Grain shape, including grain length, width, thickness, and weight and aspect ratio, is an important factor for rice production. Therefore, genetic analysis of grain shape is of great significance for increasing rice yield. Grain shape is a quantitative trait controlled by multiple genes. As compared with research into traits controlled by a single gene, that for genes controlled by multiple genes, such as grain shape, is complicated. We summarize recent progress in genetic research into grain shape in rice and future prospects.

Drought stress seriously affects crop yield and quality and constrains global agricultural production. E3 ubiquitin ligases are a large family with wide variety and are involved in many important biological processes in plants. In this paper, we summarize the drought stress regulation mechanism, plant ubiquitin ligase E3, and describe the ubiquitin ligase E3 response to plant drought stress and its mechanisms.

Rice is one of the most important cereal crops. The introduction of dwarf rice has led to the first “green revolution”. However, the genetic uniformity of dwarf gene in rice breeding is a concern, which severely affects the continuous increase in rice harvest. In the present study, we mutated the indica cultivar M804 by using ⁶⁰Coγ-Ray and obtained a genetically stable rice dwarf mutant (MU101), which was crossed with a japonica cultivar Taigeng 16 to investigate the genetic mode and map the gene. Genetic analysis revealed the phenotype of the dwarf mutant, which we designated tentatively as ds1, controlled by a pair of recessive genes. Polymorphic analysis of simple sequence repeat markers demonstrated the DS1 gene located on chromosome 5. With a larger mapping population and more Indel markers, we further mapped the DS1 gene between 2 Indel markers with a physical region of about 384 kb. These results provide a basis for molecular cloning and production application of DS1.

A rice (Oryza sativa) mutant with short root hairs (Ossrh2) was isolated from a T-DNA insertion mutant library of rice in the Zhonghua11 background. Except for root hairs, Ossrh2 did not differ from the wild type. The number and length of root hairs of Ossrh2 were only 61.4% and 22.8%, respectively, that of the wild type, and hairs were thicker. The root hairs of Ossrh2 were also morphologically abnormal and showed distortion, swelling and branching. Genetic analysis revealed that the mutant phenotype was controlled by a single recessive nuclear gene. PCR analysis of T₂ and F₂ mutants showed that the phenotype was not caused by T-DNA insertion. To map the OsSRH2 gene, we generated an F₂ population by crossing the mutant Ossrh2 with the Kasalath wild type. OsSRH2 was first mapped between the microsatellite markers RM6370 and RM474 on the short arm of chromosome 10 with genetic distance of 1.1 and 3.0 cM, respectively. Then, 3 new polymorphic sequence-tagged site markers were developed in the region. OsSRH2 was finally mapped between markers S1227 and S1531 with a physical distance of 304 kb, which would help in its cloning.

Plant height is a typical quantitative trait and can easily be influenced by genetic background and environmental factors. Single-segment-substitution lines (SSSLs) can effectively reduce the interference of the genetic background. We developed a set of genome-wide SSSLs carrying Nipponbare introgression segments in a background of Guangluai 4. Quantitative trail loci (QTL) analysis involved one-way ANOVA and Dunnett’s test for comparing SSSLs and the recurrent parent Guangluai 4 (P≤0.001). We detected 24 QTLs for plant height distributed on 11 rice chromosomes, except chromosome 10, of which 3 had a negative effect and the others a positive effect. The additive effect of these QTLs ranged from –6.5 to 31.74, with additive effect percentages –8.81% to 41.96%. These results provide useful information for exploring and using new dwarf or semi-dwarf resources.

We used quantitative real-time RT-PCR to investigate the tissue expression patterns of cytokinin bindingprotein PdCYTOB, which is related to the wood properties of Populus deltoides. PdCYTOB was expressed predominantly in immature xylem, immature phloem and the phloem zone of the stem of P. deltoides. Southern blot and RT-PCR were used to detect antisense PdCYTOB-transgenic Populus davidiana × P. bolleana plants. The antisense PdCYTOB gene was integrated into the genome of the poplar and expressed. Phenotype, anatomical studies and microfibrillar angle analysis revealed the plant height of transgenic poplar higher than that of untransformed lines, as well as xylem and the phloem zone of plants with antisense PdCYTOB wider than those of untransformed lines. In addition, the microfibrillar angle of transgenic plants was decreased in the test field. Thus, pulping and papermaking properties might be improved in antisense-PdCYTOB transformed lines. Our study sheds light on the molecular mechanism of PdCYTOB in wood formation in P. deltoides.

Gentiana rigescens is a traditional medicinal plant in China. We compared the contents of gentiopicroside, swertiamarin and sweroside in root, stem and leaf of G. rigescens in different growing seasons. The contents of the 3 active compounds in root of G. rigescens differed significantly from those in stem and leaf in different growing seasons. Gentiopicroside accumulated mainly in roots, whereas swertiamarin and sweroside accumulated in stem and leaf. Correlation analysis revealed that gentiopicroside content was affected by climate factors. Mean monthly temperature was negatively correlated with gentiopicroside content in stem and leaf (R=–0.57, P<0.01). Mean monthly rainfall was negatively correlated with gentiopicroside content in root, stem and leaf (R=–0.48, P<0.05 or R=–0.74, P<0.01). Sweroside content was positively correlated with swertiamarin content in root (R=0.62, P<0.01) and in stem and leaf (R=0.38, P<0.05). Therefore, gentiopicroside content in G. rigescens was affected by rainfall and temperature. The 3 active compounds in different parts of G. rigescens showed significant relationships. The most appropriate harvest time for G. rigescens is from September to November.

