Understudied Crop Research Articles

Phenological, Morphological and Agronomic Characterization of Bambara Groundnut Genotypes on Plinthite Soil in East-centre Area, Burkina Faso

Bambara groundnut has long been a neglected and understudied crop. Thanks to the new orientations for the développement of agriculture and achievement of food security in Burkina Faso, in recent years, studies on Bambara groundnut have experienced renewed interest. Despites nutritional, agronomic and socio-economic importance and some studies carried out on this crop. The diversity within Bambara groundnut cultivated remains poorly understood. The objective of this study was to assess phenological morphological and agronomic characterization of 20 Bambara groundnut accessions from National Institute for the Environment and Agricultural Research (INERA) genebank. The experimental device used was a completely randomized Fisher blocks with four replications on the site of University Centre of Tenkodogo. These accessions were evaluated on 23 morphological characters including four qualitative characters and 19 quantitative characters. Qualitative traits showed high proportion of oval terminal leaflet shape (70%), cream coloured seeds (45%) and 80% presence of eyes of various shapes and colours. The analysis of quantitative characters showed all the characters are discriminating except the plant spread (PlS) at the 5% treshold with regard to morphological, physiological and agronomic traits and low coefficient of variation (CV) values for the different phenological characters, except for the number of days from sowing to 50% plantlet emergence (EMG50). Pearson correlation matrix indicated positive and negative correlation. Most of the negative correlation was observed between phenological and agronomic traits The dendrogram showed organization of the variability in three different groups on the basis of the physiological, phenological and agronomic traits. The variability expressed among INERA gene bank genotypes showed important variability, which can be exploited in Bambara groundnut breeding programs using the clustering and associations of characters.

Melothria scabra [Naudin] Provides New Opportunities for Agronomic Research

This manuscript attempts to bringMelothria scabra[Naudin] to the attention of agronomic researchers as an increasingly popularand economically important crop and to identify gaps in research that should beinvestigatedwithfuturestudies.Allrelevantpeerreviewedpublications were examined in this study, with 79% of the studies published since 2000 c.e., while the remainder of the studies provide historical context.Major gaps in the research involvingM. scabraoffers a new frontier in agronomic studies, and will increase agronomist’s knowledge of this uniquely meso-American crop species. In conclusion,M. scabrais an understudied crop with world-widecultivation, and offers many opportunities foragronomists to research the genetics, physiology, and morphology of this small melon

Breeding and Agronomic Evaluation of Jilv 20, a New Mungbean (Vigna radiata L.) Cultivar

Mungbean (Vigna radiata L.), one of the most widely grown edible legumes in Asia, plays important roles in the improvement of agricultural cultivation systems as well as human diets. As an understudied crop, however, most mungbean varieties are characterized by unstable yields, poor disease resistance, and unsuitability for mechanical harvesting, thereby leading to a low production income. We, therefore, developed Jilv 20, a new mungbean cultivar with a dull seed coat, by crossing Bao 942-34 with Weilv 9002-341. After 11 years of selection and evaluation, Jilv 20 has shown wide adaptability, early maturity, high yield, halo blight resistance, and suitability for mechanical harvesting. The growth period of Jilv 20 is 79.5 and 66.7 days in the spring and summer sowing seasons, respectively, and the average plant height is approximately 56.4 cm. In this study, average yields were 1737.9, 1532.3, and 2045.1 kg/hm2 in northern spring-sowing, northern summer-sowing, and southern sites, respectively; these values were respectively 27.83%, 28.48%, and 6.96% higher than those of control cultivar Zhonglv 5, which has been popular in past decades because of its wide adaptability. The average protein and starch contents of Jilv 20 seeds were 25.0% and 49.56%, respectively. Further application and extension of Jilv 20 in China should contribute to mungbean production, breeding, and industrial development.

Development of single nucleotide polymorphism markers and genetic diversity in guava (Psidium guajava L.)

