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Allelic profile of representative germplasm lines evaluated using gene based markers Pi54 MAS (above) and Pikh-STS (below). Lane M: 100 bp DNA Ladder (Fermentas, Luthuania); Lane 1 to 14: DHMAS 70Q 164-1b, Shalimar Rice-1,
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More than 100 genes have been reported to impart resistance against rice blast, however, not all are equally effective. Their effectiveness relies on factors such as the diversity in pathogen races prevailing in a certain area, rate of pathogen evolution, genetic background of a host and few others. Pi54 is a major gene showing resistance to Magnap...
Citations
... Molecular screening with other reported blast resistance genes revealed the presence of six resistance genes, viz., Pi1, Pi38, Pi40, Pi20, Pib and Pipt in various combinations, and could be responsible for their enhanced blast resistance. Consistent with the findings of the present investigation, there are several reports on the prevalence of a number of blast resistance genes having significant associations with blast resistance across a wide array of rice germplasm [35][36][37][38][39][40][41][42]. In one study, the prevalence of Pipt in leaf-blast-resistant lines was reported [43] while significant association of Pi56(1) and pi21 explained blast resistance in another study [44]. ...
The present study evaluates marker assisted forward breeding (MAFB)-derived disease resistant introgression lines (ILs) which do not have the targeted resistance genes for bacterial blight (xa5 + xa13 + Xa21) and blast (Pi2 + Pi9 + Pi54). The ILs were derived in the background of two elite rice cultivars, Krishna Hamsa [Recurrent Parent 1 (RP1)] and WGL 14 (RP2), involving multi-parent inter-crossing. Molecular characterization with gene specific markers for seven reported resistance genes each for bacterial blight (Xa33, Xa38, xa23, Xa4, xa8, Xa27 and Xa41) and blast (Pi1, Pi20, Pi38, Pib, Pitp, Pizt and Pi40) revealed the presence of xa8 and Xa38, in addition to the targeted xa5, xa13 and Xa21 for bacterial blight resistance and Pi1, Pi38, Pi40, Pi20, Pib and Pipt, in addition to the targeted Pi9 and Pi54, for blast resistance in various combinations. A maximum of nine resistance genes xa5 + Xa21 + Pi54 + xa8 + Pipt + Pi38 + Pi1 + Pi20 + Pib was observed in RP1-IL 19030 followed by eight genes xa5 + xa13 + Xa21 + xa8 + Pi9 + Pipt + Pi1 + Pi20 in two RP2-ILs, 19344 and 19347. ANOVA revealed the presence of significant variability for all the yield traits except “days to 50% flowering” (DFF). Box plots depicted the seasonal differences in the phenotypic expression of the yield traits. There was significant positive association of grain yield with days to flowering, tiller number and panicle number. Thousand grain weight is also significantly and positively correlated with grain yield. On the contrary, grain yield showed a significantly negative association with plant height. Multi-parent selective inter-crossing in the present study not only led to the development of high yielding disease resistant ILs but also enhanced recovery of the recurrent parent via selection for essential morphological features. More than 90.0% genetic similarity in the ILs based on SNP-based background selection demonstrated the success of multi-parent selective intercrossing in the development of disease resistant NILs.
... Similarly, it was also proved that the R genes of the alleles from the Piz locus exhibit excellent resistance after combining them with certain independently distributed R genes, such as Pi56 and Pish [38]. To date, many successful marker-assisted introgression using the Pi54 gene have been made in the various backgrounds of rice varieties and hybrids all over the world [2,36,[39][40][41]. Keeping in view with this, the present study aimed to introgress the Pi54 gene from Tetep into stable restorer lines CB 87 R and CB 174 R, but susceptible to blast disease through MABB. ...
Two popular stable restorer lines, CB 87 R and CB 174 R, were improved for blast resistance through marker-assisted back-cross breeding (MABB). The hybrid rice development program in South India extensively depends on these two restorer lines. However, these restorer lines are highly susceptible to blast disease. To improve the restorer lines for resistance against blasts, we introgressed the broad-spectrum dominant gene Pi54 into these elite restorer lines through two independent crosses. Foreground selection for Pi54 was done by using gene-specific functional marker, Pi54 MAS, at each back-cross generation. Back-crossing was continued until BC3 and background analysis with seventy polymorphic SSRs covering all the twelve chromosomes to recover the maximum recurrent parent genome was done. At BC3F2, closely linked gene-specific/SSR markers, DRRM-RF3-10, DRCG-RF4-8, and RM 6100, were used for the identification of fertility restoration genes, Rf3 and Rf4, along with target gene (Pi54), respectively, in the segregating population. Subsequently, at BC3F3, plants, homozygous for the Pi54 and fertility restorer genes (Rf3 and Rf4), were evaluated for blast disease resistance under uniform blast nursery (UBN) and pollen fertility status. Stringent phenotypic selection resulted in the identification of nine near-isogenic lines in CB 87 R × B 95 and thirteen in CB 174 R × B 95 as the promising restorer lines possessing blast disease resistance along with restoration ability. The improved lines also showed significant improvement in agronomic traits compared to the recurrent parents. The improved restorer lines developed through the present study are now being utilized in our hybrid development program.
