水稻裂颖突变体sh1的鉴定及基因定位
|
摘要
【目的】本研究旨在定位和克隆水稻裂颖基因,为解析水稻裂颖性的遗传机制提供依据。【方法】从籼稻品种湘早籼6号突变体库中筛选出一个裂颖突变体(split husk 1, sh1),观察突变体的花器官和浆片形态,利用突变体与02428的F_2群体定位目标基因,进一步通过定量PCR分析相关基因的表达情况。【结果】sh1突变体的颖花形态与野生型基本一致,能正常开花,但不能正常闭颖,裂颖的主要原因是浆片不能在开颖后正常萎蔫。sh1突变体的有效穗数增加,但结实率和千粒重显著下降;遗传分析表明,sh1的裂颖表型受一对隐性核基因控制。将SH1基因定位在ID19827与ID19884两个InDel标记之间,物理距离约为110 kb。定位区间测序发现,突变体中丙二烯氧化合酶编码基因OsAOS1发生单碱基突变,导致氨基酸发生改变;SH1基因的突变显著降低了花器官中的茉莉酸含量,进而影响了茉莉酸合成及信号转导相关基因的表达。【结论】SH1基因通过影响茉莉酸的合成和信号转导调控水稻闭颖,Os AOS1可能是SH1基因的候选基因。
【Objective】The objective of the research is to identify and clone a rice split-husk gene, providing support for elucidating the genetic mechanism of rice floret closing. 【Method】A split husk mutant, sh1, was isolated from an ethylmethylsulfone(EMS) mutagenic population of indica cultivar Xiangzaoxian 6. The morphological characteristics of florets and lodicules were observed. The SH1 gene was identified by map-based cloning using an F_2 population of a cross between sh1 and 02428. In addition, expression levels of related genes were analyzed by quantitative PCR. 【Results】The sh1 mutant showed normal floral morphological characteristics, but failed to close the lemma and palea after floret opening, which was caused by delay of lodicule dehydration. The sh1 mutant was also featured by increased number of effective panicles, obviously decreased seed-setting rate and 1000-grain weight. Genetic analysis indicated that the mutant phenotype was controlled by a pair of recessive nuclear gene. The SH1 gene was fine-mapped to a 110 kb interval between markers ID19827 and ID19884 on the chromosome 3. After sequencing of this region, we found that there is a single base transition in the coding region of allene oxide synthase 1(OsAOS1), which resulted in an amino acid substitution. Correspondingly, the mutant showed reduced content of jasmonic acid(JA) and differential expression of genes related to JA synthesis and signal transduction. 【Conclusion】The SH1 gene regulates rice floret closing through JA synthesis and signal transduction, and Os AOS1 is the candidate gene for SH1.
【Objective】The objective of the research is to identify and clone a rice split-husk gene, providing support for elucidating the genetic mechanism of rice floret closing. 【Method】A split husk mutant, sh1, was isolated from an ethylmethylsulfone(EMS) mutagenic population of indica cultivar Xiangzaoxian 6. The morphological characteristics of florets and lodicules were observed. The SH1 gene was identified by map-based cloning using an F_2 population of a cross between sh1 and 02428. In addition, expression levels of related genes were analyzed by quantitative PCR. 【Results】The sh1 mutant showed normal floral morphological characteristics, but failed to close the lemma and palea after floret opening, which was caused by delay of lodicule dehydration. The sh1 mutant was also featured by increased number of effective panicles, obviously decreased seed-setting rate and 1000-grain weight. Genetic analysis indicated that the mutant phenotype was controlled by a pair of recessive nuclear gene. The SH1 gene was fine-mapped to a 110 kb interval between markers ID19827 and ID19884 on the chromosome 3. After sequencing of this region, we found that there is a single base transition in the coding region of allene oxide synthase 1(OsAOS1), which resulted in an amino acid substitution. Correspondingly, the mutant showed reduced content of jasmonic acid(JA) and differential expression of genes related to JA synthesis and signal transduction. 【Conclusion】The SH1 gene regulates rice floret closing through JA synthesis and signal transduction, and Os AOS1 is the candidate gene for SH1.