Societal impact statementThere are many understudied fruits of great economic and productive importance for regional agricultural hubs. Guava is an American fruit species with attractive nutritional and adaptability characteristics. However, in many countries like Mexico, its cultivation is still limited to small‐to‐medium size plantings and home gardens and depends on poorly controlled germplasm that diminishes productivity and expansion. Our study provides valuable insight to better understand guava diversity and generate high‐yielding, high‐quality, and better adapted materials. Supporting the study and development of understudied crops will provide us with more resources for facing climate change adversities and for diversifying cropping systems.Summary Guava (Psidium guajava L.) is a fruit crop species native to tropical and subtropical regions of America with great productive and economic potential due to its extensive environmental adaptability, nutritional value, and medicinal properties. However, the lack of molecular resources for accelerated breeding, limited knowledge about its evolutionary and domestication history, and unfavorable policies have limited its genetic improvement and broader adoption as a commercial fruit crop. Here, we present the first diversity study in guava employing genome‐wide single nucleotide polymorphisms (SNPs). Forty‐eight accessions collected from Mexico and other continents were examined with more than 6000 high‐quality SNP markers, which represents a marker density increase of ~30x compared with previous studies. Relationships between genetic groupings and geographic origins were not apparent in this diverse guava collection using principal component and structure analyses. Extensive germplasm exchange among guava‐producing regions and limited varietal control at commercial plantations might have contributed to ambiguities when defining the true origin and identities of existing germplasm materials. However, an analysis of domestication syndrome traits (fruit size and sugar) by wild or improved germplasm revealed several putative genomic regions under selection. Knowledge about germplasm origins and genetic relatedness, in conjunction with reliable molecular resources and better agronomic practices, is necessary to support breeding efforts and facilitate broader adoption of orphan crops such as guava, which have increasingly important roles in light of climate change adversities and in diversifying diets and food systems.

Farmers' Appraisal on Okra [Abelmoschus esculentus (L.)] Production and Phenotypic Characterization: A Synergistic Approach for Improvement.

Okra [Abelmoschus esculentus (L.) Moench] is a nutrient-rich economically important vegetable crop grown in tropical and sub-tropical regions of the world. Okra is one of the horticultural mandate crops of the National Horticultural Research (NIHORT), Ibadan, Nigeria. It is an under-studied crop in terms of genetic improvement in Nigeria. In response to farmers’ demand for improved varieties, the institute commenced efforts in developing novel okra varieties. However, a successful and sustainable crop improvement program depends on the identification of market-driven demands and the availability of variation in the crop germplasm. In view of the above, this research began with an appraisal study to assess the current situation of okra production and to identify farmers’ preferred traits for establishing breeding priorities. According to the results of the participatory rural appraisal, some of the important constraints affecting okra productivity are lack of improved varieties, diseases, pests, and drought. The quest to assess variability in the collected okra accessions and select superior varieties with farmers’ preferred traits, fifty (50) okra accessions were evaluated in the field for 3 consecutive years (2019–2021) using a 5 × 10 α-lattice incomplete block design with three replications. The ANOVA revealed high significant variation (p < 0.001) in the number of days to first flower, pod length, and pod girth. The variability observed among the accessions will be useful in the selection of potential parents required for hybridization and generation of progenies with desirable traits for farmers.

Combined effects of landscape composition and pesticide use on herbivore and pollinator functions in smallholder farms

BackgroundLandscape composition has the potential to foster regulating ecosystem services such as pollination and biocontrol in temperate regions. However, most landscape studies do not take pesticide use into account even though it is the main control strategy worldwide and has negative impacts on beneficial insects. Moreover, few studies have explored these combined effects in smallholder cropping system with diverse landscapes and small cultivated fields.MethodsWe assessed the effect of semi-natural cover and pesticide use on pollinator and herbivore abundances and functions in 9 fields in the Ecuadorian Andes through participatory experiments with smallholder farmers. We performed a path analysis to quantify the effects of landscape and pesticide use on herbivory, pollination and ultimately yield.ResultsPesticide use significantly reduced pollinator abundance but had no significant effect on pest abundance. Similarly, we found non-significant effects of landscape composition on either herbivory and pollination. The study also provides new information on understudied Andean lupine’s pests and pollinators, whose application for small farmers is discussed. Finally, we hypothesize that peculiarities of tropical smallholder cropping systems and landscapes could explain the non-significant landscape effects on insect-based processes, which calls for more research in places outside the well-studied temperate region.ConclusionsLandscape composition did not show any significant effect on pest and pollinator while pesticide use decreased the abundance pollinators, but with no significant effect on yield. This study also provides information about Andean lupine reproduction and overcompensation mechanisms that could be of interest for local farmers and researchers of this understudied crop.

