HOMEOBOX2, the paralog of SIX-ROWED SPIKE1/HOMEOBOX1, is dispensable for barley spikelet development.

The HD-ZIP class I transcription factor Homeobox 1 (HvHOX1), also known as Vulgare Row-type Spike 1 (VRS1) or Six-rowed Spike 1, regulates lateral spikelet fertility in barley (Hordeum vulgare L.). It was shown that HvHOX1 has a high expression only in lateral spikelets, while its paralog HvHOX2 was found to be expressed in different plant organs. Yet, the mechanistic functions of HvHOX1 and HvHOX2 during spikelet development are still fragmentary. Here, we show that compared with HvHOX1, HvHOX2 is more highly conserved across different barley genotypes and Hordeum species, hinting at a possibly vital but still unclarified biological role. Using bimolecular fluorescence complementation, DNA-binding, and transactivation assays, we validate that HvHOX1 and HvHOX2 are bona fide transcriptional activators that may potentially heterodimerize. Accordingly, both genes exhibit similar spatiotemporal expression patterns during spike development and growth, albeit their mRNA levels differ quantitatively. We show that HvHOX1 delays the lateral spikelet meristem differentiation and affects fertility by aborting the reproductive organs. Interestingly, the ancestral relationship of the two genes inferred from their co-expressed gene networks suggested that HvHOX1 and HvHOX2 might play a similar role during barley spikelet development. However, CRISPR-derived mutants of HvHOX1 and HvHOX2 demonstrated the suppressive role of HvHOX1 on lateral spikelets, while the loss of HvHOX2 does not influence spikelet development. Collectively, our study shows that through the suppression of reproductive organs, lateral spikelet fertility is regulated by HvHOX1, whereas HvHOX2 is dispensable for spikelet development in barley.

Impact of Climate Change on Altered Fruit Quality with Organoleptic, Health Benefit, and Nutritional Attributes.

As a consequence of global climate change, acute water deficit conditions, soil salinity, and high temperature have been on the rise in their magnitude and frequency, which have been found to impact plant growth and development negatively. However, recent evidence suggests that many fruit plants that face moderate abiotic stresses can result in beneficial effects on the postharvest storage characters of the fruits. Salinity, drought, and high temperature conditions stimulate the synthesis of abscisic acid (ABA), and secondary metabolites, which are vital for fruit quality. The secondary metabolites like phenolic acids and anthocyanins that accumulate under abiotic stress conditions have antioxidant activity, and therefore, such fruits have health benefits too. It has been noticed that fruits accumulate more sugar and anthocyanins owing to upregulation of phenylpropanoid pathway enzymes. The novel information that has been generated thus far indicates that the growth environment during fruit development influences the quality components of the fruits. But the quality depends on the trade-offs between productivity, plant defense, and the frequency, duration, and intensity of stress. In this review, we capture the current knowledge of the irrigation practices for optimizing fruit production in arid and semiarid regions and enhancement in the quality of fruit with the application of exogenous ABA and identify gaps that exist in our understanding of fruit quality under abiotic stress conditions.

Metabolomics and machine learning technique revealed that germination enhances the multi-nutritional properties of pigmented rice.

Enhancing the dietary properties of rice is crucial to contribute to alleviating hidden hunger and non-communicable diseases in rice-consuming countries. Germination is a bioprocessing approach to increase the bioavailability of nutrients in rice. However, there is a scarce information on how germination impacts the overall nutritional profile of pigmented rice sprouts (PRS). Herein, we demonstrated that germination resulted to increase levels of certain dietary compounds, such as free phenolics and micronutrients (Ca, Na, Fe, Zn, riboflavin, and biotin). Metabolomic analysis revealed the preferential accumulation of dipeptides, GABA, and flavonoids in the germination process. Genome-wide association studies of the PRS suggested the activation of specific genes such as CHS1 and UGT genes responsible for increasing certain flavonoid compounds. Haplotype analyses showed a significant difference (P < 0.05) between alleles associated with these genes. Genetic markers associated with these flavonoids were incorporated into the random forest model, improving the accuracy of prediction of multi-nutritional properties from 89.7% to 97.7%. Deploying this knowledge to breed rice with multi-nutritional properties will be timely to address double burden nutritional challenges.

