Changes in leaf hydraulic conductance correlate with leaf vein embolism in<Emphasis Type="Italic"> Cercis siliquastrum</Emphasis> L.

The impact of xylem cavitation and embolism on leaf (K _leaf) and stem (K _stem) hydraulic conductance was measured in current-year shoots of Cercis siliquastrum L. (Judas tree) using the vacuum chamber technique. K _stem decreased at leaf water potentials (Ψ_L) lower than ?1.0 MPa, while K _leaf started to decrease only at Ψ_L L K _leaf changes. Field measurements of leaf conductance to water vapour (g _L) and Ψ_L showed that stomata closed when Ψ_L decreased below the Ψ_L threshold inducing loss of hydraulic conductance in the leaf. The partitioning of hydraulic resistances within shoots and leaves was measured using the high-pressure flow meter method. The ratio of leaf to shoot hydraulic resistance was about 0.8, suggesting that stem cavitation had a limited impact on whole shoot hydraulic conductance. We suggest that stomatal aperture may be regulated by the cavitation-induced reduction of hydraulic conductance of the soil-to-leaf water pathway which, in turn, strongly depends on the hydraulic architecture of the plant and, in particular, on leaf hydraulics.     

Stomatal regulation in Douglas fir following a fungal-mediated chronic reduction in leaf area

Pathogens can cause chronic premature needle abscission in coniferous species. To assess the potential impacts on tree productivity, stomatal regulation was investigated in Douglas fir with chronic stomatal occlusion and defoliation from varying levels of the Swiss needle cast (SNC) fungus, Phaeocryptopus gaeumannii. Levels of SNC disease and subsequent defoliation were manipulated by choosing six sites with varying levels of disease and by foliar applications of fungicides on six trees per site. Diurnal measurements of leaf water potential (Ψ_leaf), stomatal conductance (g _s) and vapor pressure deficit (D) were made on six fungicide treated and six control trees per site. In addition, leaf specific hydraulic conductance was calculated on a single branch (K _{L_B}) from three trees per treatment per site. Stomatal conductance at D=1 kPa (g _sref) was negatively correlated with fungal colonization (number of fruiting bodies present in needle stomata) and positively correlated with K _{L_B}. Despite reduced needle retention in diseased trees, K _L declined due to a reduction in sapwood area and permeability (i.e., increasing presence of latewood in functional sapwood). In general, stomatal sensitivity to D for all foliage was consistent with stomatal regulation based on a simple hydraulic model [g _s=K _L(Ψ_soil?Ψ_leaf)/ D], which assumes strict stomatal regulation of Ψ_leaf. However, when fungal presence reduced maximum g _s below the potential maximum supported by hydraulic architecture, stomatal sensitivity was lower than expected based on the theoretical relationship: dg _s/dlnD=0.6·g _sref. The results indicate that losses in productivity associated with physical blockage of stomata and defoliation are compounded by additional losses in K _L and a reduction in g _s in remaining functional stomata.     

Impact of groundwater depth on leaf hydraulic properties and drought vulnerability of <Emphasis Type="Italic">Populus euphratica</Emphasis> in the Northwest of China

Key message

Different groundwater conditions affect leaf hydraulic conductance and leaf pressure–volume parameters in Populus euphratica at the extremely arid zone in the northwest of China.

Abstract

Efficient water transport inside leaves constitutes a major determinant of plant function, especially in drought-stressed plants. The previous researches have reported the correlation between leaf hydraulic properties and water availability. In this study, we tested the hypothesis that water relation parameters of Populus euphratica in an extremely arid zone of China are sensitive and acclimated to groundwater depth. We measured leaf hydraulic conductance (K _leaf) using rehydration kinetics methods (RKM), pressure–volume (P–V) curves, and leaf vulnerability curves of P. euphratica growing at four groundwater depth gradients. We also assessed the hydraulic safety margins across groundwater depth gradients. We found that K _leaf–max shows an increasing trend as the groundwater depth increases, while osmotic potential at full turgor (π_ft) and turgor loss point (Ψ_tlp) exhibits a decreasing trend, suggesting that increased tolerance to drought is formed as the groundwater depth increases. Furthermore, safety margins showed positive and negative variations under different groundwater depths, indicating that P. euphratica has formed special drought survival strategies, which can be summarized as a “conservative” strategy in favorable water conditions or a “risk” strategy in severe drought stress.

