QTL Mapping For Seed Size And Shape In Common Bean

Common bean is one of the most popular food legumes worldwide,providing the main food source and plant protein for people from some developing areas.It is of great importance to develop cultivar which is of good quality and high production to meet the growing need of common bean.Seed size and shape not only affect the production,but also have influence on appearance quality as commodity.Seed size and shape can be defined by seed weight,seed length,seed width,seed height,and so on.To date,the genetic basis of seed size and shape remain unknown though a lot of effort has been done to locate OTL related to these traits.In china,we need to build our basis to start this kind of work step by step,because it will be useful to facilitate breeding program and aquire well-performed cultivar.This study used two varietys that are from two different gene pools respectively and have distinctive phenotype in the aspect of seed size and shape to develop F₂ population as the materials of this study.We detected QTL related to seed weight,seed length,seed width,seed height,seed length-to-width ratio and seed length-to-height ratio.Otherwise,we located genes related to another two traits that also has different phenotype between two parents including flower colour and grouth habit.Here are the main results:1.The F₂ population is derived from the cross between the male parent F5910 that is from Mesoamerican gene pool and the female parent Long570709 that is from Andean gene pool.Phenotype identifying results reflect that all these 6 traits have a wide range variety and their distribution resemble the characters of normal distribution,which means these six traits are all quantitative traits.Relationship analysis result demonstrates that seed weight has a significant relationship with the left five traits respectively and this result remains same in two different environments;2.A total of 165 polymorphic SSR markers between two parents were picked out through the screening of about 2000 SSR markers designed by our lab and were used to construct genetic map.A total of 100 SSR markers were used in the genetic map constructed by the F₂ population planted in Harbin.This genetic map has a total length of 439.88 cM.Each chromosome contains 5 to 17 SSR markers and the average distance between two markers is 4.4 cM.The F₂ population planted in Beijing was used to construct another linkage map which contains 88 SSR markers.Compared with the first map,this map lacks one or more markers in chromosome 5,6,7,9,11.The second map has a total length of 421.91 cM and each chromosome contains 3 to 13 markers.The average distance between two markers is 4.8 cM;3.We located QTL related to these 6 traits in Harbin and Beijing respectively.A total of 38 QTL were found under the environment in Harbin.These QLT distributed 10 chromosome except the first chromosome.The PVE?phenotypic variance explained?ranged from 2.39%¹7.37%.Among them,there were 7,8,3,9,4,7 QTL related to seed weight,seed length,seed width,seed height,seed length-to-width ratio,seed length-to-height ratio respectively.There were total 21 QTL detected in the environment of Beijing distributing along chromosome1,3,6,7,8,9,11.The PVE of these QTL ranged from 5.29%²2.53%.There were respectively 4,5,3,4,3 and 2 QTL related to seed weight,seed length,seed width,seed height,seed length-to-width ratio and seed length-to-height ratio.SW7?SW7'?,SW6.1?SW6'?,SL6.1?SL6.1'?and SH11?SH11'?were identified in the same location in two different environment.SW9?SW9'??SLW7?SLW7'?and SLW8?SLW8'?were identified in the adjacent region in two different environment.The QTL above have a relatively high additive value and provide a good foundation of fine mapping and MAS;4.The F₂ population planted in Harbin was used to find a flower colour gene located on the sixth chromosome named FC6 which is linked with the marker P6S1.A growth habit gene was found on the first chromosome named GH1 which is linked with the marker P1S82.