Diversity in Qualitative and Quantitative Traits Reveals Huge Potential for the Improvement of an Orphan Crop Tef [Eragrostis tef (Zucc.) Trotter

Aims: To assess the extent and pattern of genetic diversity in major qualitative and quantitative traits of tef accessions based on collection altitudes, and administrative regions and zones.&#x0D; Study Design: Randomized complete Block Design with three replications.&#x0D; Place and Duration of Study: The study was conducted at Debre Zeit and Holetta Research Centers in 2015 main cropping season.&#x0D; Methodology: One hundred forty-four tef accessions collected from the Northern and Central Ethiopia were evaluated using five qualitative and seven quantitative traits. Microsoft Excel and Shannon-Weaver diversity index were used to determine the extent of genetic variations while cluster analysis based on the standardized data of various qualitative and quantitative traits was employed to group the accessions and collection altitudes, zones and regions.&#x0D; Results: Yellowish white lemma, loose panicle, white seed, four internodes and green basal stalk were found to be the predominant phenotypic classes of the studied qualitative traits. The highest mean Shannon diversity was observed for panicle forms (0.396) followed by seed colour (0.370) while the lowest value was for basal stalk colour (0.083). Accessions from Oromia Regional State had the highest mean Shannon diversity and grain yield compared to the other two Regional States. Similarly, accessions from South Wello and West Shewa administrative zones had the highest mean Shannon diversity and highest grain yield, respectively. Besides, accessions from altitudes below 1500 m above sea level (a. s. l.) and from 2001 to 2500 m a. s. l. also had the highest mean diversity and highest mean grain yield, respectively. In cluster analysis, dendrogram constructed based on five qualitative and seven quantitative traits grouped the accessions, collection regions, zones and altitudes into six, two, four and three distinct clusters, respectively.&#x0D; Conclusion: The present study generally revealed huge diversity among tef accessions collected from different regional states, administrative zones and altitudes which can be harnessed in future improvement of this understudied crop.

Improving yield and fruit quality traits in sweet passion fruit: Evidence for genotype by environment interaction and selection of promising genotypes

Breeding for yield and fruit quality traits in passion fruits is complex due to the polygenic nature of these traits and the existence of genetic correlations among them. Therefore, studies focused on crop management practices and breeding using modern quantitative genetic approaches are still needed, especially for Passiflora alata, an understudied crop, popularly known as the sweet passion fruit. It is highly appreciated for its typical aroma and flavor characteristics. In this study, we aimed to reevaluate 30 genotypes previously selected for fruit quality from a 100 full-sib sweet passion fruit progeny in three environments, with a view to estimating the heritability and genetic correlations, and investigating the GEI and response to selection for nine fruit traits (weight, diameter and length of the fruit; thickness and weight of skin; weight and yield of fruit pulp; soluble solids, and yield). Pairwise genetic correlations among the fruit traits showed mostly intermediate to high values, especially those associated with fruit size and shape. Different genotype rankings were obtained regarding the predicted genetic values of weight of skin, thickness of skin and weight of pulp in each environment. Finally, we used a multiplicative selection index to select simultaneously for weight of pulp and against fruit skin thickness and weight. The response to selection was positive for all traits except soluble solids, and the 20% superior (six) genotypes were ranked. Based on the assumption that incompatibility mechanisms exist in P. alata, the selected genotypes were intercrossed in a complete diallel mating scheme. It is worth noting that all genotypes produced fruits, which is essential to guarantee yields in commercial orchards.

