The TaSOC1-TaVRN1 module integrates photoperiod and vernalization signals to regulate wheat flowering.

Wheat needs different durations of vernalization, which accelerates flowering by exposure to cold temperature, to ensure reproductive development at the optimum time, as that is critical for adaptability and high yield. TaVRN1 is the central flowering regulator in the vernalization pathway and encodes a MADS-box transcription factor (TF) that usually works by forming hetero- or homo-dimers. We previously identified that TaVRN1 bound to an MADS-box TF TaSOC1 whose orthologues are flowering activators in other plants. The specific function of TaSOC1 and the biological implication of its interaction with TaVRN1 remained unknown. Here, we demonstrated that TaSOC1 was a flowering repressor in the vernalization and photoperiod pathways by overexpression and knockout assays. We confirmed the physical interaction between TaSOC1 and TaVRN1 in wheat protoplasts and in planta, and further validated their genetic interplay. A Flowering Promoting Factor 1-like gene TaFPF1-2B was identified as a common downstream target of TaSOC1 and TaVRN1 through transcriptome and chromatin immunoprecipitation analyses. TaSOC1 competed with TaVRT2, another MADS-box flowering regulator, to bind to TaVRN1; their coding genes synergistically control TaFPF1-2B expression and flowering initiation in response to photoperiod and low temperature. We identified major haplotypes of TaSOC1 and found that TaSOC1-Hap1 conferred earlier flowering than TaSOC1-Hap2 and had been subjected to positive selection in wheat breeding. We also revealed that wheat SOC1 family members were important domestication loci and expanded by tandem and segmental duplication events. These findings offer new insights into the regulatory mechanism underlying flowering control along with useful genetic resources for wheat improvement.

Rht12b, a widely used ancient allele of TaGA2oxA13, reduces plant height and enhances yield potential in wheat.

KEY MESSAGE: We identified a new wheat dwarfing allele Rht12b conferring reduced height and higher grain yield, pinpointed its causal variations, developed a breeding-applicable marker, and traced its origin and worldwide distribution. Plant height control is essential to optimize lodging resistance and yield gain in crops. RHT12 is a reduced height (Rht) locus that is identified in a mutationally induced dwarfing mutant and encodes a gibberellin 2-oxidase TaGA2oxA13. However, the artificial dwarfing allele is not used in wheat breeding due to excessive height reduction. Here, we confirmed a stable Rht locus, overlapping with RHT12, in a panel of wheat cultivars and its dwarfing allele reduced plant height by 5.4-8.2 cm, equivalent to Rht12b, a new allele of RHT12. We validated the effect of Rht12b on plant height in a bi-parent mapping population. Importantly, wheat cultivars carrying Rht12b had higher grain yield than those with the contrasting Rht12a allele. Rht12b conferred higher expression level of TaGA2oxA13. Transient activation assays defined SNP-390(C/A) in the promoter of TaGA2oxA13 as the causal variation. An efficient kompetitive allele-specific PCR marker was developed to diagnose Rht12b. Conjoint analysis showed that Rht12b plus the widely used Rht-D1b, Rht8 and Rht24b was the predominant Rht combination and conferred a moderate plant height in tested wheat cultivars. Evolutionary tracking uncovered that RHT12 locus arose from a tandem duplication event with Rht12b firstly appearing in wild emmer. The frequency of Rht12b was approximately 70% (700/1005) in a worldwide wheat panel and comparable to or higher than those of other widely used Rht genes, suggesting it had been subjected to positive selection. These findings not only identify a valuable Rht gene for wheat improvement but also develop a functionally diagnostic tool for marker-assisted breeding.

Fine mapping and characterization of a major QTL for plant height on chromosome 5A in wheat.