引文
[1]陈柏原,符辰建,秦鹏,张海清,杨远柱.水稻种子裂颖性的研究进展.杂交水稻,2014,29(3):6-9.Chen B Y,Fu C J,Qin P,Zhang H Q,Yang Y Z.Advances in studies on split husk of rice seeds.Hybrid Rice,2014,29(3):6-9.(in Chinese with English abstract)
[2]杨建菊.杂交水稻种子的裂颖及其危害.杂交水稻,2006,21(1):57-60.Yang J J.Split husk and its harm in hybrid rice seeds.Hybrid Rice,2006,21(1):57-60.(in Chinese with English abstract).
[3]曾晓春,周燮,吴晓玉.水稻颖花开放机理研究进展.中国农业科学,2004,37(2):188-195.Zeng X C,Zhou X,Wu X Y.Advances in study of opening mechanism in rice florets.Sci Agric Sin,2004,37(2):188-195.(in Chinese with English abstract).
[4]管恩相,李勇,刘陵武,姚仁祥,郭君,唐海燕.三系不育系种子裂颖形成的原因及防治措施研究.中国种业,2010(1):42-43.Guan E X,Li Y,Liu L W,Yao R X,Guo J,Tang H Y.Study on causes and control measures of split husk in three-line male sterile line seeds.China Seed Ind,2010(1):42-43.(in Chinese with English abstract).
[5]朱伟,童继平,吴跃进.水稻品种抗裂颖资源的筛选与初步研究.植物遗传资源学报,2004,5(1):52-55.Zhu W,Tong J P,Wu Y J.Preliminary study and selection of rice germplasm with glume gaping resistance.J Plant Genet Resour,2004,5(1):52-55.(in Chinese with English abstract).
[6]彭柏池,刘晓霞,张桂莲,陈立云.授粉期气象因子对水稻细胞质雄性不育系种子裂颖特性的影响.中国农业气象,2008,29(3):308-311.Peng B C,Liu X X,Zhang G L,Chen L Y.Influence of meteorological factors during pollination stage on characters of glume-gaping grains of cytoplasmic male sterile lines in rice.Chin J Agrometeorol,2008,29(3):308-311.(in Chinese with English abstract).
[7]孙廉平,张迎信,张沛沛,杨正福,占小登,沈希宏,张振华,胡霞,轩丹丹,吴玮勋,曹立勇,程式华.一个由可变剪接造成的水稻开颖不育突变体ohms1的鉴定及基因定位.中国水稻科学,2015,29(5):457-466.Sun L P,Zhang Y X,Zhang P P,Yang Z F,Zhan X D,Shen X H,Zhang Z H,Hu X,Xuan D D,Wu W X,Cao LY,Cheng S H.Characterization and gene mapping of an open hull male sterile mutant ohmsl caused by alternative splicing in rice.Chin J Rice Sci,2015,29(5):457-466.(in Chinese with English abstract).
[8]陈立凯,黄明,刘永柱,王慧,陈志强,郭涛.水稻开颖半不育突变体的观察、遗传分析和基因定位.中国农业科学,2016,49(1):1-13.Chen L K,Huang M,Liu Y Z,Wang H,Chen Z Q,Guo T.Observation,genetic analysis and gene mapping of an open hull semi-sterility mutant in rice(Oryza sativa).Sci Agric Sin,2016,49(1):1-13.(in Chinese with English abstract).
[9]曾生元,郭旻,李荣德,盛生兰,龚红兵,严长杰.水稻新裂颖突变体sg1的遗传分析与基因定位.中国水稻科学,2015,29(1):22-27.Zeng S Y,Guo M,Li R D,Sheng S L,Gong H B,Yan C J.Genetic analysis and fine mapping for a novel split glume mutant in rice.Chin J Rice Sci,2015,29(1):22-27.(in Chinese with English abstract).
[10]沈亚林,庄慧,陈欢,曾晓琴,李香凝,张君,郑昊,凌英华,李云峰.水稻颖花持续开放突变体sostenuto floret opening(sfo1)的鉴定与基因.作物学报,2017,43(8):1122-1127.Shen Y L,Zhuang H,Chen H,Zeng X Q,Li X N,Zhang J,Zheng H,Ling Y H,Li Y F.Characterization and gene mapping of sostenuto floret opening 1(sfo1)mutant in rice(Oryza sativa L.).Act Agron Sin,2017,43(8):1122-1127.(in Chinese with English abstract).
