Ⅰ A Study On Anther Culture Of Mutants Were Resistant To Rice Sheath Blight Of Rice Subspecies Cross' Progenies Close To Indica Ⅱ Resistance Identification And Analysis To Rice Sheath Blight Of Core Parents In South Rice Production Region Of China

â… A study on anther culture of mutants were resistant torice sheath blight of rice subspecies cross' progeniesclose to indicaA mutant with resistance to rice sheath blight was found from BC₂F₂ population ofShuhui 955×Kitaake (Shuhui955 being recurrent parent) in the summer of 2002,thencollected its seeds and sowed them in the next time. Only the seeds of resistant plantwere collected and sowed them into lines in the next generation. In 2004, the study onanther culture of 10 resistant lines derived from F4 of the mutant was carried out, in2005, the major traits of the separated H2 lines were analyzed. The results were asfollows:1 Large differences of anther culture effects among tested materials wereobserved and there was no positive connection between callus induction frequencyand the green plantlet differentiation frequency(r=-0.111), but there was verysignificantly positive correlation between plantlet differentiation frequency and antherculture ability(r=0.728, r_0.05=0.444, r_0.01=0.561). N₆ and SK₃ culture media wereobviously superior to the GM medium, meanwhile N₆ culture medium was slightlybetter than SK₃ culture medium in this study. It is not suggested to remove all leavesof tested materials before the cold pretreatment. Two high frequency regenerationlines were screened from 10 tested lines in this experiment, which provided idealgenetic engineering materials for the future rice breeding and molecule-based generesearch.2 The major traits of 32 segregated and varied lines among 494 H₂ lines derivedfrom anther culture progenies of BC₂F₆ developed from rice subspecies cross wereanalyzed, their segregation fashions were claasified into two types: simple segregationand severe segregation. Simple segregation included three sub-types by its variancesof plant height: (1) reduced plant height combined with other varied traits, (2)normal plant height with other varied traits, (3) increased plant height combined with other varied traits. Severe segregation was similar to that in F₂ Variance frequenciesof plant height, fertility and panicle extruding degree were the highest, those ofdensity of grain setting and heading date were the second, and panicle pattern,1000-grain weight and panicle awn were the least on this aspect.â…¡Resistance identification and analysis to rice sheath blightof core parents in south rice production region in ChinaSheath blight was one of the three largest disease of rice, which developed severelyunder high temperature and high moisture in south China and the Yangtze River Valley.Resistance to rice sheath blight of core parents in south rice production region of chinawas identified in field by an improved method of inoculation, which was carried outwith short match bars incubated with AG1-IA, and inserted the third sheath in the bootstage. These indexesof DL, DR, WAXmg/cm², WAXmg/g, RH and PH were measuredand analysed in the experiment. 17 core parents were classified into 4 types: resistance,moderate resistance, moderate susceptibility and susceptibility. This study screened 3resistance parents (Minghui63, Guanghui128 and Shuhui527), 3 moderate resistanceparents(Mianhui725, Zhenshan97B and XieqingzaoB) from 17 core parents. Averageresistance level to rice sheath blight and average RH of all core parents were 4.78 and0.52 respectively, which meaned the resistant ability to rice sheath blight of the 17 coreparents was weak. There was very significantly negative correlation between DL andWAX. DL and RH were related to its resistance of rice sheath blight significantly andvery significantly respectively, but PH was not quite correlated with DR in thisexperiments. The results suggested that RH could be used as one of indexes forresistance evaluation of rice sheath blight, and the contents of epicuticular wax couldbe used as one of indexes for resistance to Rhizoctonia solani Kuhn's adhering to andinvading the rice plants in its initial stage.