Excellent Agronomic Traits Research Articles

Transfer of the All-Stage Resistance Stripe Rust (Puccinia striifonnis f. sp. Tritici) Resistance Gene YrZH84 in Two Southwestern Chinese Wheat Cultivars

Wheat stripe rust is a fungal disease severely affecting wheat production. Breeding resistant cultivars is the most cost-effective and efficient way to control wheat stripe rust. YrZH84 is an all-stage resistance gene with good resistance to stripe rust. In this study, YrZH84 was introgressed from germplasm Lantian36 (LT36) into the two southwestern Chinese elite wheat cultivars Mianmai367 (MM367, carrying Yr10, Yr26), and Chuanmai104 (CM104, carrying Yr26), using marker-assisted selection. F1 seeds of the two cross-combinations were planted and self-crossed to develop the advanced generations in the field. A total of 397 introgression lines (ILs) were obtained in F6 and genotyped using molecular markers Xcfa2040, Xbarc32 (linked to YrZH84), Yr10 (linked to Yr10), We173, and Xbarc181 (linked to Yr26). The 397 ILs were also evaluated for resistance to stripe rust and agronomic traits, including plant height, number of tillers, spike length, thousand-grain weight, and spikelet number. Finally, 61 lines with appreciative agronomic traits and disease resistance were selected. Among these lines, 31 lines had stripe rust resistance gene YrZH84. These selected lines are expected to become new wheat varieties for their high resistance to stripe rust and excellent agronomic traits that will make important contributions to the control of stripe rust and wheat production.

A Novel SPOTTED LEAF1-1 (SPL11-1) Gene Confers Resistance to Rice Blast and Bacterial Leaf Blight Diseases in Rice (Oryza sativa L.)

Programmed cell death (PCD) plays critical roles in plant immunity but must be regulated to prevent excessive damage. In this study, a novel spotted leaf (spl11-1) mutant was identified from an ethyl methane sulfonate (EMS) population. The SPL11-1 gene was genetically mapped to chromosome 12 between the Indel12-37 and Indel12-39 molecular markers, which harbor a genomic region of 27 kb. Annotation of the SPL11-1 genomic region revealed the presence of two candidate genes. Through gene prediction and cDNA sequencing, it was confirmed that the target gene in the spl11-1 mutant is allelic to the rice SPOTTED LEAF (SPL11), hereafter referred to as spl11-1. Sequence analysis of SPL11 revealed a single bp deletion (T) between the spl11-1 mutant and the ‘Shuangkang77009’ wild type. Moreover, protein structure analysis showed that the structural differences between the SPL11-1 and SPL11 proteins might lead to a change in the function of the SPL11 protein. Compared to the ‘Shuangkang77009’ wild type, the spl11-1 mutant showed more disease resistance. The agronomical evaluation showed that the spl11-1 mutant showed more adverse traits. Through further mutagenesis treatment, we obtained the spl11-2 mutant allelic to spl11-1, which has excellent agronomic traits and more improvement and may have certain breeding prospects in future breeding for disease resistance.

Using molecular markers to assist in the selection of the rice blast resistance genes Pi1, Pi2, and Pi-ta in rice wide compatibility restorer lines

Hybridization was performed between the rice materials carrying the rice blast resistance genes Pi1, Pi2, and Pi-ta (R283) as the maternal parent and the broad compatibility restorer line R110 as the paternal parent. Molecular marker-assisted breeding techniques were used to detect the target genes in segregating generations. Through field selection and resistance identification, three stable lines with multiple resistance, strong restorer ability, and excellent agronomic traits were bred. Their agronomic and economic traits were analyzed along with their resistance to different physiological races of rice blast. These three stable lines were then crossed with seven different sterile lines (Chunjiang 23A, FA1, FA3, FA4, 81, 57, and 212A) to analyze the agronomic traits and resistance to rice blast pathogens in the hybrid combinations. JR11, JR12, and JR13 were stable, homozygous polymerized lines carrying Pi1, Pi2, and Pi-ta resistance genes and exhibited resistance frequencies ranging from 90.19 to 96.08% against different physiological races of rice blast disease. This indicates the excellent resistance of these three stable lines to rice blast disease. The seed-set frequencies in the hybrid combinations of the seven sterile lines with the three stable lines ranged from 66.4 to 84.1%, showing strong recovery ability. The yield of the selected combination of 23 A/JR11, 81 A/JR11, and 212 A/JR13 was 2.2–2.3% higher than that of the control Yongyou 1540. The research results showed that the three stable aggregated rice blast resistance genes Pi1, Pi2, and Pi-ta rice restorer lines created have good practical value in production.

