Chickpea (Cicer arietinum L.) and pigeonpea [Cajanus cajan L. (Millsp.)] play an important role in mitigating protein malnutrition for millions of poor vegetarians living in regions of the semi-arid tropics. Abiotic stresses such as excess and limited soil moisture (water-logging and drought), heat and chilling (high and low temperature stresses), soil salinity, and acidity are major yield constraints, as these two crops are grown mostly under rainfed conditions in risk-prone marginal and degraded lands with few or no inputs. Losses due to such stresses vary from 30% to 100% depending on their severity. The literature abounds in basic information concerning screening techniques, physiological mechanisms, and genetics of traits associated with resistance/tolerance to abiotic stresses in these two crops. However, the final outcome in terms of resistant/tolerant varieties has been far from satisfactory. This situation calls for improving selection efficiency through precise phenotyping and genotyping under high-throughput controlled conditions using modern tools of genomics. In this review, we suggest that an integrated approach combining advances from genetics, physiology, and biotechnology needs to be used for higher precision and efficiency of breeding programs aimed at improving abiotic stress tolerance in both chickpea and pigeonpea.

High temperatures have a detrimental effect on growth, development, and yield of Brassica napus. Even a short period of heat stress can lead to yield losses of 15%-20%. A collection of spring-type accessions available in Germplasm Resources Information Network (GRIN) were used to assess the effect of short periods of high-temperature stress at the early flowering stage of B. napus. Two sets of accessions with three replications per set were grown in a greenhouse at 22/18°C day/night temperatures. Plants from the second set at the 6-day flowering stage were exposed to heat-stress conditions (maximum temperature up to 35 °C) in a plant growth chamber for five days. The heat-stressed plants were then allowed to recover in a greenhouse. Pollen sterility, sterile/aborted pods, and number of pods on main raceme were recorded for both control (set 1) and heat stressed (set 2) plants. Heat susceptibility indices for all three traits were calculated and an association-mapping study was conducted using 37,539 Single Nucleotide Polymorphisms (SNPs) to identify genomic regions controlling the heat stress traits. A total of 5, 8, and 7 quantitative trait loci (QTL) were associated with pollen sterility, sterile/aborted pods, and number of pods on main raceme, respectively. Together they explained respectively 46.3%, 60.5%, and 60.6% of phenotypic variation. Candidate genes in the QTL regions included genes associated with flowering, male sterility, pollen abortion, embryo abortion reducing pollen development, and pod development.

Soybean [Glycine max (L.) Merrill] is a major plant source of protein and oil. An accurate and well-saturated molecular linkage map is a prerequisite for forward genetic studies of gene function and for modern breeding for many useful agronomic traits. Next-generation sequence data available in public databases provides valuable information and offers new insights for rapid and efficient development of molecular markers. In this study, we attempted to show the feasibility and facility of using genomic resequencing data as raw material for identifying putative InDel markers. First, we identified 17,613 InDel sites among 56 soybean accessions and obtained 12,619 primer pairs. Second, we constructed a genetic map with a random subset of 2841 primer pairs and aligned 300 polymorphic markers with the 20 consensus linkage groups (LG). The total genetic distance was 2347.3 cM and the number of mapped markers per LG ranged from 10 to 23 with an average of 15 markers. The largest and smallest genetic distances between adjacent markers were 52.3 cM and 0.1 cM, respectively. Finally, we validated the genetic map constructed by newly developed InDel markers by QTL analysis of days to flowering (DTF) under different environments. One major QTL (qDTF4) and four minor QTL (qDTF20, qDTF13, qDTF12, and qDTF11) on 5 LGs were detected. These results demonstrate the utility of the InDel markers developed in this work for map-based cloning and molecular breeding in soybean.

