Zinc and Iron Nutrition Status in the Philippines Population and Local Soils

Association between lead and circulating markers of inflammation among traffic enforcers in Metro Manila, Philippines: the MMDA traffic enforcer's health study

PURPOSE

Several epidemiological studies have linked lead (Pb) exposure to induced oxidative stress and the promotion of inflammatory response. We performed a within-subjects study (repeated measures study) to evaluate the relationship between the concentration of blood lead (B-Pb) and toenail lead (T-Pb) and circulating markers of inflammation.

METHODS

We evaluated the associations between B-Pb concentrations and T-Pb concentrations and circulating markers of inflammation, soluble intracellular adhesion molecule-1 (s-ICAM-1), soluble vascular adhesion molecule-1 (s-VCAM-1), and high-sensitivity C-reactive protein (hs-CRP) on 158 traffic enforcers from the Metropolitan Manila Development Authority (MMDA) traffic enforcer's health study. Linear mixed-effects models with random subject-specific intercepts were fitted to estimate the association between B-Pb and T-Pb exposure and circulating markers of inflammation, adjusting for confounding factors.

RESULTS

Traffic enforcers were middle-aged men (89.4%) with a mean age (± SD) of 37.1 years ± 8.9 years and had a total of 293 valid markers of inflammation measurements. B-Pb concentration was related to increased hs-CRP levels. A 10% increase in B-Pb was associated with a 5.7% increase in hs-CRP level [95% confidence interval (95% CI): 1.3-10.1]. However, B-Pb was not associated with s-ICAM-1 and s-VCAM-1. Furthermore, no associations were observed between T-Pb and all the circulating markers of inflammation.

CONCLUSIONS

Low-level B-Pb may increase hs-CRP among traffic enforcers. Moreover, the study suggests that Pb via the oxidative and inflammation pathways may have an essential role in the development of cardiovascular disease. Furthermore, MMDA and the Department of Labor and Employment can use our study's findings as evidence to conduct routine screening of blood heavy metals, especially Pb, among MMDA and other traffic enforcers as part of their yearly medical examination.

Meta-QTL s and haplotypes for efficient zinc biofortification of rice

Biofortification of rice with improved grain zinc (Zn) content is the most sustainable and cost-effective approach to address Zn malnutrition in Asia. Genomics-assisted breeding using precise and consistent Zn quantitative trait loci (QTLs), genes, and haplotypes can fast-track the development of Zn biofortified rice varieties. We conducted the meta-analysis of 155 Zn QTLs reported from 26 different studies. Results revealed 57 meta-QTLs with a significant reduction of 63.2% and 80% in the number and confidence interval of the Zn QTLs, respectively. Meta-quantitative trait loci (MQTLs) regions were found to be enriched with diverse metal homeostasis genes; at least 11 MQTLs were colocated with 20 known major genes involved in the production of root exudates, metal uptake, transport, partitioning, and loading into grains in rice. These genes were differentially expressed in vegetative and reproductive tissues, and a complex web of interactions were observed among them. We identified superior haplotypes and their combinations for nine candidate genes (CGs), and the frequency and allelic effects of superior haplotypes varied in different subgroups. The precise MQTLs with high phenotypic variance, CGs, and superior haplotypes identified in our study are useful for an efficient Zn biofortification of rice and to ensure Zn as an essential component of all the future rice varieties through mainstreaming of Zn breeding.

Spinel nanocomposite (nMnZnFe2O4) synchronously promotes grain yield and Fe-Zn biofortification in non-aromatic rice

