Spikelet is a typical inflorescence structure of gramineous plants. The spikelet of rice consists of a top floret, a pair of rudimentary glumes and a pair of sterile lemmas. The floret includes a lemma, a palea, two lodicules, six stamens, and one pistil. The rudimentary glumes are generally regarded as severely reduced bract organs, but the origin of sterile lemmas has been widely debated. Recent studies suggested that the sterile lemmas are the vestigial lemmas of two lateral florets. In the research, the sterile lemma of nsg2 transformed into lemma-like organ provides evidence to support the “three-florets spikelet” hypothesis, which indicate that it is possible to cultivated a “three-florets spikelet” rice. If succeed, the number of grains per panicle would be dramatically increased and affect rice yield. (See Li et al., pp. 125–134)

Photographed by Yun-Feng Li (Southwest University) in Beibei, Chongqing, China, in summer and autum, 2016 (Hitachi SU3500, NIKON SMZ1500, Nikon E600).

Autophagy is crucial for post meiotic anther development in rice; it is required for programmed cell death-mediated degradation of the tapetum and pollen maturation. In this issue, Hanamata et al. (pp. 99–105 and the Supplementary Movie S1) introduces an in vivo imaging technique to analyze the dynamics of autophagy in rice tapetum by expressing GFPATG8, a marker for autophagosomes under the control of tapetum-specific promoters.The cover shows 3-dimensional visualization of autophagosomes/autophagy-related structures in rice tapetum at stage 10 during pollen maturation.This monitoring system offers a powerful tool to analyze the regulation of autophagy in rice tapetum.

Photographed by Shigeru Hanamata and Jumpei Sawada using the LSM5 EXCITER confocal fluorescence microscope (Carl Zeiss, Germany) at Tokyo University of Science. 3D-image processing was carried out using the 3D viewer of ImageJ software.

In this issue, Kinoshita et al (Pages 7 to 11) introduces a simplified technique to extract fluorescence signals in freely moving plant leaves. The cover shows fluorescent signals emitted from yellow fluorescent protein and autofluorescence from chlorophyll during a time lapse experiment. This protocol enables seamless image capturing to quantify fluorescent signals using standard microscope software. Photo and design by Natsuko Kinoshita and Aki Sugita, University of Tsukuba, using Leica LasX.

Photograph and design by Natsuko Kinoshita and Aki Sugita, University of Tsukuba, using DFC7000T color CCD camera and LasX (both from Leica Microsystems).

Plastidial isoprenoid defective cla1 mutants grown in soil show albino and a seedling lethal phenotype. However, when the seedlings were grown in a large agripot with MS agar supplemented with sucrose, only some that grew to the flower stage with albino phenotype were obtained. In cla1-1 mutant, the elaioplast, which is the tapetum cell specific organelle derived from plastid, showed normal phenotype (upper-left photograph), though the chloroplast in cla1-1 has been reported to be the abnormal phenotype previously. The pollen coat derived from tapetum cell also showed normal phenotype in cla1-1 (upper-right photograph). In this issue, Kobayashi et al. report that the plastidial isoprenoid biosynthesis pathway is not critical for the pollen coat formation (pp. 381–385).

Photographed by Rumi Aoyama using the digital camera and the JEM-1200 EX transmission electron microscope (Jeol, Tokyo, Japan) at Japan Woman’s University (Tokyo).

The precursors of triterpene hydrocarbons are synthesized in 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. The light-dependent enzyme 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) is considered to function as a key-regulatory enzyme in this pathway. In this issue, a docking model analysis suggesting the possible association of HDR with a photosynthetic ferredoxin in this organism is discussed (pp. 297–301).
The cover picture presents an image of algal colonies stained with BODIPY493/503 and DAPI. Hydrocarbon oil (stained in green) is observed around cells (red autofluorescence) including nucleus and organelle nucleoids (stained in blue).

This picture was taken by Hidenobu Uchida using Olympus fluorescence microscope BX51, which was equipped with ×20 objective lens, according to a previous report (Kuroiwa et al. 2012, Cytologia 77: 289–299). Photographing was technically assisted by Haruko Kuroiwa from Japan Women’s University.

AgarTrap (agar-utilized transformation with pouring solutions) is an easy and efficient Agrobacterium-mediated transformation technique for liverwort Marchantia polymorpha. It is a simplified protocol that can be completed solely on a single solid medium by pouring appropriate solutions. Three main procedures of AgarTrap includes: (1) planting plant tissue for pre-culture, (2) pouring transformation buffer for co-culture with Agrobacterium tumefaciens, (3) pouring selection buffer for selection of transformants. To date, we developed AgarTrap methods by using three tissue types of M. polymorpha namely, sporelings, gemmalings, and mature thallus pieces. Gemmaling is the most effective among all the tested tissue types as its transformation efficiency of the BC3-38 strain is nearly 100%. Our review article includes the protocols of the AgarTrap methods (pp. 93-99).
The cover picture presents a BC3-38 gemmaling transformed by AgarTrap with A. tumefaciens harbouring a binary vector, pMpGWB103-Citrine, that encodes yellow fluorescent protein (Citrine) and hygromycin B phosphotransferase. The AgarTrap was performed by 2 days pre-culture, and 2 days co-culture with A. tumefaciens and sealed by Parafilm under darkness. This picture was taken at 3 days after pouring selection buffer. Red (chlorophyll) and yellow-green (Citrine fluorescence) indicate non-transformed cells and transformed cells, respectively.

This picture is taken by Shoko Tsuboyama using MZ16F stereo fluorescence microscope (Leica Microsystems) and DP73 digital camera (Olympus) at Utsunomiya University (Tochigi, Japan).

