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Chong, Yuet Tian (2025) Phenotypic and genetic investigation of plant phenological development, architecture and yield in winged bean (Psophocarpus tetragonolobus (L.) DC.). PhD thesis, University of Nottingham.

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Abstract

The worsening effects of climate change and malnutrition have significantly impacted global food and nutrition security. Diversifying food sources through the cultivation of underutilised crops could mitigate these challenges and promote resilient agricultural food systems. Winged bean (Psophocarpus tetragonolobus (L.) DC.) is a protein-rich crop grown in humid tropical regions. With its various edible plant parts, broad distribution in the tropics, and adaptation to diverse local environmental conditions, it has notable trait variations for exploration in crop improvement. Research on winged bean genetic diversity has been limited in the past 50 years, primarily relying on phenotypic assessments without the utilisation of molecular markers. However, recent advancements in genotyping techniques have enabled the integration of phenotypic and genetic data. Molecular breeding accelerates the characterisation of diverse core collections, leading to cultivar development, contributing to global initiatives for dietary diversity and nutritional resilience.

A mini-core collection of winged bean comprising 22 accessions was formed from prior genetic diversity assessment of 91 accessions originating from seven countries, and two continents, using DArTseq SNP markers. Multi-locational trials of this mini core collection were carried out at three locations: the Field Research Centre of Crops for the Future Research Centre (CFF-FRC) in Semenyih, Malaysia (May 2019 to March 2020); the rainout shelter of the University of Nottingham Malaysia (UNM) in Semenyih, Malaysia (November 2020 to August 2021); and Fireflies Organic Farm (FF) in Broga, Malaysia (January to October 2021) in a randomised complete block design (RCBD). Among them, FP15 consistently exhibited shorter days to first flower (DtFF) and days to first pod (DtFP) within 79 and 81 days after sowing (DAS) at the CFF-FRC and 62 DAS and 64 DAS in the UNM rainout shelter, respectively with significant differences (p<0.001) between these two trials. Two accessions, a6 and a30, also displayed early flowering, with similar trends observed across two locations. Similarly, days to maturity (DtMS) showed significant differences (p<0.001) among locations, with FP15 consistently exhibiting early DtMS across all three sites. A strong and positive correlation between DtFF and DtFP was observed across all sites, r=0.633 at p<0.05 at FRC, r=0.667 at p<0.05, with the strongest correlation observed at FF (r=0.894 at p<0.001). At CFF-FRC, the accession a13 recorded the highest pod yield (PodY) at 1,135 kg/ha, followed by i17 with 1,009 kg/ha and Ma3 with 925 kg/ha. For seed yield (SY), a13 achieved 484 kg/ha while i17 and a30 yielded 440 kg/ha and 425 kg/ha, respectively. Strong positive correlations between pod yield and seed yield were evident across all three locations (r=0.999 in CFF-FRC, r=0.997 in UNM, and r=0.957 in FF), all significant at p<0.001. No significant correlations (p>0.05) were found between phenological traits and yield traits. In contrast, significant positive correlations (p<0.05) were observed between architecture and yield-related traits, including stem length (StL) and pod length (PodLe) (r=0.791), PodLe and PodY (r=0.538), and PodLe and SY (r=0.526). These findings suggest that yield improvement could be achieved through selection based on plant architecture, particularly stem length, while phenological traits may have limited potential for direct yield selection. Nine accessions were identified based on their superior traits: FP15 and a57 for earliness in flowering and pod production, a10, a6, and a7 for consistent stem length, and a6, a13, a15, a35 and Ma3 for high pod yield and seed yield potential.

An in-field evaluation of 192 F2 lines (TF2) from a cross between i10 (high above-ground biomass, shorter pods) and FP15 (early flowering, early maturity, high harvest index) was conducted at Beacon Eco Farm, Mantin, Malaysia, from June to December 2022. The study assessed plant phenology, architecture, yield, and yield components in an RCBD with four blocks. Significant differences (p<0.001) were observed between parents for flowering initiation, pod production, and seed harvest, with F2 progenies showing intermediate trait values. Significant positive correlations were found between DtFF and DtFP (rs=0.707), DtFF and DtMS (rs=0.455), and DtFP and DtMS (rs=0.554) at p<0.001. No significant differences were found between parents for architectural traits including number of branches (NoB), sum of branches length (SoBL), and StL, but transgressive segregation occurred in the TF2 population. Both parents differed (p<0.05) in yield components such as seeds per pod (SPP), above-ground biomass (AGB), and harvest index (HI) while significant differences (p<0.001) were observed for PodLe, pod width (PodWi), and below-ground biomass (BGB). Five TF2 lines — L012, L013, L014, L015, and L109— produced up to 15,120 kg/ha of pods and 5,725 kg/ha of seeds, with early flowering and seed harvest comparable to FP15, making them distinguished candidates for selection and advancement to the F3 stage.

A genetic linkage map was constructed, followed by QTL analysis. Initially, a total of 4576 DArTseq SNP markers were filtered from 6025 SNP markers of 184 TF2 individual lines. A genetic linkage map consisting of ten linkage groups was constructed from 493 polymorphic SNP markers, with two linkage groups of Chromosome 03 were obtained. The map was 1053.3 cM in total. A total of 15 significant QTLs were identified for ten traits, including DtFF, DtFP, DtMS, 15th internode length (IntL15), 20th internode length (IntL20), NoB, pods per plant (PPP), PodLe, PodWi and seed colour (SC), distributed across six linkage groups: LG01, LG04, LG05, LG07, LG08, and LG09. These QTLs were major accounting for more than 15% of the phenotypic variation in each trait. Additionally, nine transcription factors potentially associated with germination, mature seed harvest, seed yield, seed colour and leaf chlorophyll content were identified.

In-field evaluation of subsequent F3 and F4 generations will aid in selecting superior lines and refining QTL mapping for marker-assisted breeding. Further study of trait inheritance will provide deeper insights into winged bean yield traits. Multi-location trials will help identify key trait correlations in phenology, architecture, and yield, laying the foundation for developing improved cultivars with early maturity and high yield potential. QTL mapping of genetic regions responsible for trait expression will inform future breeding, not only for winged bean but also for other crops facing similar challenges. Ultimately, this project contributes to the efforts aimed at improving global food and nutrition security by expanding the range of crops available and improving their yield potential to address changing environmental conditions.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Massawe, Festo Singh, Ajit Chai, Hui Hui
Keywords:	winged bean (Psophocarpus tetragonolobus (L.) DC.); plant phenology; plant architecture; plant yield; multi-locational evaluation; F2 segregating population; genetic linkage; QTL mapping
Subjects:	S Agriculture > SB Plant culture
Faculties/Schools:	University of Nottingham, Malaysia > Faculty of Science and Engineering — Science > School of Biosciences
Item ID:	80232
Depositing User:	Chong, Yuet Tian
Date Deposited:	08 Feb 2025 04:40
Last Modified:	08 Feb 2025 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/80232

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