Pre-breeding of spontaneous Robertsonian translocations for density planting architecture by transferring Agropyron cristatum chromosome 1P into wheat.

We developed T1AL·1PS and T1AS·1PL Robertsonian translocations by breakage-fusion mechanism based on wheat-A. cristatum 1P(1A) substitution line with smaller leaf area, shorter plant height, and other excellent agronomic traits Agropyron cristatum, a wild relative of wheat, is a valuable germplasm resource for improving wheat genetic diversity and yield. Our previous study confirmed that the A. cristatum chromosome 1P carries alien genes that reduce plant height and leaf size in wheat. Here, we developed T1AL·1PS and T1AS·1PL Robertsonian translocations (RobTs) by breakage-fusion mechanism based on wheat-A. cristatum 1P (1A) substitution line II-3-1c. Combining molecular markers and cytological analysis, we identified 16 spontaneous RobTs from 911 F2 individuals derived from the cross of Jimai22 and II-3-1c. Fluorescence in situ hybridization (FISH) was applied to detect the fusion structures of the centromeres in wheat and A. cristatum chromosomes. Resequencing results indicated that the chromosomal junction point was located at the physical position of Triticum aestivum chromosome 1A (212.5Mb) and A. cristatum chromosome 1P (230Mb). Genomic in situ hybridization (GISH) in pollen mother cells showed that the produced translocation lines could form stable ring bivalent. Introducing chromosome 1PS translocation fragment into wheat significantly increased the number of fertile tillers, grain number per spike, and grain weight and reduced the flag leaf area. However, introducing chromosome 1PL translocation fragment into wheat significantly reduced flag leaf area and plant height with a negative effect on yield components. The pre-breeding of two spontaneous RobTs T1AL·1PS and T1AS·1PL was important for wheat architecture improvement.

Global Analysis of the WOX Transcription Factor Family in Akebia trifoliata.

Akebia trifoliata is an economically important, self-incompatible fruit tree in the Lardizabalaceae family. Asexual propagation is the main strategy used to maintain excellent agronomic traits. However, the generation of adventitious roots during asexual propagation is very difficult. To study the important role of the WUSCHEL-related homeobox (WOX) transcription factor in adventitious root growth and development, we characterized this transcription factor family in the whole genome of A. trifoliata. A total of 10 AktWOXs were identified, with the following characteristics: length (657~11,328 bp), exon number (2~5), isoelectric point (5.65~9.03), amino acid number (176~361 AA) and molecular weight (20.500~40.173 kDa), and their corresponding expression sequence could also be detectable in the public transcriptomic data for A. trifoliata fruit. A total of 10 AktWOXs were classified into modern (6), intermediate (2) and ancient clades (2) and all AktWOXs had undergone strong purifying selection during evolution. The expression profile of AktWOXs during A. trifoliata adventitious root formation indicated that AktWOXs play an important role in the regulation of adventitious root development. Overall, this is the first study to identify and characterize the WOX family in A. trifoliata and will be helpful for further research on A. trifoliata adventitious root formation.

Pyramiding Breeding of Low-Glutelin-Content Indica Rice with Good Quality and Resistance.