Unravelling marker trait associations linking nutritional value with pigmentation in rice seed.

While considerable breeding effort has focused on increasing the yields of staple crops such as rice and the levels of micronutrients such as iron and zinc, breeding to address the problems of the double-burden of malnutrition has received less attention. Pigmented rice has higher nutritional value and greater health benefits compared to white rice. However, the genetic associations underlying pericarp coloration and accumulation of nutritionally valuable compounds is still poorly understood. Here we report the targeted genetic analysis of 364 rice accessions, assessing the genetic relationship between pericarp coloration (measured using multi-spectral imaging) and a range of phenolic compounds with potential nutritional and health-promoting characteristics. A genome-wide association study resulted in the identification of over 280 single nucleotide polymorphisms (SNPs) associated with the traits of interest. Many of the SNPs were associated with more than one trait, colocalization occurring between nutritional traits, and nutritional and color-related traits. Targeted association analysis identified 67 SNPs, located within 52 candidate genes and associated with 24 traits. Six haplotypes identified within the genes Rc/bHLH17 and OsIPT5 indicated that these genes have an important role in the regulation of a wide range of phenolic compounds, and not only those directly conferring pericarp color. These identified genetic linkages between nutritionally valuable phenolic compounds and pericarp color present not only a valuable resource for the enhancement of the nutritional value of rice but an easy method of selection of suitable genotypes.

Mineral nutrients in plants under changing environments: A road to future food and nutrition security.

Plant nutrition is an important aspect that contributes significantly to sustainable agriculture, whereas minerals enrichment in edible source implies global human health; hence, both strategies need to be bridged to ensure "One Health" strategies. Abiotic stress-induced nutritional imbalance impairs plant growth. In this context, we discuss the molecular mechanisms related to the readjustment of nutrient pools for sustained plant growth under harsh conditions, and channeling the minerals to edible source (seeds) to address future nutritional security. This review particularly highlights interventions on (i) the physiological and molecular responses of mineral nutrients in crop plants under stressful environments; (ii) the deployment of breeding and biotechnological strategies for the optimization of nutrient acquisition, their transport, and distribution in plants under changing environments. Furthermore, the present review also infers the recent advancements in breeding and biotechnology-based biofortification approaches for nutrient enhancement in crop plants to optimize yield and grain mineral concentrations under control and stress-prone environments to address food and nutritional security.

More than the main structural genes: Regulation of resistant starch formation in rice endosperm and its potential application.

In the past decade, research on resistant starch has evoked interest due to the prevention and inhibition of chronic human diseases, such as diabetes, cancer, and obesity. Increasing the amylose content (AC) and resistant starch (RS) has been pivotal in improving the nutritional benefit of rice. However, the exact mechanism of RS formation is complex due to interconnected genetic factors regulating amylose-amylopectin variation. In this review, we discussed the regulatory factors influencing the RS formation centered on the transcription, post-transcriptional, and post-translational processes. Furthermore, we described the developments in RS and AC levels in rice compared with other high RS cereals. Briefly, we enumerated potential applications of high RS mutants in health, medical, and other industries. We contest that the information captured herein can be deployed for marker-assisted breeding and precision breeding techniques through genome editing to improve rice varieties with enhanced RS content.

Metabolic Signatures from Genebank Collections: An Underexploited Resource for Human Health?

Despite the almost universal acceptance of the phrase "you are what you eat," investment in understanding diet-based nutrition to address human health has been dwarfed compared to that for medicine-based interventions. Moreover, traditional breeding has focused on yield to the detriment of nutritional quality, meaning that although caloric content has remained high, the incidence of nutritional deficiencies and accompanying diseases (so-called hidden hunger) has risen dramatically. We review how genome sequencing coupled with metabolomics can facilitate the screening of genebank collections in the search for superior alleles related to the nutritional quality of crops. We argue that the first examples are very promising, suggesting that this approach could benefit broader ranges of crops and compounds with known relevance for human health. We argue that this represents anapproach complementary to metabolic engineering by transgenesis or gene editing that could be used to reverse some of the losses incurred through a recent focus on breeding for yield, although we caution that ensuring such approaches are not (re)introducing antinutrients is also necessary.

