Effects Of Genetic Background And Environmental Conditions On Yield And Quality Of Rice DEP1-NILs

Erect panicle architecture is an accessible approach to achieving high-yield potential.The DENSE AND ERECT PANICLE 1(DEP1)gene regulating panicle morphology,grain number per panicle,and nitrogen uptake and metabolism has been widely used for the breeding of high-yield rice in northern Chinese japonica varieties.However,there has been no consensus on the genetic effects of DEP1 on grain yield and quality under different genetic backgrounds and growing environments.Meanwhile,the mechanism of high yield of the DEP1 gene has been rarely clarified in terms of capacity at the plant population level.In the present study,we developed two sets of near-isogenic lines(NILs)of DEP1(AKI-dep1,AKI-DEP1,LG 5-dep1 and LG 5-DEP1),each carrying the DEP1 region from either Liaojing 5(LG 5)or Akitakomachi(AKI)in the Akitakomachi and Liaojing 5 genetic background.This study aims to identify the effects of DEP1 on rice grain yield and grain quality under different genetic backgrounds and the interaction effect of the DEP1 genotype and environments with different locations and years and nitrogen fertilizer on rice yield and yield components.Our results showed that:Our results demonstrated that AKI-dep1/LG 5-dep1 exhibited erect panicle,and enhanced grain number per panicle,thereby consequently increasing grain yield.the grain yield improvement in AKI-dep1 was significant at 11%~12% higher yields than AKI-DEP1 in two years.And LG 5-dep1 produced 6%~12% higher grain yield than LG 5-DEP1 in two years.In addition,the panicle length and plant height of dep1 significantly decreased,the number of secondary branches significantly increased,and the number of primary branches also increased.The heading period of the background lines of Liaojing 5 was obviously delayed by about 1 week.The appearance quality of DEP1 was better than that of dep1,and dep1 showed that the grain width increased and the length-width ratio decreased significantly.At the same time,the chalky grain rate and chalkiness degree were significantly increased.There was no significant difference in GC and GT between the genetic background and genotype of the two NILs.The effect of DEP1 gene on rice processing quality and food quality was different with different genetic backgrounds.AKI-dep1 had a significantly lower milled rice rate and a slightly lower head-milled rice rate than AKI-DEP1,whereas the two traits of LG 5-dep1 were similar to that of LG 5-DEP1.AKI-dep1 had significantly higher PC% than those of AKI-DEP1.There is no significant difference between LG 5-dep1 and LG 5-DEP1.The TPS is expressed as AKI-DEP1>AKI-dep1>LG 5-dep1?LG 5-DEP1.The general rule was that heading date,brown rice rate and AAC were mainly determined by genetic background.Plant height,panicle length,panicle number,panicle grain number,secondary branch number,1000-grain weight and yield were mainly affected by DEP1 genotype.However,milled rice rate,whole milled rice rate,length-width ratio and chalky traits are regulated by genetic background and genotype,and the influence mechanism of PC% and TPS varies with the combination.Two sets of near-isogenic lines of DEP1 and dep1 genotypes with the background of Liaojing 5 and Akitakomachi were grown in the field in 2016,2017,and 2018 in Shenyang,China and Kyoto,Japan.To analyze the temperature,solar radiation,growth period,yield and yield components.The daily TMEANs in Shenyang were 21.6 ? and 20.9 ? in 2016 and 2017,which are lower than the 28.8 ? and 27.9 ? in Kyoto.No significant difference in the daily TMEANs existed between the two years in each location.The dep1 genotypes with the Akitakomachi and Liaojing 5 backgrounds in Shenyang reached the heading earlier than the DEP1 genotypes by 3 days to 5 days.In Kyoto,DEP1 with the Akitakomachi background reached the heading earlier than dep1.In Shenyang,dep1 with the Liaojing 5 background was earlier.The average yields of dep1 and DEP1 genotypes were 6.67 and 6.13 t ha-1 for the Akitakomachi background and 6.66 and 6.58 t ha-1 for the Liaojing 5 background,respectively.There was no significant difference between year and place.The average yield of dep1 is 6.67 t ha-1 significantly higher than 6.13 t ha-1 of DEP1.The effect of the dep1 genotype on panicle and grain number per square meter was positive,which mostly resulted in a positive effect on HI.By contrast,the dep1 genotype exerted a negative effect on thousand grain weight.The ratio of the performance of the dep1 genotype relative to the DEP1 genotype in terms of yield and total biomass tended to correlate positively with mean daily solar radiation during 40 days around heading.The effectiveness of the DEP1 genotype depended on the availability of solar radiation.The effect of the DEP1 genotype was consistently positive for sink formation,conditional for source capacity,and positive under a high-radiation environment.Through the analysis of the processing quality,appearance quality,food taste quality and RVA of the NILs with different background under different nitrogen fertilizer applications,the result shows that the quality characters of the NILs with erect panicle gene type are different under different nitrogen fertilizer application.With the increase of nitrogen fertilizer application amount,the ratio of grain length to width shows increased first and then decreased,with the NILs-DEP1 under different genetic backgrounds,the chalkiness grain rate and chalkiness degree showed a tendency of decreasing first and then increasing,that is,the appearance quality of rice was the best under the action of medium fertility level.Under the genetic background of Liaojing 5,the ratio of grain length to width increased the most with the increasing of nitrogen fertilizer application amount of LG 5-dep1,and reacts strongly to nitrogen fertilizer effect.With the increase of nitrogen fertilizer,brown rice rate,white rice rate,as well as the head rice rate were showed increased first and then decreased with both genetic background,however,with the Akitakomochi background the AK-dep1 NIL,brown rice under high nitrogen fertilizer application was significantly higher than that of without nitrogen fertilizer application,at the same time white rice rate and head rice rate under the effect of moderate fertility shows the biggest increase tendency.With the increase of nitrogen fertilizer application amount,the accumulation of nitrogen in grains increased,which resulted in the continuous increase of PC% of the NILs,AAC and rice value index showed increased first and then decreased,The AAC of the NILs was lower under high nitrogen application than that under no nitrogen application.The setback and cold viscosity in RVA mass spectrometry shows decrease with the increase of the application of nitrogen fertilizer.