Screening Of Resistant Resources And Preliminary Location Of Resistance Genes For Rice Seedling Blight

Rice seedling blight is one of the major fungal diseases that wrongly reduce rice production in China and worldwide.In recent years,the incidence increased year by year in northern China;rice seedling growth is a significant threat to rice seedling blight.Breeding of resistant varieties of rice blast is the most economical and efficient way.At present,the related research and genetic breeding of rice blight resistant germplasm resources,less,its genetic mechanism is rarely reported.Therefore,the screening of rice resistance to bacterial wilt species resources,the study of the genetic mechanism of disease resistance,the mining of disease resistance genes and disease resistant carrier materials will help to promote the molecular assisted breeding of resistance to bacterial wilt in rice and speed up the process of rice resistance breeding.Bulked Segregant Analysis?BSA?is an essential method for analyzing the genetic basis of complex characters and has been widely used in the location of plant resistance genes.226varieties of rice were used as experimental materials.The present study uses a natural population composed of 226 Japonica germplasms as the tested material.The F_2:3:3 population was constructed by using the screened high and high susceptible varieties as parents,and genetic analysis and BSA analysis were performed.The result is as follows:?1?In this paper,the Fusarium verticillioides used was tested for their disease resistance against,which 226 copies germplasm resources of Heilongjiang province in 2015 and 2016.The results showed that all the identified varieties were infected,and the immune varieties had not been found.The disease index in 2015 was5.36⁸3.72.The disease index in 2016 was5.11⁸3.00.?2?The results showed in the past two years that six rice accessions with high resistance?HR?to Fusarium verticillioides were identified,included Longjing 20?Heiling 2?Longjing 21?Kendao9?Longdao 5?Longjing 27,which accounted for 2.65%of the total accessions.11 rice accessions with medium resistance?MR?,included Longing 22?Mudanjiang 8?longjing 29,etc.Which accounting for 4.87%of the total accessions.30 rice accessions with medium sense?MS?,included Shangyu397?Songjing 4?Yannian 1,etc.Which accounting for 13.27%of the total accessions.65 rice accessions with the disease?S?,included Mudanjiang 5?Kenjing 3?Longjing 13,etc.Which accounting for 28.76%of the total accessions.11 rice accessions with high sense?HS?,included Hejiang 11?Dongnong 416?Kenjing 1,which accounting for 4.87%of the total accessions.?3?The F₁ and F_2:3 populations of Hejiang 11 and high resistance variety Longjing 20 were hybridized to inoculate virulent races of Fusarium verticillioides.The results showed that F₁ all showed resistance,and the F₂ group had resistance to 3:1 ratio,indicating that the resistance of Longjing 20 to this strain was controlled by a dominant gene.?4?20 extreme resistant individuals and 20 extreme susceptible individuals in the F₂ group were selected,and DNA was mixed in equal quantities.105 pairs of polymorphic SSR primers were used to amplify the parent and anti sensory pool by PCR.The results showed that RM3151and RM27318 on chromosome 11 showed the same polymorphism between the parents and the resistant and sensory pools.The F₂ population was further scanned by the polymorphic primers between RM3151 and RM27318.Finally,the resistance gene was located between the marker RM27181 and RM1233;the genetic distance was 3.3cM-8.4cM,the contribution rate was 12.6%,the additive effect was-1.3,named LK11-1.According to the comparative genome,a gene Pb1controlling rice blast and a bacterial leaf blight gene Xa10 appeared in the vicinity of LK11-1,which proved that the resistance gene loci of rice might have genetic generality,which provides an excellent reference for the study of the heredity of bacterial wilt disease.