Low-glutelin-content rice, a type of functional rice with glutelin levels below 4%, is an essential dietary supplement for chronic kidney disease (CKD) patients. Developing low-glutelin-content rice varieties is crucial to catering to the growing CKD population. In this study, we aimed to create a new low-glutelin indica rice variety with excellent agronomic traits. To achieve this, we employed a combination of molecular-marker-assisted selection and traditional breeding techniques. The cultivars W3660, Wushansimiao (WSSM), and Nantaixiangzhan (NTXZ) were crossbred, incorporating the Lgc-1, Pi-2, Xa23, and fgr alleles into a single line. The result of this breeding effort was "Yishenxiangsimiao", a new indica rice variety that inherits the desirable characteristics of its parent lines. Yishenxiangsimiao (YSXSM) possesses not only a low glutelin content but also dual resistance to blast and bacterial blight (BB). It exhibits high-quality grains with a fragrant aroma. This new low-glutelin indica cultivar not only ensures a stable food supply for CKD patients but also serves as a healthy dietary option for the general public. We also performed RNA-seq of these rice varieties to investigate their internal gene expression differences. The YSXSM exhibited a higher biotic-resistance gene expression in comparison to NTXZ. In summary, we successfully developed a novel low-glutelin indica rice variety, "Yishenxiangsimiao", with superior agronomic traits. This rice variety addresses the dietary needs of CKD patients and offers a nutritious choice for all consumers.

IGTCM: An integrative genome database of traditional Chinese medicine plants.

Fully understanding traditional Chinese medicines (TCMs) is still challenging because of the extreme complexity of their chemical components and mechanisms of action. The TCM Plant Genome Project aimed to obtain genetic information, determine gene functions, discover regulatory networks of herbal species, and elucidate the molecular mechanisms involved in the disease prevention and treatment, thereby accelerating the modernization of TCMs. A comprehensive database that contains TCM-related information will provide a vital resource. Here, we present an integrative genome database of TCM plants (IGTCM) that contains 14,711,220 records of 83 annotated TCM-related herb genomes, including 3,610,350 genes, 3,534,314 proteins and corresponding coding sequences, and 4,032,242 RNAs, as well as 1033 non-redundant component records for 68 herbs, downloaded and integrated from the GenBank and RefSeq databases. For minimal interconnectivity, each gene, protein, and component was annotated using the eggNOG-mapper tool and Kyoto Encyclopedia of Genes and Genomes database to acquire pathway information and enzyme classifications. These features can be linked across several species and different components. The IGTCM database also provides visualization and sequence similarity search tools for data analyses. These annotated herb genome sequences in IGTCM database are a necessary resource for systematically exploring genes related to the biosynthesis of compounds that have significant medicinal activities and excellent agronomic traits that can be used to improve TCM-related varieties through molecular breeding. It also provides valuable data and tools for future research on drug discovery and the protection and rational use of TCM plant resources. The IGTCM database is freely available at http://yeyn.group:96/.

A chromosome-level genome assembly of an early matured aromatic Japonica rice variety Qigeng10 to accelerate rice breeding for high grain quality in Northeast China.

Early-matured aromatic japonica rice from the Northeast is the most popular rice commodity in the Chinese market. The Qigeng10 (QG10) was one of the varieties with the largest planting area in this region in recent years. It was an early-matured japonica rice variety with a lot of superior traits such as semi-dwarf, lodging resistance, long grain, aromatic and good quality. Therefore, a high-quality assembly of Qigeng10 genome is critical and useful for japonica research and breeding. In this study, we produced a high-precision QG10 chromosome-level genome by using a combination of Nanopore and Hi-C platforms. Finally, we assembled the QG10 genome into 77 contigs with an N50 length of 11.80 Mb in 27 scaffolds with an N50 length of 30.55 Mb. The assembled genome size was 378.31Mb with 65 contigs and constituted approximately 99.59% of the 12 chromosomes. We identified a total of 1,080,819 SNPs and 682,392 InDels between QG10 and Nipponbare. We also annotated 57,599 genes by the Ab initio method, homology-based technique, and RNA-seq. Based on the assembled genome sequence, we detected the sequence variation in a total of 63 cloned genes involved in grain yield, grain size, disease tolerance, lodging resistance, fragrance, and many other important traits. Finally, we identified five elite alleles (qTGW2Nipponbare , qTGW3Nanyangzhan , GW5IR24 , GW6Suyunuo , and qGW8Basmati385 ) controlling long grain size, four elite alleles (COLD1Nipponbare , bZIP73Nipponbare , CTB4aKunmingxiaobaigu , and CTB2Kunmingxiaobaigu ) controlling cold tolerance, three non-functional alleles (DTH7Kitaake , Ghd7Hejiang19 , and Hd1Longgeng31 ) for early heading, two resistant alleles (PiaAkihikari and Pid4Digu ) for rice blast, a resistant allele STV11Kasalath for rice stripe virus, an NRT1.1BIR24 allele for higher nitrate absorption activity, an elite allele SCM3Chugoku117 for stronger culms, and the typical aromatic gene badh2-E2 for fragrance in QG10. These results not only help us to better elucidate the genetic mechanisms underlying excellent agronomic traits in QG10 but also have wide-ranging implications for genomics-assisted breeding in early-matured fragrant japonica rice.

