Application of growth rings and scars in exposed roots of Schizolobium parahyba as a tool for dating geomorphic processes in the State of São Paulo,Brazil

Water erosion is an important degradation process, which results in loss of soil, reduction in agricultural productivity, and causes severe environmental impact. Dendrogeomorphology has methods in which the structure of the wood of the stem and roots of tree and shrub species affected by sediment deposition or by root exposure is analysed, to establish the chronology of erosive events. The objective of the present work was to describe the modifications and scar formation in Schizolobium parahyba growth rings, attributed to the effect of roots exposure for determining the first year of exposure. The study area presents erosion features, such as gullies, with the consequent exposure of tree roots. The growth rings and the scars formed by the flow of water and soil particles were analysed in cross-sections of exposed roots to date the erosion processes. This paper demonstrates the potential of S. parahyba for dendrogeomorphological studies, validating dendrogeomorphology as a research tool in tropical climate. Scars used for erosion dating in cross-sections have been proven as good indicators of geomorphic processes. The relevance of this work is to become the first attempt in tropical regions to date erosion processes using dendrogeomorphological techniques on exposed roots.     

The effect of missing rings on stand-age estimation of even-aged forests in northern Hokkaido,Japan

The effectiveness of estimating stand age from increment core samples taken at stump height (20 cm above ground) was tested in an even-aged stand ofBetula ermanii that had regenerated after a forest fire in 1945 in Hokkaido, Japan. Careful cross-dating revealed that annual rings were missing in 11 cores out of a total of 42 cores sampled, and that all these missing rings occurred in the outermost part of the core. These facts indicate that precaution has to be taken in selecting trees from which cores are to be sampled. The present work also revealed that those trees with missing rings have a characteristic appearance, with a thinner stem and less crown foliage than normal trees with complete rings. It was also found that even if this appearance test failed, the possibility of missing rings could be detected from a declining growth pattern, with extremely narrow rings on the increment core which normal trees did not show.     

Cross-sectional interpolation of annual rings within a 3D root model

Ring width of a given year can be highly variable throughout the cross section of a stem. This is especially true for roots. Therefore, the entire circumference of tree rings is often needed for studies focusing on specific reactions of individual trees on certain environmental conditions. Also, ring reconstructions are of interest for biomass calculations estimated by the cross-sectional area. The aim of the study is thus to reconstruct tree rings of cross sections within a 3D root-surface model, which will be the basis for an upcoming 3D root-development model. A FARO ScanArm was used for the acquisition of the 3D root structure (Technologies Inc., 2010). Afterwards ring-width data was measured along 4 radii per cross section and the resulting ring boundaries were integrated into the 3D root model. A weighted interpolation algorithm was used to reconstruct entire ring-width profiles of the cross sections. The algorithm considered the ring-width variations of the adjacent radii as well as the outer shape of the cross section. Hence, the intention was to estimate ring width around the root circumference using ring widths measured along 4 radii and the surface dimensions of roots. Interpolated ring-width data was compared to the measured tree-ring data as a control for the developed interpolation algorithm. Comparisons between modelled and empirical values showed a mean absolute error of about 0.06 mm deviation, and with a few exceptions the growth patterns could be accurately simulated. This has permitted additional radii measurements to be replaced by model interpolations.     

牛膝根的结构发育与三萜皂苷积累的关系

应用植物解剖学、组织化学定位及植物化学技术,研究了不同发育时期牛膝根的结构特征与三帖皂苷积累的关系。结果表明:牛膝根的初生结构和次生结构类似于一般双子叶植物,其根的加粗主要是由于三生结构的发生和分化。第一圈额外形成层产生于次生韧皮部外侧的薄壁组织细胞和射线细胞,以后的每一圈由前一圈向外衍生的薄壁组织细胞产生。额外形成层无纺锤状原始细胞和射线原始细胞之分,在切向纵切面上呈叠生排列。三生维管束以离心方式排成整齐的同心环状,由薄壁结合组织将其彼此分开,其圈数与额外形成层的圈数是一致的,随着根的个体发育而不断增加。在根的初生结构中,三萜皂苷主要分布于中柱鞘、初生韧皮部及初生韧皮部和初生木质部之间的薄壁组织细胞内;在根的次生结构中,主要分布于次生韧皮部及栓内层的薄壁组织细胞内。当三生结构形成后,除次生韧皮部及栓内层细胞外,在额外形成层和三生维管束韧皮部细胞内均有皂苷类物质积累。三生结构在牛膝根中占主要地位,是三萜皂苷积累与分布的主要场所。在牛膝根的生长发育过程中,三萜皂苷元齐墩果酸的百分含量呈“S”型曲线增长,其根的增长、加粗、三生维管束圈数、三萜皂苷总量及根中干重的积累量都在出苗后约120天达到高峰,此时应为牛膝根的最佳采收期。     

