A novel mitochondrial orf147 causes cytoplasmic male sterility in pigeonpea by modulating aberrant anther dehiscence
- 22 Downloads
A novel open reading frame (ORF) identified and cloned from the A4 cytoplasm of Cajanus cajanifolius induced partial to complete male sterility when introduced into Arabidopsis and tobacco.
Pigeonpea (Cajanus cajan L. Millsp.) is the only legume known to have commercial hybrid seed technology based on cytoplasmic male sterility (CMS). We identified a novel ORF (orf147) from the A4 cytoplasm of C. cajanifolius that was created via rearrangements in the CMS line and co-transcribes with the known and unknown sequences. The bi/poly-cistronic transcripts cause gain-of-function variants in the mitochondrial genome of CMS pigeonpea lines having distinct processing mechanisms and transcription start sites. In presence of orf147, significant repression of Escherichia coli growth indicated its toxicity to the host cells and induced partial to complete male sterility in transgenic progenies of Arabidopsis thaliana and Nicotiana tabacum where phenotype co-segregated with the transgene. The male sterile plants showed aberrant floral development and reduced lignin content in the anthers. Gene expression studies in male sterile pigeonpea, Arabidopsis and tobacco plants confirmed down-regulation of several anther biogenesis genes and key genes involved in monolignol biosynthesis, indicative of regulation of retrograde signaling. Besides providing evidence for the involvement of orf147 in pigeonpea CMS, this study provides valuable insights into its function. Cytotoxicity and aberrant programmed cell death induced by orf147 could be important for mechanism underlying male sterility that offers opportunities for possible translation for these findings for exploiting hybrid vigor in other recalcitrant crops as well.
KeywordsArabidopsis Cajanus cajan Cytoplasmic male sterility Hybrid vigor Pigeonpea Tobacco
This work was undertaken as part of the CGIAR Research Program on Grain Legumes. Thanks to Rahul Nitnavare, Chavvi Srivastava, Divya and Kedarinath for their technical assistance with the transformation and gene expression studies and PS Rao for photography. Critical reviews of the manuscript by Drs. Gopalan Selvaraj, Rajeev Gupta and Damaris Odeny are gratefully acknowledged.
PBM and KKS conceptualized, designed and analyzed all experimental data. RG conducted expression studies in prokaryotic system, Sequence analysis was done by PSR, BPR assisted in cloning and transformation; DSR was involved in qPCR and Northern blot studies. RKS provided inputs on mitochondrial genomic sequence information and analysis. CVSK provided pigeonpea seed material. PBM and KKS conducted histochemical studies. PBM, KKS, RG and PSR contributed to manuscript preparation.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest. PBM, RG and KKS are inventors on the patent applications of this work and are current employees of ICRISAT who owns the IP.
- Geisler DA, Päpke C, Obata T, Nunes-Nesi A, Matthes A, Schneitz K, Maximova E et al (2012) Down regulation of the δ-subunit reduces mitochondrial ATP synthase levels, alters respiration, and restricts growth and gametophyte development in Arabidopsis. Plant Cell 24:2792–2811CrossRefPubMedPubMedCentralGoogle Scholar
- Kurek I, Ezra D, Begu D, Erel N, Litvak S, Breiman A (1997) Studies on the effects of nuclear background and tissue specificity on RNA editing of the mitochondrial ATP synthase subunits α, 6 and 9 in fertile and cytoplasmic male-sterile (CMS) wheat. Theor Appl Genet 95:1305–1311CrossRefGoogle Scholar
- Peng X, Wang K, Hu C, Zhu Y, Wang T, Yang J, Tong J, Li S, Zhu Y (2010) The mitochondrial gene orfH79 plays a critical role in impairing both male gametophyte development and root growth in CMS-Honglian rice. BMC Plant Biol 10:125. https://doi.org/10.1186/1471-2229-10-125 CrossRefPubMedPubMedCentralGoogle Scholar
- Saxena KB (2015) From concept to field: evolution of hybrid pigeonpea technology in India. Ind J Genet 75:279–293Google Scholar
- Saxena KB, Hingane AJ (2015) Male sterility systems in major field crops and their potential role in crop improvement. In: Plant biology and biotechnology, plant diversity, organization, function and improvement. Springer, New Delhi, pp 639–656Google Scholar
- Saxena KB, Sameerkumar CV, Hingane AJ, Nagesh Kumar MV, Vijaykumar RA, Saxena RK, Patil S, Varshney RK (2016) Hybrid ICPH 2740 assures quantum jump in pigeonpea productivity in peninsular India. J Food Legum 29:142–144Google Scholar
- Wang Z, Zou Y, Li X, Zhang Q, Chen L, Wu H, Su D et al (2006) Cytoplasmic male sterility of rice with boro II cytoplasm is caused by a cytotoxic peptide and is restored by two related PPR motif genes via distinct modes of mRNA silencing. Plant Cell 18:676–687CrossRefPubMedPubMedCentralGoogle Scholar
- Yoshimi M, Kitamura Y, Isshiki S, Saito T, Yasumoto K, Terachi T, Yamagishi H (2013) Variations in the structure and transcription of the mitochondrial atp and cox genes in wild Solanum species that induce male sterility in eggplant (S. melongina). Theor Appl Genet 126:1851–1859CrossRefPubMedGoogle Scholar