Sorus developmental biology of hybrid cultivar in Saccharina japonica: Environmental and endogenous regulation

The induction and regulation of sporogenesis in the kelp Saccharina japonica is particularly important due to the necessity of obtaining spores to produce “summer seedlings” in the kelp hatchery. However, some hybrid cultivars of S. japonica with excellent agronomic traits are late-maturing, which means the hybrid cultivars cannot produce spore at the time of “summer seedling” production and limits their application in practice. The effects of temperature, irradiance, nutrition level, and exogenous hormones on the sorus formation were investigated in this study, aiming to clarify the optimum inducible conditions for sorus formation of S. japonica. Based on the number of individuals forming sorus and the percentages of the sorus area on the sporophyte tissue discs, it was proposed that the optimal conditions for sorus formation were at 17 °C, 5 mg L−1 nitrate nitrogen, 0.5 mg L−1 phosphorus, 10−6 mol L−1 abscisic acid (ABA), and irradiance of 60-100 μmol photons m−2 s−1. Then, the vegetative tissue discs of S. japonica sporophyte were cultured under the above optimal conditions to induce the sorus formation, and the duration from vegetative tissue to sours formation and zoospores release was divided into five stages. The anatomical structure changes, antioxidant activity, reactive oxygen species (ROS) level, MDA content, and endogenous hormone levels were determined at the five stages during sorus formation. Significant accumulation of ROS was observed but the content of malondialdehyde stayed at a stable level indicating that ROS may have an important role in the regulation of sorus formation rather than their potential cytotoxic effects. For the endogenous hormone analysis, indole-3-acetic acid (IAA) was lowered and ABA was elevated in the early stages during sorus formation. The GA3 trend was consistent with IAA. The contents of dihydrozeatin, isopentenyladenine, and isopentenyladenosine were significantly lower in vegetative tissue than that in sorus tissue. These results indicated ROS and hormones may play an important role in the endogenous regulation of sorus formation in S. japonica. The relevant results herein can lay a foundation for studying the external conditions and endogenous regulation of sorus formation for the kelp hybrids of late-maturing.

Genetic Diversity Analysis Reveals Potential of the Green Peach Aphid (Myzus persicae) Resistance in Ethiopian Mustard.