Altered growth with blue rings: comparison of radial growth and wood anatomy between trampled and non-trampled Scots pine roots

Our understanding of wood anatomy and radial growth in tree roots remains very incomplete, particularly with respect to how ecological factors affect root growth at a relatively small spatial scale, i.e., within a single root system. Here, we compared root growth with and without trampling exposure on a hiking trail. We conducted a quantitative analysis of radial growth and wood anatomical changes, including compression wood (CW) and blue rings (BRs), of two adjacent Scots pine roots in high resolution. A total of 32 cross sections from two roots sampled every 25 cm at the same distance from the respective stem were compared. The buried root (B) was completely buried and had an unexposed segment on a hiking trail. In contrast, the exposed root (E) had an exposed segment that was trampled. 1706 growth rings were analysed for the common period 1954–2015.We found that the volume of the E root in the trampling zone exceeded ten times the volume of the B root. The root surface area of the exposed sections of the E root was on average 14 times larger than that of the unexposed B root section in the trampling zone. The highest number of missing rings was found in the B root. Root sections sampled at the shortest distance from the stem showed the highest coherence in radial growth pattern, which decreased with increasing distance from the stem.BRs were recognized for the first time in tree roots. In total 25 tree rings contained BRs, and their occurrence was restricted to cross sections of the exposed root. BRs were formed over the course of 25 calendar years, i.e., in 40% of tree rings from the common period 1954–2015. Mean monthly temperatures for the years with and without BRs formation showed that colder November (p = 0. 012) and, albeit only slightly, colder September (p = 0.051) temperatures favoured formation of BRs in Scots pine roots. In addition, mean monthly precipitation in July (p = 0.017) was significantly higher for BR years, suggesting an impact of moisture availability on the formation of BRs in Scots pine roots. The study highlights a high rate of growth discrepancies within a single root system. Further, altered growth of trampled roots with high proportions of BRs opens a new challenge for future dendroecological studies on tree roots.     

Comparing automatically generated and manually measured tree-ring transects of growth trends with Hawaiian sandalwood as an example species

Tree-ring measurements are a primary quantitative tool used in numerous scientific disciplines. Some species, however, exhibit morphological complexities leading to significant uncertainty in these measurements. Hawaiian Sandalwood (Santalum paniculatum) stems, for example, often develop asymmetric growth features that hinder tree-ring measurements. These features include faint-ring boundaries and wedging rings which disappear in portions of the cross-section. In this work we a use a novel two-dimensional transect methodology and our own open-source software, svg-dendro, to analyze particularly difficult cross-sections. Our method accomplishes this by first tracing all rings by hand and automatically generating a user-specified number of transects. On average, these traced measurements had more sensitivity to tree-ring variability without losing important equivalencies with the traditional binocular stereomicroscope technique (e.g., radii, skewness) as indicated by greater mean variance for ring number, mean tree-ring width, and standard deviation. All S. paniculatum samples had ring wedging, where certain sides of the stem had many locally absent tree rings but to different intensities. The new technique allows us to analyze the shift from complete rings with little to no wedging to rings with more wedging starting between the 19th and 40th ring, where deep stem lobes begin forming. The new method also reveals the difficulty in measuring these trees, as the wedging creates multiple lobes with different visible ring counts. This research suggests that this two-dimensional methodology would be best applied to non-circular trees with fewer incomplete rings, supporting the importance of species and population selection. Overall, we have developed an efficient and flexible means to measure otherwise unmeasurable growth features in tree samples through representing tree-ring boundaries as curves and developing software to sort and map transects.     

