Prohibitin (PHB) plays critical roles in plant growth and development.In this study,we utilized CRISPR/Cas9 gene-editing technology to generate homozygous OsPHB2 knockout transgenic plants,designated cr-osphb2. The cr-osphb2 line exhibited wider leaves,dwarfism,and shorter panicles.

Grain size is a critical yield determinant and a complex quantitative trait in rice. The major quantitative trait locus GS2, which encodes the transcriptional regulator OsGRF4, has been characterized as a key controller of grain size and grain weight in rice. Building upon existing germplasm resources, exploring the upstream and downstream genes of known grain size regulators is an effective approach to gradually refine and expand the molecular regulatory network underlying grain size. Here, we report that a suppressor of the gain-of-function allele GS2AA, SUG2, which encodes an importin β nuclear transport protein. Phenotypic characterization reveals that the sug2 GS2AA mutant exhibits small grains by inhibiting cell expansion in the spikelet hull. Protein interaction analyses demonstrate that SUG2 physically interacts with GS2 both in vivo and in vitro, and the SUG2A mutation reduces SUG2 expression levels and inhibits GS2 transcriptional activation activity, resulting in decreased GS2 expression levels and GS2 protein abundance in sug2 GS2AA. Genetic analyses indicate that SUG2 and GS2 may be partially involved in a common pathway regulating grain size and weight in rice. These findings elucidate the grain size regulatory relationship between SUG2 and GS2 and provide novel insights into the precision breeding of yield optimization in rice.

Leaf color and photosynthesis are important factors for rice growth and development. Hence, improving the photosynthetic rate is an effective approach for increasing rice yield. We isolated a gene, chlorophyllide-a oxygenase 1（OsCAO1）,

Panicle length (PL) is an important trait closely related to rice yield. More than 200 quantitative trait loci (QTL) for PL have been identified, but only a few can be used for breeding. Dongxiang wild rice contains many excellent genes, and mining favorable PL-related QTL from DXWR is helpful for rice variety improvement. Here, we report a QTL analysis for PL using a recombinant inbred line population consisting of 143 individuals derived from a cross between Dongxiang wild rice and indica cultivar Guangluai 4. A total of four QTL (qPL1-37, qPL4-26, qPL7-25, and qPL8-4) for PL were identified and located on chromosomes 1, 4, 7, and 8. Among them, qPL7-25 showed the largest F-value of 32.32 and 16.80, and the QTL explained 18.66% and 13.06% of the phenotypic variation of Dongxiang wild rice in Hangzhou and Hainan, respectively. QTL mapping was performed using a population of 1800 individuals derived from the crossing of NIL-qPL7-25 and GLA4. qPL7-25 was located between two InDel markers, InDel-24591 and InDel-24710, in a 119 kb region containing 14 predicted genes. Using Sanger sequencing and qRT-PCR analysis, we propose that LOC_Os07g41200 is probably a new allele of the well-known GL7 gene, which affects grain length and appearance quality in rice. These results provide new insights into the use of molecular marker-assisted selection for breeding high-yielding and high-quality rice varieties.

[目的]克隆水稻分蘖相关基因,为构建理想株型水稻,提高粮食产量提供理论基础及有利基因资源.[方法]在常规大田种植条件下分别比较突变体htd3(high-tillering dwarf 3)与野生型在幼苗期、抽穗期和成熟期表型及主要农艺性状差异,利用图位克隆方法克隆候选基因,利用荧光定量PCR方法分析HTD3及独脚金内酯和脱落酸相关基因的表达水平,测序比对分析HTD3在147份种质资源中的自然变异情况.[结果]与野生型相比,突变体htd3的分蘖芽生长较快,分蘖数和有效穗数显著增多,株高、一次枝梗数和每穗粒数显著降低,结实率和千粒重没有显著变化.遗传分析表明,htd3多分蘖的性状受一对隐性核基因控制.图位克隆将HTD3基因定位在第12染色体CM8和CM10之间约63.5 kb的物理区间内,互补转基因实验证明该区间内LOC_Os12g21710为控制突变体多分蘖表型的基因.HTD3在野生型和突变体中呈组成型表达,该基因突变会引起部分独脚金内酯和脱落酸相关基因的表达水平上调.水稻品种中HTD3编码区G2674A自然变异使得分蘖数显著增多.[结论]HTD3是最近报道的T20/MIT1基因的一个新的等位基因,HTD3突变导致水稻出现分蘖适度增加,株高略矮的表型,在培育理想株型水稻和高产育种上具有较大的应用潜力.