Soils deficient in essential micro-nutrients produce nutritionally starved crops that do not fulfill human nutritional requirements. This is getting serious since progressively increasing nutritional disorders are being diagnosed in residents of third-world countries like Pakistan. During this study, we synthesized a spinel nanocomposite (nMnZnFe2O4) and investigated its effectiveness in improving the micronutrient status and yield traits of rice. The nMnZnFe2O4 exhibited a cubic structure at the most prominent peak (311); a crystallite size of 44 nm, and an average grain size ranging from 7 to 9 μm. Foliar application of this nanocomposite was performed to 45 days old plants at concentrations 0, 10, 20, 30, 40, and 50 mg L-1, and data from rice plant parts (straw, husk, and grain) was recorded at maturity. Agronomic traits like the number of tillers, straw dry weight, root dry biomass, and grain yield per plant were improved by nMnZnFe2O4 application (+34.4% yield). Whereas some biochemical traits like amino acids, soluble sugars, flavonoids, and phenolics varied significantly in rice plant parts compared to the control. Above all, the maximum Zn and Fe concentrations in rice grain were recorded through foliar application of spinel nanocomposite (40 and 50 mg L-1). Therefore, results indicated that micronutrient supply in the form of a nanocomposite could positively regulate nutritional quality and rice grain yield.

Mineral Content Variation in Leaves, Stalks, and Seeds of Celery (Apium graveolens L.) Genotypes

Celery is an important nutritionally rich crop in the family Apiaceae. It is cultivated worldwide for food as well as for use in pharmaceutics. It is an excellent source of minerals, vitamins, and phytochemicals. Identification of superior genotypes with improved nutritional content is the requirement to develop cultivars for commercial cultivation. For mineral analysis of celery, an experiment was carried out taking 20 diverse genotypes. These genotypes were analysed for macro- and micronutrients which include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), and sodium (Na). The study revealed high content of K (20.3-26.1 mg/g dry weight (DW)) and Zn (0.09-0.14 mg/g DW) in leaves while the stalks were rich in Ca (41.5-51.3 mg/g DW) and Na (5.2-8.0 mg/g DW). High contents of P (5.2-6.8 mg/g DW), Fe (0.41-0.56 mg/g DW), Cu (0.015-0.026 mg/g DW), and Mn (0.020-0.029 mg/g DW) were observed in seeds. Based on the mineral content, three genotypes, viz., PAU2, PAU4, and PAU7, were found to be superior in terms of mineral composition in leaves, stalks, and seeds. Cluster analysis divided the genotypes into two major groups. These genotypes can be used in crosses as they showed great potential for use in biofortification. This study opens newer avenues for future research, encouraging researchers to enhance the product quality and production efficiency of the leaves, stalks, and seeds valuable for human consumption.

Cruz PC, Borromeo TH, Lalusin AG, Mauleon R, McNally KL, Swamy BPM. Molecular dissection of connected rice populations revealed important genomic regions for agronomic and biofortification traits

Breeding staple crops with increased micronutrient concentration is a sustainable approach to address micronutrient malnutrition. We carried out Multi-Cross QTL analysis and Inclusive Composite Interval Mapping for 11 agronomic, yield and biofortification traits using four connected RILs populations of rice. Overall, MC-156 QTLs were detected for agronomic (115) and biofortification (41) traits, which were higher in number but smaller in effects compared to single population analysis. The MC-QTL analysis was able to detect important QTLs viz: qZn_5.2, qFe_7.1, qGY_10.1, qDF_7.1, qPH_1.1, qNT_4.1, qPT_4.1, qPL_1.2, qTGW_5.1, qGL_3.1 , and qGW_6.1 , which can be used in rice genomics assisted breeding. A major QTL (qZn_5.2 ) for grain Zn concentration has been detected on chromosome 5 that accounted for 13% of R². In all, 26 QTL clusters were identified on different chromosomes. qPH_6.1 epistatically interacted with qZn_5.1 and qGY_6.2 . Most of QTLs were co-located with functionally related candidate genes indicating the accuracy of QTL mapping. The genomic region of qZn_5.2 was co-located with putative genes such as OsZIP5, OsZIP9, and LOC_OS05G40490 that are involved in Zn uptake. These genes included polymorphic functional SNPs, and their promoter regions were enriched with cis-regulatory elements involved in plant growth and development, and biotic and abiotic stress tolerance. Major effect QTL identified for biofortification and agronomic traits can be utilized in breeding for Zn biofortified rice varieties.

