Relationship between grain colour and preharvest sprouting-resistance in wheat.

Since red alleles (R) of the genes that control grain colour are important for the improvement of preharvest sprouting resistance in wheat and there are three independently inherited loci, on chromosomes 3A, 3B and 3D of hexaploid wheat, it is possible to vary the dosage of dominant alleles in a breeding program. The objective of this work was to evaluate the dosage effect of R genes on preharvest sprouting, in a single seed descent population, named TRL, derived from the cross between Timgalen, white-grained wheat, and RL 4137, red-grained wheat. The study was carried out using sprouting data in ripe ears obtained under artificial conditions in a rainfall simulator over three years. According to the results there is a significant effect on preharvest sprouting provided by colour and a weaker effect of increasing R dosage. However, the significant residual genotypic variation between red lines and all lines (reds and whites) at 0.1% level showed that preharvest sprouting was also controlled by other genes. There are no significant correlations between sprouting and date of ripeness or between ripeness, R dosage and colour intensity

Genetic control of seed dormancy and pre-harvest sprouting in wheat.

Pre-harvest sprouting (PHS) damage leads to occasional massive losses in all wheat producing areas, causing downgrading of grain quality, that severely limits' end-use applications and results in ;substantial financial losses to farmers and food processors. Red grain color is a traditional marker for,:resistance to sprouting in wheat breeding programs, however red-grained genotype alone does not always guarantee effective resistance. The objective of this work was to find genes for resistance to PHS and investigate its inheritance in Brazilian wheat cultivars. Genetic variation for dormancy was investigated in :the parents, F 1 and 300 F 2 lines derived from the cross Frontana x OR1 and its reciprocal. The germination/ dormancy sprouted grains was evaluated ,on fifty seeds per replication, germinated in paper towel rolls at woC for 5 days. A bimodal distribution for dormancy occurred in the Frontana/OR1 and OR1/Frontana ierived F 2 populations. The mean ratio of dormant and non-dormant seeds of the cross and its reciprocal was 85: 1115, fitting a digeAi~ model of 1: 15 (P < 0.05). In fact, all non after-ripened F 1 seeds germinated. The F2 distribution indicates that two major genes, here calledA,a andB,b, control seed dormancy, which ,It appears to be recessive to dormancy. Only the homozygous aabb is dormant. As expected, there was no . 'effect of maternal tIssues

Trigo: BRS Albatroz.

bitstream/item/29624/1/albatroz3.pdf1 folder

Analysis of preharvest sprouting in three Brazilian wheat populations.

The objective of this work was to evaluate the possibility of obtaining recombinant inbred wheat lines more resistant to preharvest sprouting, independently of colour genes, in three red-grained Brazilian wheat populations. The results showed statistical significance among lines within all populations, which presented a normal distribution and transgressive segregation for preharvest sprouting. The normal distribution of the lines from all red-grained populations suggests that sprouting, excluding the genes expressing seed coat pigmentation, is, probably, controlled by many genes. These findings also indicate that it may be possible to improve resistance to preharvest sprouting, independently of the colour genes