Brassica carinata (BBCC, 2n = 34) is commonly known as Ethiopian mustard, Abyssinian mustard, or carinata. Its excellent agronomic traits, including resistance to biotic and abiotic stresses, make it a potential genetic donor for interspecific hybridization. Myzus persicae (green peach aphid, GPA) is one of the most harmful pests of Brassica crops, significantly effecting the yield and quality. However, few aphid-resistant Brassica crop germplasms have been utilized in breeding practices, while the underlying biochemical basis of aphid resistance still remains poorly understood. In this study, we examined the genetic diversity of 75 B. carinata accessions and some plant characteristics that potentially contribute to GPA resistance. Initially, the morphological characterization showed abundant diversity in the phenotypic traits, with the dendrogram indicating that the genetic variation of the 75 accessions ranged from 0.66 to 0.98. A population structure analysis revealed that these accessions could be grouped into two main subpopulations and one admixed group, with the majority of accessions (86.67%) clustering in one subpopulation. Subsequently, there were three GPA-resistant B. carinata accessions, BC13, BC47, and BC51. The electrical penetration graph (EPG) assay detected resistance factors in the leaf mesophyll tissue and xylem. The result demonstrated that the Ethiopian mustard accessions were susceptible when the phloem probing time, the first probe time, and the G-wave time were 20.51-32.51 min, 26.36-55.54 s, and 36.18-47.84 min, respectively. In contrast, resistance of the Ethiopian mustard accessions was observed with the phloem probing time, the first probe time, and G-wave time of 41.18-70.78 min, 181.07-365.85 s, and 18.03-26.37 min, respectively. In addition, the epidermal characters, leaf anatomical structure, glucosinolate composition, defense-related enzyme activities, and callose deposition were compared between the resistant and susceptible accessions. GPA-resistant accessions had denser longitudinal leaf structure, higher wax content on the leaf surface, higher indole glucosinolate level, increased polyphenol oxidase (PPO) activity, and faster callose deposition than the susceptible accessions. This study validates that inherent physical and chemical barriers are evidently crucial factors in the resistance against GPA infestation. This study not only provide new insights into the biochemical basis of GPA resistance but also highlights the GPA-resistant B. carinata germplasm resources for the future accurate genetic improvement of Brassica crops.

Characterization of a new splicing variant of powdery mildew resistance gene Pm4 in synthetic hexaploid wheat YAV249

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a destructive fungal disease of wheat throughout the world. Utilization of effective powdery mildew resistance genes and cultivars is considered as the most economic, efficient, and environmental-friendly method to control this disease. Synthetic hexaploid wheat (SHW), which was developed through hybridization of diploid Aegilops and tetraploid wheat, is a valuable genetic resource for resistance to powdery mildew. SHW line YAV249 showed high levels of resistance to powdery mildew at both the seedling and adult stages. Genetic analysis indicated that the resistance was controlled by a single dominant gene, temporarily designated PmYAV. Bulked segregant analysis with wheat 660K single nucleotide polymorphism (SNP) array scanning and marker analysis showed that PmYAV was located on chromosome 2AL and flanked by markers Xgdm93 and Xwgrc763, respectively, with genetic distances of 0.8 cM and 1.2 cM corresponding to a physic interval of 1.89 Mb on the Chinese Spring reference genome sequence v1.0. Sequence alignment analysis demonstrated that the sequence of PmYAV was consistent with that of Pm4a but generated an extra splicing event. When inoculated with different Bgt isolates, PmYAV showed a significantly different spectrum from Pm4a, hence it might be a new resistant resource for improvement of powdery mildew resistance. The flanked markers GDM93 and WGRC763, and the co-segregated markers BCD1231 and JS717/JS718 were confirmed to be easily performed in marker-assisted selection (MAS) of PmYAV. Using MAS strategy, PmYAV was transferred into the commercial cultivar Kenong 199 (KN199) and a wheat line YK13 was derived at generation BC3F3 from the population of YAV249/4*KN199 due to its excellent agronomic traits and resistance to powdery mildew. In conclusion, an alternative splicing variant of Pm4 was identified in this study, which informed the regulation of Pm4 gene function.

Development and Molecular Cytogenetic Characterization of a Novel Wheat-Rye T6RS.6AL Translocation Line from Secale cereale L. Qinling with Resistance to Stripe Rust and Powdery Mildew.

In this study, a novel T6RS.6AL translocation line, 117-6, was selected from a cross between common Chuannong25 (CN25) wheat and Qinling rye. The results of nondenaturing fluorescence in situ hybridization (ND-FISH) and PCR showed that 117-6 contained two T6RS.6AL translocation chromosomes. The distal region of the 6RS chromosome in 117-6 was mutant and showed different FISH signal patterns. When inoculated with different stripe rust races and powdery mildew races in seedlings, 117-6 expressed high resistance to them. The 117-6 line also exhibited high resistance to stripe rust and powdery mildew in the field under natural Puccinia striiformis f. sp. tritici (Pst) and Blumeria graminis f. sp. tritici (Bgt) infection. The cytogenetic analysis indicated that the introduction of 6RS conferred resistance ability. Compared with wheat parent CN25, 117-6 exhibited excellent agronomic traits in the field. The present study indicated that Qinling rye may carry favorite genes as a potential source for wheat genetic improvement, and 117-6 could be a useful germplasm for wheat breeding programs in the future.

