Effects Of Meteorological And Genetic Factors On Amylopectin And Texture Properties Of Indica-Japonica Recombinant Inbred Lines

Rice(Oryza) is the second staple food crop in the world and the first staple food crop in Asia.In the process of rice domestication,the genetic differentiation of indica and japonica subspecies occurred.The morphological,physiological,and ecological characteristics were different between indica and japonica.The cultivated rice is mainly japonica rice in the northern China,mainly indica rice in the southern China,and mixed cultivated in Yangtze River Basin(the middle and east China).Indica-Japonica hybridization is an important breeding method for japonica rice in northern China,especially for Green Super Rice(GSR).The starch characteristics were significant difference between indica and japonica.Meanwhile,it was affected by meteorological factors.To explore the effects of meteorological and genetic factors on amylopectin and texture properties of Indica-Japonica Recombinant Inbred Lines,it had theoretical and practical significance for high quality and yield breeding of indica-japonica hybrids in the future.In this study,we used a series of the tenth-generation recombinant inbred population as materials,which was construct by jaoponica variety–Shenong265(SN265)as male parent,and indica variety–Luhui99(R99).They were cultivated in Liaoning(LN),Sichuan(SC),Jiangsu(JS)and Guangdong(GD)in 2016.The analysis texture properties of cooking rice,the eating quality of cooked rice,amylopectin chain length distribution(APCLD)and milled rice appearance quality in LN samples.The effects of meteorological factors and genetic factors on cooking texture qualities,eating quality and amylopectin chain length of rice were analyzed by using meteorological factors from heading to maturity,frequency of indica identified by genetic map and related genotypes,and quantitative trait loci(QTLs)of these traits were mapped.The results were as follows:(1)APCLD of the two parents in the 4 regions all showed a single peak curve.In LN,R99 had significant higher Fa chain than SN265(p<0.05).But R99 had lower Fb₂ and Fb₃ than SN265(p<0.05).Other environments were not a significant difference between the two parents.RILs had no significant difference with their parents(p>0.05)in APCLD.Environment,genotype and environment×genotype had a significant difference in APCLD.In total,the radiation indicators(Solar radiation,Lux meter and light hours)had a positive correlation with Fa chain and negative correlation with Fb₁&Fb₂chain.Temperature indicators(Daily average temperature,Day temperature and Night temperature)had a negative correlation with Fa&Fb₁chain,positive with Fb₂&Fb₃chain.Daily range had a positive correlation with Fa chain,negative correlation with Fb₁&Fb₂ chain.Relative humidity had significant positive correlation with Fa and Fb₁chain(p<0.05),significant negative correlation with Fb₂&Fb₃chain(p<0.05).The relationship between meteorological factors and the distribution of amylopectin chain length was dynamic:Fa chain had a stronger negative correlation with Daily average temperature during 10-30 days after heading(DAH)(p<0.05),and it had a stronger positive correlation with 0-25 DAH;The negative correlation between Fb₁ and daily temperature and solar radiation depends on the later period;The positive correlation between Fb₂ chain and average daily temperature depends on the middle and late periods of grain filling,while the negative correlation with solar radiation depends on the early periods of grain filling;The positive correlation between Fb₃ and average daily temperature also depends on the middle and late phases.The day and night temperature and daily average temperature are consistent with the dynamic trend of the correlation between the amylopectin chain length distribution;the day difference after the heading is positively correlated with Fa chain(p<0.05),negatively correlated with Fb₁(p<0.05),and Fb₂ chain.There was a positive correlation between 0-25 DAH but no significant correlation with Fb₃chain(p>0.05).Overall,there is no significant correlation between the frequency of indica and the distribution of amylopectin length(p>0.05);5 quantitative trait loci are located,among which q Fb₁9,q Fb₃9 and q Fb₂9 are near DEP1;Fb₂ chain is in the four ecological environments Both showed that DEP1 strain was higher than dep1,which was significantly different in LN and JS.Other chain lengths are different.(2)The texture properties are most significantly affected by meteorological factors from 0 to 20 days after the heading period.At the same time,it is found that the night environment has a stronger effect on the texture properties than the day environment.As the latitude decreases,the influence of meteorological factors gradually weakens.Hardness and viscosity increase with decreasing latitude,while elasticity is the opposite.There is no significant correlation between indica frequency and hardness,viscosity,and elasticity(p>0.05).A total of 18 QTL loci related to hardness,viscosity and springiness were detected.Some of these loci have similar regions to the previously reported sites related to starch syntheses,such as SSIIIa/Flo5 and DPE1.The DEP1 gene may affect eating quality by regulating the distribution of amylopectin chain length.(3)Sensory evaluation tests found that in LN and JS,the control parent SN 265 was better than the parent R99,while the opposite was true in SC and GD.The sensory evaluation indicators that are significantly related to meteorological factors are mainly the appearance,aroma,hardness,and sweetness of cooked rice.Dynamic correlation analysis found that meteorological factors at night have a more substantial effect on sensory evaluation indicators than during daytime.In the overall situation,the relative humidity,day and night humidity,and light factors(solar radiation,light intensity,sunshine time)are significantly correlated with the 45 days after the heading period.The appearance and taste of the sensory evaluation index were significantly positively correlated with milling quality(p<0.05),and the sensory evaluation index was not significantly correlated with chalkiness(p>0.05).The Length to Width ratio(L/W)was significantly positively correlated with sensory appearance(p<0.05),and significantly negatively correlated with hardness(p<0.05).(4)In the correlation study,there was no significant correlation between frequency of indica with texture properties of cooked rice,palatability,and APCLD in all environments(p>0.05).In LN,a part of appearance quality indicators is significantly correlated with the frequency of indica(p<0.05).It had significantly negatively correlated with the perfect white rice rate,whole floury endosperm rate and milled rice thickness(p<0.05).There was a significant positive correlation with broken rice rate and damaged rice rate(p<0.05).Fa,Fb₁and Fb₂ chains were significantly correlated with the viscosity,balance,and elasticity of texture properties(p<0.05).Fb₁ chain was significantly negatively correlated with rice polishing rate(p<0.05),significantly negatively correlated with grain width(p<0.05),and significantly positively correlated with L/W ratio(p<0.05).Fa chain was significantly negatively correlated with crude protein content(p<0.05),and Fb₁ and Fb₂ chains are significantly positively correlated with crude protein content(p<0.05).In summary,APCLD,texture properties and sensory eating quality were more affected by meteorological factors than genetic factors,among which temperature and humidity have the most significant effects,and the impact period is mainly concentrated in 0-20 days after heading.Night meteorological factors were essenital for quality of rice.Fi was not stronger correlation with APCLD,texture properties and cooking quality.The higher frequency of indica in the ecological environment of LN may result in poor appearance quality.DEP1 has a certain negative impact on eating quality,and its relationship with related QTLs and its effect on the APCLD need to be further studied.