Genome-wide expression profiling of aquaporin genes confer responses to abiotic and biotic stresses in Brassica rapa

Schematic representation of motif compositions in the BrAQP protein sequences. Different motifs, numbered 1–10, are displayed in different colored boxes. The names of all members are displayed on the left, while the length of the motif is shown in the scale at the bottom of the figure. (PPTX 269 kb

Genome-Wide Novel Genic Microsatellite Marker Resource Development and Validation for Genetic Diversity and Population Structure Analysis of Banana

Trait tagging through molecular markers is an important molecular breeding tool for crop improvement. SSR markers encoded by functionally relevant parts of a genome are well suited for this task because they may be directly related to traits. However, a limited number of these markers are known for Musa spp. Here, we report 35136 novel functionally relevant SSR markers (FRSMs). Among these, 17,561, 15,373 and 16,286 FRSMs were mapped in-silico to the genomes of Musa acuminata, M. balbisiana and M. schizocarpa, respectively. A set of 273 markers was validated using eight accessions of Musa spp., from which 259 markers (95%) produced a PCR product of the expected size and 203 (74%) were polymorphic. In-silico comparative mapping of FRSMs onto Musa and related species indicated sequence-based orthology and synteny relationships among the chromosomes of Musa and other plant species. Fifteen FRSMs were used to estimate the phylogenetic relationships among 50 banana accessions, and the results revealed that all banana accessions group into two major clusters according to their genomic background. Here, we report the first large-scale development and characterization of functionally relevant Musa SSR markers. We demonstrate their utility for germplasm characterization, genetic diversity studies, and comparative mapping in Musa spp. and other monocot species. The sequences for these novel markers are freely available via a searchable web interface called Musa Marker Database

Enhancing Legume Cultivars through Agronomy, Breeding, and Genetics

Legumes are a multipurpose crop species, with a great economic value, which, worldwide, are commonly cultivated for human food, livestock fodder, industrial raw materials, and soil health enhancement. Over the last few decades, numerous research projects have been conducted for the genetic improvements of legumes, in order to meet the Sustainable Development Goals of 2015–2030. Remarkable progress has been made in legume genetics, genomics, and breeding. The first references to the genome of legume plants were published in 2010, and these were the complete draft genome sequences of Glycine max. The chromosome scale high-quality genome assembly and annotations are available for many legume species today, including Glycine max; Lotus japonicus; Medicago ruthenica (L.); Medicago truncatula; Phaseolus lunatus; Mucuna pruriens; Vicia sativa; Trifolium pratense; Lupinus angustifolius; Cajanus cajan; Vigna radiata ssp.; and Cicer arietinum. Large-scale transcriptomic, genotyping, and phenotyping data have been generated from this diverse panel of legume cultivars for their varietal improvements. This Special Issue presents a collection of a variety of articles that cover the recent progress that has been made in legume genetics, genomics, and breeding. The authors have addressed the applications of phenotypic and genotypic diversity for the selection of the best cultivars; of morphological traits for the selection of the best local variety, the estimation of the agronomic performances of resistant and susceptible cultivars; the nutritional characteristics of the seed protein; genome-wide association studies on agronomic traits and isolation; and the characterization and function studies of many agronomically important genes

Repeats in the transcribed regions: comprehensive characterization and comparison of Citrus spp.

A large number of expressed sequences tags are available for Citrus spp., which provides an opportunity to understand genomic organization of the transcribed regions. Here, we report a detailed analysis of repetitive elements including tandem repeats (TRs) and transposable elements (TEs) in the transcribed region of the Citrus spp. On average, 22% of the expressed sequence tags (ESTs) contain TRs. The relative density of TR classes is highly taxon-specific. For instance, Citrus limonia has a high relative density of mononucleotide repeats, whereas dinucleotide repeats are rare. The proportions of 2–6, 7–30 and 31–50 bp repeats were almost identical in all studied species except for C. limonia and C. limettioides. We found that<1% of the citrus ESTs have a similarity with transposable elements. Transcriptional activity of transposable element families varied even within the same class of elements. A high proportion of transcriptional activity was observed for gypsy-like TEs compare to other TE classes. While TEs are relatively rare, TRs are abundant elements in ESTs of citrus. The high proportion of TRs that have a unit size longer than 6 bp raises the question about a possible functional or evolutionary role of these elements

