水稻矮化大粒突变体sdb1的鉴定与基因定位

Identification and Gene Mapping of sdb1 Mutant with a Semi-dwarfism and Bigger Seed in Rice

适度矮化有利于提高水稻的抗倒伏性,进而影响产量和品质,是水稻育种中重要的选择性状之一,因此研究矮秆形成的分子机制具有重要的意义。为鉴定新的矮秆资源,探讨株高形成的分子调控机制,我们对籼型恢复系缙恢10号的EMS(甲基磺酸乙酯)诱变体库进行了鉴定,从中筛选到1个植株半矮化且籽粒变大的突变体sdb1。本文对其进行了形态鉴定、细胞学观察、遗传分析和基因定位等研究。田间种植条件下,全生育期sdb1的株高都明显矮于野生型,成熟期仅76.66cm,与野生型的117.43cm相比,下降了34.72%,差异达极显著水平,进一步分析发现sdb1的穗和各节间长均显著变短。在茎秆石蜡切片中发现,纵向细胞的长度与野生型相比无显著变化,横向细胞面积极显著变小、数量则极显著增加,纵向细胞变少是导致sdb1植株半矮化的主要原因。除植株变矮外,sdb1的另一典型特征是籽粒变大,千粒重由野生型的24.83 g变为突变体的29.00 g,差异达极显著水平;颖壳中薄壁细胞数量增加了22.05%,致使籽粒的长、宽、厚均极显著变大,从而提高了sdb1的粒重。此外,sdb1叶肉细胞层数增多,导致其光合色素含量极显著高于野生型,叶片呈现深绿色。遗传分析发现, sdb1的突变表型受单隐性核基因调控,利用中花11/sdb1杂交组合的F2隐性植株,最终将调控基因定位在第4染色体SSR标记RM16632和Indel标记J50-7之间约406 kb的物理范围内。这为SDB1的克隆和功能研究奠定了基础,也有助于水稻株高发育分子机制的进一步阐释。

Moderate dwarfing is conducive to improving the lodging resistance of rice and further affecting its yield and quality,which is one of the important alternatives in rice breeding.Therefore,it is of great significance to study the molecular mechanism of shortened stem formation.In order to identify new dwarf resources and to explore the molecular regulation mechanism of plant height formation,a semi-dwarf and bigger seed(sdb1)mutant was identified from the progeny of indica restorer line Jinhui 10 with seed treated by ethyl methane sulfonate(EMS).This paper performed systematic studies in phenotypic identification,cytological observation,genetic analysis and gene mapping.At maturity stage,the plant height of sdb1 was only 76.66 cm,significantly shorter than 117.43 cm of wild type,resulting in a 34.72%decrease.It was found from the paraffin sections of the stem that the mutant had no significant change in stem cell length compared with the wild-type cells,it reduced cell width caused significantly smaller cell size,and the number of lateral cells significantly increased.The decrease of longitudinal cells should be the major cause of sdb1 semi-dwarfism.In addition to reduced plant height of sdb1,another typical mutational trait was the larger grain size,the 1000-grain weight increased from wild-type’s 24.83 g to mutant’s 29.00 g,reaching an extremely significant difference.The number of parenchyma cells increased from 666.30 in WT to 813.21 in sdb1,with an increase of 22.05%.The increase of cell number resulted in a significant increase of grain length,width and thickness.The mutant also had increased number of sdb1 mesophyll cells,resulting in significantly higher photosynthetic pigment content than wild type,and dark green leaves.Genetic analysis showed that a recessive nuclear gene regulated the mutant phenotype.Based on the F2 recessive plants of Zhonghua 11/sdb1,the gene was finally mapped between markers RM16632 and J50-7 on chromosome 4,with a physical distance of 406 kb.This research lays a foundation for gene cloning and function research,and is conducive to further understanding the genetic model of rice plant height,which has the potential value for agricultural production research.