Inheritance of resistance to anthracnose caused by Colletotrichum capsici in Capsicum P . P a kd eeva ra po rn 1 , S. W asee 2 , P . W . J . T ay lo r 3 and O . M on gk ol po rn 4 , 5 AbstractInheritance of resistance to anthracnose caused by Colletotrichum capsici (Syd.) Butler & Bisby was studied in interspecific Capsicum populations derived from a cross between a Thai elite cultivar Capsicum annuum L. ÔBangchangÕ and a resistant line C. chinense Jacq. ÔPBC932Õ. The resistance was assessed by measuring lesion area per fruit area (LFA) on detached chili fruits, using a laboratory-based injection inoculation. Nil symptoms resembling the resistant parent ÔPBC932Õ were also identified in the progeny F 2 and BC 1 populations. Segregation of resistance (nil LFA) and susceptibility in the F 2 fitted a 1 : 3 Mendelian ratio, indicating that resistance was responsible by a single recessive gene. The segregation of the trait in the testcrosses in both BC 1 s also confirmed the 1 : 3 gene segregating model as found in the F 2 .

Inheritance of resistance to anthracnose at fruiting and seedling stages was studied in two F 2 populations from a cross between Capsicum annuum cv. ÔBangchangÕ and Capsicum chinense ÔPBC932Õ. The first F 2 was used to study anthracnose resistance at fruiting stage on mature green and ripe red fruit, and the second F 2 was used to study the resistance at both seedling and fruiting stages. Fruit inoculation was performed on detached fruit using a microinjector. Disease severity was assessed on a 0-9 scale at 7 days after inoculation. Seedling inoculation was performed using a drop method on detached leaves of 4-week-old seedlings. Disease severity was assessed on a 1-9 scale at 3 days after inoculation. The distribution of the disease scores of green and red fruit, and seedlings in both F 2 populations suggested a single gene model for each trait. Three different recessive genes were responsible for the three resistances from this cross. Linkage analysis suggested that the resistances at green and red fruit were linked (recombination frequency 0.25), and that the seedling resistance was not linked to the fruit resistances.

Chilli (Capsicum spp.) is an economically important vegetable and spice. The Tropical Vegetable Research and Development Center, Kasetsart University, Kamphaeng Saen Campus has collected more than 2500 chilli germplasm accessions since 1989. Investment to maintain and evaluate such a large germplasm collection is high. For efficient germplasm management and to reduce the cost of germplasm maintenance, a core collection needs to be established. Therefore, this study aimed to investigate the genetic diversity of chilli germplasm using microsatellites. A total of 230 chilli germplasm accessions were evaluated using ten anchored Capsicum microsatellite loci. These loci generated 42 alleles with a size ranging from 87 to 323 bp. The average polymorphic information content was 0.57, ranging from 0.414 to 0.681, and the probability of identity (PI) ranged from 0.17 to 0.49. The combined PI of the ten microsatellite loci was 2.30 × 10− 6. The similarity index ranged from 0.29 to 1.00. The 230 chilli accessions were divided into two major groups. Group I comprised mainly C. annuum, and group II comprised all four Capsicum species with the majority being C. frutescens, C. chinense and C. baccatum. The matrix comparison showed that a cophenetic correlation of 0.798 indicated the best fit of the obtained dendrogram. The PowerCore program selected 28 representative chilli accessions to form a core collection, which maintained a similar level of diversity to that of the overall 230 chilli accessions. The representative alleles in those 28 core accessions equalled all the alleles present in the entire collection.

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Nine selected S 3 papaya breeding lines were evaluated for their antioxidant properties and fruit quality. The 14 antioxidant properties and fruit quality traits measured in this study showed significant genotypic differences. KK80 showed the highest ascorbic acid content (114 ± 20 mg/100 ml), antioxidant activity (8.0 ± 1.3 µmol ascorbic acid equivalents/g fresh weight [FW]), and total phenolic compounds (72.2 ± 5.8 mg gallic acid equivalents/100 g FW). KD7 contained the highest amounts of total flavonoid (21.0 ± 5.8 mg catechin equivalents/100 g FW), lycopene (11.0 ± 1.7 mg/100 g FW), and β-carotene (10.0 ± 1.7 mg/100 g FW). The significant variation in antioxidant properties and fruit quality clearly shows the potential value of selected papaya breeding lines as new cultivars and parents in a breeding programme. Lycopene had a positive correlation with β-carotene (r = 0.62). Fruit size showed a negative correlation with total phenolic compounds (r = −0.64), antioxidant activity (r = −0.45), and ascorbic acid (r = −0.44). Flesh colour as hue angle was negatively correlated to lycopene (r = −0.67), suggesting that lycopene may be estimated indirectly by using the hue angle.

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