Chemometric-Based Analysis of Metabolomics Studies of Bioactive Fractions of Pleurotus osteratus and Their Correlation with In Vitro Anti-Cancer Activity.

Richness in nutrients with an ample of the myco-bioactive molecules makes Pleurotus osteratus preferential mushroom. In this paper, we conducted a preliminary study on bio-assay-guided fractionation of dichloromethane:ethanol crude extract (1:1, v/v) of P. osteratus (CD) against human breast cancer cell line (MDA-MB-231). Later, CD and its potent hexane (H) and ethyl acetate (EA) fraction were screened against a panel of a human cancer cell lines. H fraction possesses higher cytotoxicity followed by EA and CD. Literature review revealed that polyphenol and ergosterol are the biomarkers found in P. osteratus and could responsible for its cytotoxic potential. Accordingly, hyphenated liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based polyphenol and ergosterol-targeted myco-metabolite profiling of CD, H, and EA fractions were carried out. Despite being significantly rich in polyphenol and ergosterol content, EA fraction showed moderate cytotoxicity. Considering this, liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF/MS)-based untargeted myco-metabolite profiling of CD, H and EA fractions was further conducted to identify a new biomarker. Tentatively, 20 myco-metabolites were identified, belonging to the class of steroids, alkaloid, terpenoid, fatty alcohol, and polyketide. The myco-metabolite variabilities among potent samples in correlation to their in vitro anti-cancer activity was explored using the different chemometric tools: principal component analysis (PCA), hierarchical clustering analysis (HCA), and partial least square (PLS). A probable synergistic action among identified myco-metabolites (betulin, solanocapsine, ophiobolin F, linoleoyl ethanolamide, (13R,14R)-7-labdene-13,14,15-triol, asterosterol, cholest-5-ene, (3b,6b,8a,12a)-8,12-epoxy-7(11)-eremophilene-6,8,12-trimethoxy-3-ol, beta-obscurine, myxalamid B, momordol, and avocadyne 4-acetate) may be responsible for the observed cytotoxicity potential of H fraction of P. osteratus.

The nutritional profile and human health benefit of pigmented rice and the impact of post-harvest processes and product development on the nutritional components: A review.

Pigmented rice has attracted considerable attention due to its nutritional value, which is in large conferred by its abundant content of phenolic compounds, considerable micronutrient concentrations, as well as its higher resistant starch and thereby slower digestibility properties. A wide range of phenolic compounds identified in pigmented rice exhibit biological activities such as antioxidant activity, anti-inflammatory, anticancer, and antidiabetic properties. Post-harvest processes significantly reduce the levels of these phytochemicals, but recent developments in processing methods have allowed greater retention of their contents. Pigmented rice has also been converted to different products for food preservation and to derive functional foods. Profiling a large set of pigmented rice cultivars will thus not only provide new insights into the phytochemical diversity of rice and the genes underlying the vast array of secondary metabolites present in this species but also provide information concerning their nutritional benefits, which will be instrumental in breeding healthier rice. The present review mainly focuses on the nutritional composition of pigmented rice and how it can impact human health alongside the effects of post-harvest processes and product development methods to retain the ambient level of phytochemicals in the final processed form in which it is consumed.

Systems seed biology to understand and manipulate rice grain quality and nutrition.

Rice is one of the most essential crops since it meets the calorific needs of 3 billion people around the world. Rice seed development initiates upon fertilization, leading to the establishment of two distinct filial tissues, the endosperm and embryo, which accumulate distinct seed storage products, such as starch, storage proteins, and lipids. A range of systems biology tools deployed in dissecting the spatiotemporal dynamics of transcriptome data, methylation, and small RNA based regulation operative during seed development, influencing the accumulation of storage products was reviewed. Studies of other model systems are also considered due to the limited information on the rice transcriptome. This review highlights key genes identified through a holistic view of systems biology targeted to modify biochemical composition and influence rice grain quality and nutritional value with the target of improving rice as a functional food.

Unraveling the genetics underlying micronutrient signatures of diversity panel present in brown rice through genome-ionome linkages.