KEY MESSAGE: We precisely mapped QPH.caas-5AL for plant height in wheat, predicted candidate genes and confirmed genetic effects in a panel of wheat cultivars. Plant height is an important agronomic trait, and appropriately reduced height can improve yield potential and stability in wheat, usually combined with sufficient water and fertilizer. We previously detected a stable major-effect quantitative trait locus QPH.caas-5AL for plant height on chromosome 5A in a recombinant inbred line population of the cross 'Doumai × Shi 4185' using the wheat 90 K SNP assay. Here , QPH.caas-5AL was confirmed using new phenotypic data in additional environment and new-developed markers. We identified nine heterozygous recombinant plants for fine mapping of QPH.caas-5AL and developed 14 breeder-friendly kompetitive allele-specific PCR markers in the region of QPH.caas-5AL based on the genome re-sequencing data of parents. Phenotyping and genotyping analyses of secondary populations derived from the self-pollinated heterozygous recombinant plants delimited QPH.caas-5AL into an approximate 3.0 Mb physical region (521.0-524.0 Mb) according to the Chinese Spring reference genome. This region contains 45 annotated genes, and six of them were predicted as the candidates of QPH.caas-5AL based on genome and transcriptome sequencing analyses. We further validated that QPH.caas-5AL has significant effects on plant height but not yield component traits in a diverse panel of wheat cultivars; its dwarfing allele is frequently used in modern wheat cultivars. These findings lay a solid foundation for the map-based cloning of QPH.caas-5AL and also provide a breeding-applicable tool for its marker-assisted selection. Keymessage We precisely mapped QPH.caas-5AL for plant height in wheat, predicted candidate genes and confirmed genetic effects in a panel of wheat cultivars.

Dissecting pleiotropic functions of the wheat Green Revolution gene Rht-B1b in plant morphogenesis and yield formation.

The utilization of reduced plant height genes Rht-B1b and Rht-D1b, encoding homeologous DELLA proteins, led to the wheat Green Revolution (GR). However, the specific functions of GR genes in yield determination and the underlying regulatory mechanisms remained unknown. Here, we validated that Rht-B1b, as a representative of GR genes, affects plant architecture and yield component traits. Upregulation of Rht-B1b reduced plant height, leaf size and grain weight, but increased tiller number, tiller angle, spike number per unit area, and grain number per spike. Dynamic investigations showed that Rht-B1b increased spike number by improving tillering initiation rather than outgrowth, and enhanced grain number by promoting floret fertility. Rht-B1b reduced plant height by reducing cell size in the internodes, and reduced grain size or weight by decreasing cell number in the pericarp. Transcriptome analyses uncovered that Rht-B1b regulates many homologs of previously reported key genes for given traits and several putative integrators for different traits. These findings specify the pleiotropic functions of Rht-B1b in improving yield and provide new insights into the regulatory mechanisms underlying plant morphogenesis and yield formation.

Circ_ZFR affects FABP7 expression to regulate breast cancer progression by acting as a sponge for miR-223-3p.

BACKGROUND: Breast cancer (BC) is a common malignancy in women. Circular RNAs (circRNAs) have been reported to play a key role in the development of BC; however, the effect of circular RNA zinc finger RNA binding protein (circ_ZFR) in BC is unknown. METHODS: Abundances of circ_ZFR, fatty acid binding protein 7 (FABP7), and microRNA-223-3p (miR-223-3p) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The circular structure of circ_ZFR was validated by RNase R treatment. Cell proliferation, migration, invasion, and apoptosis were assessed by colony formation, cell counting kit-8, Transwell, flow cytometry assays, respectively. All protein levels were determined by Western blot. Dual-luciferase reporter assay was used to confirm the relationship between miR-223-3p and circ_ZFR or FABP7. A xenograft model was established to understand the effect of circ_ZFR on BC cell growth in vivo. RESULTS: The expression levels of circ_ZFR and FABP7 were higher in BC tissues and cell lines, whereas miR-223-3p expression was lower. Knockdown of circ_ZFR or FABP7 in BC cells reduced proliferation, migration, invasion, and epithelial mesenchymal transition (EMT), and induced apoptosis in vitro, whereas the opposite effects were observed in circ_ZFR-overexpressed cells. Furthermore, circ_ZFR might act as a sponge for miR-223-3p to regulate FABP7 expression, thereby promoting the progression of BC cells in vitro and in vivo. CONCLUSION: Circ_ZFR might act as a miRNA sponge for miR-223-3p to regulate FABP7, thereby promoting proliferation, migration, invasion, and EMT of BC cells, and inhibiting cell apoptosis.

Rht24b, an ancient variation of TaGA2ox-A9, reduces plant height without yield penalty in wheat.

