In vitro induction of auto-allotetraploid in a newly developed wild rice line from Oryza alta Swallen

Abstract

Oryza alta Swallen is an important germplasm for rice resistance breeding; however, its CCDD genome (2n = 48) resulted in low crossability when the wild rice was crossed with O. sativa and restricted the success of transferring the desirable traits into cultivated rice. Induction of polyploidy is an efficient way for overcoming the low crossability among different species. A new O. alta line, Huaye 5, was developed by our group in 2016, which had high fertility (64.93%) and photoperiod-insensitive. Huaye 5 was used to induce auto-allotetraploidy using tissue culture in the present study. The tissue culture system was established by comparing five basic media (N6, B5, MS, NB and MB), two hormones (2,4-D and 6-BA) for induction and two differentiation media (MS and NB), and then induced auto-allotetraploid in the wild rice line by colchicine. The medium and hormone combinations of NB + 2,4-D (2.5 mg/L) + 6-BA (1.0 mg/L) produced the induction rate of 20%, and MS medium was found to be a suitable medium for callus induction with a differentiation rate of 10.15%, and the treatment of 600 mg/L colchicine for 24 h was the best protocol for inducing auto-allotetraploid. Subsequently, auto-allotetraploid plants (2n = 96) were obtained in the present study and their ploidy levels were detected by using flow cytometry, stomata size and chromosomes count methods. Many inclusions in the parenchyma cells surrounding vascular bundle were observed in auto-allotetraploid rice compared to the parent. We developed a new germplasm from O. alta, and established a protocol of in vitro induction of auto-allotetraploid, which can be used for crossing with autotetraploid rice. Key messageWe have successfully established a protocol for the in vitro induction of auto-allotetraploid in Oryza alta, which can be used to cross with autotetraploid or neo-tetraploid rice.Communicated by Manoj Prasad.

Molecular footprints of selection effects and whole genome duplication (WGD) events in three blueberry species: detected by transcriptome dataset

“…According to the age and outcomes of cytogenetics and karyotype, WGD events can be classified into two kinds, one is the recent or new polyploidization event, which results in "autopolyploids" and emerge from the fusion of gametes produced by non-meiosis, or hybridization of normal meiosis gametes of same species individuals, or "allopolyploids" produced from inter-specific hybridization [18]. About 47-70% of angiosperm species are estimated as polyploid and approximately 25% of vascular plants have undergone recent polyploidization [19,20], and this WGD event could be detected by karyotyping and flow cytometry method [21]. Another is the ancient polyploidization event, which happened in earlier geological ages.…”

Agrobacterium-Mediated High-Efficiency Genetic Transformation and Genome Editing of Chaling Common Wild Rice (Oryza rufipogon Griff.) Using Scutellum Tissue of Embryos in Mature Seeds

“…The genetic transformation of several wild Oryza accessions had been reported, however, its regeneration and transformation efficiency were low ( Zhang et al, 2019 ; Shimizu-Sato et al, 2020 ; Yu et al, 2021 ). An efficient genetic transformation system for wild rice is needed to be well established.…”

“…Allotetraploid Oryza alta Swallen with CCDD genome from South America, possesses a variety of disease and insect resistances ( Mao et al, 1995 ; Ammiraju et al, 2010 ). The tissue culture study of Swallen showed that the callus induction rate and regeneration frequencies were only 20 and 10%, respectively ( Zhang et al, 2019 ), suggesting that its callus induction and regeneration ability were extremely low. Polyploid rice 1 (PPR1) from South America is also an allotetraploid wild rice with CCDD genome.…”

Genome-wide and pan-genomic analysis reveals rich variants of NBS-LRR genes in a newly developed wild rice line from Oryza alta Swallen

“…Rice improvements help us to meet the challenge of feeding a population by breeding better varieties as fast as we can. However, with the continuous growth of the world’s population and the continuous development of the economy ( Zhang et al., 2019 ), the requirements for the quality of human life have risen sharply. Moreover, decreased relative arable land area ( Fei et al., 2018 ; Xie et al., 2018 ; Li et al., 2021 ) and deteriorated ecological environment ( Jiang et al., 2021 ; Zhou et al., 2021 ) made rice food scarcity prominent ( Guo et al., 2022 ), which attracted attention from all walks of life.…”

“…Our previous research developed a new germplasm, Huaye 5, from O. alta , and established a protocol for in vitro induction of an auto-allotetraploid line ( Zhang et al., 2019 ). Huaye 5 is an important wild rice germplasm harboring many elite genes.…”