Ergot (caused by Claviceps africana Frederickson, Mantle & de Milliano) of sorghum [Sorghum bicolor (L.) Moench] recently has become a global disease problem and is a major threat to hybrid seed production. Host‐plant resistance is one option for control; however, the genetic and physiological bases for ergot resistance are poorly understood. The objective of this study was to evaluate resistance to C. africana in 18 genetically diverse sorghum lines, including cultivated landraces and wild accessions, as well as in potential alternate hosts, including grassy weeds and range grasses commonly found in sorghum‐producing areas in the central Great Plains of the USA. These entries were evaluated for ergot resistance in the greenhouse following spray inoculation with conidial suspensions during flowering. The results of this analysis indicated that only Sorghum ssp. were susceptible to ergot; however, within the sorghum germplasm pool, several wild accessions were identified with resistance to ergot. Two of these resistant entries, IS14131 and IS14257, were characterized further in male‐sterile (A3 cytoplasm) genetic backgrounds to evaluate the physiological basis for their resistance. Parent lines, male‐sterile hybrids, and susceptible checks were evaluated for ergot resistance following spray inoculation with ergot in experiments in a winter nursery at Guayanilla, Puerto Rico, and in a greenhouse at Manhattan, KS, during the winter and spring of 2000. The expression of ergot resistance in IS14131 and IS14257 and in corresponding male‐sterile hybrids suggests that these sorghums may harbor genes for resistance to ergot.
Biological nitrogen fixation (BNF) in soybean [Glycine max (L.) Merr.] plays an important role in sustainable agriculture, reducing the limitations associated with other sources of N such as fertilizers and soils. Our major objective was to evaluate the weekly pattern of BNF in soybean influenced by nodule formation, using three different laboratory‐cultured Bradyrhizobium strains. Plants were grown in 1‐m polyvinyl chloride (PVC) columns for 17 week in a greenhouse and BNF was determined using an integrated approach by assessing nodule formation, stem ureide‐N, and N partitioning in plant parts. Bradyrhizobium strains showed overall similar plant performance and N2−fixation capacity. During the beginning of flowering/full bloom (R1/R2) growth stages, nodule formation significantly increased and reached a maximum at pod‐filling (R4) stage. Stem ureide‐N was detected at early growth stages even with fewer small nodules, which significantly increased after the beginning of pod formation (R3). Peak N2−fixing rate (g N kg−1 d−1) started to decline after the onset of seed filling (R5.5). Relationship between BNF and nodule parameters (nodule number [R2 = .65] and nodule weight [R2 = .62]) suggested that they can be used as predictors of BNF.
Burkholderia andropogonis is the causal agent of bacterial leaf stripe in sorghum. Strict import quarantine regulations of numerous countries mandate a need for development of a rapid, reliable, and cost-effective diagnostic technique for the identification of B. andropogonis. Using a primer corresponding to the bacterial repetitive BOX element and PCR, we developed a DNA fingerprint which differentiated B. andropogonis from other phytobacterial pathogens.
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.