Study On Interaction Of Dwarfing Gene Rht13 With Rht-D1b And Development Molecular Markers For Rht13 In Wheat

Wheat is the important grain reserves and commodity grain in China, the research and utilization of dwarfing genes is one of the important research directions in wheat genetics and breeding. In present study, three crosses were created by Ningchun4, Ningchun40, Ningchun44 as maternal parents and Magnif M1 as pollen donor respectively, then the homozygous individual were determined using the corresponding molecular markers to screen the F2 populations. Interactive effects of Rhtl3 and Rht-Dlb in F2 progeny were analyzed on agronomic traits. Besides molecular markers of Rhtl3 were developed by using comparative genomics approach and molecular linkage mapp of Rhtl3 were constructed in wheat. The main results were as follows:（1） Agronomic traits such as plant height, spike length and length of second internode from top etc were investigated for all F2 populations. The results showed that broad-sense heritability of plant height, peduncle length and length of third internode from top were higher than other traits in F2 progenies. In terms of CV, length of third internode from top and the grain number per spike had bigger CV than other traits and the variation coefficient of spike length was the smallest trait in four F2 populations. The effect of dwarfing gene Rhtl3 reducing plant height was detected stronger than Rht-Dlb, but the stalk reduction ability of Rht-Dlb and Rhtl3 interaction was better than two single dwarfing gene. Among four F2 populations in two years, each trait values of tall （rhtl3+Rht-Dla） were maximum and dwarfing lines（Rht-Dlb+Rhtl3） were minimum. It was found that interactive effects of Rhtl3 and Rht-Dlb restrained elongation of all the internodes to reduce plant height by 21.54%,26.54%,23.94% and 18.46% respectively and they reached significant level. Other agronomic traits of double dwarfing line revealed the same result. At the same time, compared to the three dwarfing lines with tall lines, diameter of each internode were decreased significantly. The relative content of leaf chlorophyll（SPAD） was decreased significantly on double dwarfing gene Rht-Dlb+Rhtl3 as well as single dwarfing gene Rhtl3. For yield traits, each character of the double dwarfing lines was significantly lower than those of the tall lines, which was not conducive to the formation of yield traits. This showed that the interaction between Rht-Dlb and Rhtl3 had negative cumulative effects on agronomic and yield traits.（2） Through the collection of annotated molecular markers, study of dwarfing genes and GA genes from wheat, rice, brachypodium, barely and millet were conducted by the comparative genomics approach. The results showed that 19 of 60 molecular markers screened polymorphism between two parents （Ningchu4 and Magnif Ml）, which accounted for 30.5% of total markers. Clustering analysis of dwarfing genes and GA genes from rice, Brachypodium distachyon, barley and millet as well as wheat were revealed that these genes had a certain degree of homology. According to the results of comparative genomics approach, two of 54 designed new primers had implied polymorphism in parents and named 7BLSSR1 （derived from d27 gene on rice chromosome 11） and 7BLSSR2 （derived from Traes₇DL_F51807989 gene on wheat chromosome 7DL）.（3） Detected polymorphic molecular markers were mapped in Rhtl3 bin of chromosome 7B. All markers covered 64.8 cM with an average marker of distance 3.6 cM. Using interval mapping and single marker analysis method, the statistical analysis showed QTLs affecting dwarfing traits detected in the F2 population derived from crossing of Ningchun 4 and Magnif Ml. Marker Xgwm577 had the maximum phenotype contribution rate of plant height at 21% in present population. And QTLs were located on chromosome 7B between SSR markers Stb8 and Xgwm577. After genetic analysis of F2 and F3 populations from Ningchun 4 and Magnif M1, results showed that dwarfing gene Rhtl3 was a major gene of recessive inheritance in wheat.