QTL Mapping For Tiller Angle In Wheat

The crop architecture directly affects its adaptability to the environment and the final yield.Currently,researches on crop architecture were main in rice.The wheat cultivars from north and south China show distinct architecture.The northern wheat generally shows compact architecture,suitable for planting with a high density.However,the southern wheat shows more loose architecture.The tiller angle may be one of the important factors to causes this difference,but relative studies were rare.In present study,a high-generation recombinant inbred line population constructed by cross a typical southern variety-Chinese spring and northern variety-Zhoumai 22 was used as experimental material to mapping quantitative trait loci(QTL)influencing their plant architecture.Wheat 15 K SNP array was used to genotyping this population.We hope the results will be helpful for further wheat architecture breeding.The main results are as follows:1.Both Chinese Spring and Zhoumai 22 were sensitive to gravity stimulation in the early stage after germination,showing a similar response ratio.They simultaneously arrived a relative stable stage(keep the bending angle unchanged for a long time)at about 96 minutes after horizontally placed.At about 192 minutes,both of them nearly paralleled with the anti-gravity direction,reached maximum bending angle.2.The direct traits including tiller angle at seeding and maturity stage,plant height,crown width(the widest part of the plant at maturity stage),widest height(the height of the plant at the widest point of the mature stage),tiller diameter,tiller number,heading time,and the indirect traits including tiller Tiller density(the projected area calculated by crown width divided by tiller number),ratio of the widest height divided by the plant height were analyzed.Except tiller Tiller density,the two parent varieties showed significantly different of other traits,confirming their distinct plant architecture.Except tiller diameter,remain traits segregated continuously and followed a normal distribution in the RIL population.3.Based on the genotypic data using the wheat 15 K SNP array,a genetic map with a total length of 4722.44 cM was constructed.The map contains 4285 markers with an average density of 1.1 cM/markers;the B genome has the longest map length and the most number of markers,followed by A genome,and the D genome shortest.4.A total of 24 QTL were obtained from QTL analysis.One same locus contributed to highly explain phenotypic variation of tiller angle at the seedling and adult stage,the ratio of between widest height and plant height,and heading time was mapped at 34-47 Mb of chromosome arm 2DS,where included the photoperiod gene Ppd-D1.It is suggested that the main plant architecture differences between the two parents may be related to the genes controlling the development process.Some other QTL loci affecting the plant architecture were also detected at chromosomes 2B,3A,3B,3D,4A,4B,5D,6B and 7D.