生物谷報道：中國科學院遺傳與發(fā)育生物學研究所儲成才研究組方軍博士等在水稻穗發(fā)芽研究上取得重要突破,，這一研究成果已在國際植物學權威雜志《植物雜志》上發(fā)表（Fang J., et al., Plant Journal, Advance Access published on January 16, 2008, doi:10.1111 / j.1365-313X.2008.03411.x）,。
眾所周知，禾本科作物的穗發(fā)芽是世界性的自然災害。僅在小麥上,，我國長江流域冬麥區(qū)、東北春麥區(qū)、黃淮冬麥區(qū)及西南冬麥區(qū)等約占全國小麥總面積83% 種植區(qū)都發(fā)生過嚴重的穗發(fā)芽災害,。1998年，解放軍總后勤部嫩江農(nóng)場兩萬公頃小麥發(fā)生嚴重穗發(fā)芽,，受災面積達100%,，造成下年斷種而不得不從外地調(diào)運。1984年,，四川盆地穗發(fā)芽損失面積達數(shù)十萬公頃,。這種嚴重的減產(chǎn)不僅直接影響了生產(chǎn)者的經(jīng)濟利益，而且由于穗發(fā)芽引起一系列生理生化變化,，嚴重影響面粉加工利用品質(zhì),。在水稻上，多年來由于育種更多地考慮高產(chǎn),、優(yōu)質(zhì)和抗病蟲害指標,，往往忽略了種子適度休眠的保留，尤其是雜交水稻制種過程中赤霉素（九二零）的大量使用,，導致穗發(fā)芽危害嚴重,。我國南方雜交稻制種中，正常年份穗發(fā)芽率為5%左右,，特殊年份（高溫多雨）可超過20%,，即使是在常規(guī)育種中利用秈粳交培育的高產(chǎn)品種也大多具易穗發(fā)芽的弊端。
穗發(fā)芽也是環(huán)境和植物互作最典型,、最復雜的農(nóng)藝性狀之一,。目前在禾谷類作物穗發(fā)芽機理研究上，雖然科學家以小麥和玉米為材料通過將其作為休眠的對立面開展了一些QTL定位工作,，但一直難以從分子機制上進行深入研究,。利用玉米突變體也克隆了一些穗發(fā)芽相關基因，但由于玉米基因組的復雜性和全基因組測序尚未完成,，難以從整體上對穗發(fā)芽的分子及生理調(diào)控機制進行系統(tǒng)研究,。
方軍博士等和中國水稻所錢前博士合作通過對大規(guī)模水稻突變體庫進行系統(tǒng)篩選，獲得了12份水稻穗發(fā)芽突變體材料,，并根據(jù)其表型特點將其分成三種類型,，《植物雜志》上發(fā)表的這篇文章對其中第一種類型突變體的四個穗發(fā)芽基因進行了定位和克隆，并對其進行了深入的功能分析,，發(fā)現(xiàn)這四個基因均定位于類胡蘿卜素合成途徑,。類胡蘿卜素不僅是人體不可或缺的營養(yǎng)物質(zhì)，在植物生長發(fā)育中,，類胡蘿卜素與葉綠素及蛋白質(zhì)共同構(gòu)成了類囊體膜上的光系統(tǒng)復合體,，并作為葉綠素以外的光合輔助色素在光合作用中起著吸收和傳遞光能的作用,。同時類胡蘿卜素也是控制種子休眠的重要激素——脫落酸（ABA）合成的前體。
方軍博士等的研究不僅進一步證明了ABA在植物穗發(fā)芽中起重要作用,，同時通過實驗證明了種子中GA/ABA比率變化是造成穗發(fā)芽的重要原因,。對所有三類突變體的深入研究有望在穗發(fā)芽這個重要農(nóng)藝性狀研究上獲得重大突破，不僅對解決雜交稻日益嚴重的穗發(fā)芽危害有非?，F(xiàn)實的指導作用,，對諸如小麥、玉米等其它禾谷類糧食作物穗發(fā)芽的控制也有一定的借鑒作用,。
生物谷推薦原始出處：
The Plant Journal
OnlineAccepted Articles (Accepted, unedited articles or abstracts published online for future issues)
To cite this article: Jun Fang, Chenglin Chai, Qian Qian, Chunlai Li, Jiuyou Tang, Lei Sun, Zejun Huang, Xiaoli Guo, Changhui Sun, Min Liu, Yan Zhang, Qingtao Lu, Yiqin Wang, Congming Lu, Bin Han, Fan Chen, Zhukuan Cheng, Chengcai Chu
Mutations of genes in synthesis of the carotenoid precursors of ABA lead to preharvest sprouting and photo-oxidation in rice
The Plant Journal (OnlineAccepted Articles).
