Post-Domestication Selection in the Maize Starch Pathway

Abstract

Modern crops have usually experienced domestication selection and subsequent genetic improvement (post-domestication selection). Chinese waxy maize, which originated from non-glutinous domesticated maize (Zea mays ssp. mays), provides a unique model for investigating the post-domestication selection of maize. In this study, the genetic diversity of six key genes in the starch pathway was investigated in a glutinous population that included 55 Chinese waxy accessions, and a selective bottleneck that resulted in apparent reductions in diversity in Chinese waxy maize was observed. Significant positive selection in waxy (wx) but not amylose extender1 (ae1) was detected in the glutinous population, in complete contrast to the findings in non-glutinous maize, which indicated a shift in the selection target from ae1 to wx during the improvement of Chinese waxy maize. Our results suggest that an agronomic trait can be quickly improved into a target trait with changes in the selection target among genes in a crop pathway.

Adaptation of Maize to Temperate Climates: Mid-Density Genome-Wide Association Genetics and Diversity Patterns Reveal Key Genomic Regions, with a Major Contribution of the Vgt2 (ZCN8) Locus

“…The highest local LD was observed between Su1 [93], [94], [95], [96], Tga1 [97] and Bt2 on chromosome 4, a region involved in carbohydrate metabolism [98], [99] known to have played a key role in maize domestication. Generally, a r 2 of 0.10 is considered to be the minimum LD value needed to detect associations with complex traits.…”

Genetic Diversity and Molecular Evolution of Chinese Waxy Maize Germplasm

“…certain Kulesh) is a special cultivated type of maize, and was first discovered in China in 1908 and then in other Asian countries [1]–[4]. Waxy maize, with nearly 100% amylopectin in endosperm, is mainly used as food in Asia, and is also an important raw material for food industries, textiles, paper-making and feedstuff worldwide because of its excellent characters in terms of starch composition and economic value [5].…”

“…1) [18]. Recently, waxy sequences have been determined in a number of accessions from Zea lineage [4], [19]–[22].…”

Qualitative and Quantitative Trait Polymorphisms in Maize

“…The sh2 gene was significantly correlated with both amylase content and kernel composition, as well as starch content and kernel weight (Wilson et al 2004;Manicacci et al 2007). The genetic diversity of sh1, sh2, bt2, ae1, su1, and wx1 has recently been surveyed in extensive maize panels, including a population of 40 waxy, 26 dent, and 15 sweet corns from Korea (Shin et al 2006), 55 Chinese waxy accessions (Fan et al 2009), and 67 Chinese elite maize inbred lines (Cao et al 2009), respectively. A 30-bp Indel (D7) and a 15-bp Indel (D10) in the wx1 gene were shown to be associated with a glutinous phenotype (Fan et al 2009).…”

“…The genetic diversity of sh1, sh2, bt2, ae1, su1, and wx1 has recently been surveyed in extensive maize panels, including a population of 40 waxy, 26 dent, and 15 sweet corns from Korea (Shin et al 2006), 55 Chinese waxy accessions (Fan et al 2009), and 67 Chinese elite maize inbred lines (Cao et al 2009), respectively. A 30-bp Indel (D7) and a 15-bp Indel (D10) in the wx1 gene were shown to be associated with a glutinous phenotype (Fan et al 2009). After starch, the next largest component of maize kernel is protein, 80% of which is stored in the endosperm ).…”