RESUMO
The effect of the auxin phenylacetic acid (PAA) on wheat anther and on barley anther/microspore culture was investigated. With PAA the induction response was not usually significantly different from controls but a significantly higher number of green plants were produced in wheat anther and barley microspore culture. For wheat anther culture 100 mg/L PAA was beneficial. For barley microspore culture the optimum levels were from 1 to 100 mg/L, depending on genotype. In barley anther culture there were no improvements using PAA. In wheat anther culture, 145 green plants/100 anthers were obtained with cultivar Veery'S', while the average response from twelve F1 hybrids in the breeding program was 332 green plants/100 anthers. At least 1000 green plants were obtained using isolated microspores from 100 anthers in barley cv. Igri. With cv. Bruce, regeneration occurred only when 100 mg/L PAA was used. The influence of PAA appears at the embryogenic phase of the culture system. The possible mechanisms by which PAA may improve regeneration are discussed.
RESUMO
Nuclear growth, microspore cell growth and cell cycle stage were examined in microspores of anthers of Hordeum vulgare L. cv. Klages taken from florets of the middle of the spike as per anther staging methods. Although there was wide variation in nuclear size at all stages of the cell cycle, mean nuclear size appeared to be a good indicator of cell cycle stage for microspores within anthers. Microspore cell size increased considerably during Gl of the cell cycle. Anthers bearing microspores cytologically characterized as in the mid-uninucleate stage, which have proven to yield high levels of callus production, were determined to be in G1 of the cell cycle and were regularly found in spikes taken from tillers in which the base of the flag leaf had emerged 0 to 3 cm above the penultimate leaf.
