Screening of germplasm for specific traits is a continuous pre-breeding process in deriving the drought-tolerant donors required for crop improvement. The study evaluated 17 medium-late duration finger millet genotypes under drought stress (DS) for 28 days during the reproductive stage to identify the traits and genotypes for drought tolerance using different statistical analysis. The photosynthetic rate (by 26.3%), stomatal conductance (by 26.4%), transpiration rate (by 24.8%) and grain yield (by 13.2%) were decreased and found sensitive to DS, but the leaf temperature was increased (4.7%). From the path analysis and multiple linear regression analysis, the mean ear weight and productive tillers were found to contribute to the grain yield significantly under well-watered conditions. While under DS conditions, the mean ear weight, productive tillers and threshing percentage equally contributed to grain yield. Based on the ranking of traits significantly contributing to grain yield, the genotype GE-4683 with a higher mean ear weight (10.65 g) was found superior to the popular variety, GPU-28. The Multiple linear regression equation predicts the possibility to increase the yield of GPU-28 under DS from the existing 360.0 to 459.5 g per square metre (by 29.1%) by the incorporation of three productive tillers instead of the existing two tillers per plant in the MLR equation. An additional 1.0 g of mean ear weight will be able to predict an increased grain yield from 360.0 to 392.0 gm−2, equivalent to 3.60 to 3.92 t/ha (by 9.4%).

In order to better understand the molecular mechanisms associated with salinity tolerance, transcriptome analysis of a local salt-tolerant wheat landrace (i.e. Roshan) was performed under salt stress. Transcriptome sequencing yielded 137,508,542 clean reads using the Illumina HiSeq 2000 platform. The results of two alignment programs, i.e. STAR and HISAT2, were used separately to perform the analysis of differentially expressed genes (DEGs) using DESeq2. Finally, a total of 17,897 DEGs were identified by DESeq2. Moreover, gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses identified 108 GO terms and 62 significant KEGG pathways, of which ‘metabolic process’ and ‘metabolic pathways’ were the most abundant enriched term and pathway, respectively. Additionally, key salinity-tolerant genes, including asparagine synthetase, were also identified in the present study. Out of 87 identified families of transcription factors, GAI‐RGA ‐ and ‐SCR (GRAS) was one of the most important, which participates in signal transduction, and meristem maintenance and development. Eventually, to validate the gene expression levels, six DEGs were selected for a quantitative real-time polymerase chain reaction, and the results were in line with those of RNA-Seq. The findings of the current study can guide future genetic and molecular studies and allow a better understanding and improvement of salt tolerance in wheat.

Microsatellite markers specific to Cheirostylis yunnanensis Rolfe were developed using an enriched genomic DNA library technique. The library was constructed using (AG)20 and (CAG)20 oligonucleotide repeats. A total of 48 primer pairs were designed and tested with 48 C. yunnanensis Rolfe samples, resulting in 11 polymorphic loci. The number of alleles per locus ranged from 2 to 12, with an average of six alleles. The observed and expected heterozygosity ranged from 0.0426 to 0.8085 and 0.0421 to 0.9078, respectively. Of the 11 polymorphic loci, three showed a significant deviation from Hardy–Weinberg equilibrium and one exhibited linkage disequilibrium. Cross-species amplification was tested with five samples of Cheirostylis of unknown species resulting in eight loci that could be amplified, with the number of alleles ranging from one to two. The microsatellite markers developed in this study will be useful for the genetic analysis of C. yunnanensis in order to differentiate species as well as to establish a conservation plan for this species.

Low-quality water and soil salinization are increasingly becoming limiting factors for food production, including olive – a major fruit crop in several parts of the world. Identifying putative salinity-stress tolerance in olive would be helpful in the future development of new tolerant varieties. In this study, novel salinity-responsive biomarkers (SRBs) were characterized in the species, namely, monooxygenase 1 (OeMO1), cation calcium exchanger 1 (OeCCX1), salt tolerance protein (OeSTO), proteolipid membrane potential modulator (OePMP3), universal stress protein (OeUSP2), adaptor protein complex 4 medium mu4 subunit (OeAP-4), WRKY1 transcription factor (OeWRKY1) and potassium transporter 2 (OeKT2). Unique structural features were highlighted for encoded proteins as compared with other plant homologues. The expression of olive SRBs was investigated in leaves of young plantlets of two cultivars, ‘Nabali’ (moderately tolerant) and ‘Picual’ (tolerant). At 60 mM NaCl stress level, OeMO1, OeSTO, OePMP3, OeUSP2, OeAP-4 and OeWRKY1 were up-regulated in ‘Nabali’ as compared with ‘Picual’. On the other hand, OeCCX1 and OeKT2 were up-regulated at three stress levels (30, 60 and 90 mM NaCl) in ‘Picual’ as compared to ‘Nabali’. Salinity tolerance in olive presumably engages multiple sets of responsive genes triggered by different stress levels.