     

Genetic dissection and validation of candidate genes for flag leaf size in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Key message

Two major loci with functional candidate genes were identified and validated affecting flag leaf size, which offer desirable genes to improve leaf architecture and photosynthetic capacity in rice.

Abstract

Leaf size is a major determinant of plant architecture and yield potential in crops. However, the genetic and molecular mechanisms regulating leaf size remain largely elusive. In this study, quantitative trait loci (QTLs) for flag leaf length and flag leaf width in rice were detected with high-density single nucleotide polymorphism genotyping of a chromosomal segment substitution line (CSSL) population, in which each line carries one or a few chromosomal segments from the japonica cultivar Nipponbare in a common background of the indica variety Zhenshan 97. In total, 14 QTLs for flag leaf length and nine QTLs for flag leaf width were identified in the CSSL population. Among them, qFW4-2 for flag leaf width was mapped to a 37-kb interval, with the most likely candidate gene being the previously characterized NAL1. Another major QTL for both flag leaf width and length was delimited by substitution mapping to a small region of 13.5 kb that contains a single gene, Ghd7.1. Mutants of Ghd7.1 generated using CRISPR/CAS9 approach showed reduced leaf size. Allelic variation analyses also validated Ghd7.1 as a functional candidate gene for leaf size, photosynthetic capacity and other yield-related traits. These results provide useful genetic information for the improvement of leaf size and yield in rice breeding programs.

     

Desiccation tolerance in <Emphasis Type="Italic">Pleurostima purpurea</Emphasis> (Velloziaceae)

Previous works suggested that Pleurostima purpurea (Velloziaceae—Barbacenioideae) shows a remarkable capacity to endure desiccation of its vegetative tissues. P. purpurea occurs in monocotyledons mats on soil islands in the Pão de Açucar (Sugar Loaf) one of the most recognizable rock outcrops of the world, in Rio de Janeiro, southeastern Brazil. Mats of P. purpurea occur in cliffs by the sea some meters above the tidal zone. Although living in rock outcrops almost devoid of any soil cover, P. purpurea seems to occur preferably on less exposed rock faces and slightly shady sites. Usually, less extreme adaptations to drought would be expected in plants with the habitat preference of P. purpurea. Relying on this observation, we argue if a combination of different strategies of dealing with low water availability can be found in P. purpurea as on other desiccation tolerant angiosperms. This study aims to examine the occurrence of desiccation tolerant behavior in P. purpurea together with the expression of drought avoidance mechanisms during dehydration progression. For this, it was analyzed the gas exchanges, leaf pigments and relative leaf water content during desiccation and rehydration of cultivated mature individuals. P. purpurea behaved like typical drought avoiders under moderated drought condition with stomatal closure occurring around a relative leaf water content up to 90%. During this process, it was observed a delay in the leaf relative water content (RWC _leaf) decrease comparing to the plant-soil relative water content (RWC _plant-soil). As soil dehydration worsened, gas exchanges restrictions progressed until a lack of activity which characterizes anabiosis. The loss of chlorophyll occurs before the end of total dehydration, characterizing the presence of poikilochlorophylly. The chlorophyll degradation follows the RWC _leaf decrease, which achieved the minimum average value of 17% without incurring in leaf abscission. The chlorophyll re-synthesis seems to start well after the full rehydration of the leaf. During all of this process, carotenoid content remained stable. These results are coherent with a combination of drought avoidance and desiccation tolerance in P. purpurea which seems to be coherent with the amplitude of water availability in the rock outcrop habitat where it occurs, suggesting that the periods of water availability are sufficiently long for the success of the costly desiccation tolerant behavior but too short to make a typical drought avoider species win the competition for exploring the rock outcrop substrate where P. purpurea occurs.     

