Tiller Buds Research Articles

Fine mapping of the tiller inhibition gene TIN4 contributing to ideal plant architecture in common wheat.

A tiller inhibition gene, TIN4, was mapped to an approximately 311kb genomic interval on chromosome arm 2DL of wheat. The tiller is one of the key components of plant morphological architecture and a central agronomic trait affecting spike number in wheat. Low tiller number has been proposed as a major component of crop ideotypes for high yield potential. In this study, we characterized the development of tillering in near-isogenic lines (NIL7A and NIL7B), indicating that the TIN4 gene inhibited the growth of tillering buds and negatively regulated tiller number. Low-tillering was controlled by a single gene (TIN4) located on chromosome 2DL by genetic analysis and bulked segregant RNA-seq analysis. A total of 17 new polymorphic markers were developed in this study, and 61 recombinants were identified in the secondary F2 population containing 4,266 individuals. TIN4 was finally mapped on a 0.35cM interval, co-segregated with molecular marker M380, within a 311kb genomic interval of the wheat cultivar Chinese Spring reference genome sequence that contained twelve predicted genes. Yield experiments showed that the yield of low-tillering lines was higher than that of high-tillering lines at a higher density. Overall, this study provides a foundation for the construction of a low-tillering ideotype for improving wheat yield and further cloning TIN4 by map-based cloning approach.

Working with dairy farmers to improve their pasture management skills through better understanding the principles of ryegrass growth

The relationships between leaf regrowth stage, pre- and post-grazing pasture covers, and grazing rotation length are complex. Despite the existence of well-documented grazing guidelines for managing these relationships, implementation on-farm is highly variable indicating that skill levels are often inadequate and/or farmers are not convinced of the benefits. Twenty dairy farm managers and assistant managers from the Hopkins Farming Group in the lower North Island engaged in structured observation and discussion with experts to test the potential of the 3-leaf grazing technique for increasing pasture production and reducing imported supplement use from mid-spring to mid-autumn. The farmer members of the study group initially had little knowledge of the principles of ryegrass growth at the plant level, and how their management influences pasture production and persistence. Grazing management skills developed by group members during the process included: identification of pasture species within the sward, including perennial ryegrass; identification of leaf morphology, tillers, tiller buds and daughter tillers; pasture health checks to understand when new tillers appeared and their grazing and nutrient needs; and the importance of grazing residuals for future pasture quality. Pasture productivity, as measured by the amount of silage conserved, increased by approximately 0.45 t DM/ha during the 6 months of study through the application of this grazing management technique. Managing grazing using the 3-leaf technique requires a greater depth of knowledge than previous, simple, rotation length-based systems. Many farmers are concerned about the lack of persistence of new ryegrass cultivars, whereas it may be their management practices that have a greater influence.

A gene regulatory network for tiller development mediated by Tin8 in maize.

The complex gene regulatory network underlying tiller development in maize remains largely unknown. Here we identified two major quantitative trait loci for tiller number, Tin8 on chromosome 8 and the previously known Tb1 on chromosome 1, in a population derived from a teosinte-maize cross. Map-based cloning and association mapping revealed that Tin8, corresponding to Zcn8 encoding a phosphatidylethanolamine-binding-related kinase, is down-regulated in transcription, which results in decreased tiller number. A strong interaction between Tin8 and the key gen Tb1 was detected for tiller number. Further RNA-seq analysis showed that the expression of 13 genes related to tiller development was controlled by Tin8. Our results support the existence of a complex gene regulatory network for the outgrowth of the tiller bud in maize, in which Zcn8 controls 13 tiller-related genes, including four genes for hormonal responses. In particular, Zcn8 represses Gt1, D14, and Tru1 through the interaction with Tb1.