[11]Li L,Shi C H,Zeng D D,Jin X L,Wu J G.Morphogenesis and molecular basis on the unclosed glumes,a novel mutation related to the floral organ of rice.Plant Mol Biol Rep,2015,33(3):480-489.
[12]Li X,Wang Y,Duan E,Qi Q,Zhou K,Lin Q,Wang D,Wang Y,Long W,Zhao Z.OPEN GLUME1:A key enzyme reducing the precursor of JA,participates in carbohydrate transport of lodicules during anthesis in rice.Plant Cell Rep,2018,37(2):329-346.
[13]Dhakarey R,Kodackattumannil P P,Riemann M.Functional analysis of jasmonates in rice through mutant approaches.Plants,2016,5(1):1-15.
[14]Wasternack C,Song S.Jasmonates:Biosynthesis,metabolism,and signaling by proteins activating and repressing transcription.J Exp Bot,2016,68(6):1303-1321.
[15]Cai Q,Yuan Z,Chen M,Yin C,Luo Z,Zhao X,Liang W,Hu J,Zhang D.Jasmonic acid regulates spikelet development in rice.Nat Commun,2014,5(3):3476.
[16]冯孟杰,徐恒,张华,朱英.茉莉素调控植物生长发育的研究进展.植物生理学报,2015,51(4):407-412.Feng M J,Xu H,Zhang H,Zhu Y.Recent progress in jasmonates regulation of plant growth and development.Plant Physiol J,2015,51(4):407-412.(in Chinese with English abstract).
[17]Wasternack C.Jasmonates:An update on biosynthesis,signal transduction and action in plant stress response,growth and development.Ann Bot,2007,100(4):681-697.
[18]Ishiguro S,Kawai-Oda A,Ueda J,Nishida I,Okada K.The DEFECTIVE IN ANTHER DEHISCIENCE gene encodes a novel phospholipase A1 catalyzing the initial step of jasmonic acid biosynthesis,which synchronizes pollen maturation,anther dehiscence,and flower opening in Arabidopsis.Plant Cell,2001,13(10):2191-2209.
[19]Park J H,Halitschke R,Kim H B,Baldwin I T,Feldmann K A,Feyereisen R.A knock-out mutation in allene oxide synthase results in male sterility and defective wound signal transduction in Arabidopsis due to a block in jasmonic acid biosynthesis.Plant J,2002,31(1):1-12.
[20]Zeng X C,Zhou X.Methyl jasmonate induces the opening of spikelets in rice.Chin Bull Bot,1999,41(5):560-562.
[21]Song P,Xia K,Wu C W,Bao D P,Chen L P,Zhou X,Cao X Z.Differential response of floret opening in male-sterile and male-fertile rice to methyl jasmonate.Chin Bull Bot,2001,43(5):480-485.
[22]Liu L,Zou Z,Qian K,Xia C,He Y,Zeng H,Zhou X,Riemann M,Yin C,Zhang D.Jasmonic acid deficiency leads to scattered floret opening time in cytoplasmic male sterile rice Zhenshan 97A.J Exp Bot,2017,68(16):4613-4625.
[23]黄俊宝,何永明,曾晓春,向妙莲,付永琦.水稻颖花开放前花器官茉莉酸水平变化及浆片茉莉酸信号基因表达分析.中国农业科学,2015,48(6):1219-1227.Huang J B,He Y M,Zeng X C,Xiang M L,Fu Y Q.Changes of JA levels in floral organs and expression analysis of JA signaling genes in lodicules before floret opening in rice.Sci Agric Sin,2015,48(6):1219-1227.(in Chinese with English abstract)
[24]付永琦,向妙莲,蒋海燕,何永明,曾晓春.水稻颖花开放前浆片转录组变化.中国农业科学,2016,49(6):1017-1033.Fu Y Q,Xiang M L,Jiang H Y,He Y M,Zeng X C.Transcriptome profiling of lodicules before floret opening in Oryza sativa L.Sci Agric Sin,2016,49(6):1017-1033.(in Chinese with English abstract).
[25]Fu J,Chu J,Sun X,Wang J,Yan C.Simple,rapid,and simultaneous assay of multiple carboxyl containing phytohormones in wounded tomatoes by UPLC-MS/MSusing single SPE purification and isotope dilution.Anal Sci,2012,28(11):1081-1087.