Metabolite database for root, tuber, and banana crops to facilitate modern breeding in understudied crops.

SummaryRoots, tubers, and bananas (RTB) are vital staples for food security in the world's poorest nations. A major constraint to current RTB breeding programmes is limited knowledge on the available diversity due to lack of efficient germplasm characterization and structure. In recent years large‐scale efforts have begun to elucidate the genetic and phenotypic diversity of germplasm collections and populations and, yet, biochemical measurements have often been overlooked despite metabolite composition being directly associated with agronomic and consumer traits. Here we present a compound database and concentration range for metabolites detected in the major RTB crops: banana (Musa spp.), cassava (Manihot esculenta), potato (Solanum tuberosum), sweet potato (Ipomoea batatas), and yam (Dioscorea spp.), following metabolomics‐based diversity screening of global collections held within the CGIAR institutes. The dataset including 711 chemical features provides a valuable resource regarding the comparative biochemical composition of each RTB crop and highlights the potential diversity available for incorporation into crop improvement programmes. Particularly, the tropical crops cassava, sweet potato and banana displayed more complex compositional metabolite profiles with representations of up to 22 chemical classes (unknowns excluded) than that of potato, for which only metabolites from 10 chemical classes were detected. Additionally, over 20% of biochemical signatures remained unidentified for every crop analyzed. Integration of metabolomics with the on‐going genomic and phenotypic studies will enhance ’omics‐wide associations of molecular signatures with agronomic and consumer traits via easily quantifiable biochemical markers to aid gene discovery and functional characterization.

Genetics and Breeding of Lupinus mutabilis: An Emerging Protein Crop.

Protein crops have gained increasing interest in recent years, as a transition towards plant-protein based diets appears pivotal to ensure global food security and preserve the environment. The Andean species Lupinus mutabilis emerges as an ideal protein crop with great potential for Europe and other regions with temperate climates. This species is characterized by oil and protein content similar to soybean and is highly valued for its adaptability to colder climates and low input agriculture on marginal land. However, its introduction outside the Andes has yet to take off. To date, L. mutabilis remains an under-studied crop, lacking high yield, early maturity and a consistent breeding history. This review paper identifies L. mutabilis limitations and potential uses, and suggests the main breeding targets for further improvement of this crop. It also highlights the potential of new molecular tools and available germplasm resources that can now be used to establish L. mutabilis as a viable protein crop.

Evaluation of biorational insecticides and DNA barcoding as tools to improve insect pest management in lablab bean (Lablab purpureus) in Bangladesh

Abstract Lablab bean (Lablab purpureus) is a popular vegetable crop in Bangladesh, but farmers growing this crop experience significant losses to insect pests despite heavy reliance on conventional insecticides. We conducted field studies to improve pest management in lablab bean by testing biorational insecticides as alternatives to conventional insecticides for the control of pod borers (Maruca vitrata) and aphids (Aphis craccivora), and characterizing flower-inhabiting thrips as an emerging pest in this crop. In field experiments, spinosad was the most promising biorational we tested, suppressing pod-boring caterpillars more effectively than thiamethoxam or quinalphos. In contrast, azadirachtin (neem) did not significantly suppress any of the insect pests we measured, although target aphid populations were generally low at our research site. Using DNA barcoding at the coxI locus combined with morphological identification, we found eight thrips taxa inhabiting lablab bean flowers, dominated by Megalurothrips usitatus and M. distalis/peculiaris. A preliminary regression analysis indicated that these flower-inhabiting thrips reduced lablab bean yield. Our results suggest that spinosad may be useful within lablab bean IPM programs, and that these programs will likely need to incorporate tactics against thrips to effectively protect yield. Finally, we found that DNA barcoding was a valuable tool for pest identification in an understudied crop and region, but that to reach its full potential will require an investment in more comprehensive reference libraries.

African Orphan Crops under Abiotic Stresses: Challenges and Opportunities.