EfGD: the Erianthus fulvus genome database.

Erianthus fulvus (TaxID: 154759) is a valuable germplasm resource in sugarcane breeding and research and has excellent agronomic traits, such as drought resistance, cold resistance, barren tolerance and high brix. With a stable chromosome number (2n = 20) and a small genome (0.9 Gb), it is an ideal candidate for research on sugarcane. Next-generation sequencing technology has enabled a growing number of studies to focus on genomics. Due to the large amount of omics data available, a centralized platform is necessary for ensuring the consistency, independence and maintainability of these large-scale datasets through storage, analysis and integration. Here, we present a comprehensive database for the E. fulvus genome, EfGD. By using the new high-quality reference genome and its annotations, the EfGD provides the largest whole-genome sequencing reference dataset for E. fulvus, which archives 27 165 protein-coding genes and 55 564 488 SNPs from 202 newly resequenced genomes. Furthermore, we created a user-friendly graphical interface for visualizing genomic diversity, population structure and evolution and provided other tools on an open platform. Database URL: https://efgenome.ynau.edu.cn

Engineering an oilseed crop for hyper-accumulation of carotenoids in the seeds without using a traditional marker gene.

Ketocarotenoids were synthesized successfully in Camelina sativa seeds by genetic modification without using a traditional selection marker genes. This method provided an interesting tool for metabolic engineering of seed crops. Camelina sativa (L.) Crantz is an important oil crop with many excellent agronomic traits. This model oil plant has been exploited to accumulate value-added bioproducts using genetic manipulation that depends on antibiotic- or herbicide-based selection marker genes (SMG), one of the major concerns for genetically modified foods. Here we reported metabolic engineering of C. sativa to synthesize red ketocarotenoids that could serve as a reporter to visualize transgenic events without using a traditional SMG. Overexpression of a non-native β-carotene ketolase gene coupled with three other carotenogenous genes (phytoene synthase, β-carotene hydroxylase, and Orange) in C. sativa resulted in production of red seeds that were visibly distinguishable from the normal yellow ones. Constitutive expression of the transgenes led to delayed plant development and seed germination. In contrast, seed-specific transformants demonstrated normal growth and seed germination despite the accumulation of up to 70-fold the level of carotenoids in the seeds compared to the controls, including significant amounts of astaxanthin and keto-lutein. As a result, the transgenic seed oils exhibited much higher antioxidant activity. No significant changes were found in the profiles of fatty acids between transgenic and control seeds. This study provided an interesting tool for metabolic engineering of seed crops without using a disputed SMG.

Marker-Assisted Backcross Breeding for Improving Bruchid (Callosobruchus spp.) Resistance in Mung Bean (Vigna radiata L.)

Mung bean is vulnerable to bruchids (Callosobruchus spp.), resulting in low quality and losses worldwide. Developing resistant cultivars is the most effective, economical, and eco-friendly way to protect mung bean seeds from the damage of bruchids. Previously, we identified two gene loci that are tightly linked with bruchid resistance, which makes new cultivar development possible using molecular assisted selection (MAS). In the present study, marker-assisted backcross (MABC) breeding was employed to introgress the bruchid resistance gene VrPGIP2 locus from the donor parent V2802 into a popular cultivar, Kamphaeng Saen 1. Markers VrBR-SSR013 and DMB-SSR158 were used for foreground selection, and phenotypic selection was used for background selection. Three advanced inbred lines (R67-11, R67-22, and R92-15) carrying the resistance gene VrPGIP2 were developed from the BC3F6 population. Further analysis showed that the line R67-22 performed best; it was highly resistant to bruchids and showed excellent agronomic traits in the field. Therefore, R67-22 could be further evaluated in large-scale trials for release as a variety.