Rht-B1b and Rht-D1b, the 'Green Revolution' (GR) genes, greatly improved yield potential of wheat under nitrogen fertilizer application, but reduced coleoptile length, seedling vigor and grain weight. Thus, mining alternative reduced plant height genes without adverse effects is urgently needed. We isolated the causal gene of Rht24 through map-based cloning and characterized its function using transgenic, physiobiochemical and transcriptome assays. We confirmed genetic effects of the dwarfing allele Rht24b with an association analysis and also traced its origin and distribution. Rht24 encodes a gibberellin (GA) 2-oxidase, TaGA2ox-A9. Rht24b conferred higher expression of TaGA2ox-A9 in stems, leading to a reduction of bioactive GA in stems but an elevation in leaves at the jointing stage. Strikingly, Rht24b reduced plant height, but had no yield penalty; it significantly increased nitrogen use efficiency, photosynthetic rate and the expression of related genes. Evolutionary analysis demonstrated that Rht24b first appeared in wild emmer and was detected in more than half of wild emmer and wheat accessions, suggesting that it underwent both natural and artificial selection. These findings uncover an important genetic resource for wheat breeding and also provide clues for dissecting the regulatory mechanisms underlying GA-mediated morphogenesis and yield formation.

Genome-Wide Linkage Mapping for Preharvest Sprouting Resistance in Wheat Using 15K Single-Nucleotide Polymorphism Arrays.

Preharvest sprouting (PHS) significantly reduces grain yield and quality. Identification of genetic loci for PHS resistance will facilitate breeding sprouting-resistant wheat cultivars. In this study, we constructed a genetic map comprising 1,702 non-redundant markers in a recombinant inbred line (RIL) population derived from cross Yangxiaomai/Zhongyou9507 using the wheat 15K single-nucleotide polymorphism (SNP) assay. Four quantitative trait loci (QTL) for germination index (GI), a major indicator of PHS, were identified, explaining 4.6-18.5% of the phenotypic variances. Resistance alleles of Qphs.caas-3AL, Qphs.caas-3DL, and Qphs.caas-7BL were from Yangxiaomai, and Zhongyou9507 contributed a resistance allele in Qphs.caas-4AL. No epistatic effects were detected among the QTL, and combined resistance alleles significantly increased PHS resistance. Sequencing and linkage mapping showed that Qphs.caas-3AL and Qphs.caas-3DL corresponded to grain color genes Tamyb10-A and Tamyb10-D, respectively, whereas Qphs.caas-4AL and Qphs.caas-7BL were probably new QTL for PHS. We further developed cost-effective, high-throughput kompetitive allele-specific PCR (KASP) markers tightly linked to Qphs.caas-4AL and Qphs.caas-7BL and validated their association with GI in a test panel of cultivars. The resistance alleles at the Qphs.caas-4AL and Qphs.caas-7BL loci were present in 72.2 and 16.5% cultivars, respectively, suggesting that the former might be subjected to positive selection in wheat breeding. The findings provide not only genetic resources for PHS resistance but also breeding tools for marker-assisted selection.

Quantifying senescence in bread wheat using multispectral imaging from an unmanned aerial vehicle and QTL mapping.

Environmental stresses from climate change can alter source-sink relations during plant maturation, leading to premature senescence and decreased yields. Elucidating the genetic control of natural variations for senescence in wheat (Triticum aestivum) can be accelerated using recent developments in unmanned aerial vehicle (UAV)-based imaging techniques. Here, we describe the use of UAVs to quantify senescence in wheat using vegetative indices (VIs) derived from multispectral images. We detected senescence with high heritability, as well as its impact on grain yield (GY), in a doubled-haploid population and parent cultivars at various growth time points (TPs) after anthesis in the field. Selecting for slow senescence using a combination of different UAV-based VIs was more effective than using a single ground-based vegetation index. We identified 28 quantitative trait loci (QTL) for vegetative growth, senescence, and GY using a 660K single-nucleotide polymorphism array. Seventeen of these new QTL for VIs from UAV-based multispectral imaging were mapped on chromosomes 2B, 3A, 3D, 5A, 5D, 5B, and 6D; these QTL have not been reported previously using conventional phenotyping methods. This integrated approach allowed us to identify an important, previously unreported, senescence-related locus on chromosome 5D that showed high phenotypic variation (up to 18.1%) for all UAV-based VIs at all TPs during grain filling. This QTL was validated for slow senescence by developing kompetitive allele-specific PCR markers in a natural population. Our results suggest that UAV-based high-throughput phenotyping is advantageous for temporal assessment of the genetics underlying for senescence in wheat.