A changing climate, a growing world population, and a reduction in arable land devoted to food production are all problems facing the world food security. The development of crops that can yield under uncertain and extreme climatic and soil growing conditions can play a key role in mitigating these problems. Major crops such as maize, rice, and wheat are responsible for a large proportion of global food production but many understudied crops (commonly known as “orphan crops”) including millets, cassava, and cowpea feed millions of people in Asia, Africa, and South America and are already adapted to the local environments in which they are grown. The application of modern genetic and genomic tools to the breeding of these crops can provide enormous opportunities for ensuring world food security but is only in its infancy. In this review, the diversity and types of understudied crops will be introduced, and the beneficial traits of these crops as well as their role in the socioeconomics of Africa will be discussed. In addition, the response of orphan crops to diverse types of abiotic stresses is investigated. A review of the current tools and their application to the breeding of enhanced orphan crops will also be described. Finally, few examples of global efforts on tackling major abiotic constraints in Africa are presented.

A large set of 26 new reference transcriptomes dedicated to comparative population genomics in crops and wild relatives.

We produced a unique large data set of reference transcriptomes to obtain new knowledge about the evolution of plant genomes and crop domestication. For this purpose, we validated a RNA-Seq data assembly protocol to perform comparative population genomics. For the validation, we assessed and compared the quality of de novo Illumina short-read assemblies using data from two crops for which an annotated reference genome was available, namely grapevine and sorghum. We used the same protocol for the release of 26 new transcriptomes of crop plants and wild relatives, including still understudied crops such as yam, pearl millet and fonio. The species list has a wide taxonomic representation with the inclusion of 15 monocots and 11 eudicots. All contigs were annotated using BLAST, prot4EST and Blast2GO. A strong originality of the data set is that each crop is associated with close relative species, which will permit whole-genome comparative evolutionary studies between crops and their wild-related species. This large resource will thus serve research communities working on both crops and model organisms. All the data are available at http://arcad-bioinformatics.southgreen.fr/.

Tissue biochemical diversity of 20 gooseberry cultivars and the effect of ethylene supplementation on postharvest life

The European gooseberry (Ribes uva-crispa) is still an understudied crop with limited data available on its biochemical profile and postharvest life. A variety of polyphenols were detected in the skin and flesh of 20 gooseberry cvs, representing mainly flavonol glycosides, anthocyanins and flavan-3-ols. In contrast, gooseberry seeds were for the first time characterised by the presence of considerable amounts of hydroxycinnamic acid glycosides tentatively identified by UPLC-QToF/MS. All cvs examined represented a good source of vitamin C while being low in sugar. Furthermore, the postharvest stability of bioactives was explored by supplementation of exogenous ethylene in air at 5°C. Results suggest a low sensitivity of gooseberries to ethylene. The overall quality of gooseberries remained stable over two weeks, showing potential for extended bioactive life.

A study on Maruca vitrata infestation of Yard-long beans (Vigna unguiculata subspecies sesquipedalis)

Globally, Maruca vitrata (Geyer) is a serious yield constraint on food legumes including Yard-long bean (Vigna unguiculata subspecies sesquipedalis). However, there is a dearth of information on its damage potential, distribution and population dynamics in Yard-long beans. In the present study, the level of M. vitrata larval infestation on flowers and pods of Yard-long beans in Sri Lanka was determined with respect to three consecutive cropping seasons, Yala, Off and Maha. Results indicated that larval infestation and abundance varied with developmental stage of flowers and pods, cropping season and their combined interactive effects. Flowers of Yard-long beans were more prone to M. vitrata larval attack compared to pods. Abundance and level of infestation of M. vitrata varied with plant parts, having a ranking of flower buds (highest) > open flowers > mature pods > immature pods (lowest). Peak infestation was observed six and eight weeks after planting on flowers and pods, respectively. Among the three cropping seasons, M. vitrata infestation was found to be higher during Maha and Off seasons compared to Yala. The findings of this study contribute to the identified knowledge gap regarding the field biology of an acknowledged important pest, M. vitrata, in a previously understudied crop in Sri Lanka.

