The Blast Resistance And Traits Of Backcrossing Progenies Of MH63 With Transgenic Rice

The rice blast is one of the most serious fungal diseases in the world. Lysozymegene has wide-spectrum resistance to fungal diseases. We had successfully transferreda lysozyme gene from the transgenic japonica rice ZH9(R) to an indica rice restorerMinghui63 (MH63) by backcrossing. In this research, the backcrossing lines withhomozygous lysozyme gene had been selected to cross with several male sterile lines,and the blast resistances and agronomical characters of lines and their related hybridcombinations had been analyzed, from which many excellent combinations had beenselected. In addition, three enzyme activities related to disease resistances had beendetermined.1 The blast resistance and agronomic traits evaluation of transgenic backcrossingprogeniesThe blast resistance and agronomic traits of 19 homozygous transgenic lines ofMH63 were analyzed, and their hereditary stabilities were discussed as well.(1) The blast resistances of lines appeared to identical at Taojiang and Liuyangdisease nurseries in the year 2005 and 2006, and the resistance of differentgenerations was BC₅F₄＞BC₄F₅＞BC₃F₆＞BC₂F₇. The disease index of leaf blast forBC₅F₄, BC₄F₅ and BC₃F₆ was decreased by 6.06%, 5.27% and 4.17% respectively,and the disease index of neck blast decreased by 20.41%, 15.15% and 11.19%respectively compared to that of MH63. Furthermore, there had a certain positivecorrelation between the leaf blast resistance and the neck blast resistance. However,the resistance of BC₂F₇ was instable, better than MH63 at Taojiang and worse thanMH63 at Liuyang.(2) The agronomic traits of BC₅F₄ and BC₄F₅ had no significantly different fromMH63, and most of their traits were identical to MH63, even over than MH63. Someagronomic traits of BC₃F₆ and BC₂F₇ were different from MH63, but aftermultiple-cycle artificial selection, some traits, such as plant height, 1000-grain weight, grain weight and seed setting rate approached to MH63.(3) In general, the blast resistance and agronomic traits of higher backcrossgenerateons were superior to those of lower generations. After self-crossed threecycles, the heredity of resistance and agronomic traits tended to be stable. Finally, 48excellent lines were selected for further researches, including 28 lines in BC₄F₅, 12lines in BC₃F₆ and 5 lines in BC₂F₇. In addition, 3 lines in BC₄F₅, ZP-1, ZP-2 andZP-3, were selected as the male parents of hybrid combinations.2 The blast resistance and agronomic traits evaluation of transgenic hybridcombinationsThree homozygous transgenic lines in BC₄ were crossed with the male sterile linesZhanShan97A, T98A, Jin23A,â…¡-32A, XinXiangA and ZhunS, respectively, and 54hybrid combinations were obtained.(1) The resistances of combinations were evaluated by field resistance testing andartificial inoculation resistance testing. The results indicated that the resistances ofcombinations crossed with ZhanShan97A, T98A, Jin23A,â…¡-32A or XinXiangA werebetter than the control combination, but those of combinations with ZhunS was poor,and the artificial inoculation results showed that the male parents ZP-1, ZP-2 andZP-3 had a higher wide-spectrum blast resistance.(2) The agronomic traits of hybrid combinations crossed with ZhanShan97A, T98A,Jin23A orâ…¡-32A had no significant difference from the control combination, butsome traits of hybrid combinations crossed with XinXiangA or ZhunS had a negativedifference from the control. Combined with the resistance and agronomic traits, 4combinations were selected.3 Selection of transgenic backcrossing lines of MH63 with homozygous lysozymegene and determination of disease resistant-related enzyme activities(1) Forty-five homozygous transgenic lines from 48 lines were identified by PCRanalysis, including 3 lines in BC₅F₄, 28 lines in BC₄F₅, 11 lines in BC₃F₆ and 3 linesin BC₂F₇. A specific band of foreign lysozyme gene was detected in F₁ combinationsof the homozygous transgenic lines crossed with male sterile lines, which indicatedthat the resistant gene had stably transferred to F₁.(2) The disease resistant-related enzyme activities of PAL, POX and PPO in transgenic lines were determined, and the activities of ZP-1, ZP-2 and ZP-3 werehigher than those of Minghui63 and a susceptible cultivar Lijang Xintuan Heigu.