Growth ring analysis of multiple dicotyledonous herb species—A novel community-wide approach

Longevity is a key demographic characteristic of herbaceous plants, but often unknown. While root or rhizome growth ring analysis may allow assessment plant longevity directly and conveniently, so far it has only been used in a few case studies of herbaceous dicotyledonous species. To evaluate whether growth ring analysis is applicable to a large spectrum of herbaceous dicotyledonous plant species, we used plant communities of varying species richness in a 12-year-old grassland biodiversity experiment (Jena Experiment). Cross-sections of the oldest available part of the plants were analysed for all available dicotyledonous perennial herb species (S = 37), which represented three functional groups: legumes, small herbs and tall herbs. We studied 1664 individuals representing the genet in clearly distinguishable plant individuals, and the ramet in clonally growing plant species.Roots of eleven species with permanent primary root were harvested. They showed clearly visible growth rings. Longevity was extended with a mean age of 4.0 years (SE = 0.3). Seven species, which also had a permanent primary root, showed less distinct growth rings. They were shorter-lived (mean age 3.0 years (SE = 0.3)). In six species with obligate clonal growth mostly rhizomes were sampled, but individuals were still identifiable due to their growth habit. For these species growth rings were clearly visible. Longevity of rhizomes was extended (mean age 3.3 years (SE = 0.5)). In 13 species with obligate clonal growth also rhizomes were sampled, but plant individuals were not identifiable. For these species longevity was low (mean age 2.1 years (SE = 0.2)). Community mean age was significantly lower when small herbs were present and higher when tall herbs were present, while legumes had no effect on community mean age. In summary, anatomical analysis of roots and rhizomes is a suitable tool to study the population age structure of a large spectrum of perennial dicotyledonous herbaceous species and therefore opens new perspectives for demographic studies at the community level.     

Application of Picea wilsonii roots to determine erosion rates in eastern Qilian Mountains, Northwest China

As a consequence of global change and human activities, processes of soil erosion are expected to increase in forested areas, resulting in exposed roots. Dendrogeomorphic research was conducted by analyzing exposed roots of Picea wilsonii subjected to continuous denudation along a main road in Tulugou National Forest Reserve, eastern Qilian Mountains, to reconstruct the local soil erosion dynamics. We determined the start of the exposure by examining the shifts in the ring-growth patterns from concentric to eccentric and by analyzing the detailed changes of wood anatomical features of exposed roots. We also find that the width of growth ring, the percentage of latewood and the average cell size of earlywood tracheids are all remarkable signs for soil lowering. According to the analysis of ANOVA (Fisher’s least significant difference method), the reduction of the cell size of earlywood tracheids is verified to be the key indicator for dating the first year of exposure and occurs prior to the other two indicators. Using 40 roots from 23 trees spread along the road, it has been found that erosion rates vary between 3.3 and 13.5 mm/year with an average value about 5.3 ± 2.1 mm/year. The intensity and occurrence of soil erosion may be influenced by the increase of human activities.     

A mass spectrometric approach to identify arbuscular mycorrhiza-related proteins in root plasma membrane fractions

One of the most important morphological changes occurring in arbuscular mycorrhizal (AM) roots takes place when the plant plasma membrane (PM) invaginates around the fungal arbuscular structures resulting in the periarbuscular membrane formation. To investigate whether AM symbiosis-specific proteins accumulate at this stage, two complementary MS approaches targeting the root PM from the model legume Medicago truncatula were designed. Membrane extracts were first enriched in PM using a discontinuous sucrose gradient method. The resulting PM fractions were further analysed with (i) an automated 2-D LC-MS/MS using a strong cation exchange and RP chromatography, and (ii) SDS-PAGE combined with a systematic LC-MS/MS analysis. Seventy-eight proteins, including hydrophobic ones, were reproducibly identified in the PM fraction from non-inoculated roots, representing the first survey of the M. truncatula root PM proteome. Comparison between non-inoculated and Glomus intraradices-inoculated roots revealed two proteins that differed in the mycorrhizal root PM fraction. They corresponded to an H(+)-ATPase (Mtha1) and a predicted glycosylphosphatidylinositol-anchored blue copper-binding protein (MtBcp1), both potentially located on the periarbuscular membrane. The exact role of MtBcp1 in AM symbiosis remains to be investigated.     

Comparative analysis of growth rings in perennial forbs grown in an Alpine restoration experiment

Recent studies have demonstrated that growth rings are widespread in the roots of forbs, and there is evidence that the rings are formed annually. However, the annual nature and development of the growth rings has not yet been examined in comparative experimental studies. In this study growth rings were analysed in the main roots of four alpine forbs (Lotus alpinus, Trifolium thalii, Silene willdenowii and Potentilla aurea) that were grown in an alpine restoration experiment for 6 years. All individuals of L. alpinus and T. thalii, and some individuals of S. willdenowii showed six clearly demarcated growth rings, demonstrating that the rings were formed annually. P. aurea did not show distinguishable growth rings. In L. alpinus and T. thalii there were fluctuations in growth ring width that were consistent between individuals and also between species, and matched variations in climatic growth conditions. Results of the present study indicate that conclusions drawn from previous studies suggesting that growth rings in the roots of forb species are most likely formed annually are also valid for alpine plants. In terms of annual ring width patterns, this study also provides the first strong evidence for consistent responses of different forb species and individuals to commonly experienced variations in habitat conditions.     

