The potential of Momordica charantia var. muricata, a little-known wild form, as a source of favourable alleles in breeding and improvement of bitter melons (M. charantia var. charantia), is demonstrated. The M. charantia var. charantia cultivar Priyanka and M. charantia var. muricata accession IC634896 were crossed with each other and cross ability and performance of F1 plants were studied. These botanical varieties were fully cross-compatible on either direction. Surprisingly, cross of Priyanka × IC634896 produced 80.0 fruits compared to 17.0 in Priyanka and fruit yield per plant (2287.4 g) was more than double that in Priyanka (1042.3 g). This hybrid has to be back crossed with commercial cultivar to improve its fruit size, with no compromise on fruit number. This is the first study showing the promise of M. charantia var. muricata as a potential donor in bitter melon breeding.

Dongxiang wild rice (Oryza rufipogon, DXWR) exhibits valuable agronomic traits and represents a precious germplasm resource for rice breeding. The use of genetic markers can greatly speed up the breeding process and facilitate research on genetics and genomics. In our previous study, we identified insertion–deletion polymorphisms between DXWR and cultivated rice Nipponbare (Oryza sativa ssp. japonica), using whole-genome sequencing in DXWR. In this study, to further explore the genetic variations and enrich the available genetic markers of DXWR, we identified 1,089,478 single-nucleotide polymorphisms (SNPs) (corresponding to one SNP per 0.33 kb of the genome) by genomic comparison between DXWR and Nipponbare, using the genome sequencing data and bioinformatics approaches. Furthermore, the accuracy of the identified SNPs was also validated by polymerase chain reaction amplification and Sanger sequencing. This genome-wide SNPs identification greatly increases the number of genetic markers available for DXWR and provides new opportunities to exploit this valuable and endangered germplasm resource.

Dongxiang wild rice (Oryza rufipogon, DXWR), one of the species of common wild rice, is regarded as an important genetic resource for the improvement of cultivated rice (Oryza sativa). Molecular markers are reliable tools that can greatly accelerate the breeding process and have been widely used in various species. In the present study, a total of 3681 genic simple sequence repeat (SSR) markers were developed for DXWR based on transcriptome sequencing technology. Additionally, 25 primer pairs were randomly selected and synthesized for the verification. Among them, 18 (72%) primer pairs were successfully amplified in PCR amplification with genomic DNA of DXWR and also had abundant polymorphisms between DXWR and cultivated rice. These novel genic SSR markers will enrich current genomic resources for DXWR, and provide an effective tool for genetic study and molecular marker assisted breeding for this valuable and endangered germplasm.

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is a major biotic constraint of rice production in all the major irrigated/lowland rice growing regions of Asia, including Punjab and its adjoining states in India. None of the individual BB resistant Xa/xa genes is effective against Punjab pathotypes. In the present study, we have screened 1176 accessions, comprising 1007 accessions of A genome species Oryza glaberrima, O. barthii, O. nivara, O. rufipogon, O. longistaminata, O. meridionalis, O. glumaepatula and 169 accessions from ten other wild species having CC, FF, EE, BBCC and CCDD genomes against two most recently evolved Xoo pathotypes viz. PbXo-10 and PbXo-8 in Punjab state of India, for two constitutive years 2014 and 2015. Based on 2 years of data, four accessions of O. glaberrima (IRGC102206, IRGC1022445, IRGC102512 and IRGC102520) and two of the O. longistaminata accessions (IRGC92624 and IRGC101754) were identified with immune reaction against PbXo-8. For PbXo-10, O. longistaminata showed large number of accessions with complete to partial resistance followed by O. rufipogon (8), O. nivara (2), O. punctata (2) and O. officinalis (1). Two of the O. longistaminata accessions IRGC92624 and IRGC92644 from Mali were found to have resistance against both the Xoo pathotypes indicating presence of BB resistance gene other than Xa21. These can be transferred to elite cultivars of O. sativa for better management of BB.

The legume Arachis hypogaea, commonly known as peanut or groundnut, is a very important food crop throughout the tropics and sub-tropics. The genus is endemic to South America being mostly associated with the savannah-like Cerrado. All species in the genus are unusual among legumes in that they produce their fruit below the ground. This profoundly influences their biology and natural distributions. The species occur in diverse habitats including grasslands, open patches of forest and even in temporarily flooded areas. Based on a number of criteria, including morphology and sexual compatibilities, the 80 described species are arranged in nine infrageneric taxonomic sections. While most wild species are diploid, cultivated peanut is a tetraploid. It is of recent origin and has an AABB-type genome. The most probable ancestral species are Arachis duranensis and Arachis ipaënsis, which contributed the A and B genome components, respectively. Although cultivated peanut is tetraploid, genetically it behaves as a diploid, the A and B chromosomes only rarely pairing during meiosis. Although morphologically variable, cultivated peanut has a very narrow genetic base. For some traits, such as disease and pest resistance, this has been a fundamental limitation to crop improvement using only cultivated germplasm. Transfer of some wild resistance genes to cultivated peanut has been achieved, for instance, the gene for resistance to root-knot nematode. However, a wider use of wild species in breeding has been hampered by ploidy and sexual incompatibility barriers, by linkage drag, and historically, by a lack of the tools needed to conveniently confirm hybrid identities and track introgressed chromosomal segments. In recent years, improved knowledge of species relationships has been gained by more detailed cytogenetic studies and molecular phylogenies. This knowledge, together with new tools for genetic and genomic analysis, will help in the more efficient use of peanut's genetic resources in crop improvement.

Wild peanut species are useful genetic resources for improving the levels of disease/pest resistance and for enhancing the quality of seed composition by interspecific hybridization. The variation in oil content and fatty acid composition of wild peanut species in the United States Department of Agriculture germplasm collection is unknown. Seeds available from 39 wild species (plus a cultivated peanut) were requested from the U.S. peanut germplasm collection. Oil content was measured using nuclear magnetic resonance, fatty acid composition was analysed using gas chromatography, and the D150N functional mutation of the FAD2A gene was screened by real-time PCR. Significant variability in oil content (41.7–61.3%) was identified among the wild peanut species. Arachis magna contained significantly more oil (61%) than cultivated peanut (56%). There was no functional mutation identified within the FAD2A gene target, and no wild species were identified with a high ratio of oleic acid to linoleic acid. The results from gas chromatography and real-time PCR analyses were consistent. However, Arachis sylvestris contained a significantly higher amount (22%) of long-chain fatty acid (LCFA) than the cultivated peanut (4%). Thus, A.magna and A. sylvestris may be good breeding materials to use for increasing oil content or LCFA composition of cultivated peanuts in breeding programs.