Improved Tapaswini having four BB resistance genes pyramided with six genes/QTLs, resistance/tolerance to biotic and abiotic stresses in rice

Abstract

Rice, a major food crop, is grown in a wide range of ecological conditions and suffers significant yield losses as it is constantly exposed to a wide range of environmental and biotic stresses. The prevalence of different biotypes/strains has necessitated assembling of numerous resistance genes/QTLs into elite genotypes to confer a broader scale of resistance. The current study reports successful pyramiding of genes/QTLs that confer tolerance/resistance to submergence (Sub1), salinity (Saltol), blast (Pi2, Pi9) and gall midge (Gm1, Gm4) to supplement the four bacterial blight resistance genes (Xa 4, xa5, xa13, Xa21) present in Improved Tapaswini, an elite cultivar. The precise transfer of genes/QTLs was accomplished through effective foreground selection and suitable gene pyramids were identified. Background selection was practiced using morphological and grain quality traits to enhance the recovery of the recurrent parental genome. In the bioassays, the pyramids exhibited higher levels of resistance/ tolerance against the target stresses. The novel feature of the study was successful pyramidization and demonstration of the function of ten genes/QTLs in a new genotype. This success can stimulate several such studies to realize the full potential of molecular plant breeding as the foundation for rice improvement.

Development of nutritious rice with high zinc/selenium and low cadmium in grains through QTL pyramiding

“…Many elite varieties have been successfully developed by pyramiding major QTLs or genes in rice recently (Shamsudin et al 2016; Zeng et al 2017; Das et al 2018; Feng et al 2018; Kumar et al 2018), indicating that rational design is a powerful tool to improve complex traits and create super‐varieties. GCC3 and GCC5 were two other QTLs identified for grain Cd concentration in our used population, but only GCC3 PA64s allele had a negative effect on Cd accumulation in grains (Table 1; Liu et al 2020).…”

The genetic associations between yield component traits and bacterial leaf blight resistance in rice (O. sativa L.)

“…So far, 40 BLB resistance genes (R) conferring host resistance against various strains of Xoo have been identified [7]. Nine of these genes (Xa 21 , Xa 23 , Xa 27(t) , Xa 29 , Xa 30 , Xa 32 , xa 32 , Xa 35 and Xa 36 are from wild rice [8]. Six genes have physically been mapped (Xa 2 , Xa 4 , Xa 7 , Xa 30 , Xa 33 and Xa 38 ) and other six have been cloned (Xa 1 , xa 5 , xa 13 , Xa 21 , Xa 26 /Xa 3 and Xa 27 ) [9 -14].…”

“…Nine of these genes (Xa 21 , Xa 23 , Xa 27(t) , Xa 29 , Xa 30 , Xa 32 , xa 32 , Xa 35 and Xa 36 are from wild rice [8]. Six genes have physically been mapped (Xa 2 , Xa 4 , Xa 7 , Xa 30 , Xa 33 and Xa 38 ) and other six have been cloned (Xa 1 , xa 5 , xa 13 , Xa 21 , Xa 26 /Xa 3 and Xa 27 ) [9 -14]. Several resistant rice plants carrying single to multiple resistant genes have been bred using these genes [15][16][17][18].…”

“…Several resistant rice plants carrying single to multiple resistant genes have been bred using these genes [15][16][17][18]. For instance, dominant genes Xa 4 and Xa 21 responsible for durable resistance of rice varieties have been pyramided into rice lines [19]. Bacterial blight resistance QTLs, xa 13 , xa 5 and Xa 21 have been combined with blast resistant gene Pi54 and QTL, qSBR11-1 for Sheath blast (ShB) in Pusa Basmati1 [20].…”

“…For instance, dominant genes Xa 4 and Xa 21 responsible for durable resistance of rice varieties have been pyramided into rice lines [19]. Bacterial blight resistance QTLs, xa 13 , xa 5 and Xa 21 have been combined with blast resistant gene Pi54 and QTL, qSBR11-1 for Sheath blast (ShB) in Pusa Basmati1 [20]. The genes conferring tolerance to submergence (Sub1), salinity (Saltol), blast (Pi2, Pi9) and gall midge (Gm1, Gm4) have also been pyramided to the four bacterial blight resistance genes (Xa 4 , xa 5 , xa 13 , Xa 21 ) in the improved Tapaswini, rice cultivar [21].…”