Medical genetics was revolutionized during the 1980s by the application of genetic mapping to locate the genes responsible for simple Mendelian diseases. Most diseases and traits, however, do not follow simple inheritance patterns. Geneticists have thus begun taking up the even greater challenge of the genetic dissection of complex traits. Four major approaches have been developed: linkage analysis, allele-sharing methods, association studies, and polygenic analysis of experimental crosses. This article synthesizes the current state of the genetic dissection of complex traits—describing the methods, limitations, and recent applications to biological problems.

Genetic Dissection of Complex Traits

Transcriptomics integrated with metabolomics reveals the effect of regulated deficit irrigation on anthocyanin biosynthesis in Cabernet Sauvignon grape berries.

Plants are extensively well-thought-out as the main source for nourishing natural life on earth. In the natural environment, plants have to face several stresses, mainly heat stress (HS), chilling stress (CS) and freezing stress (FS) due to adverse climate fluctuations. These stresses are considered as a major threat for sustainable agriculture by hindering plant growth and development, causing damage, ultimately leading to yield losses worldwide and counteracting to achieve the goal of "zero hunger" proposed by the Food and Agricultural Organization (FAO) of the United Nations. Notably, this is primarily because of the numerous inequities happening at the cellular, molecular and/or physiological levels, especially during plant developmental stages under temperature stress. Plants counter to temperature stress via a complex phenomenon including variations at different developmental stages that comprise modifications in physiological and biochemical processes, gene expression and differences in the levels of metabolites and proteins. During the last decade, omics approaches have revolutionized how plant biologists explore stress-responsive mechanisms and pathways, driven by current scientific developments. However, investigations are still required to explore numerous features of temperature stress responses in plants to create a complete idea in the arena of stress signaling. Therefore, this review highlights the recent advances in the utilization of omics approaches to understand stress adaptation and tolerance mechanisms. Additionally, how to overcome persisting knowledge gaps. Shortly, the combination of integrated omics, genome editing, and speed breeding can revolutionize modern agricultural production to feed millions worldwide in order to accomplish the goal of "zero hunger."

Can omics deliver temperature resilient ready-to-grow crops?

The purpose of this study was to determine whether the rates of tomato seed germination under different stress and nonstress conditions were under common genetic controls by examining quantitative trait loci (QTL) affecting such traits. Seeds of BC1 progeny of a cross between a slow-germinating tomato breeding line and a rapid-germinating tomato wild accession were evaluated for germination under nonstress as well as cold, salt, and drought stress conditions. In each treatment, the most rapidly-germinating seeds were selected, grown to maturity, and subjected to molecular marker analysis. A selective genotyping approach detected between 6 and 9 QTL affecting germination rate under each of the four conditions, with a total of 14 QTL identified. Ten QTL affected germination rate under 2 or 3 conditions, which were considered germination-related common QTL. Four QTL affected germination rate only in one treatment, which were considered germination-related, condition-specific QTL . The results indicated that mostly the same QTL affected seed germination under different stress and nonstress conditions, supporting a previous suggestion that similar physiological mechanisms contribute to rapid seed germination under different conditions. Marker-assisted selection for the common QTL may result in progeny with rapid seed germinability under different conditions.

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ResearchArticle Common QTL Affect the Rate of Tomato Seed Germination under Different Stress and Nonstress Conditions