doi:10.1111/j.1365-313X.2008.03411.x
Mutations of genes in synthesis of the carotenoid precursors of ABA lead to preharvest sprouting and photo-oxidation in rice
Jun Fang1,3*1State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China3Graduate University of the CAS, Beijing 100039, China
*These authors contributed equally to this article., Chenglin Chai1,3*1State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China3Graduate University of the CAS, Beijing 100039, China
*These authors contributed equally to this article., Qian Qian2*2State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
*These authors contributed equally to this article., Chunlai Li1,31State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China3Graduate University of the CAS, Beijing 100039, China, Jiuyou Tang1,31State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China3Graduate University of the CAS, Beijing 100039, China, Lei Sun44Centre for Biological Electron Microscopy, Institute of Biophysics, CAS, Beijing 100101, China, Zejun Huang1,31State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China3Graduate University of the CAS, Beijing 100039, China, Xiaoli Guo1,31State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China3Graduate University of the CAS, Beijing 100039, China, Changhui Sun11State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China, Min Liu11State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China, Yan Zhang55State Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, CAS, Beijing 100093, China, Qingtao Lu55State Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, CAS, Beijing 100093, China, Yiqin Wang11State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China, Congming Lu55State Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, CAS, Beijing 100093, China, Bin Han66National Centre for Gene Research, CAS, Shanghai 200233, China, Fan Chen77Key Laboratory of Developmental Biology, Institute of Genetics and Developmental Biology, CAS, Beijing 100101, China, Zhukuan Cheng11State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China, Chengcai Chu11State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China 1State Key Laboratory of Plant Genomics and National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing 100101, China
2State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
3Graduate University of the CAS, Beijing 100039, China
4Centre for Biological Electron Microscopy, Institute of Biophysics, CAS, Beijing 100101, China
5State Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, CAS, Beijing 100093, China
6National Centre for Gene Research, CAS, Shanghai 200233, China
7Key Laboratory of Developmental Biology, Institute of Genetics and Developmental Biology, CAS, Beijing 100101, China
Summary
Preharvest sprouting (PHS) or vivipary in cereals is an important agronomic trait that results in significant economic loss. A considerable number of mutations that cause preharvest sprouting have been identified in several species. However, relatively few viviparous mutants in rice have been reported. To explore the PHS mechanism in rice, we carried out an extensive genetic screening and identified 12 pre-harvest spouting (phs) mutants. Based on their phenotypes, these phs mutants were classified into three groups. Here we characterized in detail one group of them, which contains mutations in genes encoding major enzymes of the carotenoid biosynthesis pathway, including phytoene desaturase (OsPDS), ζ-carotene desaturase (OsZDS), carotenoid isomerase (OsCRTISO) and lycopene β-cyclase (β-OsLCY), which are essential for biosynthesis of carotenoid precursors of ABA. As expected, ABA amount was reduced in all four phs mutants compared to that in wild type. Chlorophyll fluorescence analysis revealed the occurrence of photoinhibition in photosystem and decreased capacity in eliminating excess energy by thermal dissipation. The greatly increased activities of reactive oxygen species (ROS) scavenging enzymes and reduced photosystem (PS) II core proteins CP43, CP47 and D1 in leaves of Oscrtiso/phs3-1mutant and OsLCY RNAi transgenic rice indicated that photooxidative damages occurred in PS II, consistent with the accumulation of ROS in these plants. These results suggest that the impairment in carotenoid biosynthesis causes photo-oxidation and ABA-deficiency phenotypes, of which the latter is a major factor controlling the preharvest sprouting trait in rice.