<Emphasis Type="Italic">Lsi1</Emphasis>-regulated Cd uptake and phytohormones accumulation in rice seedlings in presence of Si

Silicon (Si) is known for its role in regulating the response of plants to imposed abiotic stresses. Since the stresses generally hinder production of a crop, such as rice, the exploration of the biochemistry and plant physiology relating to the function is of interest. Indeed, recently, there were reports on the function of Lsi1 in regulating the tolerance of rice to cadmium (Cd) stress. This study compared the kinetics of the Cd uptakes in Lemont wild type rice and its transgenic lines exposed to Cd with or without exogenous Si supply. At the same time, changes on the endogenous phytohormones and growth of the rice seedlings were monitored. Genetically, Lsi1 overexpression was found to downregulate K_m and V_max of Cd uptake kinetics in the plants under Cd stress, especially in the presence of Si. On the other hand, Lsi1 RNAi upregulated K_m and V_max regardless whether Si was present or not. It implied that Lsi1 could be capable of regulating Si as well as Cd transports. Under Cd stress, addition of Si reduced the Cd uptake of the rice lines in the order of Lsi1-overexpression line?>?Lemont?>?Lsi1-RNAi line. In addition, it also affected the chlorophyll biosynthesis and dry mass accumulation of the rice plants under Cd stress. Analyses on phytohormones including IAA, GA₃, JA, SA and ABA, as well as physiological functions, of the seedlings further verified the active involvement of Lsi1 in the complex defense system of the plants against Cd stress.     

Mutations in <Emphasis Type="Italic">CsPID</Emphasis> encoding a Ser/Thr protein kinase are responsible for round leaf shape in cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.)

Key message

Two round-leaf mutants, rl-1 and rl-2, were identified from EMS-induced mutagenesis. High throughput sequencing and map-based cloning suggested CsPID encoding a Ser/Thr protein kinase as the most possible candidate for rl-1. Rl-2 was allelic to Rl-1.

Abstract

Leaf shape is an important plant architecture trait that is affected by plant hormones, especially auxin. In Arabidopsis, PINOID (PID), a regulator for the auxin polar transporter PIN (PIN-FORMED) affects leaf shape formation, but this function of PID in crop plants has not been well studied. From an EMS mutagenesis population, we identified two round-leaf (rl) mutants, C356 and C949. Segregation analysis suggested that both mutations were controlled by single recessive genes, rl-1 and rl-2, respectively. With map-based cloning, we show that CsPID as the candidate gene of rl-1; a non-synonymous SNP in the second exon of CsPID resulted in an amino acid substitution and the round leaf phenotype. As compared in the wild type plant, CsPID had significantly lower expression in the root, leaf and female flowers in C356, which may result in the less developed roots, round leaves and abnormal female flowers, respectively in the rl-1 mutant. Among the three copies of PID genes, CsPID, CsPID2 and CSPID2L (CsPID2-like) in the cucumber genome, CsPID was the only one with significantly differential expression in adult leaves between WT and C356 suggesting CsPID plays a main role in leaf shape formation. The rl-2 mutation in C949 was also cloned, which was due to another SNP in a nearby location of rl-1 in the same CsPID gene. The two round leaf mutants and the work presented herein provide a good foundation for understanding the molecular mechanisms of CsPID in cucumber leaf development.

     

Development of leaffolder resistant transgenic rice expressing <Emphasis Type="Italic">cry2AX1</Emphasis> gene driven by green tissue-specific <Emphasis Type="Italic">rbcS</Emphasis> promoter

The insecticidal cry genes of Bacillus thuringiensis (Bt) have been successfully used for development of insect resistant transgenic rice plants. In this study, a novel cry2AX1 gene consisting a sequence of cry2Aa and cry2Ac gene driven by rice rbcS promoter was introduced into a rice cultivar, ASD16. Among 27 putative rice transformants, 20 plants were found to be positive for cry2AX1 gene. The expression of Cry2AX1 protein in transgenic rice plants ranged from 5.95 to 122.40 ng/g of fresh leaf tissue. Stable integration of the transgene was confirmed in putative transformants of rice by Southern blot hybridization analysis. Insect bioassay on T₀ transgenic rice plants against rice leaffolder (Cnaphalocrosis medinalis) recorded larval mortality up to 83.33 %. Stable inheritance and expression of cry2AX1 gene in T₁ progenies was demonstrated using Southern and ELISA. The detached leaf bit bioassay with selected T₁ plants showed 83.33–90.00 % mortality against C. medinalis. The whole plant bioassay for T₁ plants with rice leaffolder showed significant level of resistance even at a lower level of Cry2AX1 expression varying from 131 to 158 ng/g fresh leaf tissue during tillering stage.     

