Differential belowground allelopathic effects of leaf and root of Mikania micrantha

This study evaluates the relative contributions of leaves and roots to the belowground allelopathic effects of Mikania micrantha. The hypothesis that leaves contribute more to the allelopathic effect than roots was experimentally tested. We assessed the allelopathic effects of aqueous extracts from Mikania leaves and roots on the seed germination and seedling growth of two co-occurring woody plants in southern China, Lagerstroemia indica L. and Robinia pseudoacacia L. The results showed that the aqueous extracts from Mikania leaves and roots had inhibitory effects on the woody species. Allelopathic activity depended on the concentration of the extracts, target species, and the extract sources (i.e., leaves vs. roots of Mikania). Leaf extract showed stronger allelopathic effects than root extract on germination percentage, initial germination time, speed of germination, and shoot height; while root extract had greater allelopathic effects on roots than leaf extract. The latter phenomenon might greatly promote the invasion success of Mikania due to more direct and effective allelopathy of root. Our results suggest that allelopathy of root extract on belowground biomass might be greater than that of leaf extract for some species in contrast allelopathy of leaf extract on belowground biomass might also be greater than that of root extract for other species, at least for their effects on root growth of the target species.     

外来红树植物拉关木对乡土种桐花树和正红树的化感作用研究

为了探究外来红树植物拉关木对乡土红树植物的化感作用,该研究观察了不同浓度(0.1、0.3、0.5g·mL~(-1))的拉关木根、叶水浸提液对乡土红树植物桐花树和正红树的胚轴(种子)萌发、幼苗生长及叶片抗氧化酶活性的影响。结果表明:(1)拉关木水浸提液对桐花树种子的成苗率、萌发指数和根长均存在抑制作用,其中对根长的抑制作用随水浸提液浓度的提高而增强。(2)根水浸提液对桐花树幼苗的根长、苗高、生物量等生长指标的影响总体上均表现为低浓度促进,高浓度抑制。(3)拉关木水浸提液对正红树胚轴的萌发率、萌发指数、生长指标均表现为促进作用,且根水浸提液0.1、0.3 g·mL~(-1)处理组的芽长以及根、叶水浸提液0.1、0.3 g·mL~(-1)处理组的生物量显著大于对照组;拉关木水浸提液对正红树幼苗的生物量也表现为促进作用。(4)抗性生理方面,随着拉关木水浸提液浓度的升高,桐花树和正红树幼苗SOD活性降低,正红树幼苗POD活性在根水浸提液0.3 g·mL~(-1)和叶水浸提液0.1 g·mL~(-1)处理组显著高于对照组。以上结果表明,不同乡土植物对拉关木化感作用的敏感性不同,拉关木水浸提液抑制了桐花树的生长,而对正红树的生长则表现出一定程度的促进作用。     

Infection with the fungal endophyte Epichloë festucae may alter the allelopathic potential of red fescue

Red fescue (Festuca rubra) is a perennial grass used as both forage and turfgrass. Asymptomatic plants of this species are systemically infected by the fungal endophyte Epichloë festucae, which has a beneficial effect on the infected plants. The aim of this study was to determine the effect of the endophyte Epichloë festucae on the allelopathic potential of F. rubra against four associated pasture species that are also considered as weeds in lawns, Trifolium pratense, Trifolium repens, Lotus corniculatus and Plantago lanceolata. Two experiments were designed to evaluate the allelopathic effect of extracts from the roots and leaves of endophyte‐infected (E+) and non‐infected (E?) plants on the germination and seedling growth of the four target species. Regardless of the endophyte status of the host plant, leaf extracts elicited a stronger reduction in germination and seedling growth than root extracts. Extracts from E+ plants reduced the speed of germination index of Trifolium spp. to a greater extent than those from E? plants. Radicle length of the target species was the parameter most affected by the presence of the endophyte in F. rubra. Root extracts from E+ plants had a greater inhibitory effect on the radicle growth of the target species than did root extracts from E? plants. A greater concentration in total phenolic compounds was found in the roots of E+ plants than of E?; however, this difference was not observed in the leaves. Thus, the allelopathic potential of F. rubra is altered in infected plants.     