OsNPF5.16, a nitrate transporter gene with natural variation, is essential for rice growth and yield

Rice has a large number of nitrate or peptide transporter family (NPF) genes, but the effects of most members on rice growth and development are unknown. We report that OsNPF5.16, a nitrate transporter gene with natural variation in its promoter sequence, is essential for rice growth and yield. The promoter sequence showed various differences between indica and japonica cultivars, and higher expression of OsNPF5.16 was found in indica cultivars with higher plant weight and more tillers than japonica cultivars. OsNPF5.16 was highly expressed in roots, tiller basal parts, and leaf sheaths, and its protein was localized on the plasma membrane. In cRNA-injected Xenopus laevis oocytes, OsNPF5.16 transport of nitrate at high nitrate concentration depended on pH. Overexpression of OsNPF5.16 increased nitrate content and total nitrogen content in leaf sheath as well as biomass and tiller bud length in rice. Elevated expression of OsNPF5.16 increased rice tiller number and grain yield by regulating cytokinin levels. Inhibition of OsNPF5.16 expression showed the opposite effects. Regulating OsNPF5.16 expression has potential for improving rice grain yield.

Study on Callus Induction and Regeneration of Anthurium andraeanum Tiller Bud

Using anthurium andraeanum tiller bud as explant, the methods of callus induction and regeneration at bud base were studied. The results showed that the sterile tiller seedlings could induce adamant callus with a diameter of 0.5—1.0 cm and hard texture in the medium of MS+0.5 mg/L 6-BA+0.05 mg/L NAA+30 g/L sucrose. The callus differentiated into buds in the medium of 1/2MS+0.2 mg/L 6-BA+0.05 mg/L NAA+ 30 g/L sucrose. On average, each callus had 6 effective buds. When the buds were transferred to the medium of 1/2MS+0.2—0.5 mg/L IBA+20 g/L sucrose, they could develop into rooting seedlings with a height of 3 cm or more, with adventitious roots and aerial roots.

RNA demethylation increases the yield and biomass of rice and potato plants in field trials.

RNA N6-methyladenosine (m6A) modifications are essential in plants. Here, we show that transgenic expression of the human RNA demethylase FTO in rice caused a more than threefold increase in grain yield under greenhouse conditions. In field trials, transgenic expression of FTO in rice and potato caused ~50% increases in yield and biomass. We demonstrate that the presence of FTO stimulates root meristem cell proliferation and tiller bud formation and promotes photosynthetic efficiency and drought tolerance but has no effect on mature cell size, shoot meristem cell proliferation, root diameter, plant height or ploidy. FTO mediates substantial m6A demethylation (around 7% of demethylation in poly(A) RNA and around 35% decrease of m6A in non-ribosomal nuclear RNA) in plant RNA, inducing chromatin openness and transcriptional activation. Therefore, modulation of plant RNA m6A methylation is a promising strategy to dramatically improve plant growth and crop yield.

MiR319‐targeted OsTCP21 and OsGAmyb regulate tillering and grain yield in rice

Multiple genes and microRNAs (miRNAs) improve grain yield by promoting tillering. MiR319s are known to regulate several aspects of plant development; however, whether miR319s are essential for tillering regulation remains unclear. Here, we report that miR319 is highly expressed in the basal part of rice plant at different development stages. The miR319 knockdown line Short Tandem Target Mimic 319 (STTM319) showed higher tiller bud length in seedlings under low nitrogen (N) condition and higher tiller bud number under high N condition compared with the miR319a-overexpression line. Through targets prediction, we identified OsTCP21 and OsGAmyb as downstream targets of miR319. Moreover, OsTCP21 and OsGAmyb overexpression lines and STTM319 had increased tiller bud length and biomass, whereas both were decreased in OsTCP21 and OsGAmyb knockout lines and OE319a. These data suggest that miR319 regulates rice tiller bud development and tillering through targeting OsTCP21 and OsGAmyb. Notably, the tiller number and grain yield increased in STTM319 and overexpression lines of OsTCP21 and OsGAmyb but decreased in OE319a and knockout lines of OsTCP21 and OsGAmyb. Taken together, our findings indicate that miR319s negatively affect tiller number and grain yield by targeting OsTCP21 and OsGAmyb, revealing a novel function for miR319 in rice.

