水稻黄绿叶突变体ygl-63的特征和基因定位

叶绿体的正常发育对于植物至关重要,突变体研究是探明叶绿体发育过程中基因功能的有效途径。叶色突变体已引起人们广泛的关注,通过对各种植物材料的研究,叶色突变的分子机制已取得一定进展,但远未被阐明,尤其在水稻当中。目前,已报道的水稻叶色突变体,主要表现为黄化、白化、亮绿、条斑条纹、温敏变色、转绿和转紫等。该研究使用甲基磺酸乙酯( EMS)处理粳稻日本晴,获得一份遗传稳定的突变体ygl-63,其整个生育期叶片均表现为黄绿色。通过测定ygl-63和野生型苗期叶片的叶绿素含量发现,ygl-63中叶绿素a、叶绿素b和总叶绿素含量与野生型相比分别下降了31.9％、42.2％和34.1％,同时叶绿素a/b值较野生型增加。这表明叶绿素含量的降低是导致ygl-63黄绿叶突变性状的主要原因,并且叶绿素b的降幅大于叶绿素a。在成熟后调查主要农艺性状发现ygl-63单株有效穗数和结实率分别减少8.9％和8.5％；千粒重增加10.4％；而株高,穗长和每穗着粒数和野生型相比差异并不显著。通过测量微量元素发现,ygl-63种子中的铁和锌含量较野生型显著降低,分别减少85.7％和64.8％。将ygl-63与正常绿色品种明恢63杂交获得F1和F2群体,进行遗传分析发现,ygl-63突变性状受1对隐性基因控制,通过基因定位,将该基因定位到水稻第11染色体长臂的分子标记InDel-3和InDel-5之间约2.4 cM范围内。该基因被认为是一个新的水稻叶色突变基因,暂命名为ygl-63( g)。所得结果为今后对ygl-63( g)基因的进一步研究奠定了基础。

Characteristics and gene mapping of yellowish green leaf mutant ygl-63 in rice(Oryza sativa L.)

Chloroplasts are important organelles in green plants for photosynthesis, and normal development of chloroplasts is important to plants. Mutant analysis is a useful approach to illuminate the function of gene in complex biological process of chloroplast development. Nowadays, extensive attention has been paid to the leaf-color mutation, and certain achievements have been made by studying various organisms, but the mechanism of mutation and the responsible loci have not been fully understood at molecular level, especially in rice. Up to now, many leaf-color mutants were reported in rice, mainly featured by etiolation, albino, brilliant green, stripe, temperature sensitive allochromasia, turning green and purple in leaf color. In this study, a rice yellowish green leaf mutant ygl-63 was identified, which derived from Nipponbare(Oryza sativa ssp. japonica)treated by ethyl methanesulfonate(EMS). The mutant ygl-63 exhibited distinct yellowish green leaf trait throughout the growth period. To characterize the yellowish green leaf phenotype of the ygl-63 mutant, we measured its chlorophyll contents at the seedling stage. Compared to that of its wild-type parent Nipponbare, the content of chlorophyll(Chl)a, Chl b and total chlorophyll decreased significantly in the mutant ygl-63, with 31.9%, 42.2% and 34.1% respectively, indicating that the mutant phenotype of ygl-63 was resulted from reduced chlorophyll level. In addition, the ratio of Chl a/b was increased, due likely to the potential of Chl b synthesis in suffering a more severe decline than Chl a in the ygl-63 mutant; and at maturity, the number of productive panicles per plant and seed setting rate reduced by 8.9% and 8.5%, respectively; the 1 000-grain weight increased by 10.4%; but the plant height, panicle length and the number of spikelets per panicle were not affected remarkably with its wild-type parent Nipponbare. Meanwhile, by measuring the contents of micronutrients, we found that the Fe and Zn contents in the seeds of ygl-63 mutant were significantly reduced by 85.7% and 64.8% respectively, compared with its wild-type parent Nipponbare. Genetic analysis of F₁ and F₂ generations of ygl-63 mutant crossed with the normal green variety Minghui 63(Oryza sativa ssp. indica)showed that the mutant trait of ygl-63 was controlled by a single recessive nuclear gene. Genetic mapping of the mutant gene was conducted by using SSR and InDel molecular markers and 166 F₂ plants from the cross of ygl-63 with the normal green variety Minghui 63, and the mutant gene of ygl-63 was finally mapped on the long arm of rice chromosome 11. The genetic distances from the target gene to the markers InDel-3 and InDel-5 were 0.9 and 1.5 cM, respectively. The gene ygl-63 was considered to be a new rice yellowish green leaf mutant and its mutant gene was tentatively named as ygl-63(g). These results will provide the information for the cloning and functional analysis of ygl-63(g)gene in the future.