Chemical and hydraulic signals regulate stomatal behavior and photosynthetic activity in maize during progressive drought

The objectives of this study were to investigate stomatal regulation in maize seedlings during progressive soil drying and to determine the impact of stomatal movement on photosynthetic activity. In well-watered and drought-stressed plants, leaf water potential (Ψ _leaf), relative water content (RWC), stomatal conductance (g _s), photosynthesis, chlorophyll fluorescence, leaf instantaneous water use efficiency (iWUE_leaf), and abscisic acid (ABA) and zeatin-riboside (ZR) accumulation were measured. Results showed that g _s decreased significantly with progressive drought and stomatal limitations were responsible for inhibiting photosynthesis in the initial stages of short-term drought. However, after 5 days of withholding water, non-stomatal limitations, such as damage to the PSII reaction center, became the main limiting factor. Stomatal behavior was correlated with changes in both hydraulic and chemical signals; however, changes in ABA and ZR occurred prior to any change in leaf water status. ABA in leaf and root tissue increased progressively during soil drying, and further analysis found that leaf ABA was negatively correlated with g _s (R ² = 0.907, p < 0.05). In contrast, leaf and root ZR decreased gradually. ZR in leaf tissue was positively correlated with g _s (R ² = 0.859, p < 0.05). These results indicate that ABA could induce stomatal closure, and ZR works antagonistically against ABA in stomatal behavior. In addition, the ABA/ZR ratio also had a strong correlation with g _s, suggesting that the combined chemical signal (the interaction between ABA and cytokinin) plays a role in coordinating stomatal behavior. In addition, Ψ _leaf and RWC decreased significantly after only 3 days of drought stress, also affecting stomatal behavior.     

<Emphasis Type="Italic">OsNHX2</Emphasis>, an Na<Superscript>+</Superscript>/H<Superscript>+</Superscript> antiporter gene,can enhance salt tolerance in rice plants through more effective accumulation of toxic Na<Superscript>+</Superscript> in leaf mesophyll and bundle sheath cells

The Na⁺/H⁺ antiporters play an important role in salt tolerance in plants. However, the functions of OsNHXs in rice except OsNHX1 have not been well studied. Using the gain- and loss-of-function strategies, we studied the potential role of OsNHX2 in salt tolerance in rice. Overexpression of OsNHX2 (OsNHX2-OE) in rice showed the significant tolerance to salt stress than wild-type plants and OsNHX2 knockdown transgenic plants (OsNHX2-KD). Under salt treatments of 300-mM NaCl for 5 days, the plant fresh weights, relative water percentages, shoot heights, Na⁺ contents, K⁺ contents, and K⁺/Na⁺ ratios in leaves of OsNHX2-OE transgenic plants were higher than those in wild-type plants, while no differences were detected in roots. K⁺/Na⁺ ratios in rice leaf mesophyll cells and bundle sheath cells were higher in OsNHX2-OE transgenic plants than in wild-type plants and OsNHX2-KD transgenic plants. Our data indicate that OsNHX2 plays an important role in salt stress based on leaf mesophyll cells and bundle sheath cells and can be served in genetically engineering crop plants with enhanced salt tolerance.     

Physiological characterization and allelic diversity of selected drought tolerant traditional rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) landraces of Koraput,India

Water-deficit stress tolerance in rice is important for maintaining stable yield, especially under rain-fed ecosystem. After a thorough drought-tolerance screening of more than 130 rice genotypes from various regions of Koraput in our previous study, six rice landraces were selected for drought tolerance capacity. These six rice landraces were further used for detailed physiological and molecular assessment under control and simulated drought stress conditions. After imposing various levels of drought stress, leaf photosynthetic rate (P_N), photochemical efficiency of photosystem II (Fv/Fm), SPAD chlorophyll index, membrane stability index and relative water content were found comparable with the drought-tolerant check variety (N22). Compared to the drought-susceptible variety IR64, significant positive attributes and varietal differences were observed for all the above physiological parameters in drought-tolerant landraces. Genetic diversity among the studied rice landraces was assessed using 19 previously reported drought tolerance trait linked SSR markers. A total of 50 alleles with an average of 2.6 per locus were detected at the loci of the 19 markers across studied rice genotypes. The Nei’s genetic diversity (He) and the polymorphism information content (PIC) ranged from 0.0 to 0.767 and 0.0 to 0.718, respectively. Seven SSR loci, such as RM324, RM19367, RM72, RM246, RM3549, RM566 and RM515, showed the highest PIC values and are thus, useful in assessing the genetic diversity of studied rice lines for drought tolerance. Based on the result, two rice landraces (Pandkagura and Mugudi) showed the highest similarity index with tolerant check variety. However, three rice landraces (Kalajeera, Machhakanta and Haldichudi) are more diverse and showed highest genetic distance with N22. These landraces can be considered as the potential genetic resources for drought breeding program.     