Characterization of full-length transcriptome in Saccharum officinarum and molecular insights into tiller development

BackgroundAlthough extensive breeding efforts are ongoing in sugarcane (Saccharum officinarum L.), the average yield is far below the theoretical potential. Tillering is an important component of sugarcane yield, however, the molecular mechanism underlying tiller development is still elusive. The limited genomic data in sugarcane, particularly due to its complex and large genome, has hindered in-depth molecular studies.ResultsHerein, we generated full-length (FL) transcriptome from developing leaf and tiller bud samples based on PacBio Iso-Seq. In addition, we performed RNA-seq from tiller bud samples at three developmental stages (T0, T1 and T2) to uncover key genes and biological pathways involved in sugarcane tiller development. In total, 30,360 and 20,088 high-quality non-redundant isoforms were identified in leaf and tiller bud samples, respectively, representing 41,109 unique isoforms in sugarcane. Likewise, we identified 1063 and 1037 alternative splicing events identified in leaf and tiller bud samples, respectively. We predicted the presence of coding sequence for 40,343 isoforms, 98% of which was successfully annotated. Comparison with previous FL transcriptomes in sugarcane revealed 2963 unreported isoforms. In addition, we characterized 14,946 SSRs from 11,700 transcripts and 310 lncRNAs. By integrating RNA-seq with the FL transcriptome, 468 and 57 differentially expressed genes (DEG) were identified in T1vsT0 and T2vsT0, respectively. Strong up-regulation of several pyruvate phosphate dikinase and phosphoenolpyruvate carboxylase genes suggests enhanced carbon fixation and protein synthesis to facilitate tiller growth. Similarly, up-regulation of linoleate 9S-lipoxygenase and lipoxygenase genes in the linoleic acid metabolism pathway suggests high synthesis of key oxylipins involved in tiller growth and development.ConclusionsCollectively, we have enriched the genomic data available in sugarcane and provided candidate genes for manipulating tiller formation and development, towards productivity enhancement in sugarcane.

Regulation of 2,4-D Isooctyl Ester on Triticum aestivum and Aegilops tauschii Tillering and Endogenous Phytohormonal Responses

Tillering is an important agronomic trait essential for the yield of Triticum aestivum and the propagation of Aegilops tauschii. However, the effect of phytohormones on T. aestivum and Ae. tauschii tillering and the underlying regulatory mechanisms remain poorly understood. In the study, we found that T. aestivum and Ae. tauschii exhibited different tillering sensitivities to the auxin herbicide 2,4-D isooctyl ester. At 3 days post-application, tiller bud growth was inhibited by 77.50% in T. aestivum, corresponding to 2.0-fold greater inhibition than that in Ae. tauschii (38.71%). Transcriptome analysis showed that differentially expressed genes (DEGs) in the T. aestivum response to 2,4-D isooctyl ester were mainly enriched in plant hormone metabolism and signal transduction pathways, but similar changes were not observed in Ae. tauschii. Among that, the auxin biosynthesis and signaling induced by 2,4-D isooctyl ester was quite different between the two species. A total of nine candidate genes involved in varied tillering responses were selected from the DEGs and validated by quantitative real-time PCR. Endogenous hormone levels were assayed to further verify the RNA-seq results. After 2,4-D isooctyl ester treatment, a significant increase in abscisic acid (ABA) levels was observed in T. aestivum, whereas ABA levels were relatively stable in Ae. tauschii. The herbicide induced more cytokinin (CTK) accumulation in Ae. tauschii than in T. aestivum. External ABA clearly restricted tiller bud growth in both T. aestivum and Ae. tauschii, while 6-benzyl aminopurine had no significant effect. These results indicate that ABA and CTK may be related with 2,4-D isooctyl ester-regulated tillering differences between the two species, which will help to further understand the mechanism of the auxin-mediated regulation of tillering

Tiller Outgrowth in Rice (Oryza sativa L.) is Controlled by OsGT1, Which Acts Downstream of FC1 in a PhyB-Independent Manner