Powdery mildew (PM) is one of the most severe fungal diseases of cucumber that limits its production worldwide. In this study, 140 genotypes of cucumber were screened for disease resistance under field and artificial conditions, and then validated with eight known SSR markers linked to PM resistance. Among these genotypes, genotype GS140 was found resistant (R), whereas GS148, GS16 and GS70 were moderately resistant, and GS169 was found to be tolerant. Of all the eight markers, only C31, C80, C162, SSR16472 and SSR16881 amplified the reported linked allele. The 127 bp allele of SSR16881 was found to be associated with the lowest disease severity of 37.65%. The associated markers could further be verified for their usability using linkage studies and the contrast genotypes in the present study could serve as a tool for selection in future marker-assisted selection breeding strategies for PM resistance.

Due to the high yield losses caused by late blight in potato cultivation, the development of resistant pre-breeding material is of great importance for cultivar breeding. The gene pool of the Julius Kühn Institute (JKI) includes a large collection of resistant clones whose resistance has not yet been analysed in detail with markers for relevant resistance genes. A panel of 52 pre-breeding potato clones developed at the JKI via interspecific crosses and highly resistant to late blight were tested for the presence of seven resistance genes (Rpi-blb1/Rpi-sto1, Rpi-blb2, Rpi-blb3/R2/Rpi-abpt, R1, R3a, R3b, Rpi-phu1) and one QTL allele (QTL_phu-stn) from Solanum species S. bulbocastanum, S. demissum, S. phureja and S. stoloniferum, respectively. Molecular marker assays based on sequence-specific primers revealed that 36 of the 52 pre-breeding clones carried either 1, 2, 3 or 4 resistance genes introgressed from these wild Solanum species. Results indicate that these resistance genes were retained over generations of breeding. Although highly resistant to late blight, 16 pre-breeding clones did not carry any of these resistance genes. Resistance in the gene pool may, thus, be based not only on individual resistance genes but also on QTL effects. Results help to better understand both inheritance and expression of late blight resistance of this unique gene pool and may be used for breeding programmes.

Rhazya stricta is an endangered medicinal plant that is under severe human pressure as a result of commercial harvesting. As a model of habitat fragmentation, we selected the Kohat Plateau in the Pakistani Himalaya, where populations are fragmented, with less than 100 individuals per population. We hypothesized that the populations may be threatened by rapid habitat fragmentation and by unsustainable utilization of the plant. We analysed P450-based analogue functional genomic markers and amplified fragment length polymorphism markers from six populations of R. stricta on the Kohat Plateau, and examined their variations both within and among the populations. Both the marker groups revealed lower genetic differentiation among the populations and higher genetic differentiation within the populations as a result of high gene flow. The results confirmed that habitat fragmentation is being caused by severe human pressure, and although signs of genetic erosion are not yet visible, they seem likely to become visible in the future. Therefore, the conservation of R. stricta populations is necessary.

The Sikkim-Himalaya represents one of the unique reservoirs of rice genetic resources in India owing to the presence of a large number of landraces adapted to extreme climatic and edaphic conditions. This valuable gene pool is now under threat due to the introduction of high-yielding varieties, wanting suitable genetic intervention for enhancing their productivity, and thus economic viability. Development of lodging resistant, high-yielding varieties tolerant to soil acidity through association mapping aided marker-assisted breeding programmes can help achieve this in a fast and efficient manner. But this requires information on genetic diversity, population structure, etc., of the germplasm collection, which is strikingly lacking. We, therefore, characterized a set of 53 rice landraces from Sikkim to address the above issues. The results revealed moderate diversity, poor divergence and high gene flow in our germplasm collection attesting its utility as an association mapping panel. Further, a total of 115 putative marker-trait associations (P < 0.05, R2 ≥ 10%) were obtained using the general linear model and mixed linear models of which 25 were identical in both. Some of the associated markers were positioned in those regions where Qualitative Trait Loci have been previously identified in rice, providing credence to our results. The resources generated from this study will benefit the rice breeders from this region and elsewhere for targeting the yield and related traits, in addition to conservation efforts by the interested researchers.

