Abstract
Polyploidization has played an important role in plant evolution and is a pathway for plants to increase genetic diversification and to get higher heterosis comparing with that of diploid does. This study was undertaken to assess the genetic variation and relationships among 40 autotetraploid rice genotypes and their counterpart diploid cultivars with 99 SSR markers screened from published rice genome. The 99 SSR markers detected polymorphism among autotetraploid genotypes and revealed a total of 291 alleles with an average of 2.949 alleles per locus. Autotetraploid lines showed higher genetic diversity and significant variation in agronomic traits than diploid cultivars. Phylogenetic analysis revealed that most of autotetraploid lines were genetically different from their diploid parents, and inter-subspecific hybrids were prepared on the basis of genetic distance between parents. Inter-subspecific autotetraploid hybrids showed a higher and positive heterobeltiosis and competitive heterosis than diploid hybrids, especially for grain yield. Genetic distance appeared not to predict heterosis in diploid rice for all traits; however, it showed a significant correlation with grain yield, grain length and grain length to width ratio in autotetraploid rice. This extensive research on autotetraploid heterosis and genetic diversity will be useful for the development of autotetraploid rice hybrids.
Highlights
Polyploidization has played an important role in plant evolution and is a pathway for plants to increase genetic diversification and to get higher heterosis comparing with that of diploid does (Doyle et al 2008; Luan et al 2008; Shahid et al 2012)
effective panicles number (EPN), Plant height (PH), Seed set ratio (SS), total number of grains per plant (TGP), grains per panicle (GPP), grain yield (GY) and grain density (GD) decreased in autotetraploid rice, such as EPN, the mean value was 7.10 and ranged from 4.33 to 11.00 in diploid rice, while in autotetraploid rice the mean value was 5.09 and ranged from 2.33 to 8.33
Among all the agronomic traits, we found that Panicle length (PL), TGP, EPN, 1000-grain weight (GWT), Grain length (GL), Grain width (GW), GY, SS, GPP and GD showed highly significant (P < 0.01) variation, while PH, showed significant (P < 0.05) variation in ploidy level comparison (Table 3)
Summary
Polyploidization has played an important role in plant evolution and is a pathway for plants to increase genetic diversification and to get higher heterosis comparing with that of diploid does (Doyle et al 2008; Luan et al 2008; Shahid et al 2012). A number of studies have been made in various crop plants to predict the relationship between genetic diversity and heterosis, such as diploid rice (Xiao et al 1995; Zhao et al 1999; Wang et al 2013), wheat (Martin et al 1995), maize (Smith et al 1990; Betran et al 2003), barley (Schut et al 1997) and rape seed (Liu et al 2002; Yu et al 2005) These studies showed two different and contradictory results, some revealed that markers could be used for predicting heterosis, while some other proposed markers could not predict heterosis for complicated traits
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