Tillering is one of the most important determinants of biomass and yield in rice (Oryza sativa L.). The capacity of plants to develop tillers from primordial meristems or buds is determined not only by the genotype but also by environmental cues. Here, we characterized the function of rice grassy tiller1 (OsGT1) and its interaction with other genetic and biological factors involved in tiller bud outgrowth in rice by generating OsGT1 RNA interference (RNAi) and overexpression (OX) lines. The tiller number was increased in OsGT1-RNAi mutants but strongly suppressed in OsGT1-OX lines. Expression analysis of OsGT1 in rice phyB mutants and in genotypes carrying various genetic combinations of GT1 RNAi and phyB demonstrated that OsGT1 is not involved in phyB-mediated suppression of tiller development in rice. Expression analysis of fine culm1 (fc1), a rice tb1 homolog, and molecular assays demonstrated that FC1 enhances the expression of OsGT1 by directly binding to its promoter. Comparison of the transcriptomic profiles of fc1 and OsGT1-RNAi mutants revealed differentially expressed genes (DEGs) common to both genotypes. Finally, analysis of tillering phenotypes of OX and RNAi seedlings treated with various phytohormones implied a possible role of OsGT1 in strigolactone-mediated tiller outgrowth. Overall, this study enhances our understanding of the diverse mechanisms of tiller development in grasses.

Analysis on the plant growth and yield formation of double cropping late season hybrid rice in machine transplanting with long seedling age by precision drill sowing

<p id="C3">In order to ascertain the beneficial effects of precision drill sowing (PS) in machine transplanting with long seedling age of double cropping late season hybrid rice. In this study, seed of Yongyou 1540 (YY1540) was subjected to precision drill sowing of 16 rows (PS-16, 45.7 g tray^-1), precision drill sowing of 18 rows (PS-18, 60.5 g tray^-1) and traditional broadcast sowing (BS, 60.5 g tray^-1) in standard seedling tray at the same day. Seedling ages of 20, 25, 30, and 35 days were set for machine transplanting to analyze the rice seedling quality, machine transplanting characters, rice population growth, and yield formation between PS-16, PS-18, and BS. The results were as follows: (1) PS improved the light transmittance of seedling population, compared to BS, PS enhanced the seedling quality and increased the percentage of seedlings with tillering buds, among the treatments, PS-16 got the best seedling quality and highest percentage of seedling with tillering buds. (2) Compared to BS, PS significantly reduced the missing hill percent and increased the ratio of hills with 2-3 seedlings transplanted, and there was no significant difference between PS-16 and PS-18. Seedling age prolonging increased the root injury degree and seedling injury rate, and decreased the seedling survival rate after machine-transplanting, in which, PS-16 had the minimal increasing in root injury degree and seedling injury rate, meanwhile PS-16 got the highest survival rate of seedling machine-transplanted. (3) The seedling age prolonging postponed the rice growth duration by increasing the duration of seedling rejuvenation period. Among the seedling age treatments, the shortest period of rejuvenation period was observed in PS-16, and then the growth period minimal delayed in PS-16 with the seedling age prolonging. (4) PS effectively promoted plant tillering, and PS-16 got the best effect. The number of tillers at 10 d after machine transplanting of PS-16 machine was 16.4% and 20.8% higher than that of PS-18 and BS, in average. Seedling age prolonging decreased the tiller number at tillering peak stage, and the tiller number at tillering peak stage was PS-16&gt;PS-18&gt;BS at different seedling age treatments. The productive tiller percentage presented no difference among the sowing methods and seedling ages. (5) Seedling age prolonging decreased the leaf area index and dry matter accumulation by the degree of PS-16&lt;PS-18&lt;BS. (6) PS contributed to yield enhancing by increasing the number of productive tillers, and effectively reduced the yield loss caused by the prolonging of seedling age, and rice yield was PS-16&gt;PS-18&gt;BS under different seedling age treatments, in average. In conclusion, compared to BS, PS could improve the seedling quality, reduce the missing hill percentage in machine transplanting, improve the machine transplanting quality, shorten the seedling rejuvenation period, promote plant tillering, and increase the leaf area index and dry matter accumulation, and then effectively reduce the yield loss of double late season hybrid rice with long seedling age in machine transplanting, and the benefits of PS-16 were better than that of PS-18.