Tree age estimates in Fagus sylvatica and Quercus robur: testing previous and improved methods

The accuracy of direct (based on increment cores) and indirect (based on age-size relationships) methods of tree age estimation in Fagus sylvatica and Quercus robur was tested. This was done through increment cores and stem discs taken in an old-growth forest of Northern Spain. It was found that cross-dating was more precise than ring counting by up to 7 years per tree. Furthermore, cross-dating permitted the estimation of the age of trees with floating ring-width series, which were 7% of cored F. sylvatica and 40% of Q. robur ones. In partial cores with the arcs of the inner rings, the length of the missing radius was estimated with both a geometric method, based on the curvature of the arcs, and a new graphical method, based on the convergence of xylem rays at the pith. The graphical method was more accurate when the radial growth was eccentric, as happens in Q. robur, while both methods showed a similar accuracy for F. sylvatica, whose growth is relatively concentric. Empirical models of initial radial growth (IRG), built to estimate the number of missing rings, reduced the errors associated with other methods that assume constant growth rates. Age estimates obtained from the graphical method combined with the IRG models were within 4% of the actual age. This combination ensured age estimates with a mean accuracy of 8 years for 98% of the F. sylvatica trees, and 4 years for 89% of the Q. robur. In partial cores without the arcs of the inner rings, the length of the missing radius was estimated as the distance to the geometric centre of the tree. In that case, age estimates obtained by extrapolating the mean growth rate of the 20 innermost rings in the cores were from 10 to 20% of actual age, which coincided with results obtained in other tree species with this method. Finally, the age-diameter equations of the different cohorts produced better age estimates (from 8 to 14% of actual age) than equations of the population as a whole (from 20 to 40% of actual age). These results proved that the errors derived from doubtful assumptions, such as concentric radial growth, constant growth and recruitment rates, or the absence of anomalous rings, could be reduced by applying more realistic methods of tree age estimation.     

Early development and gravitropic response of lateral roots in Arabidopsis thaliana

Root system architecture plays an important role in determining nutrient and water acquisition and is modulated by endogenous and environmental factors, resulting in considerable developmental plasticity. The orientation of primary root growth in response to gravity (gravitropism) has been studied extensively, but little is known about the behaviour of lateral roots in response to this signal. Here, we analysed the response of lateral roots to gravity and, consistently with previous observations, we showed that gravitropism was acquired slowly after emergence. Using a lateral root induction system, we studied the kinetics for the appearance of statoliths, phloem connections and auxin transporter gene expression patterns. We found that statoliths could not be detected until 1 day after emergence, whereas the gravitropic curvature of the lateral root started earlier. Auxin transporters modulate auxin distribution in primary root gravitropism. We found differences regarding PIN3 and AUX1 expression patterns between the lateral root and the primary root apices. Especially PIN3, which is involved in primary root gravitropism, was not expressed in the lateral root columella. Our work revealed new developmental transitions occurring in lateral roots after emergence, and auxin transporter expression patterns that might explain the specific response of lateral roots to gravity.     

Regulation of Growth Anisotropy in Well-Watered and Water-Stressed Maize Roots (I. Spatial Distribution of Longitudinal,Radial, and Tangential Expansion Rates)

As a system to study the regulation of growth anisotropy, we studied thinning of the primary root of maize (Zea mays L.) occurring developmentally or induced by water stress. Seedlings were transplanted into vermiculite at a water potential of approximately -0.03 MPa (well-watered) or -1.6 MPa (water-stressed). The diameter of roots in both treatments decreased with time after transplanting; the water-stressed roots became substantially thinner than well-watered roots at steady state, showing that root thinning is a genuine response to water stress. To analyze the thinning responses we quantified cell numbers and the spatial profiles of longitudinal, radial, and tangential expansion rates separately for the cortex and stele. The results showed that there was no zone of isotropic expansion and the degree of anisotropy varied greatly with position and treatment. Thinning over time in well-watered roots was caused by rates of radial and tangential expansion being too low to maintain the shape of the root. In response to low water potential, cell number in both tissues was unchanged radially but increased tangentially, which shows that thinning was caused wholly by reduced cell expansion. Water stress substantially decreased rates of tangential and radial expansion in both the stele and cortex, but only in the apical 5 mm of the root; basal to this, rates were similar in well-watered and water-stressed roots. By contrast, as in previous studies, longitudinal expansion was identical between the treatments in the apical 3 mm but in water-stressed roots was inhibited at more basal locations. The results show that expansion in longitudinal and radial directions can be regulated independently.     

