No abstract

-The formation of naked grains is directly associated with the formation of multiflorous spikelets in oats.

ABSTRACT. Multiflorous spikelets are found in several grass species of agricultural and economic interest. In oat, this morphological characteristic is associated with the production of naked grains. Although many genetic studies have been performed over the past century, the inheritance of the multiflorous spikelet trait is not fully understood in oat. The objectives of this study were to evaluate environmental effects on the multiflorous spikelet trait, to estimate the number of genes controlling the trait, and to clone and characterize sequences of the AP2 gene in oat. Two genetic populations of recombinant inbreed lines were screened for the multiflorous spikelet trait from different years and sowing dates under field experiments. Normal, multiflorous, and mosaic spikelets were analyzed in the whole panicle for both years and sowing dates. Specific primer pairs for the AP2 gene was utilized to amplify and clone oat sequences. The results demonstrate that under higher temperature and day-length conditions, the variable expressivity of the multiflorous spikelet trait was less pronounced in both populations. Genetic analyses indicated the action of one major gene and two or three modifying genes controlling the expression of the multiflorous spikelet trait in oat, depending on the genetic background. Sequences with similarity to the AP2 gene were isolated from the oat lines UFRGS 017004-2 and URS Taura, and genetic polymorphisms were identified, which are valuable to confirm the action of AP2 on the multiflorous spikelet trait. Our results provide information to assist in the development of future studies of the multiflorous spikelet trait in oat.

-The aim of this study was to estimate the number of genes that control the naked (hull-less)

ABSTRACT:The objective of this study was to identify microsatellites molecular markers linked to R genes, that confer the wheat grain color and evaluate the association with pre-harvest sprouting tolerance. This study was conducted with a F 2 population with 203 plants, derived from the cross between PFAU x CD0666 genotypes, which segregates for one grain color gene. Were analyzed 43 molecular markers located in regions that containing R genes on 3B and 3D chromosomes. The Xbarc344 molecular marker was identified as linked to the R gene at a distance of 26.1 cM with 83.25% of selection efficiency. From the phenotypic analysis was confirmed the association between grain color with Xbarc344 molecular marker, however, there was no association between Xbarc344 with pre-harvest sprouting tolerance. Also, there was no association between grain color with pre-harvest sprouting tolerance. Although the grain color in wheat is a trait easy to select, it is known that not all R genes are involved with pre-harvest sprouting tolerance. Therefore, it is important the genetic mapping and specific evaluation of each R gene with pre-harvest sprouting tolerance. Thus, the molecular markers identified as associated with each R gene can be used to select plants that contain such genes, since it is not possible to identify phenotypically which R gene each plant has.