Phenotypic, cytogenetic and spike fertility characterization of a population of male-sterile triticale

Triticale (X Triticosecale Wittmack) is a good cereal for production of flour and feed. A segregating population of triticale was developed from a male-sterile (MS) plant. To determine whether this new source of male sterility in triticale is appropriate for use in breeding programs the expression of the male sterility phenotype was characterized through spike fertility, meiotic behavior, and pollen. Controlled crosses between male-sterile plants and control varieties male-fertile (MF) of triticale were also conducted, and cytological analyses were performed in the F2 and backcross plants. Plants with male-sterile phenotypes displayed reduced spike fertility when compared to plants with male-fertile phenotypes. Compared to male-fertile plants, male-sterile plants exhibited a lower percentage of normal meiotic cells, a reduced meiotic index and reduced pollen viability. The F2 plants had improved pollen fertility when compared to the male-sterile population; however there were no corresponding improvements in the percentage of normal meiotic cells or in the meiotic index. A single generation of backcrosses resulted in an improved meiotic index and increased pollen viability. However, no changes in the percentage of normal meiotic cells were observed. Meiotic instability, which was shown to be inheritable, was the likely cause of male sterility. Therefore, the use of this population in triticale breeding was considered to be inappropriate because it could promote or contribute to the maintenance of meiotic instability, which is commonly observed in this species

Understanding the Effect of Rye Chromatin in Bread Wheat

Most experiments on 1RS translocations in wheat (Triticum aestivum L.) cannot separate the effects of introgressions of rye (Secale cereale L.) chromosome armfromthe absence of corresponding wheat chromosome arms. The objective of this research was to determine the contribution of individual wheat and rye group 1 chromosome arms. Five group 1 ditelosomics, six substitutions, and 16 translocations of 1R in wheat were compared with appropriate controls. All ditelosomics were significantly different from controls for 100-kernel weight (100-KW), flour protein content (FP), Mixograph peak time (MT) and tolerance (MTO), and sodium dodecyl sulfate sedimentation (SDSS) volume. Among the long arms, 1DL was the most important for end-use quality and 1AL the least important, ranking even below the 1RL tested. The contribution of all short arms was low. Substitutions of 1R negatively impacted agronomic performance with the long arm being entirely responsible for this effect. Among translocation lines, those with 1RS.1BL had the highest yield and those with 1RS.1DL the lowest. Negative impact of all translocations of 1RS on the end-use quality was far greater than the absence of the corresponding 1S arms of wheat. Translocation 1RS.1AL was the least detrimental to quality and 1RS.1DL the most detrimental. Both the source of the rye chromatin and its position in the wheat genome affected agronomic performance and quality. These results suggest that it may be possible to create new translocations of 1RS in wheat with improved performance. Translocation of 1RS to 1AL is preferred from a quality point of view; that to 1BL appears more beneficial for agronomic performance