Genetic mitigation strategies to tackle agricultural GHG emissions: The case for biological nitrification inhibition technology

Accelerated soil-nitrifier activity and rapid nitrification are the cause of declining nitrogen-use efficiency (NUE) and enhanced nitrous oxide (N2O) emissions from farming. Biological nitrification inhibition (BNI) is the ability of certain plant roots to suppress soil-nitrifier activity through production and release of nitrification inhibitors. The power of phytochemicals with BNI-function needs to be harnessed to control soil-nitrifier activity and improve nitrogen-cycling in agricultural systems. Transformative biological technologies designed for genetic mitigation are needed so that BNIenabled crop-livestock and cropping systems can rein in soil-nitrifier activity to help reduce greenhouse gas (GHG) emissions and globally make farming nitrogen efficient and less harmful to environment. This will reinforce the adaptation or mitigation impact of other climate-smart agriculture technologies

Cassava genetic resources: a global approach for conservation and use

An international workshop on cassava genetic resources was recently held at CIAT. The main objectives of the meeting were to assess the present status of cassava germplasm conservation and use, and to examine the possibility of establishing a global network for cassava genetic resources. A global conservation strategy was discussed, based on the present status of national and international cassava genetic resources programs. Priorities were set for future germplasm collecting expeditions and sharing of conservation workload among institutions for both cassava and wild Manihot germplasm. The discussion on a global strategy for conservation of genetic resources involved areas such as: studies on genetic diversity, definition of core collections, identification of duplicate accessions, in-vitro and cryopreservation techniques, duplication of germplasm collections in other institutions, sexual seed and pollen gene collections, etc. The existing mechanisms for safe germplasm exchange were evaluated for an effective movement of genetic resources within the network. Other important subjects discussed during the meeting were: the development of data bases for cassava germplasm, human resource development, and the integration of the germplasm network with other networks (i.e. CBN) and its implications

Application of interspecific sesquiploidy to introgression of PLRV resistance from non-tuber-bearing Solanum tuberosum to cultivated potato germplasm

Hybridization of synthetic allotetraploids of S. pinnatisectum with S. etuberosum (4x-EP) with S. acaule (2n = 4x = 48) resulted in two individuals that were highly fertile, in contrast to all other progenies. The unique individuals are hexaploids, 2n = 72, while the other progenies are tetraploids, 2n = 48. They are thought to be the products of a union between 2n eggs of S. acaule and normal 1n microspores of 4x-EP. The fertile hexaploids (designated 6x-AEP) produced abundant selfed seed and viable hybrids with cultivated diploid potato, S. phureja, when developing embryos were rescued from berries and cultured before transplanting to pot culture. The extreme variability in chromosome constitution of the hybrids with S. phureja and selfed progenies indicates that addition and substitution lines of etb chromosomes bearing genes of interest to breeders could easily be produced from this material. The production of sesquiploids, as the 6x-AEP hybrids are called, is discussed as a useful bridging step in the introduction of alien genes from genomes that share little homology with the cultivated genome

Breeding potatoes for developing countries using wild tuber bearing Solanum spp. and ploidy manipulations

The use of ploidy manipulations in potato breeding has been successfully applied by breeders at the International Potato Center (CIP) as a tool for germplasm enhancement and for the introduction of desirable genes of wild species into the cultivated gene pool. This methodology consists in reducing the ploidy level using haploids (2n = 2x = 24) and increasing it through the utilization of 2n gametes. It takes advantage of working at the 2x level to develop genotypes which combine multiple pest/disease resistance and a high frequency of 2n gametes. The specific resistances are obtained mainly from wild species. Then, desirable attributes are transferred to the 4x level by unilateral sexual polyploidization (4x x 2x crosses) using first division restitution (FOR) 2n pollen. CIP's work demonstrates that this approach has been very efficient for the transmission of resistance to cyst and root-knot nematodes, bacterial wilt, early blight and potato tuber moth as well as producing high yielding 4x genotypes which also have yield stability over environments. This recently developed germplasm is now available for potato breeders in developing countries who can produce high yielding and resistant 4x clones adapted to the growing conditions of their countries

Recursos geneticos del CIAT: su papel en la investigacion y el desarrollo

The responsibility of CIAT`s Genetic Resources Unit in the preservation of germplasm of beans (Phaseolus), cassava and its wild relatives (Manihot), and tropical forages (legumes and/or grasses) is pointed out. The main characteristics of the collections are indicated. Distribution, improvement and research activities carried out by the Unit are described. (CIAT

The influence of various types of other presence on anxiety responses

The purpose of this study was to explore the influence of varied types of other-presence on experimentally induced anxiety responses. Thirty-six female subjects were randomly assigned into the four experimental groups varied in two conditions of their relationships. These groups were named, respectively, Friend/Co-Active (FC), Friend/Audience (FA), Stranger/Co-Active (SC), and Stranger/Audience (SA). Subjects in Co-Active condition were connected in a series circuit and would receive an electrical shock in together. After the collection of subjective ratings for affiliation, anticipatory arousal was measured directly by physiological and subjective indices while waiting for the onset of electrical shock during one minute. The results were as follows; (1) In arousal level, SA was the highest, and FC was the lowest of the four experimental groups. (2) The Stranger conditions (SC, SA) were higher than the Friend conditions (FC, FA) in both physiological and subjective indices of anxiety responses. (3) The arousal level of SC was almost the same as that of FA. This implied that the Co-Active condition might heighten the intimacy of mutual relationship even if they were strangers to each other