Altered Expression of OsAAP3 Influences Rice Lesion Mimic and Leaf Senescence by Regulating Arginine Transport and Nitric Oxide Pathway.

Persistent lesion mimic can cause leaf senescence, affecting grain yield in crops. However, knowledge about the regulation of lesion mimic and leaf senescence in crop plants is still limited. Here, we report that the amino acid transporter OsAAP3, a negative regulator of tiller bud elongation and rice grain yield, is involved in lesion mimic and leaf senescence. Altered expression of OsAAP3 can initiate the nitric oxide signaling pathway through excessive accumulation of arginine in rice leaves, influencing ROS accumulation, antioxidant enzymes activities, proline concentration, and malondialdehyde concentration. This finally triggers cell death which ultimately leads to lesion mimic and leaf senescence by regulating the degradation of chloroplast and the expression abundance of components in the photosynthetic pathway. Overall, the results not only provide initial insights into the regulatory role of amino acid transport genes in rice growth and development, but also help to understand the factors regulating the leaf senescence.

Integration of high-density genetic mapping with transcriptome analysis uncovers numerous agronomic QTL and reveals candidate genes for the control of tillering in sorghum.

Phenotypes such as branching, photoperiod sensitivity, and height were modified during plant domestication and crop improvement. Here, we perform quantitative trait locus (QTL) mapping of these and other agronomic traits in a recombinant inbred line (RIL) population derived from an interspecific cross between Sorghum propinquum and Sorghum bicolor inbred Tx7000. Using low-coverage Illumina sequencing and a bin-mapping approach, we generated ∼1920 bin markers spanning ∼875 cM. Phenotyping data were collected and analyzed from two field locations and one greenhouse experiment for six agronomic traits, thereby identifying a total of 30 QTL. Many of these QTL were penetrant across environments and co-mapped with major QTL identified in other studies. Other QTL uncovered new genomic regions associated with these traits, and some of these were environment-specific in their action. To further dissect the genetic underpinnings of tillering, we complemented QTL analysis with transcriptomics, identifying 6189 genes that were differentially expressed during tiller bud elongation. We identified genes such as Dormancy Associated Protein 1 (DRM1) in addition to various transcription factors that are differentially expressed in comparisons of dormant to elongating tiller buds and lie within tillering QTL, suggesting that these genes are key regulators of tiller elongation in sorghum. Our study demonstrates the usefulness of this RIL population in detecting domestication and improvement-associated genes in sorghum, thus providing a valuable resource for genetic investigation and improvement to the sorghum community.

Responses of Plant Bud Bank Characteristics to the Enclosure in Different Desertified Grasslands on the Tibetan Plateau.

Asexual reproduction is the main mode of alpine plant reproduction, and buds play an important role in plant community succession. The purpose of this study is to explore whether the desertified grassland can recover itself through the existing bud bank. The bud bank composition, distribution and size of different desertified grasslands were studied using unit volume excavation on the Tibetan Plateau. The bud bank consisted of tiller, long and short rhizome buds, and more than 40% of buds were distributed in the 0–10 cm soil layer. Enclosure changed the bud density, distribution and composition. The bud densities were 4327 and 2681 No./m2 in light and middle desertified grasslands before enclosure, while that decreased to 3833 and 2567 No./m2 after enclosure. Tiller bud density and proportion of middle desertified grassland were the highest, increased from 2765 (31.26%, before enclosure) to 5556 No./m3 (62.67%, after enclosure). There were new grasses growing out in the extreme desertified grassland after enclosure. The meristem limitation index of moderate desertified grassland was the lowest (0.37), indicating that plant renewal was limited by bud bank. Plants constantly adjust the bud bank composition, distribution, and asexual reproduction strategy, and desertified grasslands can recover naturally, relying on their bud banks through an enclosure.