Rice (Oryza sativa) is an important staple crop to address the Hidden Hunger problem not only in Asia but also in Africa where rice is fast becoming an important source of calories. The brown rice (whole grain with bran) is known to be more nutritious due to elevated mineral composition. The genetics underlying brown rice ionome (sum total of such mineral composition) remains largely unexplored. Hence, we conducted a comprehensive study to dissect the genetic architecture of the brown rice ionome. We used genome-wide association studies, gene set analysis, and targeted association analysis for 12 micronutrients in the brown rice grains. A diverse panel of 300 resequenced indica accessions, with more than 1.02 million single nucleotide polymorphisms, was used. We identified 109 candidate genes with 5-20% phenotypic variation explained for the 12 micronutrients and identified epistatic interactions with multiple micronutrients. Pooling all candidate genes per micronutrient exhibited phenotypic variation explained values ranging from 11% to almost 40%. The key donor lines with larger concentrations for most of the micronutrients possessed superior alleles, which were absent in the breeding lines. Through gene regulatory networks we identified enriched functional pathways for central regulators that were detected as key candidate genes through genome-wide association studies. This study provided important insights on the ionome variations in rice, on the genetic basis of the genome-ionome relationships and on the molecular mechanisms underlying micronutrient signatures.

Mathematical modeling to predict rice's phenolic and mineral content through multispectral imaging.

Over half the world population relies on rice for energy, but being a carbohydrate-based crop, it offers limited nutritional benefits. To achieve nutritional security targets in Asia, we must understand the genetic variation in multi-nutritional properties with therapeutic properties and deploy this knowledge to future rice breeding. High throughput, VideometerLAB spectral imaging data has been effective in estimating total anthocyanin content, particularly bound anthocyanin content, using the high prediction power of partial least square (PLS) regression models. Multi-pronged nutritional properties of phenolic compounds and minerals, together with videometerLAB features, were utilized to develop models to classify a collection of black rice varieties into three distinct nutritional quality ideotypes. These derived models for black rice diversity panels were created utilizing videometerLAB data (L, A, B parameters), selected phenolic types (total phenolics, total anthocyanins, and bound flavonoids), and minerals (Molybdenum and Phosphorous). Random forest and artificial neural network models depicted the multi-nutritional features of black rice with 85.35 and 99.9% accuracy, respectively. These prediction algorithms would help rice breeders strategically breed nutritionally valuable genotypes based on simple, high-through-put videometerLAB readings and a small number of nutritional assays.

Identification and analysis of proline-rich proteins and hybrid proline-rich proteins super family genes from Sorghum bicolor and their expression patterns to abiotic stress and zinc stimuli.

Systematic genome-wide analysis of Sorghum bicolor revealed the identification of a total of 48 homologous genes comprising 21 proline-rich proteins (PRPs) and 27 hybrid proline-rich proteins (HyPRPs). Comprehensive scrutiny of these gene homologs was conducted for gene structure, phylogenetic investigations, chromosome mapping, and subcellular localization of proteins. Promoter analysis uncovered the regions rich with phosphorous- (BIHD), ammonium-, sulfur-responsive (SURE), and iron starvation-responsive (IRO2) along with biotic, abiotic, and development-specific cis-elements. Further, PRPs exhibit more methylation and acetylation sites in comparison with HyPRPs. miRNAs have been predicted which might play a role in cleavage and translation inhibition. Several of the SbPRP genes were stimulated in a tissue-specific manner under drought, salt, heat, and cold stresses. Additionally, exposure of plants to abscisic acid (ABA) and zinc (Zn) also triggered PRP genes in a tissue-dependent way. Among them, SbPRP17 has been found upregulated markedly in all tissues irrespective of the stress imposed. The expressions of SbHyPRPs, especially SbHyPRP2, SbHyPRP6, and SbHyPRP17 were activated under all stresses in all three tissues. On the other hand, SbHyPRP8 (root only) and SbHyPRP12 (all three tissues) were highly responsive to cold stress and ABA while SbHyPRP26 was induced by drought and Zn in the stem. Taken together, this study indicates the critical roles that SbPRPs and SbHyPRPs play during diverse abiotic stress conditions and notably the plausible roles that these genes play upon exposure to zinc, the crucial micronutrient in plants.

Abscisic acid and its role in the modulation of plant growth, development, and yield stability.