Genetics and fine mapping of a yellow-green leaf gene (<Emphasis Type="Italic">ygl</Emphasis>-<Emphasis Type="Italic">1</Emphasis>) in cabbage (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">capitata</Emphasis> L.)

Cabbage (Brassica oleracea var. capitata L.) is one of the most popular cultivated vegetables worldwide. Cabbage has rich phenotypic diversity, including plant height, head shape, head color, leaf shape and leaf color. Leaf color plays an important role in cabbage growth and development. At present, there are few reports on fine mapping of leaf color mutants in B. oleracea. In this study, a naturally occurring yellow-green leaf cabbage mutant (YL-1), derived from the self-pollinated progenies of the hybrid ‘Hosom’, was used for inheritance analysis and gene mapping. Segregation populations including F₂ and BC₁ were generated from the cross of two inbred lines, YL-1 and 01–20. Genetic analysis with the F₂ and BC₁ populations demonstrated that the yellow-green leaf color was controlled by a single recessive nuclear gene, ygl-1. Insertion–deletion (InDel) markers, designed based on the parental re-sequencing data, were used for the preliminary mapping with BSA (bulked segregant analysis) method. A genetic map constructed with 15 InDels indicated that ygl-1 was located on chromosome C01. The ygl-1 gene is flanked by InDel markers ID2 and M8, with genetic distances of 0.4 cM and 0.35 cM, respectively. The interval distance between two markers is 167 kb. Thus, it enables us to locate the ygl-1 gene for the first time in B. oleracea. This study lays the foundation for candidate gene prediction and ygl-1gene cloning.     

A review of the genera <Emphasis Type="Italic">Calotelea,Calliscelio</Emphasis>, and <Emphasis Type="Italic">Oxyscelio</Emphasis> (Scelioninae,Scelionidae, Proctotrupoidea) from the Palaearctic fauna

Nine new species of scelionids collected in Japan, Israel, and the Ukraine, Calotelea shimurai Kononova et Fursov, C. japonica Kononova, C. stellae Kononova, Calliscelio recens Kononova, C. floridum Kononova, C. parilis Kononova, C. ordo Kononova, Oxyscelio florum Kononova, and O. perpensum Kononova, are described. A brief morphological characteristics of the mentioned genera and some data on the geographical distribution of these species are given. Calotelea shimurai differs from C. striola Kononova in the sculpture of the metasoma (tergites I–III striate, whereas in C. striola striation present only on tergites I and II), fore-wing venation (stigmal vein of C. shimurai 0.43 times as long as postmarginal vein and 1.75 times as long as marginal one; in C. striola, stigmal vein 0.52 times as long as postmarginal vein and 1.3 times as long as marginal one), and the length of the metasoma (in C. shimurai and C. striola, metasoma 4.0 and 2.3 times as long as wide, respectively). Calotelea shimurai parasitizes in eggs of the dragonflies Aeshna nigroflava Martin, Planaeschna milnei Selys, and Boyeria macachlani (Aeshnidae, Odonata). C. japonica is closely related to C. originalis Kozlov and Kononova, but differs from it in the sculpture of the metasoma (metasomal tergites with longitudinal wrinkles against the bright smooth background; in C. originalis, tergites I and II with longitudinal wrinkles against the alveolate background), in the coloration of fore wing (infuscate in C. japonica and dark, with dark transverse stripes in C. originalis). C. stellae differs from C. artus Kozlov and Kononova in the more flattened mesoscutum (C. artus with protruding mesoscutum) and the sculpture of the metasomal tergites (in C. stellae, only petiolus and tergite II striate, while in C. artus, such striation present on tergites I–IV). C. stellae was reared from eggs of unidentified Orthoptera. C. recens is closely related to C. parilis Kononova. It can be distinguished by the fore-wing venation (C. recens has stigmal vein, which is twice as long as marginal vein and 0.66 times as long as postmarginal one; stigmal vein of C. parilis is 3 times as long as marginal vein and 0.83 times as long as postmarginal one), by the sculpture of the metasoma, and coloration of the coxae (yellow in C. recens and black in C. parilis). C. floridum is similar to C. mediterranea Kieffer, but can be identified by the length of the postmarginal vein, which is 3 times as long as the stigmal vein, whereas C. mediterranea has the postmarginal vein, which is only twice as long as the stigmal one. C. floridum also differs in the sculpture of the metasoma (C. floridum has all the metasomal tergites with longitudinal lines, while C. mediterranea has only metasomal petiolus with the same sculpture and tergites II–IV with alveolate sculpture, tergites V and VI are slightly stippled) and in the coloration of the legs, which are yellow (as coxae), while C. mediterranea has brownish black legs. C. parilis resembles C. recens, but differs from it in the fore-wing venation, sculpture of the metasoma, and coloration of the coxae. C. ordo differs from the closely related C. ruficollis Kozlov et Kononova in the head sculpture, which is finely alveolate in C. ordo and finely granulate in C. ruficollis. Oxyscelio florum is closely related to O. perpensum, but differs from it in the coloration of the body and size of the antennal segments, stigmal and postmarginal veins, and metasomal tergites. O. perpensum is closely related to O. florum. The main distinguishing morphological characters are similar to those in O. florum. O. perpensum was reared from eggs of unidentified Orthoptera.     