Nutritional Compositions of Aquatic Insects Living in Rice Fields, with a Particular Focus on Odonate Larvae

Although the human consumption of aquatic insects is prevalent in many regions, the nutritional composition of the insects has not been comprehensively determined. The proximate composition of Pantala sp. was shown to be a good source of protein (49.45 ± 0.32 g/100 g DW), as well as of minerals such as sodium, calcium, potassium, phosphorus, zinc, and iron. All nine essential amino acids are present in this species, with valine being the most abundant. The major fatty acids are palmitic acid (1.19 ± 0.02 g/100 g DW), oleic acid (0.63 ± 0.02 g/100 g DW), and linoleic acid (0.55 ± 0.01 g/100 g DW). Lead (Pb), arsenic (As), and cadmium (Cd) showed a value of 0.18 ± 0.01 mg·kg^-1, 3.51 ± 0.12 mg·kg^-1, and 0.17 ± 0.00 mg·kg^-1, respectively. Furthermore, microplastic (MP) contamination in odonate larvae (419 individuals belonging to three identified families) was found in varying shapes, e.g., fibers, fragments, and rods. FTIR analysis revealed the following MP polymers, polyethylene terephthalate, polyvinyl acetate, bis(2-ethylhexyl), polybutadiene, poly(methyl methacrylate-co-methacrylic acid); P(MMA-co-MA), poly(ethylene glycol) tetrahydrofurfuryl ether, poly(acrylonitrile-co-butadiene), and polypropylene glycol. The results of this work could be a nutritional reference for food security and the risk of eating insects.

Sex Differences in Dietary Patterns of Adults and Their Associations with the Double Burden of Malnutrition: A Population-Based National Survey in the Philippines

A dietary pattern transition is a risk factor for the double burden of malnutrition (DBM), but related information is limited. This study aimed to identify sex differences in dietary patterns of adults in a low–middle income country and to examine their association with DBM. A total of 8957 adults (4465 men and 4492 non-pregnant and non-lactating women) who participated in the 2013 Philippine National Nutrition Survey were included in the analysis. Logistic regression models were formulated to investigate the relationship between dietary patterns and DBM. The factor analysis derived seven dietary patterns for males and six patterns for females. Results showed that approximately 30% of Filipino adults suffered from DBM. The rice pattern was associated with lower odds of DBM for males only. The meat and sugar pattern in males and the protein-rich foods, cereal, and sugar pattern in females decreased DBM likelihood. An inverse relationship was observed for the vegetables and corn patterns, wherein females had an increased risk for DBM. Our findings suggest that rice-based and meat-containing patterns could play protective roles in DBM development among adults in the Philippines. Understanding sex-specific dietary patterns can be utilized to guide public health nutrition interventions in the prevention of malnutrition in all its forms.

OsVIT2 Mutation Increases Fe and Zn of Grain Without Compromising the Growth in Paddy Field

Nearly 2 billion people who reside in developing countries are suffering from nutrient deficiency, also known as hidden hunger. A hidden hunger includes iron (Fe) and zinc (Zn) deficiency. One of the most efficient solutions to hidden hunger is the biofortification of crops through breeding. In this study, we characterized the mutant 1095_k, which has high grain Fe (~1.4-fold) and Zn (~1.2-fold) concentration compared with wild-type plants for a 5-year field trial. The yield components of 1095_k are similar to wild-type plants in a paddy field. In addition, 1095_k has a non-sense mutation in OsVIT2, a vacuolar localized Fe transporter. F2 crosses between 1095_k and wild type having the mutation showing higher grain Fe and Zn concentration. In contrast, plants without the mutation showed similar element concentrations as the wild type. These results suggest that OsVIT2 would be responsible for high Fe and Zn of grain and the 1095_k would be a useful breeding material for the biofortification of Fe and Zn.