Comparison of radial increment and volume growth in stems and roots of Quercus petraea

Dendrochronological studies dealing with roots, stems and branches are very rare or often take the form of short notes. The difficulties of detecting rings and of quantifying the radial growth in roots have already been described for various species. In oak the anatomical root structure differs from stemwood. The roots are radial-porous or diffuse-porous, and there is often no clear distinction between individual rings. In our study visual and radiographic techniques were used to examine radial increment in roots of sessile oak (Quercus petraea L.) which was compared with radial growth in branches and along the stem. Coarse roots were cut from four 30- to 34-year-old trees that had been uprooted mechanically and disks were taken at different distances from the stem-root base. Ring widths were measured in the stem at height of 0.3 m, at breast height (1.3 m), beneath the crown, in branches of the crown, and in roots every 20 cm. The ring widths were cross-dated, and the heterogeneity of growth within a root and within the root system were analysed. Asymmetric growth frequently occurred in roots so that ovals, I-beam and T-beam shapes were developed. With the method used in our study the annual growth layers close to the central cylinder could be distinguished as well as beneath the bark. Pointer years were detected in all sections of the tree and permitted correction of ring widths in roots. Root system, stem and branch showed a basic similarity in their radial sequence of ring width. The annual biomass increment was weaker and more variable with several consecutive changes in the roots than in the stems. The root/shoot ratio reached a minimum rather early, beginning at the cambial age of 20 years. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation in field conditions of a three-dimensional architectural model of the maize root system: Comparison of simulated and observed horizontal root maps

Most existing water and nutrient uptake models are based on the assumption that roots are evenly distributed in the soil volume. This assumption is not realistic for field conditions, and significantly alters water or nutrient uptake calculations. Therefore, development of models of root system growth that account for the spatial distribution of roots is necessary.The objective of this work was to test a three dimensional architectural model of the maize root system by comparing simulated horizontal root maps with observed root maps obtained from the field. The model was built using the current knowledge on maize root system morphogenesis and parameters obtained under field conditions. Simulated root maps (0.45 × 0.75 m) of horizontal cross sections at 3 depths and 3 dates were obtained by using the model for a plant population. Actual root maps were obtained in a deep, barrier-free clay-loamy soil by digging pits, preparing selected horizontal planes and recording root contacts on plastic sheets.Results showed that both the number of cross-sections of axile roots, and their spatial distribution characterized with the R-index value of Clark and Evans (1954), were correctly accounted for by the model at all dates and depths. The number of cross-sections of laterals was also correctly predicted. However, laterals were more clustered around axile roots on simulated root maps than on observed root maps. Although slight discrepancies appeared between simulated and observed root maps in this respect, it was concluded that the model correctly accounted for the general colonization pattern of the soil volume by roots under a maize crop.     

Growth rings in the roots of temperate forbs are robust annual markers

There is increasing interest in the analysis of annual growth rings in the secondary root xylem of perennial forbs (herb-chronology). Therefore, we need to verify whether these growth rings are always formed annually. To investigate the formation of root rings we performed common garden experiments at two distinct sites in Switzerland. We grew nine unrelated forb species from seed and subjected them to competition and clipping treatments. Anatomical developments in the roots of the individuals were tracked during five growing seasons. Across all species and treatments at least 94 % of the expected growth rings associated with full growing seasons were identifiable and the development of the anatomical patterns was consistently seasonal. While the distinctness of annual rings varied somewhat between species and sites, the treatments had no effect on the presence of annual rings. In no case were false rings developed. The results of this study demonstrate that the growth rings in the roots of northern temperate forbs represent robust annual growth increments and, hence, can reliably be used in herb-chronological studies of age- and growth-related questions in plant ecology.     