TaNAC100 acts as an integrator of seed protein and starch synthesis exerting pleiotropic effects on agronomic traits in wheat.

High-molecular-weight glutenin subunits (HMW-GS) are major components of seed storage proteins (SSPs) and largely determine the processing properties of wheat (Triticum aestivum) flour. HMW-GS are encoded by the GLU-1 loci and regulated at the transcriptional level by interaction between cis-elements and transcription factors (TFs). We recently validated the function of conserved cis-regulatory modules (CCRMs) in GLU-1 promoters, but their interacting TFs remained uncharacterized. Here we identified a CCRM-binding NAM-ATAF-CUC (NAC) protein, TaNAC100, through yeast one-hybrid (Y1H) library screening. Transactivation assays demonstrated that TaNAC100 could bind to the GLU-1 promoters and repress their transcription activity in tobacco (Nicotiana benthamiana). Overexpression of TaNAC100 in wheat significantly reduced the contents of HMW-GS and other SSPs as well as total seed protein. This was confirmed by transcriptome analyses. Conversely, enhanced expression of TaNAC100 increased seed starch contents and expression of key starch synthesis-related genes, such as TaGBSS1 and TaSUS2. Y1H assays also indicated TaNAC100 binding with the promoters of TaGBSS1 and TaSUS2. These results suggest that TaNAC100 functions as a hub controlling seed protein and starch synthesis. Phenotypic analyses showed that TaNAC100 overexpression repressed plant height, increased heading date, and promoted seed size and thousand kernel weight. We also investigated sequence variations in a panel of cultivars, but did not identify significant association of TaNAC100 haplotypes with agronomic traits. The findings not only uncover a useful gene for wheat breeding but also provide an entry point to reveal the mechanism underlying metabolic balance of seed storage products.

Molecular mapping and characterization of QBp.caas-3BL for black point resistance in wheat (Triticum aestivum L.).

KEY MESSAGE: We fine-mapped QBp.caas-3BL for black point resistance in an interval of 1.7 Mb containing five high-confidence annotated genes and developed a KASP marker suitable for selection of QBp.caas-3BL. Wheat black point, which occurs in most wheat-growing regions of the world, is detrimental to grain appearance, processing and nutrient quality. Mining and characterization of genetic loci for black point resistance are helpful for breeding resistant wheat cultivars. We previously identified a major QTL QBp.caas-3BL in a recombinant inbred line (RIL) population of Linmai 2/Zhong 892 across five environments. Here we confirmed the QTL in two additional environments. The genetic region of QBp.caas-3BL was enriched with newly developed markers. Using four sets of near isogenic lines, QBp.caas-3BL was narrowed down to a physical interval of approximately 1.7 Mb, including five annotated genes according to IWGSC reference genome. TraesCS3B02G404300, TraesCS3B02G404600 and TraesCS3B02G404700 were predicted as candidate genes based on the analyses of sequence polymorphisms and differential expression. We also converted a SNP of TraesCS3B02G404700 into a breeding-applicable KASP marker and verified its efficacy for marker-assisted breeding in a panel of germplasm. The findings not only lay a foundation for map-based cloning of QBp.caas-3BL but also provide a useful marker for selection of resistant cultivars genotypes in wheat breeding.

Genetic architecture underlying light and temperature mediated flowering in Arabidopsis, rice, and temperate cereals.

Timely flowering is essential for optimum crop reproduction and yield. To determine the best flowering-time genes (FTGs) relevant to local adaptation and breeding, it is essential to compare the interspecific genetic architecture of flowering in response to light and temperature, the two most important environmental cues in crop breeding. However, the conservation and variations of FTGs across species lack systematic dissection. This review summarizes current knowledge on the genetic architectures underlying light and temperature-mediated flowering initiation in Arabidopsis, rice, and temperate cereals. Extensive comparative analyses show that most FTGs are conserved, whereas functional variations in FTGs may be species specific and confer local adaptation in different species. To explore evolutionary dynamics underpinning the conservation and variations in FTGs, domestication and selection of some key FTGs are further dissected. Based on our analyses of genetic control of flowering time, a number of key issues are highlighted. Strategies for modulation of flowering behavior in crop breeding are also discussed. The resultant resources provide a wealth of reference information to uncover molecular mechanisms of flowering in plants and achieve genetic improvement in crops.

