Successful wide hybridization and introgression breeding in a diverse set of common peppers (Capsicum annuum) using different cultivated ají (C. baccatum) accessions as donor parents

[EN] Capsicum baccatum, commonly known as aji, has been reported as a source of variation for many different traits to improve common pepper (C. annuum), one of the most important vegetables in the world. However, strong interspecific hybridization barriers exist between them. A comparative study of two wide hybridization approaches for introgressing C. baccatum genes into C. annuum was performed: i) genetic bridge (GB) using C. chinense and C. frutescens as bridge species; and, ii) direct cross between C. annuum and C. baccatum combined with in vitro embryo rescue (ER). A diverse and representative collection of 18 accessions from four cultivated species of Capsicum was used, including C. annuum (12), C. baccatum (3), C. chinense (2), and C. frutescens (1). More than 5000 crosses were made and over 1000 embryos were rescued in the present study. C. chinense performed as a good bridge species between C. annuum and C. baccatum, with the best results being obtained with the cross combination [C. baccatum (female) x C. chinense (male)] (female) x C. annuum (male), while C. frutescens gave poor results as bridge species due to strong prezygotic and postzygotic barriers. Virus-like-syndrome or dwarfism was observed in F-1 hybrids when both C. chinense and C. frutescens were used as female parents. Regarding the ER strategy, the best response was found in C. annuum (female) x C. baccatum (male) crosses. First backcrosses to C. annuum (BC(1)s) were obtained according to the crossing scheme [C. annuum (female) x C. baccatum (male)] (female) x C. annuum (male) using ER. Advantages and disadvantages of each strategy are discussed in relation to their application to breeding programmes. These results provide breeders with useful practical information for the regular utilization of the C. baccatum gene pool in C. annuum breeding.Juan P. Manzur thanks Universitat Politecnica de Valencia for a research predoctoral grant (2011-S2-4264, programa para la formacion de personal investigador). Authors are grateful to Centro Inv. Agr. Mabegondo, S. Larregla from NEIKER, P.W. Bosland from NMSU and the Consejos Reguladores of IGP Pimiento Asado del Bierzo, DOP Pimenton de Murcia, and IGP Piquillo de Lodosa for providing us with seeds from Arnoia, Guindilla de Ibarra, Numex, Bierzo, Bola and Piquillo, respectively.Manzur Poblete, JPA.; Fita, A.; Prohens Tomás, J.; Rodríguez Burruezo, A. (2015). Successful wide hybridization and introgression breeding in a diverse set of common peppers (Capsicum annuum) using different cultivated ají (C. baccatum) accessions as donor parents. PLoS ONE. 10(12). https://doi.org/10.1371/journal.pone.0144142Se0144142101

Identification of RAPD markers linked to recessive genes conferring siliqua shatter resistance in Brassica rapa

Shattering of siliquae causes significant seed loss in canola (Brassica napus) production worldwide. There is little genetic variation for resistance to shatter in canola and, hence, the trait has been studied in B. rapa. Previous studies have shown two randomly segregating recessive genes to be responsible for shatter resistance. Three random amplified polymorphic DNA markers were identified as being linked to shatter resistance using bulked segregant analysis in a F3B. rapa population. The population was derived from a cross between a shatter-susceptible Canadian cultivar and a shatter-resistant Indian line. Of the three markers, RAC-3900 and RX-71000 were linked to recessive sh1 and sh2 alleles, and SAC-201300 was linked to both dominant Sh1 and Sh2 alleles. The common marker for the dominant wild-type allele for the two loci was explained to have resulted from duplication of an original locus and the associated markers through chromosome duplication and rearrangements in the process of evolution of the modern B. rapa from its progenitor that had a lower number of chromosomes. Segregation data from double heterozygous F3 families, although limited, indicated the markers were not linked to each other and provided further evidence for the duplication hypothesis

Distribution and occurrence of myxomycetes in tropical forests in northern Thailand

The fruiting phenology and substrate relationships of myxomycetes in mid-elevation forests of northern Thailand were investigated in five 100 m 2 study plots during the period of October 2004 to October 2005. Collectively, 62 species representing 18 genera were collected. Thirty seven of these are new records for northern Thailand, and one of the species collected (Licea erecta var. erectoides) is known from only a few other localities throughout the world. Few fruitings occurred during the dry season (which extends from November through May), but fruitings were prominent in the rainy season, especially during June and July. Numbers of species recorded for these two months were 45 and 33, respectively. Forest floor litter derived from two trees (Dipterocarpus sp. and Macaranga denticulata) seemed to represent an especially favorable substrate for many of the species of myxomycetes collected in the five study areas.link_to_OA_fulltex

Identification, prevalence and pathogenicity of Colletotrichum species causing anthracnose of Capsicum annuum in Asia

Anthracnose of chili (Capsicum spp.) causes major production losses throughout Asia where chili plants are grown. A total of 260 Colletotrichum isolates, associated with necrotic lesions of chili leaves and fruit were collected from chili producing areas of Indonesia, Malaysia, Sri Lanka, Thailand and Taiwan. Colletotrichum truncatum was the most commonly isolated species from infected chili fruit and was readily identified by its falcate spores and abundant setae in the necrotic lesions. The other isolates consisted of straight conidia (cylindrical and fusiform) which were difficult to differentiate to species based on morphological characters. Taxonomic analysis of these straight conidia isolates based on multi-gene phylogenetic analyses (ITS, gapdh, chs-1, act, tub2, his3, ApMat, gs) revealed a further seven known Colletotrichum species, C. endophyticum, C. fructicola, C. karsti, C. plurivorum, C. scovillei, C. siamense and C. tropicale. In addition, three novel species are also described as C. javanense, C. makassarense and C. tainanense, associated with anthracnose of chili fruit in West Java (Indonesia); Makassar, South Sulawesi (Indonesia); and Tainan (Taiwan), respectively. Colletotrichum siamense is reported for the first time causing anthracnose of Capsicum annuum in Indonesia and Sri Lanka. This is also the first report of C. fructicola causing anthracnose of chili in Taiwan and Thailand and C. plurivorum in Malaysia and Thailand. Of the species with straight conidia, C. scovillei (acutatum complex), was the most prevalent throughout the surveyed countries, except for Sri Lanka from where this species was not isolated. Colletotrichum siamense (gloeosporioides complex) was also common in Indonesia, Sri Lanka and Thailand. Pathogenicity tests on chili fruit showed that C. javanense and C. scovillei were highly aggressive, especially when inoculated on non-wounded fruit, compared to all other species. The existence of new, highly aggressive exotic species, such as C. javanense, poses a biosecurity risk to production in countries which do not have adequate quarantine regulations to restrict the entry of exotic pathogens