A spike developmental atrophy mutant with deformed flowers (stems,leaves and other organ were developing normally),named as sda1,was first identified from wheat breeding lines.We observed the morphological characteristics of stamen,pistil,and the microspore stained with I-KI under a microscope.For genetic analyses,we generated an F₂ population by crossing sda1 with ‘Shaanmai 94’ wild type.We investigated the agronomic traits of F₂ population,and content of soluble sugar in spike and internode below ear and photosynthetic characteristics of flag leaf at filling stage were measured.By means of bulked segregation analysis and small population-based linkage analysis using the published SSR markers we mapped the gene.The results showed that:(1)The stamen and pistil developed atrophy and the microspore of sda1 was abortion.(2)The original strain of mutant segregation tests suggested that,the mutant phenotype was controlled by a single recessive nuclear gene named as SDA1 (spike development atrophy 1).(3)The mutant heading date delayed 4 days comparison with the wild type;and soluble sugar content of internode below ear and spike in mutant wheat were significantly increased 30.6% and 11.0% than those in normal wheat at filling stages.However,the heading duration was 8 days both the mutant wheat and the normal wheat;and the photosynthetic characteristics of flag leaf between mutant and normal wheat were not detected.(4)The gene mapping analysis suggested that,SDA1 locus was preliminarily mapped between marker WMC398 and BARC136 on the chromosome 6B with the genetic distances of 2.2 cM and 2.1 cM to the two markers.It is speculated that SDA1 is a pleiotropic gene controlled the heading date and the spike organ development,and also affects the transformation and utilization of soluble sugar.