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Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is an economically important disease of bitter gourd (BG; Momordica charantia) in Asia. Highlevel resistance to CPM is known in various BG accessions that have been used to develop BG breeding lines that originated in different countries. BG breeding lines THMC 113 (Belize), THMC 143 (India), THMC 153 (Thailand), THMC 167 (India), and THMC 170 (Taiwan) possess high-level resistance to BG Px race (BG-CPM), designated Mc-1 from a field at Kamphaeng Saen, Thailand, whereas THMC 144 (India) is susceptible. Our objective was to determine the inheritance of resistance to BG-CPM race Mc-1. To that end, THMC 144 (India) was crossed with the five resistant lines. The parents and their respective F1, F2, backcross progenies were evaluated for BG-CPM disease severity in inoculated field and growth chamber tests. Resistance to BG-CPM race Mc-1 in the five resistant lines was controlled by at least two independent, recessive genes. Intercrosses of the BG-CPM-resistant lines revealed allelic resistances in four of the breeding lines: THMC 113, THMC 153, THMC 167, and THMC 170. Resistance in THMC 143 was clearly non-allelic for resistance to BG-CPM with the other four BG-CPM-resistant lines. [ABSTRACT FROM AUTHOR]

Bitter gourd, Momordica charantia L., is an important commercial cucurbitaceous vegetable of enormous medicinal value in Asia because of its secondary metabolite content. We report here the characterization and evaluation of open-pollinated (OP) edible South Asian and Southeast Asian types of bitter gourd breeding lines, developed at the World Vegetable Center, for horticultural traits (11 OP) and secondary metabolites (10 OP) and their comparisons with commercial OP and F1 hybrid cultivars. Marketable yields of South Asian and Southeast Asian type breeding lines were comparable to the OP ‘BARI Karella 1’ and the hybrid ‘Benteng’, respectively. The bitter gourd cultivars and breeding lines included in this study exhibited specific patterns for five secondary metabolites (saponins, carotenoids, chlorophyll a and b, and vitamin C): in general the two cultivars and South Asian type breeding lines contained higher levels of secondary metabolites, e.g. carotenoids, than the Southeast Asian bitter gourd breeding lines. Some of these bitter gourd lines will be released to Asian home and school gardeners after conducting multi-location trials across Asia to improve vegetable consumption as a main task of bitter gourd breeding. [ABSTRACT FROM AUTHOR]

Bitter gourd (Momordica charantia L.) is a commercially and nutritionally important market vegetable in Asia cultivated mainly by smallholder farmers. Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is a nearly ubiquitous and serious fungal disease of bitter gourd. Five bitter gourd breeding lines (THMC 113, THMC 143, THMC 153, THMC 167, and THMC 170) were selected at the World Vegetable Center for resistance to a local isolate of Px in Kamphaeng Saen, Thailand. We evaluated the resistance potential of these five inbred lines against local isolates of Px at 12 locations in five Asian countries. Plants were inoculated with the respective local Px isolate 15 and 30 days after transplanting and additional Px-infected plants of the inoculated control were interplanted throughout each test. Plants were rated 60 days after transplanting forCPM reaction using a 0 (no evidence of infection) to 5 (>75% infection evident on individual leaves) disease severity scale. THMC 153 and THMC 167 were resistant to the local race of Px in all locations, whereas THMC 143 was observed resistant in all test locations except one in China. THMC 113 was resistant in each location except one in India. THMC 170 was susceptible in three locations in India. The multilocation tests revealed four unique Px races on bitter gourd in different Asian countries and sources of resistance for breeding CPM-resistant bitter gourd cultivars. Six strains of Px isolated from other cucurbits (Cucumis and Cucurbita) and representing five melon CPM races were unable to infect the susceptible M. charantia accession THMC 144 and the five resistant breeding lines, indicating pathotype differences between them and an isolate of M. charantia origin typed as race 1 on melon. THMC 143 and THMC 167, which originated from India, exhibited good yield potential in trials conducted in Thailand, Myanmar, Vietnam, and Bangladesh. [ABSTRACT FROM AUTHOR]

Bitter gourd (Momordica charantia) is widely cultivated as a vegetable and medicinal herb in many Asian and African countries. After the sequencing of the cucumber (Cucumis sativus), watermelon (Citrullus lanatus), and melon (Cucumis melo) genomes, bitter gourd became the fourth cucurbit species whose whole genome was sequenced. However, a comprehensive analysis of simple sequence repeats (SSRs) in bitter gourd, including a comparison with the three aforementioned cucurbit species has not yet been published. Here, we identified a total of 188,091 and 167,160 SSR motifs in the genomes of the bitter gourd lines 'Dali-11' and 'OHB3-1,' respectively. Subsequently, the SSR content, motif lengths, and classified motif types were characterized for the bitter gourd genomes and compared among all the cucurbit genomes. Lastly, a large set of 138,727 unique in silico SSR primer pairs were designed for bitter gourd. Among these, 71 primers were selected, all of which successfully amplified SSRs from the two bitter gourd lines 'Dali-11' and 'K44'. To further examine the utilization of unique SSR primers, 21 SSR markers were used to genotype a collection of 211 bitter gourd lines from all over the world. A model-based clustering method and phylogenetic analysis indicated a clear separation among the geographic groups. The genomic SSR markers developed in this study have considerable potential value in advancing bitter gourd research. [ABSTRACT FROM AUTHOR]

