Jinguo Hu

Plant phenotypic plasticity is the ability of plants to express different phenotypes in response to environmental variations. Genetic bases by which phenotypic plasticity affects plant adaptation to environmental change remain largely unknown. In the present study, we characterized 26 forage quality traits in a panel of alfalfa 198 accessions in a field trial under water deficit gradient. The regression analysis revealed that the values of fiber-related traits decreased, while those among energy-related traits increased, as water deficit increased. Genetic loci for forage quality traits were investigated by Genome-wide association studies (GWAS) under different levels of water deficit. Genetic loci associated with forage quality traits were identified and compared. Similar regions were found between energy-related traits when grand means were used for GWAS. Most of the associated markers were identified under water deficit, suggesting genetic mechanisms for forage quality traits were differ between well-watered and water stressed plants. Although GWAS on forage quality have been reported, we are the first to address the genetic factors for forage quality traits under water deficit in autotetraploid alfalfa. The information gained from the present study will be useful for the genetic improvement of alfalfa with enhanced drought/salt tolerance while maintaining forage quality.

Information regarding the suitability of autumn‐sown faba bean (Vicia faba L.) in southeastern Washington is lacking. Therefore, a variety trial testing the effects of two sowing dates was conducted for two seasons (2011–2012 and 2012–2013) at three locations: Central Ferry Research Farm (CF), Pomeroy, WA; Spillman Agronomy Farm (SF), Pullman, WA; Whitlow Farm (WF), Pullman, WA, with 20 northern European breeding lines, or cultivars, and U.S. Department of Agriculture‐Agricultural Research Service National Plant Germplasm System (USDA‐ARS NPGS) sourced germplasm accessions with predetermined winter‐hardiness. Winter‐hardiness and yield varied depending on location, timing of sowing, and genotype effects. Survival was greatest at CF where the extreme low air temperature was –6°C, yet multiple entries tolerated an extreme low of –14°C in Pullman. In both years, the second sowing at the CF location improved survival, whereas the first sowing was only beneficial at the Pullman locations when seedlings were established before the first hard frost. Providing a longer establishment and cold acclimation period was expected to optimize hardiness and yield potential. However, achieving two to three nodes before the first hard frost was difficult at dryland managed SF and WF locations where soil moisture was limiting. Across entries and site‐years, the mean survival was 65% with a yield of 2800 kg ha⁻¹. To realize the potential of autumn‐sown faba bean in southeastern Washington, genotypes with earlier maturity than the northern European materials tested herein will be needed.

Background: Grasspea (Lathyrus sativus L., 2n = 14), a member of the family Leguminosae, holds great agronomic potential as grain and forage legume crop in the arid areas for its superb resilience to abiotic stresses such as drought, flood and salinity. The crop could not make much progress through conventional breeding in the past, and there are hardly any detailed molecular biology studies due to paucity of reliable molecular markers representative of the entire genome. Results: Using the 454 FLX Titanium pyrosequencing technique, 651,827 simple sequence repeat (SSR) loci were identified and 50,144 nonredundant primer pairs were successfully designed, of which 288 were randomly selected for validation among 23 L. sativus and one L. cicera accessions of diverse provenance. 74 were polymorphic, 70 monomorphic, and 144 with no PCR product. The number of observed alleles ranged from two to five, the observed heterozygosity from 0 to 0.9545, and Shannon’s information index ranged from 0.1013 to 1.0980, respectively. The dendrogram constructed by using unweighted pair group method with arithmetic mean (UPGMA) based on Nei's genetic distance, showed obvious distinctions and understandable relationships among the 24 accessions. Conclusions: The large number of SSR primer pairs developed in this study would make a significant contribution to genomics enabled improvement of grasspea.

Seed-borne Epichloë/Neotyphodium Glenn, Bacon, Hanlin (Ascomycota: Hypocreales: Clavicipitaceae) fungal endophytes in temperate grasses can provide protection against insect attack with the degree of host resistance related to the grass-endophyte symbiotum and the insect species involved in an interaction. Few experimental studies with wild grass-endophyte symbiota, compared to endophyte-infected agricultural grasses, have tested for anti-insect benefits, let alone for resistance against more than one insect species. This study quantified the preference and performance of the bird cherry oat-aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) and the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), two important pests of forage and cereal grasses, on Neotyphodium-infected (E+) and uninfected (E-) plants of the wild grass Alpine timothy, Phleum alpinum L. (Poales: Poaceae). The experiments tested for both constitutive and wound-induced resistance in E+ plants to characterize possible plasticity of defense responses by a wild E+ grass. The aphid, R. padi preferred E- over E+ test plants in choice experiments and E+ undamaged test plants constitutively expressed antibiosis resistance to this aphid by suppressing population growth. Prior damage of E+ test plants did not induce higher levels of resistance to R. padi. By contrast, the beetle, O. melanopus showed no preference for E+ or E- test plants and endophyte infection did not adversely affect the survival and development of larvae. These results extend the phenomenon of variable effects of E+ wild grasses on the preference and performance of phytophagous insects. The wild grass- Neotyphodium symbiotum in this study broadens the number of wild E+ grasses available for expanded explorations into the effects of endophyte metabolites on insect herbivory.

Target region amplification polymorphism markers were used to assess the genetic diversity and relationship among 151 worldwide collected faba bean (Vicia faba L.) entries (137 accessions maintained at the USDA–ARS, Pullman, WA, 2 commercial varieties and 12 elite cultivars and advanced breeding lines obtained from Link of Georg-August University, Germany). Twelve primer combinations (six sets of polymerase chain reaction) amplified a total of 221 markers, of which 122 (55.2%) were polymorphic and could discriminate all the 151 entries. A high level of polymorphism was revealed among the accessions with an estimated average pairwise similarity of 63.2%, ranging from 36.9 to 90.2%. Cluster analysis divided the 151 accessions into five major groups with 2–101 entries each and revealed a substantial association between the molecular diversity and the geographic origin. All 101 accessions in Group V are originated from China and 13 of the 15 accessions in Group II were from Afghanistan. Thirty-two individual plants were sampled from two entries to assess the intra-accession variation. It was found that the advanced inbred line (Hiverna/5-EP1) had very little variation (5.0%), while the original collection (PI 577746) possessed a very high amount of variation (47.1%). This is consistent with the previous reports that faba bean landraces have a high level of outcrossing in production fields and thus contain larger amount variation within each landrace. One implication of this observation for germplasm management is that a relatively larger population is needed in regeneration to mitigate the possible loss of genetic variation due to genetic drift.

This study investigated the genetic diversity and relationships among the 177 public sunflower (Helianthus annuus L.) inbred lines developed and released by USDA‐ARS from the 1970s to 2005 using the target region amplification polymorphism (TRAP) marker technique. Twelve primer combinations generated a total of 230 polymorphic markers that could discriminate each of these lines, suggesting that TRAP is a powerful marker technique for fingerprinting sunflower inbred lines. The pairwise genetic similarity coefficients (simple matching) based on the TRAP markers ranged from 0.30 to 0.97 with a mean of 0.58, indicating that there is substantial genetic variability in this public collection. The average similarity coefficient of 41 confection inbred lines was significantly higher than that of 136 oilseed inbred lines. Cluster analysis grouped the 177 lines into two classes, oilseed (O) class and confection (C) class with only two exceptions. The O and C classes were further categorized into two groups: fertility maintainer (OB and CB) and fertility restorer groups (OR and CR). Moreover, inbred lines in the OB, OR, CR, and CB groups were placed into four, three, two, and two clusters, respectively. These results are useful to sunflower breeders and would promote the utilization of these public inbred lines.