[26]韩同凯,周晋军,薛彦久,陈翠霞,谢先芝.水稻丙二烯氧化物合成酶基因OsAOS1的表达研究.山东农业科学,2013,45(5):1-5.Han T K,Zhou J J,Xue Y J,Chen C X,Xie X Z.Expression analysis of allene oxide synthase gene,OsAOS1,in rice.Shandong Agric Sci,2013,45(5):1-5.(in Chinese with English abstract)
[27]Ken H,Moritoshi I.Phytochrome-mediated transcriptional up-regulation of ALLENE OXIDESYNTHASE in rice seedlings.Plant Cell Physiol,2004,45(2):119-128.
[28]Biswas K K,Ralf N,Ken H,Osamu Y,Moritoshi I.Photomorphogenesis of rice seedlings:A mutant impaired in phytochrome-mediated inhibition of coleoptile growth.Plant Cell Physiol,2003,44(3):242-254.
[29]Hibara K I,Isono M,Mimura M,Sentoku N,Kojima M,Sakakibara H,Kitomi Y,Yoshikawa T,Itoh J I,Nagato Y.Jasmonate regulates juvenile-adult phase transition in rice.Development,2016,143(18):3407-3416.
[30]Michael R,Ken H,Takafumi S,Kazunori O,Sugihiro A,Susumu M,Yoko N,Utako Y,Peter N,Masahiro Y.Identification of rice Allene Oxide Cyclase mutants and the function of jasmonate for defence against Magnaporthe oryzae.Plant J,2013,74(2):226-238.
[31]Riemann M,Takano M.Rice JASMONATE RESISTANT 1is involved in phytochrome and jasmonate signaling.Plant,Cell&Environ,2010,31(6):783-792.
[32]Xiao Y,Chen Y,Charnikhova T,Mulder P P J,Heijmans J,Hoogenboom A,Agalou A,Michel C,Morel J B,Dreni L.Os JAR1 is required for JA-regulated floret opening and anther dehiscence in rice.Plant Mol Biol,2014,86(1-2):19-33.
[33]Chen Y,Ma J,Miller A J,Luo B,Wang M,Zhu Z,Ouwerkerk P B.Os CHX14 is involved in the K+homeostasis in rice(Oryza sativa)flowers.Plant Cell Physiol,2016,57(7):1530-1543.
[2]杨建菊.杂交水稻种子的裂颖及其危害.杂交水稻,2006,21(1):57-60.Yang J J.Split husk and its harm in hybrid rice seeds.Hybrid Rice,2006,21(1):57-60.(in Chinese with English abstract).
[3]曾晓春,周燮,吴晓玉.水稻颖花开放机理研究进展.中国农业科学,2004,37(2):188-195.Zeng X C,Zhou X,Wu X Y.Advances in study of opening mechanism in rice florets.Sci Agric Sin,2004,37(2):188-195.(in Chinese with English abstract).
[4]管恩相,李勇,刘陵武,姚仁祥,郭君,唐海燕.三系不育系种子裂颖形成的原因及防治措施研究.中国种业,2010(1):42-43.Guan E X,Li Y,Liu L W,Yao R X,Guo J,Tang H Y.Study on causes and control measures of split husk in three-line male sterile line seeds.China Seed Ind,2010(1):42-43.(in Chinese with English abstract).
[5]朱伟,童继平,吴跃进.水稻品种抗裂颖资源的筛选与初步研究.植物遗传资源学报,2004,5(1):52-55.Zhu W,Tong J P,Wu Y J.Preliminary study and selection of rice germplasm with glume gaping resistance.J Plant Genet Resour,2004,5(1):52-55.(in Chinese with English abstract).
[6]彭柏池,刘晓霞,张桂莲,陈立云.授粉期气象因子对水稻细胞质雄性不育系种子裂颖特性的影响.中国农业气象,2008,29(3):308-311.Peng B C,Liu X X,Zhang G L,Chen L Y.Influence of meteorological factors during pollination stage on characters of glume-gaping grains of cytoplasmic male sterile lines in rice.Chin J Agrometeorol,2008,29(3):308-311.(in Chinese with English abstract).