铁核桃根与叶水浸提液对果园间作绿肥植物的化感作用及其生理机制

以西南地区具有代表性的16种绿肥植物为受体材料,采用培养皿药膜法研究了铁核桃(Juglans sigillata)根水浸提液对受体种子发芽率及幼苗鲜重、干重的化感效应;并进一步研究了铁核桃根、叶水浸提液和胡桃醌对化感效应存在明显差异的4种绿肥植物(绿豆、红三叶、白三叶、花生)种子萌发与幼苗生长以及抗氧化酶特性的影响,以筛选适宜中国西南地区核桃园种植的绿肥植物,探讨核桃根和凋落物对绿肥作物的化感作用机制。结果表明:(1)铁核桃根水浸提液对绿豆的发芽率没有影响,但对绿豆幼苗鲜重和干重有显著抑制作用,而对其他15种绿肥的发芽率和鲜重、干重均有抑制作用。(2)胡桃醌显著抑制绿豆种子萌发,而铁核桃根或叶水浸提液对绿豆种子萌发没有影响。(3)铁核桃根或叶水浸提液以及胡桃醌对绿肥植物幼苗生长的化感效应趋势一致,但核桃根或叶水浸提液的化感效应强于胡桃醌。(4)绿豆幼苗在铁核桃根或叶水浸提液以及胡桃醌处理下,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性均高于其他3种(红三叶、白三叶、花生)受体幼苗,表明绿豆清除活性氧能力高,细胞受损害程度较低,受化感作用影响最弱。研究认为,绿豆为适宜中国西南地区幼龄核桃园种植的间作绿肥植物。     

Leaf and root extracts of the invasive shrub, Lonicera maackii, inhibit seed germination of three herbs with no autotoxic effects

In addition to effects mediated by resource competition, some invasive plants may impact surrounding vegetation by secreting compounds that are directly inhibitory to growth. Lonicera maackii, an invasive Asian shrub of forests and open areas in eastern and midwestern North America, has devastating effects on understory vegetation, some of which persist even after this shrub is removed. In this study, we explored the potential of aqueous extracts of the leaves and roots of this plant to inhibit seed germination of Impatiens capensis, Alliaria petiolata, Arabidopsis thaliana, and L. maackii in Petri dish bioassays. Both L. maackii root and leaf extracts significantly decreased germination in the three herb species. This inhibitory effect generally increased with increasing extract concentration and was more pronounced with application of leaf extract than root extract. However, when the same extracts were applied to seeds of L. maackii itself, germination was delayed in some cases, but was not significantly reduced by the end of the experiment. Germination of L. maackii seeds even reached significantly higher levels in some extract treatments than in no-extract controls. This implies that L. maackii can successfully inhibit the germination of other plants with few autotoxic effects and may even promote the germination of its own seeds.     

Allelopathic potential of two sesquiterpene lactones from Magnolia grandiflora L.

The allelopathic effects of the two sesquiterpene lactones, costunolide and parthenolide, isolated from the leaves of Magnolia grandiflora L. were evaluated on the wheat (Triticum aestivum L.), lettuce (Lactuca sativa L.), radish (Raphanus sativus L.) and onion (Allium cepa L.). Seed germination of the test species was significantly reduced at 500 μg/ml by both compounds. Both sesquiterpenes showed pronounced inhibition of root length of the test species and the inhibitory effect was concentration-dependent. In addition, shoot growth of the four species was significantly inhibited at all the concentrations tested (10–500 μg/ml). Parthenolide reduced germination and inhibited seedling growth more than costunolide. Inhibition of root growth was generally greater than that of shoot growth. The results encourage the use of these sesquiterpenes as models for development of new herbicides.     

Effects of Barium Stress in <i>Brassica juncea</i> and <i>Cakile maritima</i>: The Indicator Role of Some Antioxidant Enzymes and Secondary Metabolites

Soil contamination by toxic trace metal elements, like barium (Ba), may stimulate various undesirable changes in the metabolic activity of plants. The plant responses are fast and with, direct or indirect, generation of reactive oxygen species (ROS). To cope with the stress imposed by the ROS production, plants developed a dual cellular system composed of enzymatic and non-enzymatic players that convert ROS, and their by-products, into stable nontoxic molecules. To assess the Ba stress response of two Brassicaceae species (Brassica juncea, a glycophyte, and Cakile maritime, a halophyte), plants were exposure to different Ba concentrations (0, 100, 200, 300 and 500 μM). The plants response was evaluated through their morphology and development, the determination of plant leaves antioxidant enzymatic activities and by the production of plants secondary metabolites. Results indicated that the two Brassicaceae species have the ability to survive in an environment containing Ba (even at 500 μM). The biomass production of C. maritima was slightly affected whereas an increase in biomass B. juncea was noticed. The stress imposed by Ba activated the antioxidant defense system in the two species, noticed by the changes in the leaves activity of catalase (CAT), ascorbate peroxidase (APX) and guaicol peroxidase (GPX), and of the secondary metabolites, through the production of total phenols and flavonoids. The enzymatic response was not similar within the two plant species: CAT and APX seem to have a more important role against the oxidative stress in C. maritima while in B. juncea is GPX. Overall, total phenols and flavonoids production was more significant in the plants aerial part than in the roots, of the both species. Although the two Brassicaceae species response was different, in both plants catalytic and non-catalytic transformation of ROS occurs, and both were able to overcome the Ba toxicity and prevent the cell damage.     

