Genetic Analysis And Gene Mapping Of The Spike Development Gene SDA1in Wheat

The vegetative growth is the basis of crop yield and quality, and the reproductive organis the decisive factor to build up the yield and quality. Since Green Revolution, theimprovement of wheat production is still in a difficult hill climbing stage. Therefore, theimportant method of breakthrough production bottleneck is to explore and exploit thehigh-yielding key gene. Nowadays, it has been more thorough about the development of thespike is critical to the production, but there were seldom reports on the key gene which playsa vital role in wheat’s vegetative and in the spike development process.The research showed that a wheat spike growth defect mutant is controlled by a singlerecessive nuclear gene (stems, leaves and other organs are normal growth), whichrepresentations are small spikes, shallow color, low growth function and imperfection form.For the moment, we named the gene SDA1(spike development atrophy1). It is deduced thatSDA1is a pleiotropic gene which maintain the vegetative growth and reproductive growth ofwheat, adjust the spike and floral organs development. At present, there are no mutants withsimilar to sda1which have been reported in the wheat research. Using this mutant tolucubrate the molecular mechanism, to reveal the polymorphism and dose effect in the geneSDA1.It has an extremely important theoretical significance to reveal the multiple role of thegrowth and development gene in determining panicle formation and floral organsdevelopment. The research tested that the mutant phenotype characteristic by means of theobservation flower anatomical structure and sterility under the microscope. At the same time,according to the mutant material near-isogenic line, we established the genetic segregationstructure, and analysed the hereditary character of mutant character. We investigated theagronomic traits, at filling stage, measured the contents of soluble sugar in spike and theinternode below stem and photosynthetic characteristics of flag leaf. On the basis, by meansof using the published SSR markers, we proceeded to make a primary mapping. The mainstudy results showed below:1. From seeding stage to heading stage, there were no significant differences in leaf size,tiller and plant height between the mutant sda1and wild type plant. The spike of sda1issmaller than the wild type. The awns are short and curved, and its glumes didn’t open withmalformation, no visible anther. Under dissecting microscope, we observed the Morphological characteristics of stamen and pistil, and researched microspore stained withI-KI of mutant plant sda1.The results showed that the sda1floral organ pathologicaldevelopment, the pistil development atrophy, the stamens deformity and the microspore wasbarren.2. By means of analysis about the mutant hybrid strain in a few years. Both the wild typeplant and the mutant were accord with3:1segregation ratio. A total of220F2populationsderived from the cross ‘Shan Mai94’ and ‘sda1’, according to observing the character ofspike, we found the character of F1is normal. The F2have the separation of mutant trait,what’s more, the wild type plant and the mutant were accord with3:1segregation ratio. Itproved that this mutant is controlled by a recessive gene.3. In the strains of “xn585”(In this strain, we found the mutant plant sda1), soluble sugarcontents of internode below steam and spike in mutant wheat were significantly increasedthan those in normal wheat at the filling stages(P<0.05).However, the photosyntheticcharacteristics of flag leaf between mutant and normal wheat were not detected.4. There was no difference between the mutant and normal plant in the agronomic traitsin the F2populations. However, comparing with the normal plant, the mutant heading datedelayed four days.5. By means of bulked segregant analysis and small population-based linkage analysisusing the published SSR markers, the gene SDA1was preliminarily located on thechromosome6B, with the genentic distance of2.1cM and2.2cM to the markers BARC136and WMC398. The results provided the theoretical basis for function detecting and finemapping of the gene.6. It is speculated that SDA1is a pleiotropic gene which controlled the heading date andthe spike organ development, and also affected the transformation and utilization of solublesugar. Hoping to explore the function of the genes, and use the gene in genetic research andcrop improvement.