The Genetic Mechanism Of The High Frequency Passing Of Monosomic Addition Lines Of The Beet

Among a set of monosomic alien addition lines of Beta corolliflora in sugar beet, aline, designated as MAAL9, constituting of the normal 18 B. vulgaris chromosomesplus B.corolliflora chromosome 9, was found to have a high chromosome transmissionfrequency in successive generations. If MAAL9 was apomictic, it would be useful toclone the genes related to apomixis and fix the crop heterosis. If the high transmissionfrequency of the line was controlled by a gametocidal chromosome, the chromosome(B.corolliflora chromosome 9) would be the first gametocidal one found in Beta andwas an important mutagen of the genus Beta. In order to find out the hereditymechanism of the high chromosome transmission frequency of MAAL9, the petiolecolor and chromosome set of the F₁ plants of green petiole MAAL9×red petioleB.vulgaris were observed, the genetic resemblance among the maternal plants ofMAAL9 and the F₁ plants (2n=19) were conducted based on the AFLP analysis, andthe chromosomal aberration was studied during MAAL9 maiosis with Southern blotting.The main results were showed below.1. The petiole color of sugar beet was controlled by a single dominant gene, the redone being dominant and the green recessive. The genotype of the red petiole B. vulgariswas homozygous in the petiole color gene site.2. All the MAAL9 plants used in the crossing experiment were pollenized from themale parent, the red petiole B.vulgaris, to reproduce the seed progeny through thefertilization. Meanwhile, the chromosome transmission frequency of MAAL9 was stillhigher than normal.3. The genotypes of the maternal plants, MAAL9, were different from the ones oftheir offspring(2n=19), likewise among the plants(2n=19) of F₁ of MAAL9×B.vulgaris according to the AFLP marker analyses. The cloned line of MAAL9 was not produced by the seeds on the basis of the hybrid test and the analysis of DNA molecularmarkers.4. The template DNAs of the reversed B.vulgaris from MAAL9 were hybridizedwith the probe1054, a B.corolliflora genome-specific dispersed repetitive DNAsequence. The results of the dot blotting and Southern blotting showed that theprobability of chromosomal aberration was very high in the process of MAAL9 maiosis.It seemed that B. corolliflora chromosome 9 was gametocidal.