Zinc (Zn) ferti-fortification using different sources and methods in Zn deficient soils is being advocated to increase Zn concentration in rice kernel as an alternative to pursuing greater Zn-use efficiency (ZnUE). A two-year field study was conducted to assess the effect of Zn application on Zn content and uptake at several growth stages and in several parts of the rice kernel: hull, bran, and the white rice kernel. Variety ‘PB 1509’ with 1.25 kg Zn ha^{− 1} as Zn-EDTA + 0.5% foliar spray (FS) at maximum tillering (MT) and panicle initiation (PI) stages registered the highest Zn content in hull, bran, and white rice kernel. Among parts of the rice kernel, Zn concentration decreased in the order hull > bran > white rice kernel, indicating that brown rice kernels are much denser in Zn content than polished rice. Considering the higher Zn accumulation in the bran, brown rice consumption, especially in Asia and Africa, could be recommended to overcome Zn malnutrition. The variety ‘PB 1401’ showed the highest Zn uptake in rice straw, while ‘PB 1509’ showed the highest Zn uptake in hull and white rice kernel. Application of 1.25 kg Zn ha^{− 1} (Zn-EDTA) + 0.5% FS at MT and PI and 2.5 kg Zn ha^{− 1} ZnSO₄·7H₂O (ZnSHH) + 0.5% FS at MT and PI resulted in higher Zn uptake than other treatments. On average, about one third of total Zn uptake remained in the white rice kernel, with the remaining two thirds accumulating in both hull and bran of brown rice. Zn-EDTA along with 0.5% FS, despite the application of a lower quantity of Zn leading to the highest Zn mobilization efficiency index (ZnMEI) and Zn-induced nitrogen recovery efficiency (ZniNRE), produced the highest kernel yield. However, of the two Zn sources, Zn-EDTA contributed more to the increase in ZnUE than did ZnSHH.

A study was conducted in four compartments of a polycarbonate greenhouse at Gainesville, FL, USA to investigate how a soybean (Glycine max L. Merr.) cultivar, Maverick (maturity group III, indeterminate), responded to three elevated temperatures, ELT, (day/night of 34/26?°C, 38/30?°C, and 42/34?°C) in comparison to a control growth temperature (30/22?°C). Carbon dioxide (CO₂) concentration was maintained at 700?μmol?mol⁻¹ in each compartment by a processor controlled air-sampling and CO₂-injection system. Three sequential experiments were conducted at different times of year (summer, autumn, and early spring) to investigate the effect of intensity, timing, and duration of ELT on soybean node number, internode elongation, mainstem length, and number of pods set per plant. At the control temperature, the soybean plants grown in the polycarbonate greenhouse were taller than field-grown plants. When plants were grown under continuous ELT applied soon after sowing or at initial flowering, the number of nodes increased with increasing ELT intensity, whereas the length of individual internodes decreased. When ELT treatment was applied during the beginning of flowering stage (R1-R2) or earlier, more nodes were produced and the length of affected internodes was decreased. When the ELT was imposed later at reproductive stage R5+ just before the beginning of seed filling, effects on node numbers and internode lengths were negligible. Short-term (10-day) duration of ELT applied at four stages from V3 to R5+ did not significantly affect final mean numbers of nodes or mean mainstem lengths. Possible mechanisms of elevated temperature effects on soybean internode elongation and node number (internode number) are discussed. Total pod numbers per plant increased linearly with mainstem node numbers and mainstem length. Furthermore, total pod numbers per plant were greatest at 34/26?°C rather than at the control temperature of 30/22?°C (and remained high at 38/30?°C). Mild increases in temperature might not threaten, but actually increase, yields of soybean in northerly zones where this crop is currently grown at slightly suboptimal temperatures. However, a sustained increase in ambient temperature would likely threaten soybean yields.

Soybean is one of the world's most important oil and protein crops. Efficient transformation is a key factor for the improvement of soybean by genetic modification. We describe an optimized protocol for the Agrobacterium rhizogenes-mediated transformation of soybean and the induction of hairy root development in vitro. Cotyledons with 0.5-cm hypocotyls were cut from 5-day-old seedlings and used as explants. After infection and co-cultivation, hairy roots were produced in induction culture medium after 10-12 days. Using this method, 90%-99% of the infected explants of five different cultivars produced hairy roots within one month. Observations using reporter constructs showed that 30%-60% of the hairy roots induced were transformed. Based on high transformation efficiency and short transformation period, this method represents an efficient and rapid platform for study of soybean gene function.

Simple sequence repeats (SSRs) are important molecular markers for assessing genetic diversity in Arachis hypogaea L. and many other crops and constructing genetic linkage maps for important agricultural traits. In this study, 29,357 potential SSRs were identified in 22,806 unigenes assembled from A. hypogaea transcript sequences. Of these unigenes, 1883 and 4103 were annotated and assigned in Kyoto Encyclopedia of Genes and Genomes Orthology and Eukaryotic Orthologous Groups databases, respectively. Among the SSR motifs, mono- (19,065; 64.94%) and trinucleotide (5033; 17.14%) repeats were the most common, and the three most dominant motifs were A/T (18,358; 62.54%), AG/CT (2804; 9.55%), and AAG/CTT (1396; 4.76%). Polymerase chain reaction (PCR) primer pairs were designed for 4340 novel SSR markers and 210 new SSRs were validated using 24 A. hypogaea varieties. Of the 210, 191 (91%) yielded PCR products, with 37 (18%) identifying polymorphisms. The 37 polymorphic SSR markers detected 146 alleles (2-10 alleles per locus), and the average polymorphic information content was 0.403 (with a range of 0.077 to 0.819). The new SSRs enrich the current marker resources for A. hypogaea and may also be useful for genetic diversity analysis, functional genomics research, and molecular breeding.

