水稻叶片表皮毛是由表皮细胞分化发育形成，表皮毛在植物的抗逆以及防止紫外直射等过程中都具有重要的作用，但关于水稻毛状体发育的研究还存在很大未知。在本研究中，我们对野生型籼系水稻西大1B进行EMS (ethylmethane sulfonate) 诱导，通过表型观察分析筛选出了毛状体发育缺陷突变体，将其命名为lhl1 (Less Hairy Leaf 1)。我们对其进行了基因定位和图位克隆，将其定位在2号染色体两个分子标记的70 kb的区间内，通过基因测序将LOC_Os02g25230确定为候选基因。之后我们构建了干涉以及超表达株系，扫描电镜观察分析发现LHL1-RNAi叶片同lhl1一样存在毛状体发育缺陷，但LHL1-OE株系叶片表面的毛状体形态与野生型相似，但数目大大增加。qRT-PCR分析发现，与野生型相比，突变体lhl1中正向调控毛状体发育相关的基因表达下调。对生长素相关基因定量分析发现，突变体hl7中生长素相关基因的表达严重下调，进一步通过激素响应分析发现HL7的表达受到生长素的诱导，证明了HL7影响水稻叶片毛状体的发育可能与生长素途径有关。

   Leaves play a key role in photosynthesis in rice plants. The premature senescence of such plants directly reduces the accumulation of photosynthetic products and also affects yield and grain quality significantly and negatively. A novel premature senescence mutant, mps1 (mid-late stage premature senescence 1), was identified from a mutant library consisting of ethyl methane sulfonate (EMS) induced descendants of Jinhui 10, an elite indica restorer line of rice. The mutant allele, mps1, caused no phenotypic differences from the wild type (WT), Jinhui 10, but drove the leaves to turn yellow when mutant plants grew to the tillering stage, and accelerated leaf senescence from the filling stage to final maturation. We characterized the agronomic traits, content of photosynthetic pigments and photosynthetic efficiency of mps1 and WT, and fine-mapped MPS1. The results showed that the MPS1-drove premature phenotype appeared initially on the leaf tips at the late tillering stage and extended to the middle of leaves during the maturing stage. Compared to the WT, significant differences were observed among traits of the number of grains per panicle (–31.7%) and effective number of grains per panicle (–38.5%) of mps1 individuals. Chlorophyll contents among the first leaf from the top (Top 1st), the second leaf from the top (Top 2nd) and the third leaf from the top (Top 3rd) of mps1 were significantly lower than those of WT (P<0.05), and the levels of photosynthetic efficiency from Top 1st to the forth leaf from the top (Top 4th) of mps1 were significantly lower than those of WT (P<0.01). Results from the genetic analysis indicated that the premature senescence of mps1 is controlled by a recessive nuclear gene, and this locus, MPS1 is located in a 37.4-kb physical interval between the markers Indel145 and Indel149 on chromosome 6. Genomic annotation suggested eight open reading frames (ORFs) within this physical region. All of these results will provide informative references for the further researches involving functional analyses and molecular mechanism exploring of MPS1 in rice.

    The nuclear-encoded light-harvesting chlorophyll a/b-binding proteins (LHCPs) are specifically translocated from the stroma into the thylakoid membrane through the chloroplast signal recognition particle (cpSRP) pathway. The cpSRP is composed of a cpSRP43 protein and a cpSRP54 protein, and it forms a soluble transit complex with LHCP in the chloroplast stroma. Here, we identified the YGL9 gene that is predicted to encode the probable rice cpSRP43 protein from a rice yellow-green leaf mutant. A phylogenetic tree showed that an important conserved protein family, cpSRP43, is present in almost all green photosynthetic organisms such as higher plants and green algae. Sequence analysis showed that YGL9 comprises a chloroplast transit peptide, three chromodomains and four ankyrin repeats, and the chromodomains and ankyrin repeats are probably involved in protein-protein interactions. Subcellular localization showed that YGL9 is localized in the chloroplast. Expression pattern analysis indicated that YGL9 is mainly expressed in green leaf sheaths and leaves. Quantitative real-time PCR analysis showed that the expression levels of genes associated with pigment metabolism, chloroplast development and photosynthesis were distinctly affected in the ygl9 mutant. These results indicated that YGL9 is possibly involved in pigment metabolism, chloroplast development and photosynthesis in rice.