Physiological Races of Rice Blast Pathogen and Host Resistant Genes Under Egyptian Conditions

Abstract

Experiments were carried out at Rice Research and Training Center during 2009 to 2012 growing seasons. This study aimed at evaluation of some commercial Egyptian rice cultivars and some promising lines against blast disease, identification of effective rice blast resistant genes, and distribution of physiological races and common races of Pyricularia grisea. One hundred and thirty two of P. grisea isolates were collected from rice-cultivating governorates in Egypt, namely Kafr EL-Sheikh (36 isolates), Gharbia (48 isolates), Dakahlia (18 isolates), Sharkia (12 isolates), Damietta (6 isolates) and Beheira (12 isolates). IH race group was the most common race (47.69%), followed by IC (26.58%) and IF (12.15%) groups, While IG, ID and IE (6.06, 6.04 and 1.49%, respectively) were the minor race groups during this study period. The promising line GZ 9057-6-1-3-2 revealed the highest level of resistance against most isolates tested (98.48%) followed by Giza 178 and GZ 9523-2-1-1-1 (96.22% for each). On the other hand, the susceptible rice cultivars, Sakha 101 and Sakha104, were infected with the most tested isolates (25.76 and 61.36 % resistance, respectively). Pi-z-5 gene found in IRBLz5-CA and IRBLz5-CA (R) lines scored the highest effective gene of blast resistance (97.76 and 95.50%, respectively). This gene was followed by pita-2 gene, found in the monogenic line IRBLta2-Re (91.70%). On the other hand, Pia gene found in IRBLa-A and IRBLa-C lines was the lowest effective resistant gene with zero efficacy against the tested isolates. The highest percentage of race groups from the total identified isolates were obtained from Gharbia and Kafr El-Sheikh governorates (36.53 and 27.27%, respectively). On other hand, Damietta governorate had the lowest percentage of race groups (4.56% from the total identified races).

Genetic Diversity Analysis and Molecular Characterization of Elite Rice Promising Lines for Yield, Blast Disease Resistance and Rice Stem Borer تحليل التنوع الوراثى والتوصيف الجزيئي لمحصول سلالات الارز المبشرة، ومقاومتها لمرض اللفحة وثاقبة ساق الارز

“…However the promising line (GZ11190-3-13-4-2) was infected by 9 isolates. These results agree with Shabana et al (2013), Kalboush (2019) and Marvet et al (2021) who showed the distribution of races with different rice entries and locations and this new physiological race was associated with breakdown for new rice genotypes. In rice improvement programs the blast resistance genes are very important tools.…”

“…Typical blast lesion of rice samples were collected from locations of five governorates; Kafrelsheikh, Gharbia, Dakahlia, Sharkia and Beheira during 2020 growing season and isolated according to Shabana et al (2013). Spore production was prepared for 26 isolates by growing on banana glucose agar medium under florescent light for 10 days at 28 o C. The spores were collected at a density of at least 25 per microscopic field and examined using a 10x objective (Shabana et al, 2013).…”

“…Typical blast lesion of rice samples were collected from locations of five governorates; Kafrelsheikh, Gharbia, Dakahlia, Sharkia and Beheira during 2020 growing season and isolated according to Shabana et al (2013). Spore production was prepared for 26 isolates by growing on banana glucose agar medium under florescent light for 10 days at 28 o C. The spores were collected at a density of at least 25 per microscopic field and examined using a 10x objective (Shabana et al, 2013). Pathogenicity test, identification of pathogen physiological races and determination effective resistant blast genes under greenhouse condition Pathogenicity tests and race identification studies were carried out on the obtained fungal isolates under greenhouse condition with artificial infection.…”

“…These genes are recommended to be used by rice breeders as donors for blast resistance under Egyptian conditions (Sehly et al, 2008) or under China conditions (Wang et al, 2013). Shabana et al (2013) recorded the reaction of monogenic lines to 132 isolates of rice blast, and found that the reaction ranged between zero and 97.76%, depending on the effectiveness of the present resistance gene. Piz-5 gene was the most effective to blast isolates followed by the gene pita-2 , Pi5 (t) and then Piz, Pii, Pi9, Pita-2 , and Pit.…”

Conventional Breeding and Molecular Markers for Blast Disease Resistance in Rice (Oryza sativa L.)

“…On the other hand, the genes Pia, Pik-s, Pik, Pik-p, Pik-h, Pi 3, Pi 5(t), Pi 9(t), Pi 12(t), Pik-m, Pita-2, Pita and Pi 11(t) gave 80% resistance, while the genes Pia, Piz-t, Pi, Pi sh, Pi 7(t), Pi 19(t) and Piz-5 gave 60% resistance (Table 4). These results were found with [27][28][29][30].…”