So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Principles of Plant Breeding

Fusarium wilt (FW) is one of the most important biotic stresses causing yield losses in pigeonpea. Genetic improvement of pigeonpea through genomics-assisted breeding (GAB) is an economically feasible option for the development of high yielding FW resistant genotypes. In this context, two recombinant inbred lines (RILs) (ICPB 2049 × ICPL 99050 designated as PRIL_A and ICPL 20096 × ICPL 332 designated as PRIL_B) and one F2 (ICPL 85063 × ICPL 87119) populations were used for the development of high density genetic maps. Genotyping-by-sequencing (GBS) approach was used to identify and genotype SNPs in three mapping populations. As a result, three high density genetic maps with 964, 1101 and 557 SNPs with an average marker distance of 1.16, 0.84 and 2.60 cM were developed in PRIL_A, PRIL_B and F2, respectively. Based on the multi-location and multi-year phenotypic data of FW resistance a total of 14 quantitative trait loci (QTLs) including six major QTLs explaining >10% phenotypic variance explained (PVE) were identified. Comparative analysis across the populations has revealed three important QTLs (qFW11.1, qFW11.2 and qFW11.3) with upto 56.45% PVE for FW resistance. This is the first report of QTL mapping for FW resistance in pigeonpea and identified genomic region could be utilized in GAB.

Construction of genotyping-by-sequencing based high-density genetic maps and QTL mapping for fusarium wilt resistance in pigeonpea

Fusarium wilt (FW) disease is the key constraint to grain legume production worldwide. The projected climate change is likely to exacerbate the current scenario. Of the various plant protection measures, genetic improvement of the disease resistance of crop cultivars remains the most economic, straightforward and environmental-friendly option to mitigate the risk.We begin with a brief recap of the classical genetic efforts that provided first insights into the genetic determinants controlling plant response to different races of FW pathogen in grain legumes. Subsequent technological breakthroughs like the sequencing technologies have enhanced our understanding of the genetic basis of both plant resistance and the pathogenicity. We present noteworthy examples of targeted improvement of plant resistance using genomic-assisted approaches. In parallel, modern functional genomic tools like RNAseq are playing a greater role in illuminating the various aspects of plant-pathogen interaction. Further, proteomics and metabolomics have also been leveraged in recent years to reveal molecular players and various signaling pathways and complex networks participating in host-pathogen interaction. Finally, we present a perspective on the challenges and limitations of high-throughput phenotyping and emerging breeding approaches to expeditiously develop FW-resistant cultivars under the changing climate.

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Breeding, Genetics, and Genomics Approaches for Improving Fusarium Wilt Resistance in Major Grain Legumes.

Pigeonpea production is severely constrained by wilt disease caused by Fusarium udum. In the current study, we discover the putative genomic regions that control resistance response to variant 2 of fusarium wilt using association mapping approach. The association panel comprised of 89 diverse pigeonpea genotypes including seven varieties, three landraces and 79 germplasm lines. The panel was screened rigorously for 3 consecutive years (2013–14, 2014–15 and 2015–2016) against variant 2 in a wilt-sick field. A total of 65 pigeonpea specific hypervariable SSR markers (HASSRs) were screened representing seven linkage groups and 29 scaffolds of the pigeonpea genome. A total of 181 alleles were detected, with average values of gene diversity and polymorphism information content (PIC) of 0.55 and 0.47, respectively. Further analysis using model based (STRUCTURE) and distance based (clustering) approaches separated the entire pigeonpea collection into two distinct subgroups (K = 2). The marker trait associations (MTAs) were established based on three-year wilt incidence data and SSR dataset using a unified mixed linear model. Consequently, six SSR markers were identified, which were significantly associated with wilt resistance and explained up to 6% phenotypic variance (PV) across the years. Among these SSRs, HASSR18 was found to be the most stable and significant, accounting for 5–6% PV across the years. To the best of our knowledge, this is the first report of identification of favourable alleles for resistance to variant 2 of Fusarium udum in pigeonpea using association mapping. The SSR markers identified here will greatly facilitate marker assisted resistance breeding against fusarium wilt in pigeonpea.

