Minsu Kim

Drought is a main factor limiting crop yields. Modern agricultural technologies such as irrigation systems, ground mulching, and rainwater storage can prevent drought, but these are only temporary solutions. Understanding the physiological, biochemical, and molecular reactions of plants to drought stress is therefore urgent. The recent rapid development of genomics tools has led to an increasing interest in phenomics, i.e., the study of phenotypic plant traits. Among phenomic strategies, high-throughput phenotyping (HTP) is attracting increasing attention as a way to address the bottlenecks of genomic and phenomic studies. HTP provides researchers a non-destructive and non-invasive method yet accurate in analyzing large-scale phenotypic data. This review describes plant responses to drought stress and introduces HTP methods that can detect changes in plant phenotypes in response to drought.

Summary: Phytophthora blight, caused by pathogen Phytophthora nicotianae , is responsible for a huge reduction in sesame ( Sesamum indicum L.) crop yields. In this study, we utilized a combinatorial approach involving biparental QTL mapping and genome-wide association (GWAS) analysis to identify genes associated with Phytophthora blight resistance in sesame. Evaluation of resistant of the parental varieties (Goenbaek, Osan and Milsung) and the RILs of both the populations in greenhouse conditions suggested the qualitative nature of the trait.. The genetic map comprised thirteen LGs covering a total map length of 887.49 cM with an average inter-marker distance of 4.69 cM. Significant QTLs explaining phenotypic variation in the range of 2.25% to 69.24% were identified on chromosomes 10 and 13 (Chr10 and Chr13). A resistance locus detected on Chr10 was found to be highly significant. The association of this locus to PBR was also identified through BSA and single marker analysis in Goenbaek × Milsung cross and through genome-wide association mapping of 87 sesame accessions. The GWAS analysis identified 44 SNP loci significantly associated with Phytophthora disease-resistant traits on Chr10. Further, the haplotype block analysis conducted in order to find whether the SNPs associated with resistance in this study showed that the SNPs are in high LD with the resistance QTL. We obtained a total of 68 candidate genes, which included a number of defense-related R genes. One of the genes, SIN_1019016 ( At1g58390) showed high expression in the resistant parent. The results from this study would be highly useful in identifying genetic and molecular factors associated with Phytophthora blight resistance in sesame.

Soybean has been consumed in Asia traditionally as a staple food. Soybean can be a source of essential fatty acids—linoleic (18:2, ω-6) and α-linolenic acid (18:3, ω-3)—for humans. Intake of fatty acids with high ω-3 concentration or low ω-6/ω-3 ratios is more desirable for human health. However, in soybean, the unsaturated fatty acids are less stable than the saturated fatty acids in different environments. The objective of the present study is to expand the understanding of the environmental stability of elevated α-linolenic acid of soybean genotypes with alleles from wild soybean grown in three Asian countries. The results highlighted an environmental effect on the accumulation of 18:3, following the growth of soybean genotypes with elevated α-linolenic acid in eight environments. Particularly, temperature influenced the accumulation of 18:3 concentration. The soybean genotype, UT-385-4-4, produced the highest 18:3 concentration and is more stable than all the other soybean genotypes, excluding PT-100-3. UT-385-4-4 is a potential genetic resource to develop novel cultivars with high 18:3 concentration, which could be dietary sources of plant-derived ω-3 fatty acids.

A high ω‐6/ω‐3 fatty acid ratio in the soybean seed adversely affects human health. The objective of the present study was to improve the fatty acid biosynthesis to reduce the ω‐6/ω‐3 ratio by combining the FAD2‐1A and FAD2‐1B mutant alleles with α‐linolenic acid (ω‐3) related alleles from wild soybean. The F₂ population comprising 2320 F_2:3 lines developed from S08‐14717 × PI 483463 cross exhibited significant variation for fatty acid components. Of these, 114 lines were advanced to the F_5:6 generation and genotyped for FAD2‐1A and FAD2‐1B alleles. The lines carrying mutant FAD2‐1A and FAD2‐1B alleles showed ~ 761 g kg⁻¹ oleic, and ~ 50 g kg⁻¹ linoleic acids, which reduced ω‐6/ω‐3 ratios to ~ 0.6. Conversely, the lines carrying FAD2‐1A or FAD2‐1B mutant alleles had 267 or 399 g kg⁻¹ oleic, 327 or 471 g kg⁻¹ linoleic, and 120 or 130 g kg⁻¹ α‐linolenic acids concentration, respectively. The elevated α‐linolenic acid resulted in the reduction of ω‐6/ω‐3 ratios in the range 2.5–3.9. The present study demonstrated that combining FAD2 mutant alleles with α‐linolenic acid‐related alleles from wild soybean reduces the seed ω‐6/ω‐3 ratio.

Soybean [Glycine max (L.) Merr.] is one of the most important forage crops in the world. This study aimed to map quantitative trait loci (QTL) for crude protein (CP), crude fat (CF), neutral detergent fiber (NDF) and acid detergent fiber (ADF) in soybean. A set of 188 recombinant inbred lines (RILs) derived from a cross between PI 483463 and ‘Hutcheson’ were grown for three consecutive years. Plants of each RIL were harvested at the R6 stage and quality traits were measured using near‐infrared reflectance spectroscopy (NIRS). The variance components of genotype, environment, and genotype × environment (G × E) interactions were highly significant for all quality traits in the RIL population. Significant positive and negative correlations were observed among forage quality traits. Composite interval mapping analysis identified six QTL for CP, two for CF, six for NDF, and two for ADF. Individual QTL explained phenotypic variation in the range 7.04 to 26.46% for CP, 6.62 to 29.33% for CF, 5.79 to 28.19% for NDF, and 7.66 to 41.72% for ADF. Coincident QTL for all traits were observed on chromosome 19. Novel QTL identified in this study may be useful for developing soybean genotypes with improved forage quality.