Improving Zinc and Iron Biofortification in Wheat through Genomics Approaches

Globally, about 20% of calories (energy) come from wheat. In some countries, it is more than 70%. More than 2 billion people are at risk for zinc deficiency and even more, people are at risk of iron deficiency, nearly a quarter of all children underage group of 5 are physically and cognitively stunted, and lack of dietary zinc is a major contributing factor. Biofortified wheat with elevated levels of zinc and iron has several potential advantages as a delivery vehicle for micronutrients in the diets of resource-poor consumers who depend on cereal-based diets. The conventional breeding strategies have been successful in the introduction of novel alleles for grain Zn and Fe that led to the release of competitive Zn enriched wheat varieties in South Asia. The major challenge over the next few decades will be to maintain the rates of genetic gains for grain yield along with increased grain Zn/Fe concentration to meet the food and nutritional security challenges. Therefore, to remain competitive, the performance of Zn-enhanced lines/varieties must be equal or superior to that of current non-biofortified elite lines/varieties. Since both yield and Zn content are invisible and quantitatively inherited traits except few intermediate effect QTL regions identified for grain Zn, increased breeding efforts and new approaches are required to combine them at high frequency, ensuring that Zn levels are steadily increased to the required levels across the breeding pipelines. The current review article provides a comprehensive list of genomic regions for enhancing grain Zn and Fe concentrations in wheat including key candidate gene families such NAS, ZIP, VLT, ZIFL, and YSL. Implementing forward breeding by taking advantage of the rapid cycling trait pipeline approaches would simultaneously introgress high Zn and Fe QTL into the high Zn and normal elite lines, further increasing Zn and Fe concentrations.

Recent Advances in the Gastrointestinal Fate of Organic and Inorganic Nanoparticles in Foods

Inorganic or organic nanoparticles are often incorporated into foods to enhance their quality, stability, nutrition, or safety. When they pass through the gastrointestinal environment, the properties of these nanoparticles are altered, which impacts their biological effects and potential toxicity. Consequently, there is a need to understand how different kinds of nanoparticles behave within the gastrointestinal tract. In this article, the current understanding of the gastrointestinal fate of nanoparticles in foods is reviewed. Initially, the fundamental physicochemical and structural properties of nanoparticles are discussed, including their compositions, sizes, shapes, and surface chemistries. Then, the impact of food matrix effects and gastrointestinal environments on the fate of ingested nanoparticles is discussed. In particular, the influence of nanoparticle properties on food digestion and nutraceutical bioavailability is highlighted. Finally, future research directions are highlighted that will enable the successful utilization of nanotechnology in foods while also ensuring they are safe.

Association of Grain Iron and Zinc Content With Other Nutrients in Pearl Millet Germplasm, Breeding Lines, and Hybrids

Micronutrient deficiency is most prevalent in developing regions of the world, including Africa and Southeast Asia where pearl millet (Pennisetum glaucum L.) is a major crop. Increasing essential minerals in pearl millet through biofortification could reduce malnutrition caused by deficiency. This study evaluated the extent of variability of micronutrients (Fe, Zn, Mn, and Na) and macronutrients (P, K, Ca, and Mg) and their relationship with Fe and Zn content in 14 trials involving pearl millet hybrids, inbreds, and germplasm. Significant genetic variability of macronutrients and micronutrients was found within and across the trials (Ca: 4.2–40.0 mg 100 g⁻¹, Fe: 24–145 mg kg⁻¹, Zn: 22–96 mg kg⁻¹, and Na: 3.0–63 mg kg⁻¹). Parental lines showed significantly larger variation for nutrients than hybrids, indicating their potential for use in hybrid parent improvement through recurrent selection. Fe and Zn contents were positively correlated and highly significant (r = 0.58–0.81; p < 0.01). Fe and Zn were positively and significantly correlated with Ca (r = 0.26–0.61; p < 0.05) and Mn (r = 0.24–0.50; p < 0.05). The findings indicate that joint selection for Fe, Zn, and Ca will be effective. Substantial genetic variation and high heritability (>0.60) for multiple grain minerals provide good selection accuracy prospects for genetic enhancement. A highly positive significant correlation between Fe and Zn and the nonsignificant correlation of grain macronutrients and micronutrients with Fe and Zn suggest that there is scope to achieve higher levels of Fe/Zn simultaneously in current pearl millet biofortification efforts without affecting other grain nutrients. Results suggest major prospects for improving multiple nutrients in pearl millet.