The stagnation of sorghum grain yields worldwide and utilization of inbred lines by public and private organizations (multinational seed companies) warrant the understanding of genetic diversity present in inbred lines. The objectives of this study were (1) to compare morphological and molecular diversity analysis and (2) to identify heterotic pools from the genotypes evaluated. Sixty-five rainy-season elite lines were evaluated during the 2006 and 2007 rainy seasons, and 15 post-rainy-season genotypes in the 2003 and 2004 post-rainy seasons for their distinctiveness, uniformity and stability at the Directorate of Sorghum Research, Hyderabad, India. Ninety-three genotypes (ten rainy-season B lines, 13 rainy-season R lines, 36 rainy-season varieties, seven rainy-season hybrids, ten forage varieties and 17 post-rainy-season genotypes) were evaluated using 48 simple sequence repeat (SSR) markers that are uniformly distributed over the sorghum genome. From the 93 genotypes analysed, 310 alleles were observed, with an average of 6.5 alleles per locus. A high level of polymorphism (mean 97%) was detected. A significant positive correlation (r = 0.463; P = 0.001) between genetic similarities and morphological similarities was obtained. Unlike previous reports, both methods clearly distinguished B lines, R lines, rainy-season varieties, post-rainy-season varieties and forage varieties. Forage and post-rainy-season varieties present a higher diversity of 60%. This could be because the post-rainy-season varieties are developed from local landraces and forage genotypes from crosses such as Sorghum bicolor × Sudan grass. Herein, we further discuss the grouping of elite genotypes into different heterotic pools.

Selection of lines from segregating generations and breeding hybrids to exploit heterosis or heterobeltiosis is an effective tool for improving economically important traits in the genus Capsicum. The objective of this study was to identify high potential parents to obtain high-yielding F1 hybrids using a Line × Tester (8 × 2) mating design in the Habanero pepper improvement programme. Ten parents and 16 hybrids were evaluated in order to determine their values of general combining ability, specific combining ability, heterosis, and heterobeltiosis. Parent NKA-11 had the highest values of GCA for different quantitative variables of the fruit, which does it suitable for future improvement works, and tester RNJ-04 showed the highest value of GCA for fruit length. The quantitative variables evaluated confirm a significant genetic variability among the Habanero pepper genotypes studied. The best hybrids were NEK-03xRNJ-04, NBA-06xRNJ-04, AKN-07xRNJ-04, and RKI-10xRNJ-04, which showed their high productive potential with values between 3.13 and 4.92 Kg/Pta, a quality, that would open to them the national market for fresh consumption. Based on the GCA values of the parents and heterosis of the progenies, it is concluded hybridization would be the most appropriate genetic improvement method to increase both yield (YP) and the number of fruits for plant.

Two unique black pepper accessions with very long spikes, hitherto unreported in the world genepool of black pepper, were collected from the centre of origin of the species and characterized. The two accessions can be a valuable genetic source in the improvement of spike length.

Rice crop is affected by different types of floods at different stages of the crop cycle. Constant efforts of researchers resulted in the development of rice varieties for anaerobic germination, flash floods and stagnant flooding by both conventional and molecular breeding approaches. Detection of QTLs for different types of floods in new genetic source (AC39416A) is needed to combat adverse effects of climate change. Present investigation was carried out to identify QTLs for flood tolerance using recombinant inbred lines derived from Indra and AC39416A. QTL mapping resulted in identification of QTLs, qAG3.1 on chromosome 3 for anaerobic germination and qSF10.1 on chromosome 10 for plant survival % under stagnant flooding. These QTLs explain 59.08 and 13.21% of phenotypic variance respectively. Two candidate genes were identified in qAG3.1 region, LOC_Os03g42130 gibberellin 20 oxidase2 and LOC_Os03g44170 glutathione S-transferase. The underlying mechanism might be the inhibition of gibberellic acid synthesis and thereby protecting seedlings from oxidative stress under anoxia condition. Genomic region of qSF10.1 revealed LOC_Os10g35020 glycosyltransferase and LOC_Os10g35050 aquaporin protein loci, which might be responsible for adaptive mechanism for plant survival % under stagnant flooding. This indicates that the new genetic resource AC39416A has an ability to adopt to different types of flood tolerance in response to environmental stress. Unveiling physiological and molecular mechanisms for flood tolerance in AC39416A using advanced omics studies would help in precise genomic selections for sustained production in flood-prone areas.

