摘要
落粒性是水稻非常重要的农艺性状,适度落粒有利于减少产量损失和水稻机械化收割,提高生产效率.因此鉴定落粒基因对水稻生产具有重要意义.本研究以日本晴为受体亲本、优良恢复系R225为供体亲本,采用高代回交和SSR标记辅助选择相结合的方法,鉴定了一个携带易落粒主效单基因的水稻染色体片段代换系Z481.Z481含有4个染色体代换片段,位于第1,3,6染色体上,其代换片段长度分别为8.30,6.17,3.12和10.79 Mb,平均为7.10 Mb.与受体日本晴相比,Z481的株高、穗长、倒一节间长、倒二叶宽显著降低,剑叶宽和结实率显著增加,其他重要农艺性状如叶长、有效穗数、每穗粒数和千粒重均无显著差异.扫描电子显微镜观察表明Z481的护颖和枝梗之间的离层在成熟时期已被完全降解,而日本晴的离层完整,在细胞学上解释了Z481易落粒性产生的原因.进一步利用日本晴与Z481杂交产生的F_1和F_2群体对易落粒基因进行了遗传分析和分子定位.该易落粒性状受单基因隐性调控,最终将该基因定位于第6染色体RM253和ZTQ53之间824 kb的区域,暂命名为SH6(t).目前,在第6染色体尚无落粒基因克隆的报道.由于染色体片段代换系除代换片段外与受体亲本的遗传背景一致,且Z481易落粒遗传行为简单,基本未携带育种不利性状.因此,本研究无论对SH6(t)的克隆,还是进行基因聚合育种培育适度落粒新品种均具有重大利用价值.
Seed shattering is an important agronomic trait in rice. Moderate shattering is favorable to improve production efficiency by reducing rice production losses and mechanical harvesting. Therefore, identification of genes for shattering is important for rice production. Here, in 2014 a novel chromosome segment substitution line （CSSL） Z481 with easy seed-shattering was identified deriving from advanced backcrosses between Nipponbare as recipient and excellent rice restorer R225 as donor by SSR marker-assisted selection （MAS）. In 2015, seed shattering ratio together with 16 other phenotypic traits were measured with 10 plants of ZA81 and Nipponbare, and then t-test analysis was conducted. Furthermore, the abscission layer between lemma and branch of Z481 and Nipponbare were obverved with SU3500 type scanning electron microscopy. Finally, genetic analysis and gene mapping for the easy seed-shattering were done using the F1 and F2 population obtainted by Nipponbare crossed with the Z481. The results showed as follows： （i） Z481 contained four substitution segments which located on chromosomes 1, 3, 6 and 6. The length of these substitution segments was 8.30, 6.17, 3.12 and 10.79 Mb, respectively, and the average length was 7.39 Mb. CSSLs are developed by a series of backcrosses to the recipient parent until its genome is fully recovered except one or several marker-defined chromosome segment（s） from donor parents in each line. Thus, the use of CSSLs can simplify the study of complex genetic traits and are considered excellent materials for combining the identification of genes with their use in the strategic breeding of rice. （ii） The seed shattering ratio of Z481 was 5.3%, while 94.1% was Nipponbare, which was at 0.01 significance level. Compared with Nipponbare, plant height, panicle length, length of 1st internode and width of the 2nd leaf in Z481 were significantly reduced, and width of the flag leaf and seed setting ratio were significantly increased. Other important agronomic traits such as length of the leaf, panicle number, spikelets per panicle, 1000-grain weight were not significantly different. Due to carrying many advantageous traits, Z481 can be directly used in MAS breeding strategy. （iii） Abscission layer of Z481 was completely degraded at maturity stage, whereas that of Nipponbare was complete, which revealed the cytological reason of easy shattering in Z481. The result riches the conclusion of other researchers that shattering is related to the development of abscission layer of rice grains. （iv） The distribution of seed shattering ratio in the F2 population displayed bimodal. The peak values of difficult shattering were mainly distributed at 61%-100%, and those of easy shattering mainly ranged from 0% to 40%. Chi-square test showed that the ratio of plant number with difficult shattering （423） to that with easy shattering （128） fitted to 3：1 segregation ratio （χ^2=0.87〈χ^2（0.05,1）=3.84）. These results showed that the easy shattering in Z481 was controlled by a single recessive nuclear gene, named SH6（t）, which was mapped between SSR markers RM253 and ZTQ53 on chromosome 6, with a physical distance of 824 kb. It is different from the 5 cloned genes for shattering, such as qSH1 on chromosomel, SH4/SHAland SHAT1 on chromosome4, SH5 on chromosome 5, and OsCPLI/SH-H on chromosome 7. Although the location of qSH1 is within the substitution region of chromosomel of Z481, however, it is not linked with all the markers there, which indicated that qSH1 and SH6（t） might be all major genes for controlling shattering between rice subspieses of indica and japonica. To date, none of genes for seed-shattering was reported yet on the chromosome 6. In conclusion, a novel CSSL named Z481 carrying 4 substituton segments was identified with easy seed-shattering and many favorable agronomic traits. The easy shattering was caused by degradation of abscission and controled by a single recessive nuclear gene SH6（t）, which was mapped at the region of 824 kb on chromosome 6 and has not been cloned. Consequently, it will be not only beneficial for further cloning and functional analysis of SH6（t）, but also important in breeding novel varieties with moderate shattering by MAS.
出处
《科学通报》
EI
CAS
CSCD
北大核心
2016年第7期748-758,共11页
Chinese Science Bulletin
基金
重庆市重点实验室能力提升项目(cstc2014pt-sy80001)
重庆市科技攻关计划重大项目(CSTC2012gg C80002)资助
关键词
水稻
落粒性
染色体片段代换系
基因定位
rice （Oryza sativa L.）, seed shattering, chromosome segment substitution line, gene mapping
