Plant-symbiotic fungi as chemical engineers: multi-genome analysis of the Clavicipitaceae reveals dynamics of alkaloid Loci

The fungal family Clavicipitaceae includes plant symbionts and parasites that produce several psychoactive and bioprotective alkaloids. The family includes grass symbionts in the epichloae clade (Epichloë and Neotyphodium species), which are extraordinarily diverse both in their host interactions and in their alkaloid profiles. Epichloae produce alkaloids of four distinct classes, all of which deter insects, and some—including the infamous ergot alkaloids—have potent effects on mammals. The exceptional chemotypic diversity of the epichloae may relate to their broad range of host interactions, whereby some are pathogenic and contagious, others are mutualistic and vertically transmitted (seed-borne), and still others vary in pathogenic or mutualistic behavior. We profiled the alkaloids and sequenced the genomes of 10 epichloae, three ergot fungi (Claviceps species), a morning-glory symbiont (Periglandula ipomoeae), and a bamboo pathogen (Aciculosporium take), and compared the gene clusters for four classes of alkaloids. Results indicated a strong tendency for alkaloid loci to have conserved cores that specify the skeleton structures and peripheral genes that determine chemical variations that are known to affect their pharmacological specificities. Generally, gene locations in cluster peripheries positioned them near to transposon-derived, AT-rich repeat blocks, which were probably involved in gene losses, duplications, and neofunctionalizations. The alkaloid loci in the epichloae had unusual structures riddled with large, complex, and dynamic repeat blocks. This feature was not reflective of overall differences in repeat contents in the genomes, nor was it characteristic of most other specialized metabolism loci. The organization and dynamics of alkaloid loci and abundant repeat blocks in the epichloae suggested that these fungi are under selection for alkaloid diversification. We suggest that such selection is related to the variable life histories of the epichloae, their protective roles as symbionts, and their associations with the highly speciose and ecologically diverse cool-season grasses

Short-Lived Trace Gases in the Surface Ocean and the Atmosphere

The two-way exchange of trace gases between the ocean and the atmosphere is important for both the chemistry and physics of the atmosphere and the biogeochemistry of the oceans, including the global cycling of elements. Here we review these exchanges and their importance for a range of gases whose lifetimes are generally short compared to the main greenhouse gases and which are, in most cases, more reactive than them. Gases considered include sulphur and related compounds, organohalogens, non-methane hydrocarbons, ozone, ammonia and related compounds, hydrogen and carbon monoxide. Finally, we stress the interactivity of the system, the importance of process understanding for modeling, the need for more extensive field measurements and their better seasonal coverage, the importance of inter-calibration exercises and finally the need to show the importance of air-sea exchanges for global cycling and how the field fits into the broader context of Earth System Science

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Not AvailableMillets are important crops in the developing countries in the semiarid tropics. Incidentally these are the regions where most of the world’s poor people live. These crops provide high-energy, nutritious, and healthy food recommended for children, convalescents as well as the elders. Millets can be consistently grown under extreme agricultural conditions (low precipitation, high temperature, and poor soils) where other cereals fail to produce an acceptable harvest. Under the changing climatic scenario millets are being assigned as the crops for future attention. Biotic stresses particularly diseases, insect pests, weeds, and birds are major constraints in the way of realizing the potential yield of millets. In the future these problems are likely to increase because of the perceptible changes in the global climate. Management of biotic stresses in millets is attempted more through resistant cultivars and less or negligibly through the use of chemicals. Host-plant resistance is the most economical and ecosafe method for management of biotic stress and the only affordable method for the poor farmers. A lot of information has been generated on this aspect over time by numerous millets researchers. However, the information is scattered through the literature and there is hardly any publication that has discussed the diseases, insect pests, weeds, Striga, and birds resistance of all the millets including sorghum, pearl millet, and small millets in a single book. In this book, a sincere attempt has been made to present updated information on the subject with emphasis on literature published in the 21st century. All aspects of host-plant resistance including screening techniques, sources, mechanisms and genetics of resistance, and utilization of host resistance by conventional and molecular breeding methods have been discussed in depth. In addition to biology, epidemiology, and resistance, other aspects of millets such as the origin, distribution, production, and their importance have been covered for the beginners. The book will be highly useful for researchers and research-planners who are involved in plant protection and production research on millets and related cereals. This book, which is authored by experts in the respective field of studies, will primarily act as a guide for the researchers to formulate suitable research strategies on plant protection. Industry sectors like the “millets seed industry” will benefit from information on biotic stress-related issues that are constraints in seed productionNot Availabl