Next-generation sequencing is a new technique for plant genome sequencing at a large scale that is faster and cheaper than previous sequencing technologies. The present work reports the development of new polymorphic simple sequence repeat (SSR) markers in oil palm (Elaeis guineensis Jacq.) using Illumina HiSeq sequencing data. More than 39 Gb (total 39,086,646,904 bases) was generated from the selected oil palm clone, D4. After de novo assembly, a total of 130,840 potential SSRs were identified. For SSR validation, 144 out of 762 SSR primer pairs were designed, including tri-nucleotide motifs, from the D4 contigs. Using 11 lines from three different clones of oil palm, 61 SSR primers revealed polymorphic alleles and high average polymorphic information content (PIC) values. Cluster analysis separated all oil palm plants into three clusters: clones A, B and C. These identified genome-wide SSR markers will enrich current genomic resources of the oil palm crop.

The genebank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India holds a collection of 542 accessions from the Caribbean and Central American (CCA) regions, of which 424 were evaluated for eight qualitative and 17 quantitative traits at ICRISAT farm. A hierarchical cluster analysis was performed using the scores of the first nine principal components that resulted in four clusters. The accessions of these four clusters exhibited the following good characteristics: cluster 1 had high pod-bearing length and high seed protein content; those of cluster 2 had high degree of branching, large number of pods per plant and high seed yield per plant; those of cluster 3 had long pods; and those of cluster 4 had larger seeds. In the whole collection of accessions, diversity was found to be maximum (H′ = 0.630+0.026) for plant height and minimum for tertiary branches per plant (H′ = 0.259+0.026). The highest correlation coefficient was observed between racemes per plant and pods per plant (r= 0.914) followed by between pods per plant and seed yield per plant (r= 0.744), and between shelling percentage and the harvest index (r= 0.703). In view of the poor representation of the world collection of pigeonpea (13,771 accessions) from the CCA regions, launching of collection missions in these countries has been suggested to fill gaps and increase the variability. Multi-location evaluation of the collections for agronomic traits at potential locations in the CCA regions and systematic evaluation for nutritional traits and resistance to biotic and abiotic stress could result in the identification of useful genotypes, particularly vegetable types, for use in breeding programmes to develop high-yielding cultivars as well as to release as varieties in these regions.

Camelina (Camelina sativa (L.) Crantz), an oilseed crop, belongs to the Brassicaceae family. Two unique features of camelina in comparison with the main oil crops are an adaptation to different environments and also its unique oil composition. The development of doubled haploid plants is one of the essential methods for crop improvement. The study of genetic diversity is an important step in planning crop breeding programmes. This research was conducted to evaluate the genetic variation of 81 camelina doubled haploid lines obtained from 15 crosses by inter simple sequence repeat (ISSR) markers. The total number of amplified bands was 243, of which 239 bands (98.3%) showed polymorphism. The percentage of polymorphic bands varied between 93.75 and 100. The size of the bands ranged from 50 to 1700 base pairs. The informative ISSRs were identified by estimating marker features: polymorphism information content, effective multiplex ratio, marker index and resolving power. Three markers had higher resolving power values (9.88, 8.5 and 7.46) and were the most informative markers to identify the lines. Cluster analysis based on the complete algorithm divided the lines into five groups, indicating relatively clear configuration from the geographic distribution patterns of the parents of the doubled haploid lines. Principal coordinate analysis classified the 81 camelina doubled haploid lines into six groups. The ISSR markers detected high polymorphism to reveal the genetic variation of camelina lines. The findings of this research, along with the characterization of biochemical traits of the lines, can improve breeding programmes achieve high-yielding camelina varieties with higher and better oil content.