Association mapping to discover significant marker-trait associations for resistance against fusarium wilt variant 2 in pigeonpea [Cajanus cajan (L.) Millspaugh] using SSR markers

Inheritance of resistance to Fusarium wilt (FW) disease caused by Fusarium udum was investigated in pigeonpea using four different long duration FW resistant genotypes viz, BDN-2004-1, BDN-2001-9, BWR-133 and IPA-234 Based on the F2 segregation pattern, FW resistance has been reported to be governed by one dominant gene in BDN-2004-1 and BDN-2001-9, two duplicate dominant genes in BWR-133 and two dominant complimentary genes in resistance source IPA-234 Further, the efficacy of six simple sequence repeat (SSR) markers namely, ASSR-1, ASSR-23, ASSR-148, ASSR-229, ASSR-363 and ASSR-366 reported to be associated with FW resistance were also tested and concluded that markers ASSR-1, ASSR-23, ASSR-148 will be used for screening of parental genotypes in pigeonpea FW resistance breeding programs The information on genetics of FW resistance generated from this study would be used, to introgress FW resistance into susceptible but highly adopted cultivars through marker-assisted backcross breeding and in conventional breeding programs

Genetics of Fusarium Wilt Resistance in Pigeonpea (Cajanus cajan) and Efficacy of Associated SSR Markers

Drumstick (Moringa oleifera) originated in India is one of the most useful tropical tree. With its high nutritive values every part of the tree is used for nutritional or commercial purpose. Moringa leaves are rich source of minerals, vitamins especially vitamin A, vitamin B and vitamin C and it is used as antioxidant, anticancer, anti-inflammatory, antidiabetic, antimicrobial agent and it is widely consumed for self-medication by patients affected by diabetes, hypertension, or HIV/AIDS. The young leaves are edible in some quantities and it can be dried and make into powder for use in some food products. In this study, processing of fresh moringa leaves into dry form for consumption purpose and nutritional composition of dried drumstick leaf powder (Moisture, Protein, Crude Fibre, Ash, Fat, Total Carbohydrate, Calories, Calcium, Magnesium, Iron, Zinc and s- Carotene) was described.

https://www.phytojournal.com/archives/2018/vol7issue2/PartD/7-1-213-373.pdf

Studies of Genetic variability, heritability and genetic advance for yield and related traits in French bean (Phaseolus vulgaris L.)

Molecular characterization and genetic diversity among fourteen cucumber genotypes were carried out by using eleven Inter Simple Sequence Repeat (ISSR) markers. All the eleven ISSR markers used were found polymorphic having 97.72% polymorphism among fourteen cucumber genotypes comprising pathenocarpic, gynoecious and monoecious cucumbers. These eleven polymorphic markers produced a total of 69 alleles, of which 4 were unique alleles. The allele number for each ISSR locus varied between 4 to 10 with an average of 6.27 alleles per marker. Polymorphic information content values of ISSRs ranged from 0.43 to 0.84 with an average of 0.68. Jaccard’s similarity coefficient was employed to study the molecular diversity of 14 cucumber genotypes. The pair wise genetic similarity among 14 cucumber genotypes varied from 0.36 to 0.83. The dendrogram constructed based on genetic similarities among 14 cucumber genotypes identified two major clusters. The four major parthenocarpic genotypes viz., PCUCP-2, PCUCP-4, PCUCP-6 and PCUCP-8 having high genetic resemblance (80-83%) and two major gynoecious genotypes viz., PGYC-3 and PGYC-2 with 68% similarity value were grouped in a single cluster and three monoecious genotypes viz., PCUC-8, PCUC-25 and Pant Khira-1 were grouped in another cluster with 76-78% similarity value. This study provides information about diversity among pathenocarpic, gynoecious and monoecious cucumber genotypes and remains helpful in future exploration and utilization of diverse germplasm for developing cultivars and hybrids.

https://www.phytojournal.com/archives/2020/vol9issue2/PartAI/9-2-335-405.pdf

Genetic diversity analysis of cucumber (Cucumis sativus L.) genotypes based on ISSR markers

Cucumber (Cucumis sativus L., 2n=2x=14) is one of the most important member of the family cucurbitaceae including several crops of economic importance. It is thought to be one of the oldest vegetable crops, being grown for at least five thousand years. It is the fourth most important vegetable crop after tomato, cabbage and onion in Asia. The fruits are used for preparation of cosmetic items like soap and cream and in many other ways (Dhiman and Parkash, 2005). The crop is of Asian origin and the progenitor may be closely related to its wild relative Cucumis sativus var. hardwickii, first found in the International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 4 (2020) Journal homepage: http://www.ijcmas.com

Estimation of Genetic Variability, Heritability and Genetic Advance in Cucumber (Cucumis sativus L.) for Yield and Its Components under Protected Structure

Dinesh Kumar Singh

Papers

Genetics of Fusarium Wilt Resistance in Pigeonpea (Cajanus cajan) and Efficacy of Associated SSR Markers

Studies of Genetic variability, heritability and genetic advance for yield and related traits in French bean (Phaseolus vulgaris L.)

Genetic diversity analysis of cucumber (Cucumis sativus L.) genotypes based on ISSR markers

Estimation of Genetic Variability, Heritability and Genetic Advance in Cucumber (Cucumis sativus L.) for Yield and Its Components under Protected Structure

Estimates of combining ability for development of F1 hybrids in cucumber.