To explore trait variation, assess relative performance and establish association among yield and its associated traits in maize under organic system, 373 maize genotypes that consisted of landraces, open-pollinated varieties and single-cross hybrids were tested under organic management in Sikkim midhills. Data of 8 years (2009–2015 and 2019) for 12 agronomic traits viz., plant height, days to 50% tasselling, days to 50% silking, days to 75% dry husk, grain yield per ha, anthesis–silking interval, cob length, cob diameter, kernel rows per cob, kernels per row, number of cobs per plot and test weight were taken for analysis. Conventionally bred maize hybrids yielded 95.36% higher than the landraces and 58.60% higher than the open-pollinated varieties. Landraces displayed highest mean anthesis–silking interval of 7.18 days. In open-pollinated varieties, test weight showed a positive association with grain yield (0.37) while plant height (0.33) and kernels per row (0.34) were positively correlated to grain yield in case of landraces. Number of cobs per plot showed a very strong association with grain yield in hybrids (1.0). Kernels per cob and test weight contributed 24% to the variation in grain yield in open-pollinated varieties while anthesis–silking interval, days to maturity, number of cobs/plot, test weight and kernel per row accounted for 97% of the variation in grain yield in landraces. Grain yield in single-cross hybrids is contributed maximum (97%) by days to tasselling, silking, anthesis–silking interval, plant height and number of cobs per plot. The study indicates attaining high number of cobs per unit area along with emphasis on traits such as kernels per row, cob length and diameter for achieving higher yields in single-cross hybrids, selection of high test weight genotypes for open-pollinated varieties and emphasis on cob length, kernels per row and plant height for yield improvement in landraces.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Triggered by the need to develop inter-seasonal, multi-cut cereal forage crops, this study aimed at the exploitation of phenotypic variations among the rich pearl millet (Pennisetum glaucum L.) collections in Sudan for possible utilization in forage-type breeding programmes. A total of 100 pearl millet accessions were used in three field trials grown in rainy, winter and summer seasons (2008–2009) at the Gezira Research Station Farm and the Gezira University Experimental Farm. Wide diversity and highly significant differences in the total dry forage yield, days to harvest, plant height, number of tillers/plant and leaf/stem ratio were found among the accessions. At an 80% morphological similarity level, the 100 accessions of pearl millet were clustered into four main groups. In the rainy and winter seasons, 71 and 56% of the accessions produced forage yield of more than 5 t/ha, respectively. In contrast, 77% of the accessions produced less than 5 t/ha in the summer season. Among the top-ranking 25 accessions, two accessions (HSD 2190 and HSD 2236) were common in dry matter yield in the three seasons, whereas 11 accessions were identified in at least two seasons. The presence of such common accessions in more than one season is encouraging for growing pearl millet as a multi-cut crop for a longer period. These results indicated the possibility of the development of forage-suited varieties of pearl millet directly through further evaluation of those common accessions or indirectly through a crop breeding programme.

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.

The search for disease resistance in wild types is continuing, in order to introduce resistant genes from wild relatives. In this study, we found that the wild melon Cucumis prophetarum was comparably more tolerant to salinity, the damping-off disease caused by the fungus Rhizoctonia solani and the root-knot nematode Meloidogyne incognita. The percentage of wild melon survival was 60% compared to that of the cultivated cucumber Cucumis sativus, which was 15%, when irrigated with NaCl at a concentration of 2500 ppm; and 96% for the wild melon compared with 44% for the cultivated cucumber when irrigated with CaSO4.2H2O at a concentration of 1000 ppm. Wild melon plants were more tolerant to R. solani attack, as only 20% of the plants were infested compared with 100% of infestation observed for the cultivated cucumber. The average number of nematode galls was 250 per plant on the cultivated cucumber when compared with 6.3 per plant on the wild species. Wild melon could be a potential source of resistant or tolerant genes that can be transferable to cultivated cucumbers.

Chinese jiaotou is an economically important crop that is widely cultivated in East Asia. The lack of simple sequence repeat (SSR) markers has been a major obstacle for genetic studies of this crop. In the present study, SSR markers were developed for Chinese jiaotou on a large scale, based on the crop's transcriptome assembled de novo by a previous study. A search for SSR loci in the transcriptome's expressed sequence tags (ESTs) revealed 2157 SSRs, of which primer pairs could be developed for 1494. Among these resulting SSRs, trinucleotide repeat motifs were the most abundant type, with GAA/TTC motifs occurring most frequently. Analysing the annotated function of SSR-containing ESTs revealed that they enriched into the GO categories involved in transcription regulation, oxidation–reduction, transport, etc. The quality and transferability of these markers were also assessed using 100 randomly selected EST–SSRs, and the result showed that these markers were of good quality and possessed high cross-species transferability. In addition, the developed SSR markers were used to analyse the genetic diversity of 19 cultivated and four wild accessions, resulting in three distinct groups, cluster I, II and III. Interestingly, all four wild accessions were assigned to cluster III, and two local varieties from northern Hunan, China, were closely related to the wild genotypes. These results provide new insights into the origin of Chinese jiaotou. The EST–SSRs developed herein represent the first large-scale development of SSR markers in Chinese jiaotou, and they can be widely used for genetic studies of the crop.