Temporal–spatial changes in the belowground bud bank in interdune lowlands of an active sand dune ecosystem in northeastern China

Abstract Aims The belowground bud bank plays an important role in vegetation restoration of sand dune ecosystems in semi-arid regions. However, few studies have focused on the temporal–spatial changes of belowground bud banks in interdune lowlands. Methods The size and composition of belowground bud bank in five interdune lowlands with different sizes were investigated for one growing season to determine the temporal and spatial changes in belowground bud bank. Important Findings Total bud bank density was the highest in the medium-sized interdune lowland as was tiller bud density. The density of stem-base buds exhibited an opposite trend while rhizome bud density did not change with interdune lowland size. There was a significant seasonal change in the bud bank size. The total bud density peaked in August and was the lowest in October. A similar trend was found for rhizome bud density, whereas the density of stem-base buds showed an opposite trend, and tiller bud density did not change significantly during the growing season. We conclude that the belowground bud bank density is changed with interdune lowland size and season. These results contribute to the understanding of adaptive strategies of plants growing in active dune ecosystems and provide pointers for adopting effective measures to restore and conserve dune vegetation in semi-arid regions.

A transporter for delivering zinc to the developing tiller bud and panicle in rice.

Tiller number is one of the most important agronomic traits that determine rice (Oryza sativa) yield. Active growth of tiller bud (TB) requires high amount of mineral nutrients; however, the mechanism underlying the distribution of mineral nutrients to TB with low transpiration is unknown. Here, we found that the distribution of Zn to TB is mediated by OsZIP4, one of the ZIP (ZRT, IRT-like protein) family members. The expression of OsZIP4 was highly detected in TB and nodes, and was induced by Zn deficiency. Immunostaining analysis revealed that OsZIP4 was mainly expressed in phloem of diffuse vascular bundles in the nodes and the axillary meristem. The mutation of OsZIP4 did not affect the total Zn uptake, but altered Zn distribution; less Zn was delivered to TB and new leaf, but more Zn was retained in the basal stems at the vegetative growth stage. Bioimaging analysis showed that the mutant aberrantly accumulated Zn in enlarged and transit vascular bundles of the basal node, whereas in wild-type high accumulation of Zn was observed in the meristem part. At the reproductive stage, mutation of OsZIP4 resulted in delayed panicle development, which is associated with decreased Zn distribution to the panicles. Collectively, OsZIP4 is involved in transporting Zn to the phloem of diffuse vascular bundles in the nodes for subsequent distribution to TBs and other developing tissues. It also plays a role in transporting Zn to meristem cells in the TBs.

OsWUS promotes tiller bud growth by establishing weak apical dominance in rice

Two branching strategies are exhibited in crops: enhanced apical dominance, as in maize; or weak apical dominance, as in rice. However, the underlying mechanism of weak apical dominance remains elusive. OsWUS, an ortholog of Arabidopsis WUSCHEL (WUS) in rice, is required for tiller development. In this study, we identified and functionally characterized a low-tillering mutant decreased culm number 1 (dc1) that resulted from loss-of-function of OsWUS. The dc1 tiller buds are viable but repressed by the main culm apex, leading to stronger apical dominance than that of the wild-type (WT). Auxin response is enhanced in the dc1 mutant, and knocking out the auxin action-associated gene ABERRANT SPIKELET AND PANICLE 1 (ASP1) de-repressed growth of the tiller buds in the dc1 mutant, suggesting that OsWUS and ASP1 are both involved in outgrowth of the rice tiller bud. Decapitation triggers higher contents of cytokinins in the shoot base of the dc1 mutant compared with those in the WT, and exogenous application of cytokinin is not sufficient for sustained growth of the dc1 tiller bud. Transcriptome analysis indicated that expression levels of transcription factors putatively bound by ORYZA SATIVA HOMEOBOX 1 (OSH1) are changed in response to decapitation and display a greater fold change in the dc1 mutant than that in the WT. Collectively, these findings reveal an important role of OsWUS in tiller bud growth by influencing apical dominance, and provide the basis for an improved understanding of tiller bud development in rice.

