Characterization of the common wheat (Triticum aestivum L.) mutation line producing three pistils in a floret

摘要

Wheat (Triticum spp. L.) is the most important food crop in the world and becomes even more important as the global population increases. Because the arable land is very limited, improving the yield is essential. One way to improve wheat yield potential is to increase grain number per spike (Coffman 1924; Frederic and Bauer 2000). For this purpose, wide genetic variability in wheat spike morphological structure has been considered by wheat scientists (Sharman 1944; Martinek 1994) as one possible way to obtain high grain number per spike. Supernumerary spikelet, an abnormal spike type, was considered as an ideal type for high yield breeding (Koric 1966; Rawson and Ruwali 1972). Supernumerary spikelet was also named as branched ear (spike) in some literature. It showed additional sessile spikelet at rachis nodes, or floret on an extended rachilla (Pennell and Halloran 1983). Because of its visually impressive extra spikelet per spike, supernumerary spikelet could considerably raise the grain number per spike. However wheat breeders have found that it was very difficult to overcome the low kernel weight in development of supernumerary spikelet cultivars (Koric 1966), which made many wheat breeders turn to utilize multispikelet to increase the grain number per ear (Millet 1983; Dencic 1994). Multispikelet expressed normal spike morphology, but possessed over 26 spikelets in a spike. Like the supernumerary spikelet, multispikelet could raise grain number per spike. But large number of spikelets in a normal wheat spike commonly delayed heading date (Rawson 1971; Rahman and Wilson 1977). Furthermore, multispikelet showed wrinkled grains (Millet 1987; Zheng et al. 1994). Although some breeders are trying to improve these two wheat variation lines (Zheng et al. 1993; Peng et al. 1998, 2000), the creation of, and research on, new genetic variation to increase the grain number per spike is still very interesting to most wheat breeders. The common wheat (T. aestivum L.) mutant Three Pistils (TP) is a new variation of this kind. The TP line posses normal spike morphology but three pistils in a floret, two more than normal plants, which made it have the potentiality to increase the grain number per spike. The morphology of TP's floret and inheritance of this trait was reported in previous paper (Peng 2003). This study was initiated to provide information about the location of gene for three pistils trait, and the seed set of the mutation line.