Plants have several strategies to adapt to different environments. Lonicera confusa is a typical species in karst calcium (Ca)-rich environments; to adapt to the Ca-rich environment, it excretes calcium by leaf stoma. In the present study, the calcium-excretion process of L. confusa was investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX). We compared the different types of Ca crystals by self-assembly of secreted products with point and line-by-line scanning. Ca crystals are formed after Ca salt is excreted by stoma of L. confusa in the karst Ca-rich environment. Ca salt could self-assemble 3 types of crystals, prisms, ball and crystal sand. Crystals have a large amount of Ca, and sulfur (S) and other elements, which are present in certain ratio. The crystal nucleus protein is rich in S element, which is beneficial for biomineralization of Ca-related crystal and others. EDX could be effectively used for microprobe analysis of plant leaves and identifying plant-excreted products.

Pistacia chinensis is an important woody oil plant. We observed oil bodies in the pericarp, seed coat and cotyledon during fruit development of P. chinensis by optical microscopy and transmission electron microscopy. The oil content in the pericarp began to increase gradually when the fruit turned red. The oil in the seed coat accumulated in the early stage of fruit development. In the embryo, oil bodies first appeared in the globular embryo. Oil bodies appeared in the endoplasmic reticulum in seed coat and embryo. The oil in the pericarp originated from the endoplasmic reticulum, plastid and vacuole. The endoplasmic reticulum showed budded oil bodies. Nile red staining revealed oil bodies accumulated as small, separate units. Protein bodies were in the seed coat and embryo. The protein bodies developed later than oil bodies. A small amount of starch granules were found in the pericarp, seed coat and embryo.

Data for geographic location, climatic conditions, and carbon isotope values of 325 C₃ herbaceous plant samples were obtained at 47 sampling sites through systematic investigation of a wide variety of natural habitats and δ¹³C data from the published literature of C₃ herb species in northern China. We calculated the humidity indices for different climatic areas in northern China and compared the spatial characteristics of δ¹³C composition and carbon isotope values for C₃ herbaceous plants with climatic environment factors (especially humidity index). The δ¹³C values for C₃ plant species in northern China as a whole ranged from –29.9‰ to –25.4‰, with a mean of –27.3‰. From the sub-humid to semi-arid and arid areas, the mean δ¹³C values of C₃ plants increased with decreasing mean annual precipitation. The variation in δ¹³C values differed among the 3 climatic areas in northern China, namely –29.9‰ to –26.7‰ (sub-humid area), –28.4‰ to –25.6‰ (semi-arid area) and –28.0‰ to –25.4‰ (arid area). Single-element regression analysis revealed a difference in relationship between δ¹³C values of C₃ herbaceous plants and humidity index among climatic areas. The δ¹³C values of sampling sites in semi-arid area, semi-humid area and the whole northern China all were negatively related to humidity index (P<0.05), and the mean δ¹³C values of plants decreased with increasing humidity index. In contrast, δ¹³C values in the northern arid area was positively related with humidity index (P<0.05). A 0.1 increase in humidity index in the arid area would produce a 1.3‰ increase in δ¹³C, and annual mean temperature has an important role in differences in humidity index and isotope fractionation among sampling points in the arid area.

Use of matrix attachment regions (MARs) is an important method to improve gene transformation and transgenic expression in plants. We constructed the TM2 MAR from tobacco at the flanking sides of the expression cassettes of reporter gene GUSA and selective gene NPTII in a plant expression vector, pBI121. The recombinant constructs were introduced into tomato plants by Agrobacterium-mediated cotyledon transformation. The transgenes were increasingly transformed and expressed in the transformants. Comparison of the effect of TM2 on different lengths of CaMV 35S promoter showed that the transcription enhancement of TM2 depended on the existence of promoter and showed partial functional redundancy. The effect of TM2 on transcription regulated by heat-inducible promoter indicated that the MAR did not change the regulation pattern but improved the expression level of the heat-inducible promoter. These characteristics of TM2 MAR fulfill the regulation requirements for transgenic expression and can be widely used in diverse plant biotechnology.

Photosynthesis, the most important chemical reaction on earth and one of life's top 10 greatest inventions, plays a key role in biological evolution, biosphere formation and operation, human appearance and sustainable development of economy and society. According to recent international and national conferences on photosynthesis, current research covers wide fields and deep levels with more advanced techniques. Research emphases are on reaction mechanism, structure and function of photosynthesis; mechanisms of assembly, operation and regulation of photosynthetic apparatus; and photosynthesis and sustainable development of human society.