Abstract
BackgroundDirect-seeded rice (DSR) is a potential technology for sustainable rice farming as it saves water and labor. However, higher incidence of weed under DSR limits productivity. Therefore, there is a need to develop herbicide tolerant (HT) rice varieties.ResultsWe used marker assisted backcross breeding (MABB) to transfer a mutant allele of Acetohydroxy acid synthase (AHAS) gene, which confers tolerance to imidazolinone group of herbicides from the donor parent (DP) “Robin” into the genetic background of an elite popular Basmati rice variety, Pusa Basmati 1121 (PB 1121). Foreground selection was done using the AHAS gene linked Simple Sequence Repeat (SSR) marker RM6844 and background selection was performed using 112 genome-wide SSR markers polymorphic between PB 1121 and Robin. Phenotypic selection for agronomic, Basmati grain and cooking quality traits in each generation was carried out to improve the recovery of recurrent parent phenome (RPP). Finally, a set of 12 BC4F4 near isogenic lines (NILs), with recurrent parent genome (RPG) recovery ranging from 98.66 to 99.55% were developed and evaluated. PB 1121-HT NILs namely 1979-14-7-33-99-10, 1979-14-7-33-99-15 and 1979-14-7-33-99-66 were found superior to PB 1121 in yield with comparable grain and cooking quality traits and herbicide tolerance similar to Robin.ConclusionOverall, the present study reports successful development of HT NILs in the genetic background of popular Basmati rice variety, PB 1121 by introgression of mutated AHAS allele. This is the first report on the development of HT Basmati rice. Superior NILs are being evaluated in the national Basmati trials, the release of which is likely to provide a viable option for the adoption of DSR technology in Basmati rice cultivation.
Highlights
Direct-seeded rice (DSR) is a potential technology for sustainable rice farming as it saves water and labor
The F1 seeds were produced by crossing Pusa Basmati (PB) 1121 as female and Robin as male and the hybridity of the F1 plants was tested using the Simple Sequence Repeat (SSR) marker RM6844 linked with acetohydroxyacid synthase (AHAS) gene
Development of Pusa Basmati 1121 (PB 1121)-Near-isogenic line (NIL) with Herbicide Tolerance The recurrent parent PB 1121 and donor Robin were validated for their tolerance to herbicide, Imazethapyr
Summary
Direct-seeded rice (DSR) is a potential technology for sustainable rice farming as it saves water and labor. In South-East Asian countries, where rice is primarily cultivated by transplanting, DSR holds great promise as it is a potential water and labor saving technology, which offers the possibility of saving huge amount of water and labour needed for puddling and transplanting. AHAS is a critical enzyme for the biosynthesis of branched-chain amino acids namely, leucine, isoleucine and valine in plants. These herbicides, have low mammalian toxicity due to lack of AHAS gene (Tan et al 2006; Piao et al 2018). Due to the above benefits, the herbicides of imidazolinone group are most widely used for weed control in crops like soybean, groundnut etc., which possess natural tolerance to these herbicides. Several variants of AHAS genes conferring imidazolinone tolerance have been developed through mutagenesis and selection in different crops and commercialized as Clearfield® crops
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