Analysis of food sources and nutrient intakes of selected breastfeeding mothers in Metro Manila, Philippines

BACKGROUND

This study evaluated the food and nutrient intakes of selected breastfeeding mothers and identified the top food sources of nutrient intakes.

METHODS

This is a cross-sectional, non-interventional study conducted in one of the private medical centers in Metro Manila, Philippines.

PARTICIPANTS

The sample size included 70 mothers of healthy, term, exclusively breastfed infants aged 21-26 days at enrollment. Mothers were scheduled to visit the clinic at days 1, 22, 57, and day 90.Similarly, food diaries were obtained during these periods with a 3-day food record per clinic visit totaling to 12 records per mother at the end of 90 days. At every clinic visit, the records were validated face - to - face by the registered nutritionist - dietitians. An extension of the mother's participation until day 155 was implemented for the collection of clinical outcomes used by Pediatricians. Mean food intakes were calculated. A PC-Software for Intake Distribution Estimation (PC-SIDE) program was used in the estimation of inadequate intakes. Socio-economic status was collected using standard questionnaires. Weight and height were measured using standard techniques to compute for BMI.

RESULTS

Anthropometric results for the breastfeeding mothers reported a mean weight of 56.9 kg (SE = 1.3) and a mean height of 152.4 cm (SE = 0.6). In terms of body mass index (BMI), 8.6% were chronic energy deficient, and 34.3% were overweight while 12.9% were obese. Mean energy intake of breastfeeding mothers was 2516.7 kcal/day, which was 28.6% higher than the EER of 1957 kcal/day. Mean protein intake was 78.4 g/day, which was 37% inadequate while fat intake as percentage of total energy was excessive by 4%. Nutrient inadequacy is high for almost all nutrients: iron (99%), folate (96%), riboflavin (39%), vitamin B6 (63%), vitamin B12 (46%) and thiamine (22%). The top 5-food sources with highest percent contribution to energy are rice (43.1%), bread (8.1%), pork (7.7%), powdered milk (5.9%), and sweet bakery products (5%).

CONCLUSIONS

There is a high prevalence of protein and micronutrient inadequacies in the diet of breastfeeding mothers. The prevalence of overweight and obesity is high among breastfeeding mothers. These findings might be explained by the low variety and nutrient-poor foods consumed by the breastfeeding mothers. Understanding the major food sources of nutrient intake of breastfeeding mothers could be used to intensify if not craft interventions to address the nutrient gaps. Improving the maternal nutrition may contribute to having quality breastmilk to infants.

Improving Nitrogen Use Efficiency—A Key for Sustainable Rice Production Systems

Fertilizer use and genetic improvement of cereal crops contributed to increased yields and greater food security in the last six decades. For rice, however, fertilizer use has outpaced improvement in yield. Excess application of nutrients beyond crop needs, especially nitrogen (N), is associated with losses to the environment. Environmental pollution can be mitigated by addressing fertilizer overuse, improving N use efficiency, while maintaining or improving rice productivity and farmers' income. A promising approach is the site-specific nutrient management (SSNM), developed in the 1990s to optimize supply to meet demand of nutrients, initially for rice, but now extended to other crops. The SSNM approach has been further refined with the development of digital decision support tools such as Rice Crop Manager, Nutrient Expert, and RiceAdvice. This enables more farmers to benefit from SSNM recommendations. In this mini-review, we show how SSNM can foster sustainability in rice production systems through improved rice yields, profit, and N use efficiency while reducing N losses. Farmer adoption of SSNM, however, remains low. National policies and incentives, financial investments, and strengthened extension systems are needed to enhance scaling of SSNM-based decision support tools.