Tomato, one of the most important crops worldwide, has a high demand in the fresh fruit market and processed food industries. Despite having considerably high productivity, continuous supply as per the market demand is hard to achieve, mostly because of periodic losses occurring due to biotic as well as abiotic stresses. Although tomato is a temperate crop, it is grown in almost all the climatic zones because of widespread demand, which makes it challenge to adapt in diverse conditions. Development of tomato cultivars with enhanced abiotic stress tolerance is one of the most sustainable approaches for its successful production. In this regard, efforts are being made to understand the stress tolerance mechanism, gene discovery, and interaction of genetic and environmental factors. Several omics approaches, tools, and resources have already been developed for tomato growing. Modern sequencing technologies have greatly accelerated genomics and transcriptomics studies in tomato. These advancements facilitate Quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and genomic selection (GS). However, limited efforts have been made in other omics branches like proteomics, metabolomics, and ionomics. Extensive cataloging of omics resources made here has highlighted the need for integration of omics approaches for efficient utilization of resources and a better understanding of the molecular mechanism. The information provided here will be helpful to understand the plant responses and the genetic regulatory networks involved in abiotic stress tolerance and efficient utilization of omics resources for tomato crop improvement.

Advances in Omics Approaches for Abiotic Stress Tolerance in Tomato

Metabolic profile analysis and identification of key metabolites during rice seed germination under low-temperature stress

Seed vigor is an important seed quality trait in rice (Oryza sativa L.) that profoundly affects seedling morphogenesis in different environments. Generally, highly vigorous seeds have many advantages in agricultural production, such as resistance to adverse stresses, rapid emergence, and yield improvement. In the present study, one germplasm collection and one recombinant inbred line (RIL) population were used to identify quantitative trait loci (QTLs) for seed vigor. A total of 19 single nucleotide polymorphisms (SNPs) were found to be significantly associated with seed vigor (−log10(P) > 6) in the germplasm collection, which consisted of 200 rice cultivars. Nine loci responsible for seed vigor were identified via QTL mapping by using a high-density bin map. To screen the candidate genes more efficiently, we selected six loci that were co-localized in GWAS and QTL mapping, overlapped previous reports, repeat detected across two seasons, or high contribution rate as reliable loci. A total of 44 differentially expressed genes were obtained from the reliable loci via gene expression profile analysis. Among these 44 genes, Os06g0108600, Os06g0110200, Os06g0253100, Os06g0282000, Os07g0583600, Os07g0592600, and Os09g0432300 were the most promising candidates associated with seed vigor.

Integrating GWAS, QTL, mapping and RNA-seq to identify candidate genes for seed vigor in rice (Oryza sativa L.)

Anaerobic germination tolerance is an important trait for direct-seeded rice varieties. Understanding the genetic basis of anaerobic germination is a key for breeding direct-seeded rice varieties. In this study, a recombinant inbred line (RIL) population derived from a cross between YZX and 02428 exhibited obvious coleoptile phenotypic differences. Mapping analysis using a high-density bin map indicated that a total of 25 loci were detected across two cropping seasons, including 10 previously detected loci and a total of 13 stable loci. Analysis of the 13 stable loci demonstrated that the more elite alleles that were pyramided in an individual, the higher the values of these traits were in the two cropping seasons. Furthermore, some anaerobic germination-tolerant recombinant inbred lines, namely G9, G10, G16, and G151, were identified. A total of 84 differentially expressed genes were obtained from the 13 stable loci via genome-wide expression analysis of the two parents at three key periods. Among them, Os06g0110200, Os07g0638300, Os07g0638400, Os09g0532900, Os09g0531701 and Os12g0539751 constitute the best candidates associated with anaerobic germination. Both the anaerobic germination-tolerant recombinant inbred lines and the loci identified in this study will provide new genetic resources for improving the anaerobic germination tolerance of rice using molecular breeding strategies, as well as will broaden our understanding of the genetic control of germination tolerance under anaerobic conditions.

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Dongxiu Li

Papers

Metabolic profile analysis and identification of key metabolites during rice seed germination under low-temperature stress

Integrating GWAS, QTL, mapping and RNA-seq to identify candidate genes for seed vigor in rice (Oryza sativa L.)

Identification of stable QTLs and candidate genes involved in anaerobic germination tolerance in rice via high-density genetic mapping and RNA-Seq.

Genome-wide association study reveals novel genetic loci involved in anaerobic germination tolerance in Indica rice