[7]孙廉平,张迎信,张沛沛,杨正福,占小登,沈希宏,张振华,胡霞,轩丹丹,吴玮勋,曹立勇,程式华.一个由可变剪接造成的水稻开颖不育突变体ohms1的鉴定及基因定位.中国水稻科学,2015,29(5):457-466.Sun L P,Zhang Y X,Zhang P P,Yang Z F,Zhan X D,Shen X H,Zhang Z H,Hu X,Xuan D D,Wu W X,Cao LY,Cheng S H.Characterization and gene mapping of an open hull male sterile mutant ohmsl caused by alternative splicing in rice.Chin J Rice Sci,2015,29(5):457-466.(in Chinese with English abstract).
[8]陈立凯,黄明,刘永柱,王慧,陈志强,郭涛.水稻开颖半不育突变体的观察、遗传分析和基因定位.中国农业科学,2016,49(1):1-13.Chen L K,Huang M,Liu Y Z,Wang H,Chen Z Q,Guo T.Observation,genetic analysis and gene mapping of an open hull semi-sterility mutant in rice(Oryza sativa).Sci Agric Sin,2016,49(1):1-13.(in Chinese with English abstract).
[9]曾生元,郭旻,李荣德,盛生兰,龚红兵,严长杰.水稻新裂颖突变体sg1的遗传分析与基因定位.中国水稻科学,2015,29(1):22-27.Zeng S Y,Guo M,Li R D,Sheng S L,Gong H B,Yan C J.Genetic analysis and fine mapping for a novel split glume mutant in rice.Chin J Rice Sci,2015,29(1):22-27.(in Chinese with English abstract).
[10]沈亚林,庄慧,陈欢,曾晓琴,李香凝,张君,郑昊,凌英华,李云峰.水稻颖花持续开放突变体sostenuto floret opening(sfo1)的鉴定与基因.作物学报,2017,43(8):1122-1127.Shen Y L,Zhuang H,Chen H,Zeng X Q,Li X N,Zhang J,Zheng H,Ling Y H,Li Y F.Characterization and gene mapping of sostenuto floret opening 1(sfo1)mutant in rice(Oryza sativa L.).Act Agron Sin,2017,43(8):1122-1127.(in Chinese with English abstract).
[11]Li L,Shi C H,Zeng D D,Jin X L,Wu J G.Morphogenesis and molecular basis on the unclosed glumes,a novel mutation related to the floral organ of rice.Plant Mol Biol Rep,2015,33(3):480-489.
[12]Li X,Wang Y,Duan E,Qi Q,Zhou K,Lin Q,Wang D,Wang Y,Long W,Zhao Z.OPEN GLUME1:A key enzyme reducing the precursor of JA,participates in carbohydrate transport of lodicules during anthesis in rice.Plant Cell Rep,2018,37(2):329-346.
[13]Dhakarey R,Kodackattumannil P P,Riemann M.Functional analysis of jasmonates in rice through mutant approaches.Plants,2016,5(1):1-15.
[14]Wasternack C,Song S.Jasmonates:Biosynthesis,metabolism,and signaling by proteins activating and repressing transcription.J Exp Bot,2016,68(6):1303-1321.
[15]Cai Q,Yuan Z,Chen M,Yin C,Luo Z,Zhao X,Liang W,Hu J,Zhang D.Jasmonic acid regulates spikelet development in rice.Nat Commun,2014,5(3):3476.
[16]冯孟杰,徐恒,张华,朱英.茉莉素调控植物生长发育的研究进展.植物生理学报,2015,51(4):407-412.Feng M J,Xu H,Zhang H,Zhu Y.Recent progress in jasmonates regulation of plant growth and development.Plant Physiol J,2015,51(4):407-412.(in Chinese with English abstract).
[17]Wasternack C.Jasmonates:An update on biosynthesis,signal transduction and action in plant stress response,growth and development.Ann Bot,2007,100(4):681-697.
[18]Ishiguro S,Kawai-Oda A,Ueda J,Nishida I,Okada K.The DEFECTIVE IN ANTHER DEHISCIENCE gene encodes a novel phospholipase A1 catalyzing the initial step of jasmonic acid biosynthesis,which synchronizes pollen maturation,anther dehiscence,and flower opening in Arabidopsis.Plant Cell,2001,13(10):2191-2209.
[19]Park J H,Halitschke R,Kim H B,Baldwin I T,Feldmann K A,Feyereisen R.A knock-out mutation in allene oxide synthase results in male sterility and defective wound signal transduction in Arabidopsis due to a block in jasmonic acid biosynthesis.Plant J,2002,31(1):1-12.