Abscisic acid (ABA) is known to confer stress tolerance; however, at elevated levels it impairs plant growth under prolonged stress. Paradoxically, at its basal level, ABA plays many vital roles in promoting plant growth and development, including modulation of tillering, flowering, and seed development, as well as seed maturation. In this review, we provide insight into novel discoveries of ABA fluxes, ABA signaling responses, and their impact on yield stability. We discuss ABA homeostasis implicated under pre- and postanthesis drought and its impact on productive tillers, grain number determination, and seed development to address yield stability in cereal crops while considering the new knowledge that emerged from the model plant systems.

Metabolomics based inferences to unravel phenolic compound diversity in cereals and its implications for human gut health.

Background: Whole grain cereals are a good source of nutrients. Several cutting-edge metabolomic platforms have been deployed to identify various phenolic compounds and enhance cereal bioactive bioavailability. A diet rich in cereal phenolics may modify the microbial composition, support gut homeostasis, and increase gut health, thereby lowering the risk of non-communicable illness. Scope and approach: In this work, we reviewed current metabolomic breakthroughs in cereal phenolic profiling and their effects on human health via gut microbiota modulation. We argue that the information presented in this paper will assist in the development of nutritionally superior cereal breeds and functional foods. Key findings and conclusion: Most cereal grains contain ferulic acid derivatives, caffeoyl glycerides, and feruloyl and coumaroyl esters. While there has been significant progress in discovering novel phenolic compounds in cereals, quantifying these molecules, and translating their therapeutic effects from animal model systems to humans remains a challenge. To this end, metabolomics, and other high-throughput-omics-based platforms must be integrated to further examine the structure and functionality of phenolic metabolites to breed nutritionally rich cereals as well as map their influence on human health benefits. Rare alleles must be introduced to improve bioactive content in cereal grains while maintaining yield. Following that, these exceptional varieties must be effectively processed to maximize phenolic bioavailability.

Intriguing Role of Proline in Redox Potential Conferring High Temperature Stress Tolerance.

Proline is a proteinogenic amino acid synthesized from glutamate and ornithine. Pyrroline-5-carboxylate synthetase and pyrroline-5-carboxylate reductase are the two key enzymes involved in proline synthesis from glutamate. On the other hand, ornithine-δ-aminotransferase converts ornithine to pyrroline 5-carboxylate (P5C), an intermediate in the synthesis of proline as well as glutamate. Both proline dehydrogenase and P5C dehydrogenase convert proline back to glutamate. Proline accumulation is widespread in response to environmental challenges such as high temperatures, and it is known to defend plants against unpropitious situations promoting plant growth and flowering. While proline accumulation is positively correlated with heat stress tolerance in some crops, it has detrimental consequences in others. Although it has been established that proline is a key osmolyte, its exact physiological function during heat stress and plant ontogeny remains unknown. Emerging evidence pointed out its role as an overriding molecule in alleviating high temperature stress (HTS) by quenching singlet oxygen and superoxide radicals. Proline cycle acts as a shuttle and the redox couple (NAD+/NADH, NADP+/NADPH) appears to be highly crucial for energy transfer among different cellular compartments during plant development, exposure to HTS conditions and also during the recovery of stress. In this review, the progress made in recent years regarding its involvement in heat stress tolerance is highlighted.

Post-genomics revolution in the design of premium quality rice in a high-yielding background to meet consumer demands in the 21st century.

The eating and cooking quality (ECQ) of rice is critical for determining its economic value in the marketplace and promoting consumer acceptance. It has therefore been of paramount importance in rice breeding programs. Here, we highlight advances in genetic studies of ECQ and discuss prospects for further enhancement of ECQ in rice. Innovations in gene- and genome-editing techniques have enabled improvements in rice ECQ. Significant genes and quantitative trait loci (QTLs) have been shown to regulate starch composition, thereby affecting amylose content and thermal and pasting properties. A limited number of genes/QTLs have been identified for other ECQ properties such as protein content and aroma. Marker-assisted breeding has identified rare alleles in diverse genetic resources that are associated with superior ECQ properties. The post-genomics-driven information summarized in this review is relevant for augmenting current breeding strategies to meet consumer preferences and growing population demands.