Plants synthesize the red/purple pigment anthocyanin upon environmental stimuli such as excess light exposure. An intact leaf of Arabidopsis thaliana exhibits green color, whereas a detached leaf after incubation on water under light illumination for four days accumulates anthocyanin (left). In this issue, Koyama and Sato document that the leaf of the double mutant of class II ETHYLENE RESPONSE FACTOR (ERF) genes decreased the rate and extent of the production of anthocyanin after the incubation under light illumination (right). This mutant also decreased the production of anthocyanin in the strong light condition and, thus, the authors propose the roles of these class II ERFs in the photoinhibition-mediated anthocyanin biosynthesis.

Photographed by Tomotsugu Koyama at Suntory Foundation for Life Sciences in Kyoto, Japan (PowerShot A2300 digital camera, Canon).

For a plant disease to occur, pathogen, plant and environmental conditions must interact. The susceptibility of host plant may change both with developmental stage and time of day. Rice blast caused by Pyricularia oryzae (syn. Magnaporthe oryzae) is a devastating disease of rice. The mechanisms of resistance to P. oryzae have been extensively studied, and the rice-P. oryzae pathosystem has become a model system in plant-microbe interaction studies. However, the mechanisms of resistance to P. oryzae in nonhost remain poorly understood. Yamauchi et al. have used the Arabidopsis-P. oryzae pathosystem to study nonhost resistance (NHR). In this issue, authors (pp. 207–210) reported that NHR to P. oryzae varies with time of inoculation under diurnal conditions in old leaves and old leaves become more susceptible to P. oryzae penetration after inoculation at dusk in pen2-1 plants (lower). These results suggested that leaf age and time of inoculation are involved in NHR to P. oryzae in Arabidopsis.

Photographed by Yuri Yamauchi (Fukui Prefectural University, FPU) in FPU, Japan, 2017 (AxioCam MRc, ZEISS).

GATA4 is a transcription factor that belongs to the GATA family. In this issue Shin et al., reports that the expression of the chimeric repressor for GATA4 (35S:GATA4-SRDX) results in tolerance to nitrogen deficiency in Arabidopsis (pp. 151–158). Roots, which are directly exposed to various environmental conditions in the soil, are important organs that determine plant nutritional balance. Morphological changes in roots can adapt to nutritional availability and increase nutrition uptake efficiency. In particular, an increase in root hair density increases the root surface area and increases the absorption of nutrients and water from the soil. 35S:GATA4-SRDX plants change in root structure and suppress root growth and increase root hair density both under nitrogen sufficient (left upper) and deficient conditions (left lower).

Photograph Location: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan Photograph Equipment: A fluorescence stereomicroscope (MZ16FA, Leica) equipped with a CCD camera (DFC300FX, Leica)

Powdery mildew is a popular disease caused by ascomycete fungi. As this disease affects near 10,000 plants and causes significant economic loss every year, a development of new tools to combat this disease is of great interest. In this issue, Inada et al. reported that overexpression of the active form of ARA6, a plant-specific member of RAB5 GTPase, impairs powdery mildew proliferation. Powdery mildew fungi form specialized infection hyphae called the haustorium in the apoplast of host epidermal cells. The haustorium is surrounded by the host-derived membrane called the extrahaustorial membrane. Previously, authors reported that host RAB5 GTPases, both plant-specific ARA6 and conventional ARA7, localized to the extrahaustorial membrane. In this issue, authors found that an overexpression of active form of ARA6, but not that of ARA7, suppresses powdery mildew proliferation. These results indicate a specific role of ARA6 in the plant-powdery mildew interaction. In addition, manipulation of the ARA6 activity was suggested to be a possible methodology to overcome this disease.

Photographed by Noriko Inada (Nara Institute of Science and Technology, NAIST) in NAIST, Japan, 2012 (Panasonic DMC-FX30).

Japanese pepper (Zanthoxylum piperitum), “Sansho” in Japanese, is a deciduous shrub, belonging to the family Rutaceae. In Japan, fresh young leaves are sometimes used as garnish and in sauces after mixed with miso (soybean paste) for some Japanese dishes because of its characteristic aroma. The fruits exhibit pungent taste together with strong aroma, and are also utilized as one of the seven components of Japanese blended spices called “Shichimi”. Oil secretory cavities are found at all sinuses of leaves, as shown in this photograph, as well as the surface of fruits and contain high amount of volatile compounds. The grade of Japanese pepper is sometimes determined according to the flavor of high quality of volatile mono- and sesqui-terpenes. In this issue, Fujita et al. have reported the formation of volatile terpenes and their biosynthetic enzymes in secretory cavities of Japanese pepper.

Photographed by Mitsuhiro Aida (Nara Institute of Science and Technology, NAIST) in NAIST, Japan, 2015 (ECLIPSE Ni-U microscope equipped with DIC optics, Nikon; VB-7010 cooled CCD camera, Keyence).

Apple cultivars with homeotic changes, petals to sepals and stamens to carpels, set parthenocarpic fruits. The floral organ changes were caused by destruction of apple MdPISTILLATA (MdPI) gene, which is an orthologue of Arabidopsis class B gene PISTILLATA. The MdPI gene is able to recover the Arabidopsis pi mutant phenotype. The expression of MdPI localized at petals and stamens of apple flowers. The connection between the parthenocarpy and class B mutation was obscure, then transgenic apples suppressed MdPI function was produced. The cover picture represents a flower of antisense MdPI transgenic apple, which was analyzed about parthenocarpy in this article (pp. 395–401).

Location: Division of apple Research (Morioka), NIFTS, NARO Camera: Olympus SP-350