Severity of zinc and iron malnutrition linked to low intake through a staple crop: a case study in east-central Pakistan

Micronutrients deficiency in soil-plant and human is well-addressed; however, little is known about their spatial distribution, magnitude of deficiency and biological nexus. Zinc deficiency (ZnD) and iron-deficiency anemia (FeD) are two serious nutritional concerns which are negatively affecting human health. Herein, a survey-based case study was conducted in major wheat-based cropping system of east-central Pakistan. Soil and grain samples were collected from 125 field-grown wheat from 25 distinct sites/villages and GPS coordinates were taken for mapping. The collected samples were tags according to the names of 25 sites, i.e., UCs (union councils; an administrative unit). The quantified amount of zinc (Zn) or iron (Fe) in soil-wheat grains was compared with their recommended concentrations (RCZn, RCFe) for human nutrition. Additionally, clinical features of ZnD and FeD were diagnosed among local farmers who used to consume these grains, throughout the year, cultivated on their farm, and quantified their deficiency prevalence (ZnDP, FeDP). Results revealed, the collected 64% (0.54 to 5.25 mg kg^-1) soils, and 96% (1.4 to 31 mg kg^-1) grain samples are Zn-deficient (RCZn) along with ZnDP recorded among 68% of population. Meanwhile, FeD is quantified in 76% (1.86 to 15 mg kg^-1) soil, 72% grain (2.1 to 134 mg kg^-1) samples, and FeDP is found among 84% of studied population. A strong and positive correlation is developed in the Zn-or FeDP with their deficiencies in soil and grain by plotting multivariate analysis. In line with spatial distribution pattern, the UCs, namely, 141, 151, 159 and 132 are quantified severe deficient in Zn and Fe, and others are marginal or approaching to deficient level. Our findings rationalize the biological nexus of Zn and Fe, and accordingly, draw attention in the biofortification of staple crop as a win-win approach to combat the rising malnutrition concerns.

Factors associated with the progression and prevention of noncommunicable diseases in community-dwelling Filipino adults: A cross-sectional study

Noncommunicable diseases (NCDs) are an important cause of disability and death in Muntinlupa, Manila, Philippines. However, there is little community-based research on lifestyle behaviors that affect the progression of NCDs or on the hindrances to NCD prevention.This cross-sectional study investigated the lifestyle behaviors associated with the progression and prevalence of NCDs and clarified factors associated with health promotion for the NCDs prevention among 168 Filipino adults aged 50 years and above in the community setting.The prevalence of diabetes, cardiovascular disease, cancer, chronic respiratory disease, hypertension, and overweight/obesity found 13.1%, 8.9%, 1.8%, 4.2%, 59.5%, and 36.9%, respectively. Of 63 adults who underwent blood tests, high blood glucose and abnormal lipids found 20.6% and 80.9%, respectively. Filipino adults ate breakfast, lunch, and dinner more than 5 days a week, Merienda 4.2 days a week, and a midnight snack 1.7 days a week. The mean frequencies of physical activity at vigorous, moderate, and light intensity levels were 2.6 times a week, 1.9 times a week, and 3.8 times a week, respectively. Men were more likely to be smokers than women. Mean frequencies of alcohol consumption were 0.6 days a week. Filipino adults who practiced diet control, regular physical activities, no smoking, limited alcohol intake, stress control, and regular health checkups were 68.3%, 34.1%, 35.9%, 35.3%, 32.9%, and 24.6%, respectively. Hypertension was positively associated with the duration of tobacco use and frequency of salt intake. Overweight/obesity was positively associated with the frequency of Merienda. Diet control was positively related with internal Multidimensional Health Locus of Control scale. Smoking and alcohol control were significantly related with income level.Community-dwelling Filipino adults in this study had a high prevalence of NCD progression and insufficient awareness of preventative behaviors. Diet control is associated with self-awareness of health and smoking and alcohol control are associated with economic status. These findings ought to contribute to develop the effective strategies for NCD prevention in community-dwelling Filipino adults.