Small auxin-upregulated RNAs (SAURs) are genes regulated by auxin and environmental factors. In this study, we identified a SAUR gene in wheat, TaSAUR75. Under salt stress, TaSAUR75 is downregulated in wheat roots. Subcellular localization revealed that TaSAUR75 was localized in both the cytoplasm and nucleus. Overexpression of TaSAUR75 increased drought and salt tolerance in Arabidopsis. Transgenic lines showed higher root length and survival rate and higher expression of some stress-responsive genes than control plants under salt and drought stress. Less H₂O₂ accumulated in transgenic lines than in control plants under drought stress. Our findings reveal a positive regulatory role of the auxin-responsive gene TaSAUR75 in plant responses to drought and salt stress and provide a candidate gene for improvement of abiotic stress tolerance in crop breeding.

Increase grain yield potential is one of the most important objectives of any cereal crop breeding program. To efficiently develop superior rice lines by the introgression of favorable alleles for yield and yield component traits, a strategy of alternate phenotype-genotype selection was used. The present study aimed to (i) investigate the allelic diversity of loci associated with major yield-component traits and (ii) phenotype and genotype advanced populations derived from crosses between NERICA-L-20 and Giza178 for yield component traits using agro-morphological descriptors and GRiSP polymorphic markers to select superior high-yielding rice lines. A total of 100 F_2:3 progeny were selected from 1000 F₂ plants and genotyped with 16 polymorphic markers linked to four major yield-component traits. Four promising F_2:3 lines (ARS 563-14, ARS 563-62, ARS 563-286, and ARS 563-41) bearing combinations of desirable alleles were selected. A selected set of 20 F_2:4 lines showed moderate to high heritability for all target traits. Fourteen F_2:5 lines derived from ARS 563-14 and 17 F_2:5 from ARS 563-286 families were evaluated in preliminary trials to estimate yield gain. The three top lines, ARS 563-286-16-1-1, ARS 563-286-5-1-1, and ARS 563-14-10-1-1, showed an increase of more than 10% grain yield over the best check, Sahel 108, which is widely cultivated in the Senegal River valley. The 16 markers linked to the target yield component traits can be used to fast-track breeding programs targeting rice productivity.

Sesame is an important oilseed crop in Africa and Asia, owing to its high nutritional quality seed and market value. Variation in sesame seed components including oil, oleic acid, linoleic acid, and protein was investigated by near-infrared reflectance spectrometry in 139 samples collected from different countries. Oil and protein contents were between 40.8% and 60.3% (mean 53.0%) and 15.5% to 25.5% (mean 20.4%), respectively. Linoleic acid, ranging from 31.8% to 52.4% (mean 46%) was more abundant than oleic acid (31.8%-50.6%, mean 38.1%). Light-seeded samples displayed higher nutritional quality, as they were richer in oil, protein, and linoleic acid than dark seeds. Samples from Africa had higher oil and linoleic acid contents, while Asian samples had higher oleic content. The analysis revealed West African sesame cultivars containing especially high levels of seed components, which may command high market values. Two clusters of sesame samples grouped by seed composition were obtained, including one cluster with high oil and oleic acid content and the other with high protein and linoleic acid content. This study revealed that sesame samples from Africa and Asia harbor high variation for major seed components and also provided background information for breeding high-nutrition varieties according to the demands of sesame seed markets.

Genetic resources from other countries or regions play an important role in broadening the genetic background of local breeding varieties. Here we describe observations on the adaptability of mung bean germplasm obtained from the United States Department of Agriculture and their genetic diversity assessment using SSR markers. Several accessions were shown to be mixtures, based on their phenotypes for some characters. Most accessions were able to complete their lifecycles when grown in Beijing, China, making them ideal for crossbreeding without day length control. High diversity was revealed by the SSR markers, with an average of 4.2 alleles per locus and a PIC value of 0.650 per locus. STRUCTURE analysis divided the accessions into six groups. There was no obvious trend of accessions forming groups according to their geographical origin, owing mainly to germplasm exchange and an uneven distribution of accessions. The present results indicate that this germplasm would enrich the local gene pool, and provide information for the further use of germplasm in breeding programs.