TaVrt2, an SVP-like gene, cooperates with TaVrn1 to regulate vernalization-induced flowering in wheat.

TaVrn1, encoding a MADS-box transcription factor (TF), is the central regulator of wheat vernalization-induced flowering. Considering that the MADS-box TF usually works by forming hetero- or homodimers, we conducted yeast-two-hybrid screening and identified an SVP-like MADS-box protein TaVrt2 interacting with TaVrn1. However, the specific function of TaVrt2 and the biological implication of its interaction with TaVrn1 remained unknown. We validated the function of TaVrt2 and TaVrn1 by wheat transgenic experiments and their interaction through multiple protein-binding assays. Population genetic analysis also was used to display their interplay. Transcriptomic sequencing and chromatin immunoprecipitation assays were performed to identify their common targets. TaVrt2 and TaVrn1 are flowering promoters in the vernalization pathway and interact physically in vitro, in planta and in wheat cells. Additionally, TaVrt2 and TaVrn1 were significantly induced in leaves by vernalization, suggesting their spatio-temporal interaction during vernalization. Genetic analysis indicated that TaVrt2 and TaVrn1 had significant epistatic effects on flowering time. Furthermore, native TaVrn1 was up-regulated significantly in TaVrn1-OE (overexpression) and TaVrt2-OE lines. Moreover, TaVrt2 could bind with TaVrn1 promoter directly. A TaVrt2-mediated positive feedback loop of TaVrn1 during vernalization was proposed, providing additional understanding on the regulatory mechanism underlying vernalization-induced flowering.

Rapid identification and characterization of genetic loci for defective kernel in bread wheat.

BACKGROUND: Wheat is a momentous crop and feeds billions of people in the world. The improvement of wheat yield is very important to ensure world food security. Normal development of grain is the essential guarantee for wheat yield formation. The genetic study of grain phenotype and identification of key genes for grain filling are of great significance upon dissecting the molecular mechanism of wheat grain morphogenesis and yield potential. RESULTS: Here we identified a pair of defective kernel (Dek) isogenic lines, BL31 and BL33, with plump and shrunken mature grains, respectively, and constructed a genetic population from the BL31/BL33 cross. Ten chromosomes had higher frequency of polymorphic single nucleotide polymorphism (SNP) markers between BL31 and BL33 using Wheat660K chip. Totally 783 simple sequence repeat (SSR) markers were chosen from the above chromosomes and 15 of these were integrated into two linkage groups using the genetic population. Genetic mapping identified three QTL, QDek.caas-3BS.1, QDek.caas-3BS.2 and QDek.caas-4AL, explaining 14.78-18.17%, 16.61-21.83% and 19.08-28.19% of phenotypic variances, respectively. Additionally, five polymorphic SNPs from Wheat660K were successfully converted into cleaved amplified polymorphic sequence (CAPS) markers and enriched the target regions of the above QTL. Biochemical analyses revealed that BL33 has significantly higher grain sucrose contents at filling stages and lower mature grain starch contents than BL31, indicating that the Dek QTL may be involved in carbohydrate metabolism. As such, the candidate genes for each QTL were predicated according to International Wheat Genome Sequence Consortium (IWGSC) RefSeq v1.0. CONCLUSIONS: Three major QTL for Dek were identified and their causal genes were predicted, laying a foundation to conduct fine mapping and dissect the regulatory mechanism underlying Dek trait in wheat.

Molecular Mapping of Reduced Plant Height Gene Rht24 in Bread Wheat.

Height is an important trait related to plant architecture and yield potential in bread wheat (Triticum aestivum L.). We previously identified a major quantitative trait locus QPH.caas-6A flanked by simple sequence repeat markers Xbarc103 and Xwmc256 that reduced height by 8.0-10.4%. Here QPH.caas-6A, designated as Rht24, was confirmed using recombinant inbred lines (RILs) derived from a Jingdong 8/Aikang 58 cross. The target sequences of Xbarc103 and Xwmc256 were used as queries to BLAST against International Wheat Genome Sequence Consortium database and hit a super scaffold of approximately 208 Mb. Based on gene annotation of the scaffold, three gene-specific markers were developed to genotype the RILs, and Rht24 was narrowed to a 1.85 cM interval between TaAP2 and TaFAR. In addition, three single nucleotide polymorphism (SNP) markers linked to Rht24 were identified from SNP chip-based screening in combination with bulked segregant analysis. The allelic efficacy of Rht24 was validated in 242 elite wheat varieties using TaAP2 and TaFAR markers. These showed a significant association between genotypes and plant height. Rht24 reduced plant height by an average of 6.0-7.9 cm across environments and were significantly associated with an increased TGW of 2.0-3.4 g. The findings indicate that Rht24 is a common dwarfing gene in wheat breeding, and TaAP2 and TaFAR can be used for marker-assisted selection.

