Studies On Physiology, Biochemistry Basic And Localization Of QTL On Yield Relative Traits In High Yield Rice Luliangyou 996

Rice is one of the most important grain crops, which fed more than half of worldpopulation. Early rice has drastically contradicted with grain yield and early maturity.Luliangyou 996 solved the problem. Compared with control Jinyou 402, it increasedby 7.8% in grain yield and shortened 1 day in growth duration. The paper indicatedthe cause of high yield by photosynthesis character and related enzymes activitywhich led to senescence with two line early hybrid rice Luliangyou 996 and itsparents. The mechanism of anther abortion was clarified by physiological andbiochemical studies. It constructed genetic linkage map and localized main agronomictraits. The main results are as follows:Firstly, in production constitution, super-hybrid early rice combination Luliangyou996 had more effective tiller numbers in the unit area, higher seed setting rate andkilo-weight, lower spikelets per panicle and lower filled grain number per paniclethan male 996 which attributed to 5.81% in grain yield. The significant differencewas found between spikelets per panicle and upper second leaf length, flag leaf length,functional leaf acre. So was filled grain number per panicle. They had no correlationin leaf width and other traits.Secondly, measuring and correlation analysis were made on the chlorophyll contentof flag leaf and yield. The results indicated that it was significant correlation ofchlorophyll content and yield on Luliangyou 996 and its parents. The content ofchlorophyll a dominated the total chlorophyll content level, while the content of chlorophyll b controlled the chlorophyll a/b ratio. Significant correlation, lied inchlorophyll content, chlorophyll a content and net photosynthetic rate. Lul 8S is thehighest of chlorophyll content and chlorophyll a content, while 996 is the most ofchlorophyll b content and Luliangyou 996 standing in the middle of three varieties.No direct correlation existed between photosynthetic rate and chlorophyll a/b ratiowhich promoted energy absorption in weak light intensity, which it is weak lightcompensation point. Lul 8S photosynthetic rate is lower than other varieties at bootingstage, although it is the highest after full heading stage. Photosynthetic rate wassignificant correlation to stomatal conductance and no significant relation with thesubstomatal CO₂ concentration. The correlation was obvious between stomatalconductance and transpiration rate of flag leaf. High chlorophyll content and lowchlorophyll a/b ratio varieties facilitate high grain yield in selecting parents.Thirdly, significant varience was found in soluble sugar, starch and praline of flagleaf between Luliangyou 996 and male 996. The starch and praline content of two-linemale sterile Lu18s is lower drastically than that of the other varieties. Pralinemetabolism losing balance led to lack of medium of starch and thermo-sensitive malesterility. The activity of SOD enzyme, CAT enzyme and POD enzyme in flag leaf wasdetected that Luliangyou 996 is between that of higher Lu18S and lower 996. MDAcontent of Lu18s was lower than that of 996 during in the latter of developmentperiod. High activity of resisting senescence of flag leaf had a close relation withprolonging leaf functional period in maturing stage which was the reason that led tohigh production of Luliangyou 996 and uneasily senescence of Lu18s.Fourthly, the result showed that flag leaf length and plant height had vast significantcorrelation with spikelets per panicle among F₂ population of Luliangyou 996. Plantheight had positive effect on panicle length and had negative effect on effectivepanicle numbers. So exploiting heterozygous advantage, it deals with the advantage ofcomplement characters of parents and mediates the relationship.Fifthly, SRAP is a kind of newly developed molecular marker system with theadvantages of simplicity, high effectiveness, numerous co-dominant makers, highlyreproducibility and ready to sequence, especially preferential targeting ORFs. Its forward primer may amplify exon, while reverse primer may amplify intron, promoterand interval sequence. A F₂ population (117 lines), derived from the cross betweenvarieties Lu18s and 996, was used for genetic linkage map by SRAP and RAPDmarkers. 37 of the 270 SRAP primers and 32 of the 308 RAPD primers had distinctpolymorphism between parents. 62 of 97 markers constructed 13 genetic linkagegroups, and the coverage length was 1106.2cM with an average interval size 18.44cM.The maximum linkage group consists of 12 markers whose length is 270cM and only9.4cM of minimum group. The maximum distance is 47.8cM, while 0.9cM ofminimum distance. The composite interval mapping was employed to detect thequantitative trait locus. 6 QTL loci were found, for example, 2 loci which controlfilled grain number per panicle (Gpp) were detected, whose additive effect adds up to93.57. Furthermore, one locus that control plant height(Ph), effective tilleringnumber(Etn) and Gpp stood 9.4cM interval area, which were intensely linked. Last, itdemonstrated negative correlation with Ph and Etn.Sixthly, the genetic analyses showed that male-sterile gene of Lu18s belonged toone recessive nucleus gene inheritance by pollen fertility and seed setting observationin exploring crossing with three male varieties by bulk segregant analysis of F₂population between the parents and two bulks population representing fertile andsterile plants. One RAPD primer S490 amplified a length of 0.85 Kb fragments. Itshowed close linked with sterile gene. The length of the fragment was coincided withKotb's result.Seventhly, some especial fragments were chosen by recycling and transformationwith PMD 18-T vector through RAPD and SRAP screening. They were sequenced bySangon. To study the biological function of these fragments, according to theprediction result from Blastn in the NCBI website, the results showed that A370 fromLu18s is a high homology fragment which was found in 6 of 12 chromosomes. Theratio of homology attached over 88% in over 330bp sequence fragment. They may bea gene family that has functional similarity. Another 880bp gene fragment whose twoends about 350bp are high homology (99%, 98% respectively) E value is near equalto 0 that is accurate. To our surprised, a small fragment which lies in the center of 90bp distributed all chromosomes. The phenomenon will be allowed to do much workin later research.Finally, DNA fingerprints of 1 male sterile lines and 1 male parent lines oftwo-line hybrid rice were constructed by using 270 SRAP (Sequence relatedamplified polymorphism) primers. The 200 single plants of Luliangyou 996 weretested by a specific complement SRAP marker (Me3Em8) in laboratory. The seedpurity was 97.50 %, which was the same as the field purity (97.50 % in Hainan). Theresults of this research suggested that SRAP technique could be used in seed purityidentification of two-line hybrid rice.