Identification of rapd marker linked to blast resistance gene in a somaclone of rice cultivar Araguaia

Abstract

The gene Pi-ar confers resistance to Pyricularia grisea race IB-45 in a somaclone derived from immature panicles of the susceptible rice (Oryza sativa) cultivar Araguaia. RAPD technique was used to identify molecular markers linked to this gene utilizing bulked segregant analysis. Initially, the two parental DNAs from the resistant donor SC09 and 'Araguaia' were analyzed using random primers. Of the 240 primers tested, 203 produced amplification products. The two parental DNAs along with the resistant and susceptible bulks of F2 population were screened using 48 primers that differentiated resistant and susceptible parents. Even though eight primers differentiated the resistant bulk from the susceptible bulk, as well as somaclone SC09 and 'Araguaia', only one primer, OPC02 ('GTGAGGCGTC'), was found to be tightly linked (1.7cM) to the resistance gene of somaclone SC09.

RAPD Marker Linked to a Gene Conferring Resistance to Race IB-9 of Pyricularia grisea in a Somaclone of the Rice Cultivar Araguaia

“…These results are in conformity with those obtained by Araújo et al (1999) in earlier studies in relation to the inheritance of resistance of the somaclones SC09, SC10 and SC23 for the race IB-45 of P. grisea. Filippi and Prabhu (1996) observed that in the majority of crosses studied the resistance to the predominant races IB-1 e IB-9 of P. grisea was dominant and controlled by one or three genes.…”

“…These somaclones differed from the original parental cultivar in fan-shaped plant type, blast resistance and yield potential. In the advanced R 6 generation, among 20 somaclones highly resistant to blast, both in the greenhouse and field tests, the somaclone SC09 was selected, based on similar yield potential as Araguaia (Araújo et al, 1999(Araújo et al, , 2000. The expression of blast resistance among the regenerated plants may be attributed to the pre-existing variation present in the original explant resulting from residual heterozygosity of the genotype introduced in vitro (Morrish et al, 1990) or mitotic crossing over (Evans et al, 1984).…”

“…Somaclones of Araguaia, resistant to rice blast were developed from the callus cultures of immature panicles (Araújo et al, 2000). The resistance of this somaclone to the race IB-45 of P. grisea was controlled by a dominant major gene and designated as Pi-ar (Araújo et al, 1999). The incorporation of this gene by conventional backcross method may be limited due to the presence of other resistance genes and possible epistatic effects (Haley et al, 1993).…”

“…RAPD markers combined with bulked segregant analysis has been utilized for identifying specific markers linked to blast resistance genes in rice (Naqvi et al, 1995;Chen et al, 2000;Zheng et al, 2000). Araújo et al (2002) in an earlier investigation, identified the primer OPC02 tightly linked (1.7 cM) to the major resistance gene to P. grisea race IB-45 in a somaclone SC09 of the cultivar Araguaia.…”

Search for a Microsatellite Marker Linked with Resistance Gene to <i>Xanthomonas axonopodis</i> pv. <i>malvacearum</i> in Brazilian Cotton

“…Invariably, the artificial inoculations with bacteria give a margin for misinterpretation of the results because of the inconsistent reactions influenced by unsuccessful inoculations especially under field conditions [4]. Marker assisted selection (MAS) is being advocated to aid selection of resistant plants in early generations in some plant species [5][6][7][8][9][10][11][12]. The MAS technique allows us to identify the presence of resistance gene(s) in segregating populations of early generations within a few days and avoids repeated inoculations under field conditions.…”