Effect of climate on the growth of annual rings in the main roots of perennial forbs in an Inner Mongolian semi‐arid grassland,China

Question: Is there a pattern in growth of annual rings in roots of perennial forbs in relation to climate and climate extremes in grassland ecosystems? Location: Semi‐arid grassland in Duolun (42°27′N, 116°41′E, 1380 m a.s.l.), central Inner Mongolia, China. Methods: Main roots of three perennial species, Potentilla anserina L., Cymbaria dahurica L. and Lespedeza daurica Schindl., were sampled. Cross‐sections (10–15‐μm thick) were produced from the proximal end of sampled roots using a sledge microtome. Annual growth rings in the main roots were identified and measured by differentiating between earlywood and latewood in the secondary xylem. Relationships between annual growth rings and monthly mean temperature and total monthly precipitation were identified using correlation analysis. Differences in an annual ring width to the previous and following years were examined by calculating a distinctness score. Results: The three perennial forbs showed clearly demarcated annual growth rings in all individuals and the same fluctuation patterns. Their ring widths were generally positively correlated with precipitation from April to October (except for August) and with temperature from February to June (except June for L. daurica), September to October, and the annual mean. Strong deviations of annual ring widths from their neighbour rings were observed in 1998 and 2000. The trend of absolute distinctness scores (D_m) increased significantly from 1988 to 2003, indicating an increase in the frequency of annual ring width variation. Conclusions: Annual growth rings in the main roots of three perennial forb species can be used as an indicator of the influence of climate on below‐ground grassland growth. The change in below‐ground conditions and effects on the functioning of grassland should receive more attention in future studies.     

Fine root growth and element concentrations of Norway spruce as affected by wood ash and liquid fertilisation

A field experiment to test various management practices of sustainable forestry was conducted in a Swiss spruce forest for two growing seasons. Treatments were a control (C), yearly application of 4000 kg ha^–1 wood ash (A), daily irrigation with a steady state fertilisation as `optimal nutrition` (F) and irrigation with a water control (W). Samples were taken on a 5 × 5 m grid once a year with a soil corer to determine fine root biomass ( 2 mm) and soil pH of the topsoil. A subset of the fine root samples was further analysed for its nutrient composition by CN and ICP-AES analyses. The dynamics of root growth were observed with the aid of ingrowth-cores after 1, 1.5, and 2 years of treatment and the growth pattern was analysed in terms of biomass, tips, forks, length and root diameter of the samples. The A, F and also the W treatment resulted in a significant increase of soil pH in the topsoil. The fine root density increased over the two growing seasons, irrespective of the treatment. The root growth was only slightly different between the treatments with a initially faster growth under the A treatment. The W treatment reduced the number of root tips and forks, and the root length, while the A treatment increased the number of root tips, forks and the root length, but reduced the diameter. The differences between the three harvesting times (March 1999, October 1999, March 2000) of the ingrowth-cores stressed seasonal differences in root growth and the development of quasi `steady state' root dynamics. The root turnover was not changed by the treatments. The elements in the fine roots were strongly affected by the treatments A and F and sometimes by W. Fine root N increased with the F treatment, while C concentrations decreased under the A, F and W treatments. The Ca and Mg concentrations were strongly enhanced by A but also by the F treatment. The K and P concentrations in the fine roots were improved by all three applications. Due to the pH increase Al, Fe and Mn concentrations in the fine roots were decreased by the A and F treatments. S and Zn concentrations showed inconsistent changes over the growing seasons. The results of this study were comparable with those of other studies in Europe and confirm the abilities of the fine roots as indicators of forest nutrition, to some extent more sensitive than the commonly used foliar analysis.     

OsCYT-INV1 for alkaline/neutral invertase is involved in root cell development and reproductivity in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L<Emphasis Type="Italic">.</Emphasis>)

A short root mutant was isolated from an EMS-generated rice mutant library. Under normal growth conditions, the mutant exhibited short root, delayed flowering, and partial sterility. Some sections of the roots revealed that the cell length along the longitudinal axis was reduced and the cell shape in the root elongation zone shrank. Genetic analysis indicated that the short root phenotype was controlled by a recessive gene. Map-based cloning revealed that a nucleotide substitution causing an amino acid change from Gly to Arg occurred in the predicted rice gene (Os02g0550600). It coded an alkaline/neutral invertase and was homologous to Arabidopsis gene AtCyt-inv1. This gene was designated as OsCyt-inv1. The results of carbohydrate analysis showed an accumulation of sucrose and reduction of hexose in the Oscyt-inv1 mutant. Exogenously supplying glucose could rescue the root growth defects of the Oscyt-inv1 mutant. These results indicated that OsCyt-inv1 played important roles in root cell development and reproductivity in rice.