Identification and application of thePigm‐1gene in rice disease resistance breeding

Abstract

Rice blast, caused by Magnaporthe oryzae, is one of the most destructive diseases of rice worldwide. The identification and utilization of resistance genes are crucial and significant for breeding resistant rice cultivars. We identified a resistance gene from Shuangkang77009, which is highly resistant to the rice blast isolate Guy11 using map‐based cloning. We performed bulked segregant analysis combined with specific length amplified fragment sequencing. We also performed association analysis, candidate gene prediction and cDNA sequencing to identify the candidate gene. The resistance gene is located on chromosome 6, and we ultimately mapped the resistance locus to a 92‐kb region. The resistance gene in Shuangkang77009 was allelic to PigmR, hereafter referred to as Pigm‐1. The Pigm‐1 protein had one amino acid change: serine (Ser) residue 860 was replaced by tyrosine (Tyr) in Pigm‐1 compared with the previously identified Pigm protein, which significantly changed the structure of the Pigm‐1 protein based on 3‐D structure simulation. In addition, using the developed molecular marker linked to the Pigm‐1 gene and molecular marker‐assisted selection technology, we introduced the Pigm‐1 gene into Minghui86, a widely used and excellent restorer. We generated 11 stable homozygous rice lines with desirable agronomic traits and strong resistance to rice blast. In conclusion, Pigm‐1, a natural allelic variant of PigmR, was responsible for blast resistance in Shuangkang77009 rice. The molecular marker‐assisted breeding strategy for Pigm‐1 was highly efficient.

Importance of OsRac1 and RAI1 in signalling of Pigm-1 mediated resistance to rice blast disease

“…Among the various dominant blast resistance genes being considered for breeding resistant varieties, the PigmR gene has shown broad-spectrum and durable resistance to blast in different rice production areas around the world 10 . In addition, since varieties derived from resistance gene donors have been cultivated in large areas for many years, resistance genes may decompose due to high selection pressure 21 . Therefore, broad-spectrum rice blast genes have high utilization value.…”

“…Therefore, broad-spectrum rice blast genes have high utilization value. Meanwhile, Pigm-1, the PigmR allele, also shows broad-spectrum and durable resistance to blast 21 . In the early stage, we transferred Pigm-1 into different materials through molecular marker-assisted breeding, and we obtained new materials with different genetic backgrounds for disease resistance.…”

“…In a previous study, Pigm-1, a broad-spectrum rice blast resistance gene, was cloned from Shuangkang 77009 by mapping cloning 21 . To improve the resistance of 9311 rice blast, we used 9311 (Food Crops Research Institute, Jiangsu Academy of Agricultural Sciences), an indica cultivar, as a recipient and Shuangkang 77009 (Rice Research Institute, Fujian Academy of Agricultural Sciences), a restorer indica cultivar, as a donor.…”

“…However, for R proteins other than Pit, Pia, Pi9, and Pid3, is the activation of blast resistance in the OsRac1 signalling pathway equally conserved? Previously, we cloned Pigm-1, a new allele of the broad-spectrum rice blast resistance gene PigmR, from Shuangkang 77009 by mapping cloning 21 . In this study, to further verify whether OsRac1 is a common factor downstream of the Pigm-1 protein, we found that Pigm-1 associated with OsRac1 through its NBS domain, and regulated OsRac1 activation, while OsRac1 is importance for blast resistance mediated by Pigm-1.…”

Analysis of Applications of the Rice Blast Disease-Resistance Pita-R Gene and Development of Pita-R-dCAPS Marker for Efficient Marker-Assisted Selection

“…The rice seedlings with 3-4 leaves were moved to an inoculation chamber with high humidity, and the spore suspension of the M. oryzae isolate KJ201 was sprayed on the plants with a spray gun. The inoculated plants were transferred to a plastic box covered with a wet sponge and cultured in a dark room (95-100% relative humidity (RH), 25℃) for 24 h, and then transferred to a greenhouse at 25-28℃ for 6 days 23 . Grades 0-3 corresponded to resistant, and grades 4-9 corresponded to susceptible.…”