Physiological alterations due to field salinity stress in melon (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.)

This study was aimed to assess physiological responses of melon (Cucumis melo L.) cultivars to salinity stress under field conditions. Seventeen melon cultivars including 16 widely distributed native and one exotic (‘Galia’) were subjected to 2-year (2014–2015) field salinity stress. Leaf relative water content (RWC), membrane stability index (MSI), pigments [chlorophyll a, b, total chlorophyll (TChl), carotenoid (Car) and their ratios], malondialdehyde (MDA), H₂O₂ content, proline content (Pro), total soluble sugar content (TSC), salinity tolerance and susceptibility indices as well as yield were evaluated. The results of combined analysis of variance showed significant genotypic variation for all the traits and significant effect of salinity stress on all the traits with the exception of Chla/Chlb and TChl/Car ratios. Overall, field salinity stress caused an increase in leaf MDA, H₂O₂, Chla, Chlb, TChl, Car, Pro and TSC and caused a reduction in leaf MSI and RWC as well as yield. The results of correlation coefficients showed that accumulation of osmolytes (proline and TSC) led to an increase in RWC and a decrease in MDA contents. In addition, the results of multiple regression analysis showed that leaf MDA, TSC, MSI and Chla contents were the most important predictors of yield justifying 72% total variation of yield under saline conditions. These results may highlight a dynamic interplay among biomarkers for lipid peroxidation (MDA), sugar osmolytes (TSC) and photosynthetic pigment (Chla) to maintain cell viability and cell wall integrity under salinity stress conditions in melon.     

Characterization and fine mapping of <Emphasis Type="Italic">osh15</Emphasis>(<Emphasis Type="Italic">t</Emphasis>), a novel dwarf mutant gene in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Plant height is one of the most important agronomic traits of plant architecture, and also affects grain yield in rice. In this study, we obtained a novel dwarf rice mutant of japonica variety Shennong9816, designated Shennong9816d. Compared with wild-type, the Shennong9816d plant height was significantly reduced, and the tiller number significantly increased. Additionally, the mutant yield component, and the number of large and small vascular bundles were significantly decreased compared with wild-type. Genetic analysis indicated that the Shennong9816d dwarf phenotype was controlled by a recessive nuclear gene, while the plant was shown to be sensitive to gibberellic acid. Using a large F₂ population derived from a cross between Shennong9816d and the indica rice variety Habataki, the osh15(t) gene was fine mapped between RM20891 and RM20898, within a physical distance of 73.78 kb. Sequencing analysis showed that Shennong9816d carries a 1 bp mutation and a 30 bp insertion in the OSH15 region. These results suggest that osh15(t) is a novel allelic mutant originally derived from japonica variety Shennong9816, which may be useful for introducing the semi-dwarf phenotype to improve plant architecture in rice breeding practice.