Transgenic Eimeria magna Pérard, 1925 Displays Similar Parasitological Properties to the Wild-type Strain and Induces an Exogenous Protein-Specific Immune Response in Rabbits (Oryctolagus cuniculus L.).

Rabbit coccidiosis causes great economic losses to world rabbitries. Little work has been done considering genetic manipulation on the etiological agents, rabbit Eimeria spp. In this study, we constructed a transgenic line of Eimeria magna (EmagER) expressing enhanced yellow fluorescent protein (EYFP) and red fluorescent protein (RFP) using regulatory sequences of Eimeria tenella and Toxoplasma gondii. We observed the life cycle of EmagER and confirmed that the transgenic parasites express exogenous proteins targeted to different cellular compartments throughout the entire life cycle. EYFP was expressed mainly in the nucleus and RFP both in the nucleus and cytoplasm. Then, coccidia-free, laboratory-reared 40-day-old rabbits were primarily infected with either EmagER or wild-type strain oocysts and challenged with the wild-type strain. EmagER showed similar reproductivity and immunogenicity to the wild-type strain. Finally, we examined the foreign protein-specific immune response elicited by EmagER. Rabbits were immunized with either transgenic or wild-type oocysts. Immune response against parasite-soluble antigen, EYFP and RFP in spleen, and mesenteric lymph nodes were detected by quantitative real-time PCR. The relative expression level of IFN-γ, IL-2, and TNF-α were higher in EmagER-immunized rabbits than wild-type parasites-immunized rabbits after stimulation with EYFP and RFP. Our study confirmed that a specific immune response was induced by the exogenous protein expressed by EmagER and favored future studies on application of transgenic rabbit coccidia as recombinant vaccine vectors.

[Forest biomass and its spatial pattern in Guizhou Province].

Based on the forest inventory data of 5500 sampling plots from 1996 to 2000 in Guizhou Province and according to the biomass expansion factors (BEF) of various forest types, the forest biomass in the Province was estimated, with its spatial pattern and its differences between karst and non-karst regions analyzed. In the study period, the total biomass of trees and shrubs on forest and non-forest lands was 3.51 x 10(8) t, 18% and 82% of which came from karst and non-karst regions, respectively. Different forest types had different forest biomass. Forest stands had the highest forest biomass, accounting for 71.4% of the total, and the total forest biomass in karst region was obviously lower than that in non-karst region. Among the dominant tree species and groups, Cunninghamia lanceolata had the highest total biomass (5.38 x 10(7) t), followed by sclerophyll broadleaved woods (4.99 x 10(7) t), Pinus massoniana, P. yunnanensis, and Quercus (2.87 x 10(7) -3.54 x 10(7) t), Cupress (1.52 x 10(7) t) and malacophyll broadleaved woods (1.43 x 10(7) t), and the others (< 1.00 x 10(7) t). Based on the administrative division, the total forest biomass (9.83 x 10(7)t) and forest stand biomass (5.88 x 10(7)t) in South Guizhou were 1-2 folds higher than those in Zunyi, Tongren and Qiannan Districts, and far higher than those in Qianxinan, Bijie, Guiyang, Anshun, and Liupanshui Districts (total forest biomass 0.53 x 10(7) -1.85 x 10(7) t and forest stand biomass 0.16 x 10(7) -0.86 x 10(7)t). High biomass (> 400 t x hm(-2)) and medium-high biomass density (100-400 t x hm(-2)) mainly occurred in the bamboo forest and other forest stands in Southeast, East, and Northwest Guizhou, while medium-low biomass (30-100 t x hm(-2)) occurred in the forest and non-forest areas of the Province. Low forest biomass (0-30 t x hm(-2)) mainly occurred in karst region. Overall, the forest biomass in the Province was relatively low, being closely related to the topography of plateau and mountains, the rocky-desertification in karst region, and the shallow soil layer and dry habitat under karst forests, as well as the strong disturbance of human activities.