The ratoon stunting disease (RSD) of sugarcane,caused by the bacterium Leifsonia xyli subsp.xyli,is one of the major concerns to sugarcane production and breeding programs worldwide.Due to no obvious external symptoms...The ratoon stunting disease (RSD) of sugarcane,caused by the bacterium Leifsonia xyli subsp.xyli,is one of the major concerns to sugarcane production and breeding programs worldwide.Due to no obvious external symptoms,RSD cannot be easily detected by the growers,hence has reduced the world’s sugarcane production significantly.This study aimed to identify quantitative trait loci (QTL) associated with RSD resistance and to assist in the development of linked molecular markers for marker-assisted breeding to minimize the reduction in sugarcane yield by the RSD infection.A set of 146 individuals derived from a self-crossing of CP80-1827 were evaluated for RSD resistance in a mechanically duplicated inoculated field trial from 2014 to 2017 using tissue blot immunoassay.Leveraging the genetic data and the four years phenotyping data of CP80-1827 selfing population,linkage map construction and QTL analysis were conducted based on clonal F_1 and F_2 mapping population types with GACD V.1.2 and Ici Mapping V.3.3,respectively.A total of 23 QTL associated with RSD resistance were identified,which explained 6%to13%of the phenotypic variation with the two types of software.A total of 82 disease resistance genes were identified by searching these 23 QTL regions on their corresponding regions on the Sorghum bicolor genome (44 genes),sugarcane R570 genome (20 genes),and S.spontaneum genome (18 genes),respectively.Compared with Ici Mapping V.3.3,GACD V.1.2 identified more major (6 vs.3) and stable QTL (2vs.0),and more disease resistance genes (51 vs.31),indicating GACD V.1.2 (clonal F_1 mapping type) is most likely to be more efficient than Ici Mapping (F_2 mapping type) for QTL analysis of a sefling population or clonal F_1 population in clonal species.The identified QTL controlling RSD resistance along with the associated SNP markers will assist sugarcane molecular breeding programs in combating this disease.展开更多
Nonfunctionality of engineered water sources after two catastrophic cyclones—Sidr in November 2007 and Aila in May 2009—created acute scarcity of safe drinking water in coastal Bangladesh.The objective of this study...Nonfunctionality of engineered water sources after two catastrophic cyclones—Sidr in November 2007 and Aila in May 2009—created acute scarcity of safe drinking water in coastal Bangladesh.The objective of this study was to estimate households’willingness to pay(WTP)for disaster resilient water sources in Dacope upazila of Khulna District in southwestern coastal Bangladesh.By applying the double bounded dichotomous contingent valuation method to a dataset of 250 randomly selected households,we found that the mean WTP is BDT 263 and that inaccessibility to functional safe drinking water sources is the most significant determining factor of households’WTP.Projecting mean WTP for a disaster resilient water source project in the study area,we measured a present value of aggregate WTP over project’s life span worth about BDT 624(USD 7.37)million,which is about14.30 times the present value of project’s aggregate establishment and maintenance cost.However,charging the local inhabitants a water tariff at mean WTP would lead to the exclusion of around 50%of the people from getting access to the improved water services or create a free riding problem.Through simulation exercises this study determined that the socially optimal water tariff is BDT 50 per month.This tariff would not only generate revenue of more than five times the project cost but would also create access to disaster resilient improved drinking water sources for almost 99%of the people.展开更多
基金supported by Florida Sugarcane League, United States Department of Agriculture-Agricultural Research Service CRIS Project 6030-21000-005-00DUSDA National Institute of Food and Agriculture, Hatch Project 1011664。
文摘The ratoon stunting disease (RSD) of sugarcane,caused by the bacterium Leifsonia xyli subsp.xyli,is one of the major concerns to sugarcane production and breeding programs worldwide.Due to no obvious external symptoms,RSD cannot be easily detected by the growers,hence has reduced the world’s sugarcane production significantly.This study aimed to identify quantitative trait loci (QTL) associated with RSD resistance and to assist in the development of linked molecular markers for marker-assisted breeding to minimize the reduction in sugarcane yield by the RSD infection.A set of 146 individuals derived from a self-crossing of CP80-1827 were evaluated for RSD resistance in a mechanically duplicated inoculated field trial from 2014 to 2017 using tissue blot immunoassay.Leveraging the genetic data and the four years phenotyping data of CP80-1827 selfing population,linkage map construction and QTL analysis were conducted based on clonal F_1 and F_2 mapping population types with GACD V.1.2 and Ici Mapping V.3.3,respectively.A total of 23 QTL associated with RSD resistance were identified,which explained 6%to13%of the phenotypic variation with the two types of software.A total of 82 disease resistance genes were identified by searching these 23 QTL regions on their corresponding regions on the Sorghum bicolor genome (44 genes),sugarcane R570 genome (20 genes),and S.spontaneum genome (18 genes),respectively.Compared with Ici Mapping V.3.3,GACD V.1.2 identified more major (6 vs.3) and stable QTL (2vs.0),and more disease resistance genes (51 vs.31),indicating GACD V.1.2 (clonal F_1 mapping type) is most likely to be more efficient than Ici Mapping (F_2 mapping type) for QTL analysis of a sefling population or clonal F_1 population in clonal species.The identified QTL controlling RSD resistance along with the associated SNP markers will assist sugarcane molecular breeding programs in combating this disease.
文摘Nonfunctionality of engineered water sources after two catastrophic cyclones—Sidr in November 2007 and Aila in May 2009—created acute scarcity of safe drinking water in coastal Bangladesh.The objective of this study was to estimate households’willingness to pay(WTP)for disaster resilient water sources in Dacope upazila of Khulna District in southwestern coastal Bangladesh.By applying the double bounded dichotomous contingent valuation method to a dataset of 250 randomly selected households,we found that the mean WTP is BDT 263 and that inaccessibility to functional safe drinking water sources is the most significant determining factor of households’WTP.Projecting mean WTP for a disaster resilient water source project in the study area,we measured a present value of aggregate WTP over project’s life span worth about BDT 624(USD 7.37)million,which is about14.30 times the present value of project’s aggregate establishment and maintenance cost.However,charging the local inhabitants a water tariff at mean WTP would lead to the exclusion of around 50%of the people from getting access to the improved water services or create a free riding problem.Through simulation exercises this study determined that the socially optimal water tariff is BDT 50 per month.This tariff would not only generate revenue of more than five times the project cost but would also create access to disaster resilient improved drinking water sources for almost 99%of the people.
