Large ex situ germplasm collections generally harbor a wide range of crop diversity. AVRDC – The World Vegetable Center is holding in trust the world’s second largest mungbean (Vigna radiata) germplasm collection with more than 6,700 accessions. Screening large collections for traits of interest is laborious and expensive. To enhance the access of breeders to the diversity of the crop, mungbean core and mini core collections have been established. The core collection of 1,481 entries has been built by random selection of 20% of the accessions after geographical stratification and subsequent cluster analysis of eight phenotypic descriptors in the whole collection. Summary statistics, especially the low differences of means, equal variance of the traits in both the whole and core collection and the visual inspection of quantile-quantile plots comparing the variation of phenotypic traits present in both collections indicated that the core collection well represented the pattern of diversity of the whole collection. The core collection was genotyped with 20 simple sequence repeat markers and a mini core set of 289 accessions was selected, which depicted the allele and genotype diversity of the core collection. The mungbean core and mini core collections plus their phenotypic and genotypic data are available for distribution to breeders. It is expected that these collections will enhance the access to biodiverse mungbean germplasm for breeding.

Bruchid beetles are an important storage pest of grain legumes. Callosobruchus sp. infect mungbean (Vigna radiata) at low levels in the field, multiply during grain storage and can destroy seed stocks in a few months. Resistance against bruchid beetles has been found in wild mungbean V. radiata var. sublobata TC1966 and in cultivated mungbean line V2802. Bruchid resistance data were obtained from recombinant inbred line populations TC1966 (V. radiata var. sublobata) × NM92 (F12) and V2802 (V. radiata) × NM94 (F7). More than 6,000 single nucleotide polymorphic markers were generated through genotyping by sequencing (GBS) for each of these populations and were used to map bruchid resistance genes. One highly significant quantitative trait locus (QTL) associated with bruchid resistance was mapped to chromosome 5 on genetic maps of both populations, suggesting that TC1966 and V2802 contain the same resistance locus. Co-segregation of all markers associated with resistance indicated the presence of only one major resistance QTL on chromosome 5, while QTL analysis based on physical map positions of the markers suggested the presence of multiple QTLs on different chromosomes. The diagnostic capacity of the identified molecular markers located in the QTL to correctly predict resistance was up to 100 %. Molecular markers tightly linked to bruchid resistance loci of two different mungbean resistance sources were developed and validated. These markers are highly useful for developing resistant lines.

Okra (Abelmoschus esculentus) is a heat tolerant vegetable crop with high economic and nutritional importance in parts of Asia, Africa, and America. The okra biodiversity held in gene bank collections could be mined for traits for breeding more stress tolerant and nutritional cultivars. An okra core collection of 166 accessions comprising A. esculentus, A. moschatus, A. caillei, and A. manihot has been assembled from the World Vegetable Center germplasm collection (840 accessions) based on diversity analysis with 20 microsatellite markers. A selection of A. esculentus accessions of the core collection (75 accessions) and 20 breeder-selected genotypes have been screened for variation of their response to flooding stress under field conditions using a high throughput phenotyping system. Growth increment per day and changes of physiological indices were measured before, during, and after application of 9 days of flooding stress. Several accessions showed only a small reduction in daily growth increment during flooding. Across the germplasm panel, maintained growth was correlated with maintained normalized differential vegetation index and was negatively correlated with plant senescence index. Accessions with maintained growth and health under flooding were selected for future further analysis and use in breeding.

Tomato (Solanum lycopersicum L.) production faces major yield loss due to biotic stresses. Developing genetically resistant cultivars presents a sustainable alternative to chemical controls, which are often costly and ineffective. This study utilized 10 molecular markers, including SSR, SCAR, and CAPS markers, to assess resistance to six major diseases, including Fusarium wilt, late blight, bacterial wilt, root-knot nematode, Tomato Mosaic Virus (ToMV), and Tomato Yellow Leaf Curl Virus (TYLCV), across 964 tomato accessions comprising both wild germplasm (371) and cultivars (593). Wild germplasm, especially S. peruvianum, showed the highest frequencies of resistance loci. Markers linked to TYLCV and Fusarium wilt were particularly prevalent, with frequencies of 31.8% (TY-1/3_K), 34.0% (P1-16), and 55.8% (I2(OH)). Several wild accessions carried up to six resistance loci, highlighting the potential for gene pyramiding and the utility of wild species as reservoirs of multi-locus resistance. In contrast, resistance loci were limited in S. lycopersicum. Two S. lycopersicum germplasm collections were screened: a geographically representative collection from four Southeast Asian national genebanks and a genetically representative core collection from global public genebanks. The highest resistance frequencies in S. lycopersicum were observed for bacterial wilt-associated markers SLM12-2 and SLM12-10. However, the overall scarcity of resistance alleles in S. lycopersicum emphasizes the need for further introgression of resistance genes from wild relatives. This study provides valuable genetic insights into tomato germplasm for combating biotic stress, forming a foundation for sustainable breeding strategies to enhance disease resistance and safeguard global tomato production.

Background: High temperature severely limits tomato reproductive development and yield, particularly in tropical production systems. Pollen viability and fruit set are commonly used as indicators of reproductive heat tolerance, but much of the supporting evidence has been obtained under controlled conditions. Their relevance to breeding under variable open-field environments remains less clear. This study investigated reproductive performance and its genetic basis under open-field heat stress using a multi-parent advanced generation inter-cross (MAGIC) population. Results: We developed a MAGIC population from eight Solanum lycopersicum parents combining heat tolerance and multiple disease resistances and evaluated 262 F _5:6 lines under natural open-field heat stress. Flower number showed the highest heritability (0.64), followed by pollen viability (0.56), fruit number (0.48), and days to flowering (0.25), whereas fruit set showed negligible heritability (<0.01). Despite its moderate heritability, pollen viability was only weakly correlated with fruit set ( r = 0.22). In contrast, fruit number was strongly correlated with fruit set ( r = 0.86), supporting fruit number as a practical selection criterion for reproductive performance under open-field heat stress. Restriction enzyme-associated DNA sequencing generated 16,350 high-quality SNPs for genome-wide association analysis, which identified multiple QTLs for reproductive traits, several overlapping previously reported loci. A region on chromosome 6 at approximately 31–33 Mb was particularly notable because it was associated with multiple reproductive traits and coincided with a previously reported heat-responsive QTL region. Candidate-gene analysis highlighted floral developmental regulation, represented by positional candidates SlAGO7 , ENO , and SlWUS , and cellular and protein homeostasis, supported by direct candidates including MON1, ECM29, and ubiquitin-related genes. Conclusions: Selection criteria established under controlled environments may not fully predict reproductive performance under open-field heat stress. Fruit number provides an integrative and moderately heritable indicator of realized reproductive success under field conditions. The identified QTLs and candidate genes provide targets for validation and development of heat-tolerant tomatoes adapted to tropical open-field production.