Growing resistant varieties is the most effective and economical method for controlling rust of wheat (Triticum aestivum L.). Resistance to leaf rust and stripe rust, caused by Puccinia triticina Erikss. and P. striiformis Westend. f. sp. tritici, respectively, was investigated in 148 F5 recombinant inbred lines derived from a cross between ‘Avocet’ and ‘New Pusa 876’ (NP876). The parents and population were phenotyped for resistance in field trials for 3 and 2 yr for leaf rust and stripe rust, respectively, and genotyped with gene‐linked molecular markers. The segregation analyses indicated that the adult plant resistance to leaf rust and stripe rust was conferred by five and four additive effect genes, respectively. Among them, the slow‐rusting adult plant resistance gene Lr46/Yr29 reduced 14 and 16% of mean leaf rust and stripe rust severities, respectively, whereas a severity reduction of 26% occurred due to Lr67/Yr46 for both rusts. Both resistance genes were contributed by NP876. An additive effect between leaf rust resistance genes Lr46 and Lr67 was detected, with a reduction up to 11% when they were present together. The effect of combining Yr29 and Yr46 was additive but not significant, with a mean reduction of 5% in severity. New Pusa 876 can be used as a multiple rust resistance source to breed wheat varieties that may contribute towards durable resistance.
The application of modern biotechnology for improvement of chili pepper productivity requires an efficient in vitro plant regeneration protocol. In this study, a reliable protocol was developed for the in vitro regeneration of four types of chili, Capsicum annuum var. annuum (Jalapeño and Serrano), C. annuum var. glabriusculum/ aviculare (Piquin), and C. chinense (Habanero) by direct organogenesis using three different explants (cotyledon, hypocotyls, and embryo) and three induction media. All evaluated culture media promoted the formation of adventitious shoots. When embryos or hypocotyls were used as explants, morphologically normal adventitious shoots developed, while culturing cotyledons resulted in nonelongating rosette-shaped shoots. The highest in vitro regeneration efficiency (14.6 shoots per explant) was achieved when Habanero chili hypocotyls were grown on Murashige and Skoog medium containing 1.7 μM indole-3-acetic acid and 22.2 μM N 6 -benzyladenine. This regeneration rate is higher than that obtained in previous reports. Regenerated plants were ready to be transferred to the greenhouse 13 wk after the explant culture. An evaluation carried out under greenhouse conditions showed differences in agronomic performance between in vitro regenerated plants and plants developed from seeds with the magnitude of the differences depending on the genotype being studied.
Maize (Zea mays L.) hybrids with enhanced provitamin A (proVA) content have been deployed in sub‐Saharan Africa, where low soil nitrogen and drought stress are common. The objectives of this study were to assess: (i) the effects of drought and low‐N stress on grain proVA content of hybrids with enhanced proVA content, and (ii) the inheritance of proVA carotenoids under these stress conditions. An 11‐line diallel cross (55 F1 crosses) was evaluated for carotenoid content and grain yield under optimum conditions, drought, and low‐N stress. Compared with the optimum treatment, mean proVA was lower under both stress treatments. The consistency of genetic effects across stress treatments suggested that hybrids with improved proVA content can be developed for a broad range of environments, provided they are sufficiently adapted. General combining ability (GCA) was significant (P < 0.01), and accounted for >85% of the variation among hybrids, whereas specific combining ability (SCA) effects were generally weak (P < 0.05), accounting for 5 to 15% of hybrid sums of squares across the three treatments. These results indicated that the inheritance of proVA was not affected by stress treatments. A negative correlation between grain yield and proVA carotenoids was detected, but the data suggested that it was caused by the genetic background of the germplasm used rather than pleiotropy. Our results provide insights that may help breeders design effective breeding strategies to develop proVA‐enriched cultivars for resource‐limited farming systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.