AUTHOR=Abhilash Kumar V. , Balachiranjeevi C. H. , Bhaskar Naik S. , Rambabu R. , Rekha G. , Harika G. , Hajira S. K. , Pranathi K. , Anila M. , Kousik M. , Vijay Kumar S. , Yugander A. , Aruna J. , Dilip Kumar T. , Vijaya Sudhakara Rao K. , Hari Prasad A. S. , Madhav M. S. , Laha G. S. , Balachandran S. M. , Prasad M. S. , Viraktamath B. C. , Ravindra Babu V. , Sundaram R. M. 

TITLE=RETRACTED: Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01195

DOI=10.3389/fpls.2016.01195

ISSN=1664-462X

ABSTRACT=<p>RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., <italic>Xa21</italic> and <italic>Xa33</italic> for BB resistance and <italic>Pi2</italic> and <italic>Pi54</italic> for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing <italic>Xa21</italic> + <italic>Pi2</italic>), RPBio Patho-2 (possessing <italic>Xa21</italic> + <italic>Pi54</italic>) and FBR1-15EM (possessing <italic>Xa33</italic>) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, <italic>Rf3</italic> and <italic>Rf4</italic>, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC<sub>2</sub> generation. At BC<sub>2</sub>F<sub>2</sub>, plants possessing the gene combination- <italic>Xa21</italic> + <italic>Pi2, Xa21</italic> + <italic>Pi54</italic> and <italic>Xa33</italic> in homozygous condition and with &gt;92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F<sub>3</sub> generation (DICF<sub>3</sub>). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the experimental hybrids derived by crossing the gene-pyramid lines of RPHR-1005 with APMS6A (the female parent of DRRH-3), showed heterosis levels equivalent to or higher than DRRH-3. The results of present study exemplify the utility of MABB for targeted improvement of multiple traits in hybrid rice.</p>