Anther culture in rice proportionally rescues microspores according to gametophytic gene effect and enhances genetic study of hybrid sterility

Yoshitaka Kanaoka,Daichi Kuniyoshi,Yoshihiro Okamoto,Hideshi Yasui,Eri Inada,Yuji Kishima,Yohei Koide

doi:10.1186/s13007-018-0370-z

Yoshitaka Kanaoka, Daichi Kuniyoshi + Show 5 more

Open Access

https://doi.org/10.1186/s13007-018-0370-z

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Journal: Plant methods	Publication Date: Nov 17, 2018
Citations: 5	License type: open-access

Affiliation: Hokkaido University, Rakuno Gakuen University

Abstract

BackgroundTo investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima). Male gametes of these hybrids display complete sterility owing to a dozen of hybrid sterility loci, termed HS loci, but this complicated genetic system remains poorly understood.ResultsMicrospores from these interspecific hybrids form sterile pollen but are viable at the immature stage. Application of the anther culture (AC) method caused these immature microspores to induce callus. The segregation distortion of 11 among 13 known HS loci was assessed in the callus population. Using many individual calli, fine mapping of the HS loci was attempted based on heterozygotes produced from chromosome segment substitution lines (CSSLs). Transmission ratio distortion (TRD) from microspores was detected at 6 of 11 HS loci in the callus population. The fine mapping of S1 and S19 loci using CSSLs revealed precise distances of markers from the positions of HS loci exhibiting excessive TRD.ConclusionsWe demonstrated that AC to generate callus populations derived from immature microspores is a useful methodology for genetic study. The callus population facilitated detection of TRD at multiple HS loci and dramatically shortened the process for mapping hybrid sterility genes.

Highlights

To investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima)
Of the three parental lines used as controls, the highest callus formation rate on RI-13 callus-induction medium (CIM) was observed in the japonica cultivar Nipponbare (4.37%); the two O. glaberrima cultivars, WK21 and WK18, had rates of 1.10% and 2.12%, respectively
Taken together, our results demonstrate that the genotype segregation patterns of hybrid sterility (HS) loci in anther culture (AC)-induced calli associated with microspore developmental stages are informative for understanding when HS loci determine the viability of male gametes

Summary

Introduction

To investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima) Male gametes of these hybrids display complete sterility owing to a dozen of hybrid sterility loci, termed HS loci, but this complicated genetic system remains poorly understood. Sativa–glaberrima S1 heterozygotes can only transmit the gamete carrying the S1g allele from O. glaberrima to progenies, while the S1s allele from O. sativa cannot participate in fertilization [17] Such differential transmission between two alleles from their heterozygote is generally referred to as transmission ratio distortion (TRD) and results in segregation distortion (SD) in the progenies [17, 18]. Major pollen sterility in sativa–glaberrima F1 hybrids results from the integration of multiple HS loci that individually may cause only partial sterility [18]

Results

Discussion

Conclusion