The formation of Maize Foundation Inbred Lines: Analysis in Different Perspective
Abstract
Maize breeding has made a greater contribution to the increases of maize yield. Maize foundation inbred lines play an irreplaceable role in maize breeding . The formation of foundation lines were the results of many factors , the key factors of which were accord with breeding trends, adapt to environment in much of region , and have appropriate representativeness for particular heterotic group. Foundation lines possess well structure of source and better yield stability, this contribute to their combination s with coordinated source -sink relationship and adapt to close planting . Foundation lines resist major stress factor and adapt to the cropping systems and cultural practices of main maize producing areas . And foundation lines concentrate numerous unique allele s of particular heterotic group , so they are easy to generate heterotic with lines from other heterotic group . For new foundation lines breeding, the existing foundation lines are preferred basic germplasm and cross breeding unites with pedigree selection is effective breeding method . Moreover, we give a integrate breeding method base on rapid advances in plant -breeding technology.
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Introduction
Maize (Zea mays L.) is one of the most important crop which extensive as food, fodder and industrial raw materials. According to investigation statistics by Food and Agriculture Organization of the United Nations(FAO, http://faostat.fao.org), maize total production in the world more than rice and wheat from 2001 to 2011 and reached 885milliontons in 2011. China is the second largest maize producer, planted area and total yield, in the world. The area planted of maize in China over wheat in 2002 and over rice in 2007. The average yields of China maize from 0.96 tons per hectare in 1949 rose to 5.87 tons per hectare in 2012, more than six fold increase(http://www.stats.gov.cn/). It is estimated that40-60% of total gain in maize yield was contribution by genetics improve (Ci et al2011a; Duvick1992, 2004; Li2009a; Russell1991). Maize is one of the earliest and largest grown area crop which utilization of heterosis in crops, and over 97% of maize plantings are hybrid in China(Duvick1992, 1999; Li2009a). The chiefly process of maize breeding and utilization of heterosis is breeding inbred lines and test cross to testers. Foundation inbred lines, such as B73, Mo17, Oh43, Huangzao4, Ye478, Dan340 et al., play an important role in maize breeding (Li and Wang2010; Teng et al.2004; Troyer1999,2004).
Several lines of evidence indicate that maize was domesticated approximately 10,000 years ago in the Balsas River Basin of southwestern Mexico (Matsuoka et al.2002; Piperno et al.2009; Van Heerwaarden et al.2011). It was undergoing narrow selection in domestication from teosinte (Zea mays ssp. parviglumis or spp. mexicana) to maize(Wang et al.1999).The variation in a few critical regions of genome between maize and teosinte generate their obvious difference of morphological (Doebley2004).The chief process of maize domestication are increase apical dominance, and decrease branches, unfallen, number of female inflorescences per plant, thus enhance single ear grain weight (Doebley1997, 2006). And the main process of maize improvement are enhance grain yield, improve plant type, and increase tolerances to biotic and abiotic stress (Crosbie et. al.2006; Duvick2005; Russell1991). The ultimate aim of maize domestication and improvement is increase yield potential, and convenient for manage and harvest.
This paper reviews the formation of foundation maize inbred lines, by means of analyze yield-related traits in level of performance and genes (Figure 1).In the level of performance, the foundation lines with fine plant type could harmonize individual growing development and the construct of population structure, even more it could coordination of source and sink. At the genetic level, on the one hand the foundation lines own high general combining ability (GCA) effects because it get together a lot of favorable alleles; on the other hand the foundation linesown some distinctive alleles so that it is apt to generate heterosis with different heterotic group material.