Phenotypic variations of wheat cultivars from the North China Plain in response to cadmium stress and associated single nucleotide polymorphisms identified by a genome-wide association study

Understanding the genetic mechanisms for cadmium (Cd) uptake and translocation in common wheat (Triticum aestivum) is of significance in food Cd contamination control. In this study, a diverse panel of 132 wheat cultivars was collected from the North China Plain. The cultivars were evaluated in terms of their phenotypic variations in response to Cd stress and subjected to a genome-wide association study (GWAS) to identify single nucleotide polymorphisms (SNPs) associated with the phenotypic variations at the seedling stage. Significant phenotypic variations with high heritability were observed among the wheat cultivars exposed to 40 μmol L-1 Cd for the studied traits, including root length (RL), shoot length (SL), root and shoot dry biomasses (RDW and SDW, respectively), root and shoot Cd concentrations (RCD and SCD, respectively), and Cd translocation factor (TF). Mean RCD, SCD, and TF ranged from 1.0 to 33.8, 0.125 to 2.022, and 0.009 to 0.321 mg g-1, respectively. Cluster analysis showed that wheat cultivars with higher RL, SL, RDW, and SDW under Cd stress were able to accumulate more Cd in root, leading to a lower Cd TF. Mixed linear model-based association analysis detected 17 novel significant marker-trait associations (MTAs), four of which were significant at a genome-wide scale. Most of the significant MTAs controlled Cd TF and explained 17.17%–26.47% of the phenotypic variations. Some of the SNP loci were physically close to a reported Cd-related quantitative trait locus or gene on wheat chromosomes. Results of this study provided a list of wheat cultivars with the potential of low Cd accumulation and enriched our knowledge on the genetic basis of Cd uptake and translocation in wheat. Pyramiding breeding of superior alleles detected in this study may additionally reduce Cd accumulation of improved wheat cultivars with excellent agronomic traits.

Identification and chromosome doubling of Fragaria mandshurica and F. nilgerrensis

Genetic factors that control various excellent agronomic traits are present in wild strawberries; however, barriers such as ploidy differences and interspecific incompatibility prevent the transmission of these genetic factors to cultivated strawberries. Using the colchicine method to induce doubling, the autotetraploids of Fragaria mandshurica and F. nilgerrensis were obtained, and the biological characteristics of the autotetraploids and the compatibility status distribution in different cross-pollination combinations relating to the two species were further examined. The autotetraploids showed thicker and stronger morphological characteristics than those of their corresponding diploids, especially the F. mandshurica species. The change in ploidy can cause the appearance of new excellent agronomic traits: the autotetraploid of F. nilgerrensis is more resistant to anthracnose disease, caused by Colletotrichum gloeosporioides, than the diploid, and the flowering period is significantly longer, with an increase in flower quantity. There is unilateral incompatibility between the two self-compatible species. The autotetraploids are similar to the corresponding diploid in pollination compatibility; however, due to the decline in pollen viability, the related hybridisation combinations show slightly lower compatibility. The closer the ploidy is, the easier it is to obtain hybrid offspring; the tetraploids of both species crossed with cultivated strawberries, showing possible increases in compatibility after chromosome doubling.

Genetic and Transcriptomic Analysis Reveal the Molecular Basis of Photoperiod-Regulated Flowering in Xishuangbanna Cucumber (Cucumis sativus L. var. xishuangbannesis Qi et Yuan).

Xishuangbanna (XIS) cucumber (Cucumis sativus L. var. xishuangbannesis Qi et Yuan), is a botanical variety of cucumber cultivars native to southwest China that possesses excellent agronomic traits for cucumber improvement. However, breeding utilization of XIS cucumber is limited due to the current poor understanding of its photoperiod-sensitive flowering characteristics. In this study, genetic and transcriptomic analysis were conducted to reveal the molecular basis of photoperiod-regulated flowering in XIS cucumber. A major-effect QTL locus DFF1.1 was identified that controls the days to first flowering (DFF) of XIS cucumbers with a span of 1.38 Mb. Whole-genome re-sequencing data of 9 cucumber varieties with different flowering characteristics in response to photoperiod suggested that CsaNFYA1 was the candidate gene of DFF1.1, which harbored a single non-synonymous mutation in its fifth exon. Transcriptomic analysis revealed the positive roles of auxin and ethylene in accelerating flowering under short-day (SD) light-dark cycles when compared with equal-day/night treatment. Carbohydrate storage and high expression levels of related genes were important reasons explaining early flowering of XIS cucumber under SD conditions. By combining with the RNA-Seq data, the co-expression network suggested that CsaNFYA1 integrated multiple types of genes to regulate the flowering of XIS cucumber. Our findings explain the internal regulatory mechanisms of a photoperiodic flowering pathway. These findings may guide the use of photoperiod shifts to promote flowering of photoperiod-sensitive crops.