Mineral and Fatty Acid Content Variation in White Oat Genotypes Grown in Brazil

A healthy diet is directly associated with a nutrient-rich and toxic contaminant poor intake. A diet poor in diversity can lead to micronutrient deficiency. The intake of functional foods can provide benefits in the prevention and treatment of diseases. Oats are a functional food; are a source of soluble fiber, lipids, proteins, vitamins, minerals, and polyphenols; and are low in carbohydrate content. Thus, in this study, we characterize mineral accumulation, fatty acid composition, and the absence of contaminants in oat genotypes to evaluate the potential of this cereal as food to minimize the effects of micronutrient deficiency. Most of the oat genotypes showed higher mineral levels than other cereals such as wheat, rice, and maize. FAEM 5 Chiarasul, Barbarasul, UPFA Ouro, URS Altiva, URS Brava, and URS Taura showed higher iron concentration while URS Brava showed the highest zinc concentration. The oat genotypes did not show significant arsenic, strontium, and cadmium accumulation. Considering the accumulation of trace elements in the grain, little genetic diversity among the analyzed oat accessions was detected, dividing into two groups. Regarding fatty acid composition, IPR Afrodite, FAEM 4 Carlasul, FAEM 5 Chiarasul, URS Taura, Barbarasul, and URS 21 showed higher essential fatty acid concentrations. These genotypes can be used in crosses with URS Brava, which displayed a higher Fe and Zn accumulation and is genetically distant from the other cultivars. Oat is a functional food showing ability for the accumulation of minerals and also essential fatty acids.

Stable SNP Allele Associations With High Grain Zinc Content in Polished Rice (Oryza sativa L.) Identified Based on ddRAD Sequencing

Polished rice is widely consumed staple food across the globe, however, it contains limited nutrients especially iron (Fe) and zinc (Zn). To identify promising genotypes for grain Zn, a total of 40 genotypes consisting 20 rice landraces, and 20 released high yielding rice varieties were evaluated in three environments (wet seasons 2014, 2015 and 2016) for nine traits including days to 50% flowering (DFF), plant height (PH), panicle length (PL), total number of tillers (TNT), single plant yield (SPY), Fe and Zn in brown (IBR, ZBR) and polished rice (IPR, ZPR). Additive Main Effect and Multiplicative Interaction (AMMI), Genotype and Genotype × Environment Interaction (GGE) analyses identified genotypes G22 (Edavankudi Pokkali), G17 (Taraori Basmati), G27 (Chittimuthyalu) and G26 (Kalanamak) stable for ZPR and G8 (Savitri) stable for SPY across three environments. Significant negative correlation between yield and grain Zn was reaffirmed. Regression analysis indicated the contribution of traits toward ZPR and SPY and also desirable level of grain Zn in brown rice. A total of 39,137 polymorphic single nucleotide polymorphisms (SNPs) were obtained through double digest restriction site associated DNA (dd-RAD) sequencing of 40 genotypes. Association analyses with nine phenotypic traits revealed 188 stable SNPs with six traits across three environments. ZPR was associated with SNPs located in three putative candidate genes (LOC_Os03g47980, LOC_Os07g47950 and LOC_Os07g48050) on chromosomes 3 and 7. The genomic region of chromosome 7 co localized with reported genomic regions (rMQTL₇.₁) and OsNAS3 candidate gene. SPY was found to be associated with 12 stable SNPs located in 11 putative candidate genes on chromosome 1, 6, and 12. Characterization of rice landraces and varieties in terms of stability for their grain Zn and yield identified promising donors and recipients along with genomic regions in the present study to be deployed rice Zn biofortification breeding program.

Genetic architecture of subspecies divergence in trace mineral accumulation and elemental correlations in the rice grain

Genome differentiation has shaped the divergence in element concentration between rice subspecies and contributed to the correlation among trace minerals in the rice grain. The balance between trace minerals in rice, a staple food for more than half of the world's population, is crucial for human health. However, the genetic basis underlying the correlation between trace minerals has not been fully elucidated. To address this issue, we first quantified the concentrations of 11 trace minerals in the grains of a diversity panel of 575 rice cultivars. We found that eight elements were accumulated at significantly different levels between the indica and japonica subspecies, and we also observed significant correlation patterns among a number of elements. Further, using a genome-wide association study, we identified a total of 96 significant association loci (SALs). The differentiation of the major-effect SALs along with the different number of high-concentration alleles present in the two subspecies shaped the different element performance in indica and japonica varieties. Only a few SALs located in clusters and the majority of SALs showed subspecies/subgroup differentiation, indicating that the correlations between elements in the diversity panel were mainly caused by genome differentiation instead of shared genetic basis. The genetic architecture unveiled in this study will facilitate improvement in breeding for trace mineral content.