Bitter gourd (Momordica charantia L.) is an important market vegetable in the tropics. The objectives of this study were to (1) conduct a preliminary evaluation of genetic diversity in bitter gourd flesh (without seeds) for phytonutrient (carotenoid, ascorbic acid and tocopherol) contents with the aim to understand which phytonutrients might be increased through breeding, (2) assess the association between fruit traits and phytonutrient contents and (3) evaluate the effect of the fruit harvest stage on phytonutrient contents. A total of 17 diverse bitter gourd entries of various commercial market types were evaluated for fruit traits and phytonutrient contents for 2 years. Significant differences (P= 0.05) among the entries were detected for total carotenoids, total tocopherols, dry matter and fruit traits. Mean total carotenoid contents of the entries ranged from 10 to 1335 μg/100 g fresh weight in year 1 and 10 to 1185 μg/100 g fresh weight in year 2. Mean ascorbic acid contents were 69 and 61 mg/100 g fresh weight in year 1 and year 2, respectively. Total tocopherol contents among the entries ranged from 480 to 1345 and 445 to 2145 μg/100 g fresh weight in year 1 and year 2, respectively. Total carotenoid and ascorbic acid contents were highest at 12 days after fruit set (DAFS), but total tocopherol contents were highest from 14 to 20 DAFS. A 100 g portion of bitter gourd fruit can meet 190, 17 and 8% of the recommended daily allowances of vitamin C, vitamin E and vitamin A, respectively, for adults. [ABSTRACT FROM AUTHOR]

Bitter gourd (Momordica charantia L.) is an economically and nutritionally important vegetable in Asia. The objective of this study was to evaluate a diverse collection of bitter gourd germplasm for identifying early staminate flowering monoecious lines for blending with predominantly gynoecious hybrids or gynoecious open pollinated cultivars to provide the pollen necessary for fruit set. We evaluated 186 cultigens (182 monoecious inbred lines, four commercial hybrids, collectively referred to as cultigens) of bitter gourd for early staminate flowering (days from sowing to first open staminate flower) in a two seasons study. The inbred lines were derived from 182 bitter gourd accessions in the collection of AVRDC. Cultigens were transplanted to the field at the two-leaf stage of growth each season with three plants in each of three replications. The cultigens differed significantly in both seasons (P<0.05) for mean number of days to first open staminate flowers, which was affected by season (day length). The earliest staminate flowering cultigen was THMC 62 (Philippines); the latest was THMC 17 (Thailand). Days to 50% staminate flowering and pollen viability (%) of the earliest staminate flowering monoecious lines ranged from 61.8% to 73.7% and 96.0% to 98.2%, respectively. The early staminate flowering monoecious lines identified have potential for use as pollenizers to optimize early and total yield of gynoecious hybrids and gynoecious open-pollinated cultivars. [ABSTRACT FROM AUTHOR]

The Squash Leaf Curl China Virus (SLCCNV) and Tomato Leaf Curl New Delhi Virus (ToLCNDV) are species of Begomovirus (whitefly-vectored Geminiviridae) and cause serious damage to the cucurbit crops of the genus Cucurbita in the areas of South and Southeast Asia, across Asia, the Middle East and the Mediterranean, respectively. Cucurbita moschata's inbred line AVPU1426, developed at the World Vegetable Center (WorldVeg) from a Bangladeshi landrace through pedigree selection, was observed to be resistant to both begomoviruses in field tests conducted at the WorldVeg Research and Training Station, Kasetsart University, Kamphaeng Saen, Thailand, which is a hotspot for these viruses. When AVPU1426 was tested for reaction to inoculation by viruliferous whiteflies with Squash Leaf Curl Philippines Virus (Taiwan strain) (SLCPV-TW) in the screen net-house at WorldVeg headquarters in Taiwan, it showed good resistance, though SLCPV-TW DNA-A could be detected in all inoculated plants, indicating that it did not show immunity to this virus. The objective of this study was to validate the resistance to SLCCNV and ToLCNDV in AVPU1426 by using whitefly-mediated inoculations to determine the mode of inheritance of the resistance. The results showed that AVPU1426 was resistant to SLCCNV and ToLCNDV. Upon crossing AVPU1426 with a susceptible check variety, Waltham Butternut, the resistance to both begomoviruses was observed to be conferred by a single recessive gene. This open-pollinated pumpkin line AVPU1426 bears flat round, mottled green immature fruits with yellow flesh in mature fruit. The fruit yield of AVPU1426 (20.74 t/ha−1) was comparable to 'Rajah' (18.61 t/ha−1), a recently released commercial F1 hybrid of East-West Seed (EWS). The fruit of AVPU1426 were estimated to have a good average β-carotene content (1.57 mg/100 g fresh weight). This line is a good source to breed pumpkins resistant to the three begomoviruses. [ABSTRACT FROM AUTHOR]

The article explores the Asian origins of familiar and exotic cucurbits. It cites India and Southeast Asia, including China, as the primary and secondary centers of diversity of cucumber. An overview of the positive impact of Asian cucurbit germplasm and technology on U.S. melon, cucumber, and watermelon production and the potential for bitter gourd is also provided.