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Not AvailableSpotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae), is the most important pest of sorghum in Asia and south and eastern Africa. Host plant resistance is an important control tactic for controlling this pest. Two breeding lines 27B PB 15881-3 and 463B PB 15881-3 with their parents, resistant and susceptible genotypes were evaluated in the field, glasshouse and laboratory for different resistance parameters. Breeding lines and genotypes varied significantly in foliar damage ratings, percentage of stem length tunneled, percentage of plants with deadhearts, larval survival, larval and pupal weights, larval and pupal duration, and percentage pupation and adult emergence in diets amended with leaf powder of different sorghum genotypes. The breeding lines 27B PB 15881-3 and 463B PB 15881-3 showed antixenosis and antibiosis to C. partellus in terms of reduced eggs per plant, larval survival and development. The levels of antixenosis and antibiosis of both breeding lines were similar to their resistant parents. Results indicate that transmission of characteristics responsible for resistance to the progeny from the resistant parent occurred.Not Availabl

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Not AvailableNot AvailGeneration mean analyses were carried out to study genetics of traits associated with shoot fly resistance in three crosses using male sterile susceptible female and resistant male parents (104B x IS18551, 104B x IS2312 and 104B x RSE03) during 2006-07 at two locations. The mean performance of families showed that resistance as indicated by lower deadheart percentage is governed by recessive genes. Both additive and nonadditive gene actions were important for resistance, and this trait is influenced by environment. The line RSE 03 was a better source of resistance with relatively simple genetics for shoot fly resistance and component traits. Indirect selection through the component traits such as glossiness and seedling height which were under the control of additive genes would be effective for developing sorghum varieties resistant to shoot fly infestationableNot Availabl

Diversity for grain oil content and seed hardness in Sorghum [Sorghum bicolor (L.) Moench]

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Components of resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is one of the major constraints in sorghum production, and host plant resistance is one of the components to control sorghum shoot fly. Thirty sorghum genotypes were evaluated for different mechanisms of resistance and morphological and agronomic traits during the rainy and postrainy seasons. The sorghum genotypes, Maulee, Phule Anuradha, M 35-1, CSV 18R, IS 2312, Giddi Maldandi, and RVRT 3 suffered lower shoot fly damage, and also exhibited high grain yield potential during the postrainy season. ICSB 433, ICSV 700, ICSV 25019, ICSV 25022, ICSV 25026, ICSV 25039, PS 35805, Akola Kranti, and IS 18551 exhibited antixenosis for oviposition and antibiosis against sorghum shoot fly, A. soccata. Leaf glossiness, plant vigor, leafsheath pigmentation and trichomes were associated with resistance/susceptibility to shoot fly. Path coefficient analysis indicated that direct effects and correlation coefficients of leaf glossiness, plant vigor, plant height, plant color and trichomes were in the same direction, suggesting that these traits can be used to select sorghum genotypes for resistance to shoot fly. Principal co-ordinate analysis based on shoot fly resistance traits and morphological traits placed the test genotypes into different groups. The genotypes placed in different groups can be used to increase the levels and broaden the genetic base of resistance to shoot fly. The environmental coefficient of variation and phenotypic coefficient of variation for shoot fly resistance and morphological traits were quite high, indicating season specific expression of resistance to sorghum shoot fly. High broadsense heritability, genetic advance and genotypic coefficient of variation suggested the predominance of additive nature of genes controlling shoot fly resistance, suggesting that pedigree breeding can be used to transfer shoot fly resistance into high yielding cultivars. This information will be useful for developing shoot fly-resistant high yielding cultivars for sustainable crop production