The transferability and polymorphism of mung bean SSR markers in rice bean germplasm

Rice bean (Vigna umbellata (Thunb.) Ohwi and Ohashi) is an understudied crop grown on poor soils in East Asia. Since no simple sequence repeat (SSR) markers have been developed for rice bean, our goal was to evaluate genomic SSR markers from mung bean (Vigna radiata L. Wilczek) and to provide basic tools for genetic study of rice bean. A total of 2,540 pairs of newly developed SSR primers from mung bean were tested to determine their transferability and polymorphism in rice bean. The results showed that 787 primers pairs (Vr markers) could be used to successfully amplify rice bean DNA loci. Of these markers, 47 showed reliable banding and polymorphisms among 24 rice bean accessions. These SSR markers were further analyzed using 230 acces- sions from a rice bean core collection held in the Chinese Academy of Agricultural Science: 165 alleles were detected in the accessions, and the number of alleles varied from 2 to 6 with a mean of 3.51 per locus. The PIC values varied from 0.042 to 0.711 and averaged 0.418. Population structure analysis indicat- ed that these 230 rice bean genotypes could be divided into six clusters, somewhat in agreement with the eco- regions across 12 different provinces where rice bean is originally collected. The present study supplies a set of useful group of SSR markers to accelerate the genetic study of rice bean and provide information for breeding program design.

Increasing Food Production in Africa by Boosting the Productivity of Understudied Crops

The Green Revolution has enabled Asian countries to boost their crop production enormously. However, Africa has not benefitted from this agricultural revolution since it did not consider local, but important crops grown in the continent. In addition to their versatile adaptation to extreme environmental conditions, African indigenous crops provide income for subsistence farmers and serve as staple food for the vast majority of low-income consumers. These crops, which are composed of cereals, legumes, vegetables and root crops, are commonly known as underutilized or orphan crops. Recently, some of these under-researched crops have received the attention of the national and international research community, and modern improvement techniques including diverse genetic and genomic tools have been applied in order to boost their productivity. The major bottlenecks affecting the productivity of these crops are unimproved genetic traits such as low yield and poor nutritional status and environmental factors such as drought, weeds and pests. Hence, an agricultural revolution is needed to increase food production of these under-researched crops in order to feed the ever-increasing population in Africa. Here, we present both the benefits and drawbacks of major African crops, the efforts being made to improve them, and suggestions for some future directions.

Millet improvement through regeneration and transformation

Millets, comprising the small-seeded group of the Poaceae family, represent one of the major food- and feed-crops in the semi-arid tropical regions of Africa and Asia. Compared to major crops of the world, these indigenous crops possess a number of beneficial characteristics including tolerance to extreme climatic and soil conditions; hence, adapts to poor soil fertility and moisture deficient areas. Moreover, millets are also nutritionally rich especially in vitamins and minerals, and most of them are gluten-free. Despite all these benefits, millets are encountered with several production constraints. The major bottleneck affecting millets are their extremely low yield since they are mostly cultivated in marginal areas with poor moisture and fertility conditions. Inherent characteristics, such as susceptibility to lodging, also significantly affect the productivity of millets. Millets are also commonly known as orphan- or neglected-crops due to too little attention given to them by the world scientific community. Genetic improvement in millets could be achieved not only by conventional approaches but also through modern techniques such as genetic modification or transgenics. The main benefits of regeneration and transformation in millet improvement are: i) the multiplication of identical copies of plants that are free of diseases and pests, and ii) the regeneration of the whole plant from transformed tissues with desirable traits. Success in plant transformation is largely dependent on the efficiency of regeneration. Establishing optimum regeneration method for each plant species and ecotype is therefore, a pre-requisite before embarking on plant transformation. In this review, we present various studies made to identify optimum regeneration and transformation methods for major millets. The prospects of applying advanced regeneration and transformation techniques to these vital but under-studied crops of the developing world are also discussed. Key words: Millets, under-researched crops, orphan crops, in vitro regeneration, transformation.