OsPIN9, an auxin efflux carrier, is required for the regulation of rice tiller bud outgrowth by ammonium.

The degree of rice tillering is an important agronomic trait that can be markedly affected by nitrogen supply. However, less is known about how nitrogen-regulated rice tillering is related to polar auxin transport. Compared with nitrate, ammonium induced tiller development and was paralleled with increased 3 H-indole-acetic acid (IAA) transport and greater auxin into the junctions. OsPIN9, an auxin efflux carrier, was selected as the candidate gene involved in ammonium-regulated tillering based on GeneChip data. Compared with wild-type plants, ospin9 mutants had fewer tillers, and OsPIN9 overexpression increased the tiller number. Additionally, OsPIN9 was mainly expressed in vascular tissue of the junction and tiller buds, and encoded a membrane-localised protein. Heterologous expression in Xenopus oocytes and yeast demonstrated that OsPIN9 is a functional auxin efflux transporter. More importantly, its RNA and protein levels were induced by ammonium but not by nitrate, and tiller numbers in mutants did not respond to nitrogen forms. Further advantages, including increased tiller number and grain yield, were observed in overexpression lines grown in the paddy field at a low-nitrogen rate compared with at a high-nitrogen rate. Our data revealed that ammonium supply and an auxin efflux transporter co-ordinately control tiller bud elongation in rice.

The spatial pattern of the belowground bud bank and its responses to soil water status in the interdune lowlands of active sand dunes of Inner Mongolia, China

Bud bank composition in interdune lowlands plays a key role in population colonization and vegetation restoration in active sand dune ecosystems. However, no studies have explicitly explored the spatial pattern of belowground bud banks in the interdune lowlands of active sand dune ecosystems and their response to soil moisture conditions. Therefore, this study investigated belowground bud banks and measured soil moisture contents in four interdune lowlands in the Horqin Sandy Land of northeastern Inner Mongolia. The density of total buds, rhizome buds, and tiller buds decreased significantly at the windward slope‐interdune and leeward slope‐interdune transitional zones (p &lt; 0.05), while the densities of both root‐collar buds and root‐sprouting buds were the highest at the edge of the interdune lowland. Rhizome buds (60–100%) were predominant over tiller buds in the windward slope transitional zone, while root‐collar buds (57–62%) and tiller buds (60–79%) were prominent in the leeward slope transitional zone. Furthermore, all bud types except the root‐collar bud had obvious water dependence. It was concluded that there is a significant difference in bud density between the different interdune lowland positions, and root‐collar buds were more resistant to water stress than the other bud banks. These survival strategies and responses may be important in the recovery of both artificial and sand‐fixing vegetation in semiarid regions of China.

Effects of small-herbivore disturbance on the clonal growth of two perennial graminoids in alpine meadows

Graminoids are typically the dominant plants in certain grassland communities, and their clonal growth is considered an important method of evaluating their adaptation to environmental disturbances. Whether disturbances caused by small burrowing herbivores influence clonal growth in graminoids is not well documented. A field experiment was conducted to investigate the effects of disturbances by small burrowing herbivores, the plateau pika, on the clonal growth of the tussock-forming Kobresia pygmaea and the rhizomatous K. humilis across three sites. This study showed that disturbance by plateau pikas increased the shoot number, spacer number and tiller bud number per clonal fragment of both the tussock-forming K. pygmaea and the rhizomatous K. humilis across three sites. This study also showed that disturbance by plateau pikas increased the rhizome branch number, rhizome length, and rhizome bud number per clonal fragment of rhizomatous K. humilis at each site, while the effects of disturbance by plateau pikas on the rhizome branch number, rhizome length, and rhizome bud number per clonal fragment of the tussock-forming K. pygmaea were different among the three sites. These results suggested that disturbance by plateau pikas benefits for current and potential population recruitment in the tussock-forming K. pygmaea and the rhizomatous K. humilis due to the resulting higher shoot number and tiller bud number per clonal fragment.