A Comprehensive Plant microRNA Simple Sequence Repeat Marker Database to Accelerate Genetic Improvements in Crops

Microsatellites, or simple sequences repeat (SSRs), are distributed in genes, intergenic regions and transposable elements in the genome. SSRs were identified for developing markers from draft genome assemblies, transcriptome sequences and genome survey sequences in plant and animals. The identification, distribution, and density of microsatellites in pre-microRNAs (miRNAs) are not well documented in plants. In this study, SSRs were identified in 16,892 pre-miRNA sequences from 292 plant species in six taxonomic groups (algae to dicots). Fifty-one percent of pre-miRNA sequences contained SSRs. Mononucleotide repeats were the most abundant, followed by di- and trinucleotide repeats. Tetra-, penta-, and hexarepeats were rare. A total of 9,498 (57.46%) microsatellite loci had potential as pre-miRNA SSR markers. Of the markers, 3,573 (37.62%) were non-redundant, and 2,341 (65.51%) primer pairs could be transferred to at least one of the plant taxonomic groups. All data and primer pairs were deposited in a user-friendly, freely accessible plant miRNA SSR marker database. The data presented in this study, accelerate the understanding of pre-miRNA evolution and serve as valuable genomic treasure for genetic improvements in a wide range of crops, including legumes, cereals, and cruciferous crops

Novel polymorphic EST-based microsatellite marker isolation and characterization from Poncirus trifoliata (Rutaceae)

Novel Poncirus trifoliata simple sequence repeat (SSR) markers were developed to evaluate their utility for genetic diversity and breeding studies of P. trifoliata and related species. A total of 108 primer pairs were characterized by PCR amplification experiments. Among these, 61 were polymorphic and transferable to other citrus species. The number of alleles per locus ranged from 2 to 6, with an average of 2.37 alleles per locus. The expected heterozygosity and observed heterozygosity ranged from 0 to 0.83 and 0 to 1.00, respectively. These novel polymorphic SSR markers will be useful for citrus cultivar identification and evaluation as well as breeding studies

Recent advances in fruit crop genomics

In recent years, dramatic progress has been made in the genomics of fruit crops. The publication of a dozen fruit crop genomes represents a milestone for both functional genomics and breeding programs in fruit crops. Rapid advances in high-throughput sequencing technology have revolutionized the manner and scale of genomics in fruit crops. Research on fruit crops is encompassing a wide range of biological questions which are unique and cannot be addressed in a model plant such as Arabidopsis. This review summarizes recent achievements of research on the genome, transcriptome, proteome, miRNAs and epigenome of fruit crops

Genome Wide Characterization of Short Tandem Repeat Markers in Sweet Orange (<i>Citrus sinensis</i>)

<div><p>Sweet orange (<i>Citrus sinensis</i>) is one of the major cultivated and most-consumed citrus species. With the goal of enhancing the genomic resources in citrus, we surveyed, developed and characterized microsatellite markers in the ≈347 Mb sequence assembly of the sweet orange genome. A total of 50,846 SSRs were identified with a frequency of 146.4 SSRs/Mbp. Dinucleotide repeats are the most frequent repeat class and the highest density of SSRs was found in chromosome 4. SSRs are non-randomly distributed in the genome and most of the SSRs (62.02%) are located in the intergenic regions. We found that AT-rich SSRs are more frequent than GC-rich SSRs. A total number of 21,248 SSR primers were successfully developed, which represents 89 SSR markers per Mb of the genome. A subset of 950 developed SSR primer pairs were synthesized and tested by wet lab experiments on a set of 16 citrus accessions. In total we identified 534 (56.21%) polymorphic SSR markers that will be useful in citrus improvement. The number of amplified alleles ranges from 2 to 12 with an average of 4 alleles per marker and an average PIC value of 0.75. The newly developed sweet orange primer sequences, their <i>in silico</i> PCR products, exact position in the genome assembly and putative function are made publicly available. We present the largest number of SSR markers ever developed for a citrus species. Almost two thirds of the markers are transferable to 16 citrus relatives and may be used for constructing a high density linkage map. In addition, they are valuable for marker-assisted selection studies, population structure analyses and comparative genomic studies of <i>C. sinensis</i> with other citrus related species. Altogether, these markers provide a significant contribution to the citrus research community.</p></div