greater number of initial QTLs (≥5) were utilized to extract 2255 gene models, of which 105 were believed to be associated with different traits under study. Furthermore, eight of these MQTLs were observed to overlap with several marker‐trait associations or significant SNPs identified in previous genome‐wide association studies. Furthermore, synteny and ortho‐MQTL analyses among pigeonpea and four related legumes crops, such as chickpea, pea, cowpea, and French bean, led to the identification of 117 orthologous genes from 20 MQTL regions. Markers associated with MQTLs can be employed for MQTL‐assisted breeding as well as to improve the prediction accuracy of genomic selection in pigeonpea. Additionally, MQTLs may be subjected to fine mapping, and some of the promising candidate genes may serve as potential targets for positional cloning and functional analysis to elucidate the molecular mechanisms underlying the target traits