The Development Of Molecular Markers Related To Resistance Of Phytophthora Capsici And Functional Identification Of Disease Resistant Genes In Pepper (Capsicum Annuum L.)

Phytophthora blight,caused by Phytophthora capsici,is a devastating disaster in pepper cultivation worldwide.Cultivating disease resistant varieties is the fundamental method for preventing and controlling phytophthora blight.To study the genetic mechanism of resistance to pepper blight,and to clarify the function of disease resistance related genes is the premise for resistance breeding.Marker assisted selection（MAS）makes breeding selection easier and shortens the breeding cycle.Therefore,the development of efficient molecular markers for the identification of resistance to P.capsici is particularly important in pepper resistance breeding.In this study,a series of markers,including In Del,SSR and SNP,were developed on the inside and on both sides of the localization interval based on previous gene mapping of pepper resistance to P.capsici,and were verified in resistant and susceptible pepper variations and F₂individuals.Besides,a series of EST-SSR markers developed by the research group were used to screen for the resistance related markers.The genetic mechanism resistance to P.capsici race 3 of Y1 was established by constructing the F₂segregating population of the disease resistant material Y1 and the susceptible material‘Qiemen’.The function of genes in Y1 disease resistance mapping region was verified in CM334 by using VIGS and the relationship between resistance genes of different resistance materials was studied.1.54 pairs of In Del primers,42 pairs of SSR primers,17 pairs of CAPS primers and 13pairs of d CAPS primers were synthesized in the pepper resistance location segment.25,36,6and 3 polymorphic markers were obtained,with a polymorphism ratio of 46.3%.,59.52%,35.29%and 23.08%,respectively.The accuracy of the developed markers was identified and two markers,In D9 and In D34,with accuracy of 78.26%and 79.31%respectively.2.A total of 626 pairs of EST-SSR primers synthesized in the study group were screened and 232 polymorphic markers were obtained.The polymorphism ratio was 37.06%.12markers that can be used to distinguish the insensitivity from 7 materials were screened,and the applicability of the markers was further evaluated in 22 Capsicum materials.A marker NW224 with an accuracy rate of 82.76%and another marker,Ca ES73,identified 100%of the disease resistant material were obtained.3.The disease resistance of the Y1בQiemen’F₂population was identified.The results showed that the resistance of Y1 race 3 P.capsici was monogenic dominant inheritance.The genotype of markers in P.capsici resistant region and plant phenotype were highly consistent,suggesting that the spectral resistance of Y1 to Phytophthora blight is controlled by one site.4.The function of two genes Ca Myb-like and Ca BRI1-like in the Y1 disease resistance mapping region were studied in CM334 by VIGS technology.The results showed that Ca BRI1-like can reduce the resistance to P.capsici of CM334.It was speculated that the gene Ca BRI1-like was involved in the resistance response of CM334.