Association Genetics of Grain Mineral Elements of Wheat from Pakistan

Abstract

Wheat (T r iticum aestivum L.) as a staple food crop is an essential source of protein and minerals. To address the difficulties associated with malnutrition, it is critical to fortify basic grains such as wheat with vital minerals. The first part of study aimed to assess the level of 11 micronutrients, including grain iron (GFe) and zinc (GZn) in 62 wheat cultivars released in Pakistan between 1911 and 2016. In the first part of study, GFe and GZn and other mineral concentration were measured over a two-year period in wheat cultivars using inductively coupled plasma optical emission spectroscopy (ICP-OES) and an energy-dispersive X-ray fluorescence spectrophotometer (EDXRF). The GZn concentration varied from 18.4 to 40.8 mg kg-1 according to ED-XRF and 23.7 to 38.8 mg kg-1 according to ICP-OES. Similarly, ICP-OES found GFe levels ranging from 24.8 to 44.1 mg kg-1 . while EDEXR found levels ranging from 26.8 to 36.6 mg kg-1 . GZn had a greater coefficient of correlation (r = 0.90) than GFe (r = 0.68). Modern cultivars like Zincol-16 and AAS-2011 demonstrated increased GFe and GZn levels as well as enhanced yield components. Old wheat cultivars WL-711, C-518, and Pothowar-70, which were released before to 1970, also had greater GFe and GZn values; nevertheless, their agronomic performance was poor. A multivariate study of eleven micronutrients (Fe, Zn, Al, Ca, Cu, K, Mg, Mn, Na, Se, and P) as well as agronomic characteristics and genome-wide SNP markers found a promising cultivar with increased yield, biofortification, and more genetic diversity. Over the course of 100 years, genetic gain analysis revealed a substantial rise in grain yield (0.4 % year 1), but there was a negative gain for GFe (0.111 % year 1) and GZn (0.15 % year 1). Plant height and grain yield (GY) were strongly associated with the Green Revolution Rht-B1 and Rht-D1 genes, whereas semi-dwarfing alleles had a negative influence on GFe and GZn levels. The second part of the study was aimed to assess the level of nine micronutrients, including grain iron (GFe) and zinc (GZn), as well as five biochemical characteristics across 188 wheat land races. Over the course of two years, field experiments were undertaken, and GFe, GZn, and other minerals were measured using flame photometer. The coefficient of variation was highest for P contents (108.8 %), and the lowest CV % was observed for oil (17.5 %). The GZn. 2019 concentration ranges from 13.5 mg kg-1 to 54 mg kg 1 and GZn.2020 concentration ranges from 11.8 mg kg-1 to 54.5 mg kg-1 . There was no Page xi significant increase observed in GZn concentration in wheat landraces between years 2019 to 2020. The GFe.2019 concentration ranges from 8.20 mg kg-1 to 56 mg kg-1 and GFe.2020 concentration ranges from 15 mg kg-1 to 60 mg kg-1 . There is prominent increase observed in GZn concentration in wheat landraces between years 2019 to 2020. The highest correlation among the morphological and mineral traits was between P and N (r=0.99). The other trait has non-significant correlation. All biochemical and mineral traits of wheat land races show higher variation across different provinces of Pakistan. The mean of fiber was highest in AJK province (1.91 mg kg-1 ) with a range of 1.87-1.99 mg kg-1 and lowest in Gilgit province (1.17 mg kg-1 ) with a range of 0.93-1.29 mg kg-1 . Protein has seven MTAs on chromosome 1A, 3B (2), 4A, 5A, 6B, 7D with R2 range of 0.28-0.44. Fiber has four MTAs on chromosome 6A (2), 7A, 2B with R2 range of 0.04- 0.05. A total eighty-four MTAs were identified on different chromosomes in wheat related to mineral traits in wheat landraces. GZn. 2019 has five MTAs on chromosome 7D, 1A, 7B (3) with R2 range of 0.84- 1.11. GZn. 2020 has four MTAs on chromosome 3D, 3B, 5D, 2A with R2 range of 0.61-0.70. GZn average has two MTAs on chromosome 1A, 6B with R2 range of 0.56-0.59.Fe. 2019 has large number of twenty MTAs on chromosome 1B (3), 4A, 2B (2), 2A, 3B, 2D, 2A, 7B, 5A (4),7D, 7A, 6A (2), 5B with R2 range of 5.60-11.26. Fe 2020 has fourteen MTAs on chromosome 2B (6), 5B, 1A (3), 1B, 6B, 4B, 7A with R 2 range of 4.01-6.53.GFe average has seven MTAs on chromosome 2B (2), 3B (2), 6A (2), 4A with R 2 range of 4.51-9.17. Na has one MTA on chromosome 5A with R 2 value of 0.002. B has one MTA on chromosome 1B with R 2 value of 0.11. P has 3MTAs on chromosome 3A (2), 3B with R 2 range of 0.07-0.12. K has fifteen MTAs on chromosome 5A, 7A, 6B (4), 2B (4), 6A (2), 7B, 6D, 1A with R2 range of 0.01-0.03. Mn has seven MTAs on chromosome 1A (2), 1B, 2B, 3A, 4A, 4B with R 2 range of 0.80-1.68. Cu has one MTA on chromosome 6D with R 2 value of 0.36. N has three MTAs on chromosome 3A (2), 3B with R2 range of 0.42-0.69. GFe.2019 has maximum number of MTAs. B, Cu, Na has minimum number of MTAs. This study offered significant information into the biofortification status of wheat cultivars used historically in Pakistan as well as the biofortification status and GWAS of wheat landraces from Pakistan. It is a good starting point for developing a breeding strategy for simultaneous improvement in wheat phenology and biofortification