Genetic Analysis And Gene Mapping Of A Poly-row-and-branched Spike Mutant In Barley

Barley was an important crop. Acquiring barley mutants and research on them was key for gene clone and function analysis, and was the base of improvement for agricultural character using biotechnology. Poly-row-and-branched spike (prbs) in barley was a mutant from D₂ of Pudamai 2 whose inflorescence was treated with maize nuclear DNA. prbs had multi-spikelet and the number of spikelet on every spike axis's node was not definite, and its spike had the tendency to branch, so its spike behaved non-regular poly-rowed. Preliminary genetic analysis demonstrated that the mutant character was recessive contrast to two-row of Pudamai 2, controlled by one pair of recessive genes (prb), and was one variant of row- types. Genes controlling row-types detected distributed on 5 chromosomes, respectively were vrs1 (2H) vrs2 (5H), vrs3 (1H), vrs4 (3H) and int-4 (4H), and interaction in the alleles and between the alleles generated various row-types. Six-row was the most common row-type besides two-row. We further studied the genetic relationship between prb and genes controlling six-row(recorded as n), and determined the location on chromosome for prb and n using SSR, and studied the strategies for mapping interactive genes. Main results were summarized as follows:1. Genetic analysis for prbs: Four barley crosses (six-row x two-row, prbs x two-row, prbs x six-row and six-row x prbs) were built, and the row types of F₁, F₂ and F₃ of the four crosses were investigated and analyzed. For the cross six-row × two-row, six-row in contrast to two-row is controlled by one pair of recessive genes (recorded as n); and for the cross prbs x two-row, prbs mutant traits in contrast to two-row is also controlled by one pair ofrecessive genes (recorded as prb); for the crosses prbs x six-row and six-row x prbs, two-row:six-row:prbs=9:3:4 in F2, so row types are controlled by two pairs of genes, one pair controls two-row vs. six-row, the other controls prbs mutant traits vs. not, prbs mutant traits is controlled by recessive genes (prb), and prblprb has recessive epistasis on the pair of genes controlling two-row vs. six-row.2. Strategies for mapping interactive genes: Gene interaction was a common genetic phenomenon. But special ways for locating intertactive genes hadn't been reported so far. Common for single gene location, Bulked Segregant Analysis (BSA) combining Mapmaker/Exp was familiarized by many researchers. Considering this, we developed this technique for interactive genes location. The basic strategy for locating interactive genes put forward in this study was generally fit for interactions controlled by two pairs of independent genes. Usually, only F2 group was needed for mapping interactive genes by "BSA+ Mapmaker/Exp", F3 were needed for BSA for one pair of genes in inhibition effect and two pairs of genes in complementary effect. Two were key in the basic strategy: 1) found two phenotypes between which alleles on the target locus differed, and formed two responding DNA pools for BSA; 2) among the segregating group, found individuals having definite genotype to form the mapmaking sub-group. Usually, only one pair of DNA pools for BSA was needed for two pairs of interactive genes, but DNA pools for BSA were needed respectively for every pair of genes in inhibition effect. Sub-groups for mapmaking could be found simultaneously suitable for two pairs of interactive genes in all types of interaction. Thus heighten the efficiency of BSA and Mapmaker/Exp for interactive genes. So this strategy for mapping interactive genes was practicable. The mapping groups for...