Development and Molecular Cytogenetic Identification of a New Wheat-Psathyrostachys huashanica Keng Translocation Line Resistant to Powdery Mildew.

Psathyrostachys huashanica Keng, a wild relative of common wheat with many desirable traits, is an invaluable source of genetic material for wheat improvement. Few wheat–P. huashanica translocation lines resistant to powdery mildew have been reported. In this study, a wheat–P. huashanica line, E24-3-1-6-2-1, was generated via distant hybridization, ethyl methanesulfonate (EMS) mutagenesis, and backcross breeding. A chromosome karyotype of 2n = 44 was observed at the mitotic stage in E24-3-1-6-2-1. Genomic in situ hybridization (GISH) analysis revealed four translocated chromosomes in E24-3-1-6-2-1, and P. huashanica chromosome-specific marker analysis showed that the alien chromosome fragment was from the P. huashanica 4Ns chromosome. Moreover, fluorescence in situ hybridization (FISH) analysis demonstrated that reciprocal translocation had occurred between the P. huashanica 4Ns chromosome and the wheat 3D chromosome; thus, E24-3-1-6-2-1 carried two translocations: T3DS·3DL-4NsL and T3DL-4NsS. Translocation also occurred between wheat chromosomes 2A and 4A. At the adult stage, E24-3-1-6-2-1 was highly resistant to powdery mildew, caused by prevalent pathotypes in China. Further, the spike length, numbers of fertile spikelets, kernels per spike, thousand-kernel weight, and grain yield of E24-3-1-6-2-1 were significantly higher than those of its wheat parent 7182 and addition line 24-6-3-1. Thus, this translocation line that is highly resistant to powdery mildew and has excellent agronomic traits can be used as a novel promising germplasm for breeding resistant and high-yielding cultivars.

Registration of ‘FloRun ‘331’ ’ peanut

Abstract‘FloRun ‘331’ ’ (Reg. no. CV‐144, PI 680624) is a high‐oleic, runner market‐type peanut (Arachis hypogaea L. ssp. hypogaea var. hypogaea) cultivar with medium runner seed size developed by the University of Florida, Florida Agricultural Experiment Station, North Florida Research and Education Center, near Marianna, FL. It was tested under the experimental designation UF15302 and was approved for release in 2016. FloRun ‘331’ has a semi‐prostrate growth habit, with a tall and prominent center stem and dark green leaves. The seed testa is tan and the seeds are smaller than seeds of ‘Georgia‐06G’ (68.8 g vs. 76.9 g per 100 seeds, P < .001). FloRun ‘331’ was released based on its pod yield and grading potential, disease resistance, and high oleic oil content. During the 3‐yr period from 2013 to 2015, at three locations, FloRun ‘331’ had higher pod yield (8,101 vs. 7,533 kg ha–1; P = .0088) than ‘Georgia‐06G’, the dominant cultivar in the southeastern United States. The total sound mature kernels grade of FloRun ‘331’ was slightly less than that of Georgia‐06G (77.1 vs. 79.9%, P < .0032. It also has the benefit of high oleic oil chemistry. with oil composed of 79.3% oleic fatty acid versus 61.3% for Georgia‐06G (P < .01). In addition, FloRun ‘331’ has very good tolerance to two major fungal diseases: late leaf spot and white mold. Therefore, it combines excellent agronomic, grade, disease, and oil chemistry traits and should be beneficial to farmers and manufacturers of peanut foods.