Premature leaf senescence negatively affects rice yield and quality. Identifying premature senescence mutants and examining their gene functions are important for the genetic improvement of crops. In this study, a leaf senescence mutant dls-1 was obtained from japonica Yundao by ethyl methane sulfonate mutagenesis, which showed the phenotypes of premature leaf senescence, reduced plant height and decreased yield-associated traits including panicle length, seed setting rate, and 1000-grain weight. Biochemical analysis revealed the accumulation of reactive oxygen species in dls-1 leading to increased apoptosis rates, stomata length extension, higher water loss, and a decline in leaf silicification. Transcriptomic data showed that pathogen resistance-related genes were down-regulated in dls-1, causing increased sensitivity to bacterial-induced blight. Genetic analysis indicated that the mutant trait of dls-1 was controlled by a single recessive nuclear gene, and the gene was fine-mapped to a 159 kb region on rice chromosome 1 using map-based cloning strategy. A total of 23 open reading frames were found in the interval, and no similar phenotypic genes have been reported. However, all candidate coding genes and promoter regions were sequenced, and no mutation sites were found. RNA-seq analysis and qRT-PCR showed that the candidate gene LOC_Os01g71670, encodes a rice endo-1,3-β-glucanase, showed significantly different expression levels in dls-1 compared to the wild-type. LOC_Os01g71670 is highly homologous with GII in barley, and Gns4 and glu1 in rice, which participates in the hormone response pathway affecting plant growth and development, and also involve in the regulation of PR2 expression. Taken together with the phenotypes of dls-1, we conclude that LOC_Os01g71670 may be the candidate gene, causing the premature senescence of the leaf tip and loss of pathogen resistance.

水稻叶倾角是指叶片与茎秆之间的夹角,叶倾角影响叶片光合作用速率,与株型和产量密切相关,如直立叶片就是水稻理想株型形态因素之一.叶倾角的大小受到多种植物激素的调控,是油菜素内酯、生长素、赤霉素、茉莉酸等多种激素相互作用的结果,另外,其他因素如根系分布、叶片大小、生长环境等也会对水稻叶倾角大小产生一定的影响.本文根据水稻叶倾角的研究进展,着重从叶枕的发育、激素水平及其他因素等方面,对水稻叶倾角的分子机制及其在育种中的应用进行阐述与总结,以期为水稻株型的分子设计育种提供参考,为进一步提高水稻的产量奠定理论基础.

The duration of the rice growth phase has always been an important target trait. The identification of mutations in rice that alter these processes and result in a shorter growth phase could have potential benefits for crop production. In this study, we isolated an early aging rice mutant, pe-1, with light green leaves, using γ-mutated indica rice cultivar and subsequent screening methods, which is known as the phytochrome synthesis factor Se5 that controls rice flowering. The pe-1 plant is accompanied by a decreased chlorophyll content, an enhanced photosynthesis, and a decreased pollen fertility. PE-1, a close homologue of HY1, is localized in the chloroplast. Expression pattern analysis indicated that PE-1 was mainly expressed in roots, stems, leaves, leaf sheaths, and young panicles. The knockout of PE-1 using the CRISPR/Cas9 system decreased the chlorophyll content and downregulated the expression of PE-1-related genes. Furthermore, the chloroplasts of pe-1 were filled with many large-sized starch grains, and the number of osmiophilic granules (a chloroplast lipid reservoir) was significantly decreased. Altogether, our findings suggest that PE-1 functions as a master regulator to mediate in chlorophyll biosynthesis and photosynthetic pathways.