“…To date, many genes governing grain shape have been identified and cloned, such as GW2 (Song et al, 2007), GIF1 (Wang et al, 2008), qSW5 (Shomura et al, 2008), GS3 (Mao et al, 2010), GS5 (Li et al, 2011), qGL3 (Zhang et al, 2012), GW8 (Wang S. et al, 2012), GS6 (Sun et al, 2013), GS2 (Hu et al, 2015), GL7 / GW7 (Wang S. et al, 2015; Wang Y. et al, 2015), OsMAPK6 (Liu S. et al, 2015), and GLW7 (Si et al, 2016). Besides these genes, many QTL affecting grain size have been identified through linkage mapping and association studies (Zhao et al, 2011; Singh et al, 2012; Zhang W. et al, 2013; Yang et al, 2014; Liu D. et al, 2015; Qiu et al, 2015; Edzesi et al, 2016; Feng et al, 2016), and some of them have been fine mapped such as GW1-1 and qGRL1.1 (Singh et al, 2012), GW3 and GW6 (Guo et al, 2009), qGL-7 (Bai et al, 2010), qGRL7.1 (Singh et al, 2012). For grain chalkiness, only one gene, Chalk5 is cloned (Li et al, 2014).…”