Identification and fine mapping of a candidate gene for oil yellow leaf 2 conferring yellow leaf phenotype in maize

Leaf colour is an important agronomic trait for studying molecular mechanisms in chlorophyll biosynthesis and chloroplast development. Here, a novel mutant oil yellow leaf 2 (Oy2) with a typical yellow leaf phenotype at the seedling stage was identified from the mutant population derived from the maize inbred line RP125. Compared with wild type, Oy2 mutant displays decreased chlorophyll content, reduced photosynthetic capacity and impaired chloroplast structure, which is likely controlled by a single recessive gene. The Oy2 locus was then delimited into a 117 kb region on chromosome 5 harbouring four genes, amongst which the gene Zm00001d013013, encoding a magnesium chelatase subunit D, was identified as the only candidate gene associated with Oy2 mutant phenotype. Moreover, the expression levels of candidate gene Oy2 and genes associated with chlorophyll biosynthesis and photosynthesis were tested by RNA‐seq and qRT‐PCR, implying that the causal gene Oy2 playing a critical role in chlorophyll synthesis. Taken together, we propose that the causal gene Oy2 highly associated with the yellow leaf phenotype may be helpful in elucidating photosynthetic pigments biosynthesis and chloroplast development in maize.     

南方根结线虫侵染下罗汉果WRKY转录因子的鉴定分析

为了确定南方根结线虫侵染早期罗汉果植株中与侵染相关的WRKY基因,以接种南方根结线虫7 d后的罗汉果侧根为材料进行转录组测序分析。基于测序序列的Nr、SwissProt注释结果,共鉴定到21个WRKY基因,其中有4个转录因子含有2个WRKY结构域,其余17个转录因子只有1个WRKY结构域。系统发育分析表明,5个WRKY转录因子为第一家族成员,2个为第三家族成员,其余14个为第二家族成员。有8个WRKY转录因子与已报道的根结线虫诱导相关WRKY转录因子同源性较高,初步推测下调表达的SgWRKY2、SgWRKY3和SgWRKY17可能与南方根结线虫的早期侵染有关,它们很可能参与了线虫取食位点与巨细胞形成的复杂调控作用。本研究将为今后阐明根结线虫与罗汉果互作的分子机制提供参考依据。