[20]Zeng X C,Zhou X.Methyl jasmonate induces the opening of spikelets in rice.Chin Bull Bot,1999,41(5):560-562.
[21]Song P,Xia K,Wu C W,Bao D P,Chen L P,Zhou X,Cao X Z.Differential response of floret opening in male-sterile and male-fertile rice to methyl jasmonate.Chin Bull Bot,2001,43(5):480-485.
[22]Liu L,Zou Z,Qian K,Xia C,He Y,Zeng H,Zhou X,Riemann M,Yin C,Zhang D.Jasmonic acid deficiency leads to scattered floret opening time in cytoplasmic male sterile rice Zhenshan 97A.J Exp Bot,2017,68(16):4613-4625.
[23]黄俊宝,何永明,曾晓春,向妙莲,付永琦.水稻颖花开放前花器官茉莉酸水平变化及浆片茉莉酸信号基因表达分析.中国农业科学,2015,48(6):1219-1227.Huang J B,He Y M,Zeng X C,Xiang M L,Fu Y Q.Changes of JA levels in floral organs and expression analysis of JA signaling genes in lodicules before floret opening in rice.Sci Agric Sin,2015,48(6):1219-1227.(in Chinese with English abstract)
[24]付永琦,向妙莲,蒋海燕,何永明,曾晓春.水稻颖花开放前浆片转录组变化.中国农业科学,2016,49(6):1017-1033.Fu Y Q,Xiang M L,Jiang H Y,He Y M,Zeng X C.Transcriptome profiling of lodicules before floret opening in Oryza sativa L.Sci Agric Sin,2016,49(6):1017-1033.(in Chinese with English abstract).
[25]Fu J,Chu J,Sun X,Wang J,Yan C.Simple,rapid,and simultaneous assay of multiple carboxyl containing phytohormones in wounded tomatoes by UPLC-MS/MSusing single SPE purification and isotope dilution.Anal Sci,2012,28(11):1081-1087.
[26]韩同凯,周晋军,薛彦久,陈翠霞,谢先芝.水稻丙二烯氧化物合成酶基因OsAOS1的表达研究.山东农业科学,2013,45(5):1-5.Han T K,Zhou J J,Xue Y J,Chen C X,Xie X Z.Expression analysis of allene oxide synthase gene,OsAOS1,in rice.Shandong Agric Sci,2013,45(5):1-5.(in Chinese with English abstract)
[27]Ken H,Moritoshi I.Phytochrome-mediated transcriptional up-regulation of ALLENE OXIDESYNTHASE in rice seedlings.Plant Cell Physiol,2004,45(2):119-128.
[28]Biswas K K,Ralf N,Ken H,Osamu Y,Moritoshi I.Photomorphogenesis of rice seedlings:A mutant impaired in phytochrome-mediated inhibition of coleoptile growth.Plant Cell Physiol,2003,44(3):242-254.
[29]Hibara K I,Isono M,Mimura M,Sentoku N,Kojima M,Sakakibara H,Kitomi Y,Yoshikawa T,Itoh J I,Nagato Y.Jasmonate regulates juvenile-adult phase transition in rice.Development,2016,143(18):3407-3416.
[30]Michael R,Ken H,Takafumi S,Kazunori O,Sugihiro A,Susumu M,Yoko N,Utako Y,Peter N,Masahiro Y.Identification of rice Allene Oxide Cyclase mutants and the function of jasmonate for defence against Magnaporthe oryzae.Plant J,2013,74(2):226-238.
[31]Riemann M,Takano M.Rice JASMONATE RESISTANT 1is involved in phytochrome and jasmonate signaling.Plant,Cell&Environ,2010,31(6):783-792.
[32]Xiao Y,Chen Y,Charnikhova T,Mulder P P J,Heijmans J,Hoogenboom A,Agalou A,Michel C,Morel J B,Dreni L.Os JAR1 is required for JA-regulated floret opening and anther dehiscence in rice.Plant Mol Biol,2014,86(1-2):19-33.
[33]Chen Y,Ma J,Miller A J,Luo B,Wang M,Zhu Z,Ouwerkerk P B.Os CHX14 is involved in the K+homeostasis in rice(Oryza sativa)flowers.Plant Cell Physiol,2016,57(7):1530-1543.