Pyramiding of Pi46 and Pita to improve blast resistance and to evaluate the resistance effect of the two R genes

Abstract

Utilization of R (resistance) genes to develop resistant cultivars is an effective strategy to combat against rice blast disease. In this study, R genes Pi46 and Pita in a resistant accession H4 were introgressed into an elite restorer line Hang-Hui-179 (HH179) using the marker-assisted backcross breeding (MABB) procedure. As a result, three improved lines (e.g., R1791 carrying Pi46 alone, R1792 carrying Pita alone and R1793 carrying both Pi46 and Pita) were developed. The three improved lines had significant genetic similarities with the recurrent parent HH179. Thus, they and HH179 could be recognized as near isogenic lines (NILs). The resistance spectrum of the three improved lines, which was tested at seedling stage, reached 91.1, 64.7 and 97.1%, respectively. This was markedly broader than that of HH179 (23.5%). Interestingly, R1793 showed resistance to panicle blast but neither R1791 nor R1792 exhibited resistance at two natural blast nurseries. The results implied that the stacking of Pi46 and Pita resulted in enhanced resistance, which was unachievable by either R gene alone. Further comparison indicated that the three improved lines were similar to HH179 in multiple agronomic traits; including plant height, tillers per plant, panicle length, spikelet fertility, and 1 000-grain weight. Thus, the three improved lines with different R genes can be used as new sources of resistance for developing variety. There is a complementary effect between the two R genes Pi46 and Pita.

Improvement of rice blast resistance by developing monogenic lines, two-gene pyramids and three-gene pyramid through MAS

“…In this study, two indica accessions, H4 and Huazhan, were used as donor parents (DPs). The accession H4, conferring broad-spectrum resistance to blast at both seedling and adult stages, was found to carry at least two major R genes, with Pi46 on the long arm of chromosome 11 (Xiao et al 2011) and Pita on chromosome 12 (Xiao et al 2016). The R gene Pi46 was confirmed to be a different allele of Pik / Pi1 locus, for several SNPs that could discriminate them were identified (data not shown).…”

“…Moreover, some broad-spectrum resistant varieties were identified to harbor multiple R genes, including Tetep (Barman et al 2004), IR64 (Sallaud et al 2003), Sanhuangzhan 2 (Liu et al 2004), Digu (Chen et al 2004; Shang et al 2009) and Gumei2 (Wu et al 2005). These findings suggest that the combination of multiple race-specific R genes is an effective strategy to develop cultivars with broad-spectrum resistance to blast disease (Hittalmani et al 2000, Tacconi et al 2010, Khanna et al 2015, Xiao et al 2016). However, multiple R genes mean intensive pressure to promote the evolution of M. oryzae races, which is highly various in population due to a high level of genomic instability of the pathogen (Dean et al 2005; Ballini et al 2008).…”

Genotyping for Blast (Pyricularia oryzae) Resistance Genes in F2 Population of Supa Aromatic Rice (Oryza sativa L.)

“…In the present study, there were plants which had both the aroma and blast resistance genes, similar to the findings by Luo et al [24] who reported a successful development of WH6725 resistant line to blast disease which possessed both genes. In the present study, the presence of Pita gene in resistant or moderately resistant plants may be attributed to the fact that Pita gene has been found to confer a medium-spectrum resistance [25].…”

Recent Advances in Rice Varietal Development for Durable Resistance to Biotic and Abiotic Stresses through Marker-Assisted Gene Pyramiding

“…Pyramiding of multiple genes can lead to broad-spectrum disease resistance. For example, the Pi21 + Pi34 + qBR4-2 + qBR12-1 genes together [141], the Pi5 + Pi54 + Pid3 + Pigm genes together [140] and the Pik + Pita genes [142] were stacked to achieve broad-spectrum resistance to blast pathogen M. oryzae.…”