Genetic Research On Roots Of Populations Derived From Super Rice (Oryza Sativa L.) XieYou 9308

Rice is one of the major food sources in the world; roots play multiple roles in anchorage of the whole plant, absorbing soil moisture and nutrient, synthetic transportation of amino acids, plant hormones and other bioactive substances during course of the growth and development of plant, and indirectly determined the grain yields, grain quality and lodging resistance et al. Consequently, special attention should be given to the root architecture of rice.To clarify the genetic mechanism of root architecture in rice; In this study, the root architecture of the XBR, RIL, and ZHR populations derived from super rice Xieyou9308 was investigated at heading stage, QTL associated with roots and shoot agronomic traits analyzed, qRL7 fine mapped and candidate gene cloned. The main results were as follows.1. Studies have revealed that phenotypic distribution characteristic of TRL, RSA, RV, and RT at different RD interval. TRL and RT showed an index distribution, the peak value of TRL and RT was at RD of 0.00<.RD.<=0.20 mm interval, accounted for 50.00% and 96.00% of the population TRL, respectively, the RSA showed three-peak distribution, the peak value was at RD of 0.00<.RD.<=0.20 mm, 0.40<.RD.<=0.60 mm, and 0.80<.RD.<=1.00 mm interval, accounted for 9.00%, 13.00%, and 12.00% of the population RSA, respectively, the RV showed a single-peak distribution, the peak value was at RD of 0.80<.RD.<=1.00 mm interval, accounted for 7.00%.2. PCC between roots and shoot agronomic traits has demonstrated that RL correlated positively with five root morphological traits including TRL, RSA, RV, RT, and DRW in three populations. However, the correlations between RD and the other six traits of RL, TRL, RSA, RV, RT, and RDW were insignificantly correlatvie. Seven shoot agronomic traits including HD, PH, PL, SPP, GSD, GW and GYPP showed a significantly positive correlation with the six root morphological traits, while the SPP, GSR and GW correlated with roots insignificantly negative, respectively. All shoot agronomic traits correlated with RD insignificantly correlatvie among three populations.3. Additive-effect and dominant-effect of QTLs play an important role for root architecture and no epistatic QTLs was detected for root architecture in three populations. One major QTL was detected for five root architecture of RL, TRL, RSA, RT and RDW, respectively, and flanked repeatedly by marker RM180 and RM5436 on the short arm of the 7th chromosome for TRL, RSA, RV, and RT at different RD interval, and explained 24.12% of the root phenotypic variation in the RIL population. The other major QTL was detected for root architecture of TRL, RSA, RV, RT, and RDW, respectively, and flanked repeatedly by the marker RM5436 and RM3670 on the short arm of the 7th chromosome for TRL, RSA, RV, and RT at different RD interval, and explained 21.55% of the root phenotypic variation in the XBR population. Consequently, the major QTL associated with multiple root morphological traits, designated as qRL7.4. Additive-effect QTLs and dominant-effect QTLs play an important role in three populations and no epistatic QTL was detected for all shoot agronomic traits, altogether 21 additive-effect QTLs detected in RIL, 22 dominant-effect QTLs detected in XBR, and 19 dominant-effect QTLs detected in ZHR population, respectively. Of these, three QTLs (qHD7a, qPPP3a, and qPL10) of 21 were detected repeatedly in the RIL and XBR or ZHR populations, 10 QTLs underlying four traits were only detected repeatedly in XBR and ZHR populations, and 9 QTLs associated with more than two traits were detected repeatedly in three populations. No QTLs associated with shoot agronomic traits was detected between RM180 and RM5436 on the short arm of 7th chromosome in three populations.5. Fine mapping of qRL7. By XQZB/ZH9308 RIL population, qRL7 was preliminary mapped on the short arm of 7^th chromosome between RM180 and RM5436. We designed 17 pairs of InDel primer according to the genomic sequence of the XQZB and ZH9308 between RM180 and RM5436, qRL7 was fine mapped between InDel7-11 and InDel7-12, the genomic range about 54kb.6. Nine putative genes of LOC_Os07g14610, LOC_Os07g14620, LOC_Os07g14630, LOC_Os07g14640, LOC_Os07g14650, LOC_Os07g14660, LOC_Os07g14670, LOC_Os07g14680 and LOC_Os07g14690 were predicated according to the aim sequence by http://rice.plantbiology.msu.edu/. The putative gene LOC_Os07g14610 was associated with endoplasmic reticulum, hydrolase activity, protein metabolic process, cellular process, IAA-amino acid hydrolase ILR1-like 6 precursors, and cytokinin response in roots and leaves.