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Peppers (Capsicum sp.) are an increasingly important crop because of their use as a vegetable, spice, and food colorant. The oomycete Phytophthora capsici is one of the most devastating pathogens to pepper production worldwide, causing more than $100 million in losses annually. Developing cultivars resistant to P. capsici is challenging because of the many physiological races that exist and new races that are continuously evolving. This problem is confounded by the lack of a universal system of race characterization. As a basis to develop a global anticipatory breeding program, New Mexico recombinant inbred lines (NMRILs) functioned as a host differential for Phytophthora root rot to characterize the race structure of P. capsici populations in Taiwan. Using the NMRILs, 24 new races were identified, illustrating the utility and usefulness of the NMRILs for anticipatory breeding. Virulence of P. capsici was observed to be geographically specific and in two virulence clusters. Interestingly, all but two isolates collected in 2016 were the A2 mating type, which is a shift from the predominantly A1 mating type isolates collected prior to 2008. The NMRILs host differential provides an approach for scientists to work together on a global scale when breeding for resistance as well as on a local level for regional gene deployment. Additionally, we propose that the current race numbering system, which has no biological meaning, be supplemented with the virulence phenotype, based on the susceptible NMRILs to a given isolate. This work provides insights into the population dynamics of P. capsici and interactions within the highly complex Capsicum-Phytophthora pathosystem, and offers a basis for similar research in other crops.

The number of virus species infecting pepper (Capsicum spp.) crops and their incidences has increased considerably over the past 30 years, particularly in tropical and subtropical pepper production systems. This is probably due to a combination of factors, including the expansion and intensification of pepper cultivation in these regions, the increased volume and speed of global trade of fresh produce (including peppers) carrying viruses and vectors to new locations, and perhaps climate change expanding the geographic range suitable for the viruses and vectors. With the increased incidences of diverse virus species comes increased incidences of coinfection with two or more virus species in the same plant. There is then greater chance of synergistic interactions between virus species, increasing symptom severity and weakening host resistance, as well as the opportunity for genetic recombination and component exchange and a possible increase in aggressiveness, virulence, and transmissibility. The main virus groups infecting peppers are transmitted by aphids, whiteflies, or thrips, and a feature of many populations of these vector groups is that they can develop resistance to some of the commonly used insecticides relatively quickly. This, coupled with the increasing concern over the impact of over- or misuse of insecticides on the environment, growers, and consumers, means that there should be less reliance on insecticides to control the vectors of viruses infecting pepper crops. To improve the durability of pepper crop protection measures, there should be a shift away from the broadscale use of insecticides and the use of single, major gene resistance to viruses. Instead, integrated and pragmatic virus control measures should be sought that combine (1) cultural practices that reduce sources of virus inoculum and decrease the rate of spread of viruliferous vectors into the pepper crop, (2) synthetic insecticides, which should be used judiciously and only when the plants are young and most susceptible to infection, (3) appropriate natural products and biocontrol agents to induce resistance in the plants, affect the behavior of the vector insects, or augment the local populations of parasites or predators of the virus vectors, and (4) polygenic resistances against viruses and vector insects with pyramided single-gene virus resistances to improve resistance durability.

Abstract: Experiments were conducted to study genetics of fertility restoration and to examine distribution of RAPD markers (OPW19800 and OPP131400) linked with fertility restoration gene (Rf) in pepper (Capsicum annuum L.) inbreds. Forty-two hot and five sweet pepper inbreds were crossed on a cytoplasmic male sterile (cms) line CCA-4261 and F1s were evaluated for fertility restoration under open field conditions. DNA of 5 plants of CCA-4261 and individual plants of 47 inbreds was isolated and PCR reaction was performed using OPW19 and OPP13 primers. The results revealed that most of the hot pepper lines posses Rf gene. The Rf gene associated two markers, viz., OPW19800 and OPP131400 were not frequently distributed in the restorer inbred lines because presence of marker bands often does not coincide with the presence of Rf gene identified in many restorer inbreds. The case specific applications of both the RAPD markers have been described. [Copyright &y& Elsevier]

Abstract: Three hundred and seven genotypes belonging to four cultivated and one wild species of Capsicum were screened against pepper leaf curl virus (PepLCV) causing devastating leaf curl disease of chilli (Capsicum annuum). Initial screening was done under field conditions based on coefficient of infection (CI), disease reaction to each genotype was assigned. Subsequently, selfed progenies of eight symptom-less and highly resistant lines were challenged by viruliferous white fly under glasshouse conditions, out of which only three genotypes, viz. GKC-29, BS-35 and EC-497636 showed no symptom. Using scion and root stalk of susceptible genotype (Pusa Jwala), these three putative symptom-less genotypes were further challenged by grafting and alternate grafting. The resistant reactions of GKC-29, BS-35, EC-497636 were confirmed because even after 50 days of successful grafting/alternate grafting, no viral symptom appeared on all the grafted plants of these genotypes. When subjected to PCR amplification with degenerate primers deigned to detect gemnivirus like PepLCV, the three symptom-less genotypes did not show any amplification, suggesting that the resistant reaction in three identified symptom-less resistant sources was because of the absence of viral genome and they are not symptom-less carrier. [Copyright &y& Elsevier]

Abstracts: Cytoplasmic male sterility (CMS) is increasingly being utilized for hybrid seed production of hot pepper (Capsicum annuum). Two CMS specific sequenced characterized amplified regions (SCARs), viz., atp6 607 and coxII 708 developed elsewhere were validated in an array of genotypes possessing male sterile (S-) and normal/male fertile (N-) cytoplasms and their feasible uses in CMS based pepper hybrid breeding have been elaborated. A set of eight maintainer and restorer inbreds were crossed on four CMS lines possessing two independently isolated and commercially utilized S-cytoplasms (Peterson''s and Reddy''s). Based on fertility restoration/maintenance reaction of 32 resulted F1s and on the presence of two SCARs (atp6 607 and coxII 708) in both the S-cytoplasms, it has been concluded that although two S-cytoplasms were isolated and commercially utilized independently, they are genetically same or similar. Through inter-specific hybridization between C. chacoense and C. annuum, a new alloplasmic S-cytoplasm in the genus Capsicum has been isolated and the CMS F1 has been advanced to CMS BC1F1. [Copyright &y& Elsevier]