Plant viruses pose a threat to the acquisition, maintenance and distribution of lupin germplasm (genus Lupinus, family Fabaceae). The availability of sufficient quantities of healthy and virus-free seeds from maintained lupin collections is mandatory for conducting lupin research. The objective of this research was to determine which lupin species were potentially infected with potyviruses (presumably seed-borne) upon germination in the greenhouse. The procedure for screening lupin seedlings in the greenhouse for potyviruses incorporated enzyme-linked immunosorbent assay followed by elimination or segregation of infected seedlings from the population before transplantation into the field plots for regeneration and accession characterization. None of the accessions in this evaluation had been tested previously for virus. From 2002 to 2005, 15 perennial (30 accessions) and 6 annual lupin species (213 accessions) were evaluated on site at the Western Regional Plant Introduction Station in Pullman, WA, USA. While none of the greenhouse perennial seedlings tested positive for potyvirus, seedlings in three annual species (Lupinus albus, Lupinus angustifolius and Lupinus luteus) were infected by potyviruses, presumably by seed transmission. Future testing may focus on the annual species, thus saving limited germplasm maintenance resources.

In India, the restriction of genetically modified (GM) crops and derived products not approved in the country necessitates surveillance for transgene(s) in plant material/products imported into the country. CDC Triffid expressing acetolactate synthase (ALS) conferring tolerance to sulphonylurea herbicide is the only GM flax event that has got approval in Canada in 1990s and subsequently deregistered in 2001. In spite of deregistration, the unexpected and unauthorized detection of traces of GM flax in the consignments imported from Canada to Europe has further necessitated the stringent monitoring of flax shipments from Canada for suspected GM incidents. This study reports on the detection of transgenic elements being present in GM flax employing polymerase chain reaction assays, in a set of 123 flaxseed accessions imported from Canada for research purpose. Based on the tests conducted, none of the transgenic elements, namely, nos promoter (P-nos), nos terminator (T-nos), nptII marker gene, ALS transgene, as present in the GM flax CDC Triffid were detected in any of the tested accessions. The well-known herbicide tolerance gene cp4-epsps, being employed in Roundup® Ready events of other crops, was also not detected in these samples. This case study has demonstrated the importance of monitoring the presence of transgene(s) in flaxseed imports, and such studies need to be carried out for the imported seeds from the country where GM events of respective crop are being approved whereas they have not been approved in the country of import as a part of precautionary approach.

In this study, a near-isogenic line (BC4F10) CR572 developed by introgressing a chromosomal segment from Oryza rufipogon (accession no. 105491) into the Oryza sativa subsp. japonica cv. Hwaseong was found to exhibit a significant increase in the number of spikelets per panicle (SPP) and grain weight compared with the recurrent parent Hwaseong. Quantitative trait locus (QTL) analysis in F2 generation derived from the cross between CR572 and Hwaseong revealed that two QTLs, qSPP1 and qTGW1, were linked to a simple sequence repeat marker, RM283, on chromosome 1. The additive effect of the O. rufipogon allele at qSPP1 was 13 SPP, and 21.6% of the phenotypic variance was explained by the segregation of RM283. The qTGW1 QTL explained 19.1% of the phenotypic variance for grain weight. Substitution mapping was carried out with five F3 lines derived from F2 plants having informative recombination breakpoints within the target region. Substitution mapping indicated the linkage of qSPP1 and qTGW1. The grain yield of CR572 was 18.2 and 15.8% higher than that of Hwaseong at two locations, respectively, mainly due to the increase in 1000-grain weight and SPP. These results are very useful for QTL cluster transfer by molecular marker-assisted selection in rice breeding programmes and for QTL gene cloning by map-based cloning.

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.

High-throughput genotyping using single-nucleotide polymorphisms (SNP) is one tool that can be used to study the genetic relationships between wild rice relatives and cultivated rice. In this study, a set of 96 indica–japonica SNP markers, which can differentiate indica and japonica subspecies of rice, were used to characterize 227 Oryza accessions including 93 AA genome accessions from seven wild Oryza species. A total of 72 markers of the 96 markers were selected for the phylogenetic study and allele polymorphism survey. A subset of SNP markers were present only in Oryza sativa and evolutionarily close species, Oryza nivara and Oryza rufipogon. These markers can be used for distinguishing cultivated rice from the other species and vice versa. Eight clusters were generated through phylogenetic analysis, and Oryza meridionalis and Oryza longistaminata appeared to be the most distantly related species to cultivated rice. In this study, Oryza barthii and Oryza glaberrima accessions were found to exhibit high genetic similarity. Across the wild species, more indica-type alleles were detected for most accessions. In this study, a set of markers selected to be informative across O. sativa accessions were used, but it will be interesting to compare the results of this study with SNP data obtained through next-generation sequencing in the future.