4种植物水浸提液对乌丹蒿的化感作用研究

分布于科尔沁沙地西部的固沙先锋植物乌丹蒿近些年呈现出衰退趋势。本研究选取了该地区3种主要飞播植物白沙蒿、柠条、羊柴以及乌丹蒿自身进行了化感作用的研究,结果表明：3种飞播植物及乌丹蒿自身的水浸提液对乌丹蒿的生长均有不同程度的化感作用,并且不同部位（根、叶、果皮或总苞片）中存在的化感物质的作用不同。主要表现为：乌丹蒿种子的萌发率在各供体的根浸提液中均下降,除羊柴外均达到显著,白沙蒿总苞片和羊柴果皮浸提液也有着同样的结果,而乌丹蒿叶浸提液则有一定的促进作用;4种植物不同部位的水浸提液对乌丹蒿种子发芽速度及幼根的生长均有显著的抑制作用。从综合效应来看,4种植物对乌丹蒿均有抑制作用,抑制作用由强到弱的顺序为：白沙蒿>柠条>乌丹蒿>羊柴。     

Potential allelopathic effect of <Emphasis Type="Italic">Eucalyptus</Emphasis><Emphasis Type="Italic">grandis</Emphasis> across a range of plantation ages

Allelopathy of the eucalypt has been considered as an important mechanism for the biodiversity reduction in the eucalypt plantation. To understand the allelopathic potential of the eucalypt (Eucalyptus grandis) roots and rhizosphere soil along a chronosequence (2, 4, 6, 8, 10 years), the germination and growth characteristics of three plant species (Raphanus sativus, Phaseolus aureus, and Lolium perenne) growing nearby or beneath the eucalypt plantations were measured. The results showed that aqueous extract of E. grandis root suppressed the germination and early seedling growth of the target plants. The younger E. grandis exhibited a comparatively stronger allelopathic potential. The highest dose root extracts from 4 years old E. grandis showed the strongest inhibitory effects on the germination rates of the target species, the inhibitory rates were about 48, 51.2, and 56.56% for R. sativus, P. aureus, and L. perenne, respectively. However, present biotests of rhizosphere soils from 6, 8, and 10-year-old plantations exhibited a remarkable stimulative effect on L. perenne, which indicated that the soil might neutralize or dilute allelopathic agents with the increase of plantation age. In addition, according to GC–MS analysis, more allelopathic potential compounds were found in the rhizosphere soil and roots of younger E. grandis plantation. Moreover, more allelochemicals were obtained from soil than from roots. The allelopathic compounds in roots and rhizosphere soil may play important roles in allelopathy of E. grandis plantation. More attention should be paid to the younger E. grandis plantations for the relative higher allelopathic effects.     

POTENTIAL OF DISCARIA AMERICANA FOR METAL STABILIZATION ON SOILS AMENDED WITH BIOSOLIDS AND ASH-SPIKED BIOSOLIDS

Biosolids (B) may contain various types of environmental pollutants, which can exert phytotoxic effects in plants. The effect of aqueous extracts on seed germination and the primary root growth of discaria (Discaria americana) obtained from different soil-application rates of B and a mixture of B and incinerated B were investigated. The objective was to evaluate the potential use of discaria for the stabilization of B-amended soils. Ryegrass (Lolium perenne L.) was used for comparison. Compared to ryegrass, relative seed germination (RSG) was significantly lower for discaria. RSG of discaria and rye grass was inversely correlated to the electrical conductivity of extracts, although a significant adverse effect was only observed for ryegrass with the highest dose of the mixture of B and incinerated B. This dose also produced a reduction in the germination index of discaria, which could not be correlated with the parameters studied. The B extracts did not exert any significant adverse effect on the relative root growth of both species. An increase in relative root growth and germination index was observed for discaria with a field application rate equivalent of 156 t DW ha^?1 of B, suggesting a stimulating effect of the amendment. The results obtained in this study suggest that germinated seedlings of discaria might be used for the stabilization of B-amended soils. However, further greenhouse and field experiments should be performed to confirm these findings.     

Phytotoxicity induced by Phragmites australis: an assessment of phenotypic and physiological parameters involved in germination process and growth of receptor plant

This study investigated the possible phytotoxicity induced by Phargmites australis on phenotypic and physiological parameters of recipient plants with identification of major inhibitors in the donor plant. This was achieved using aqueous extracts of different organs and root exudates of P. australis in laboratory and greenhouse experiments with Lactuca sativa as the model test plant. The observed reduced liquid imbibition and altered resource mobilization in seeds of L. sativa, in particular an insufficient carbohydrate supply, demonstrated that the onset of germination might be negatively affected by phytotoxicity. Dose-response studies pointed out that oxidative stress through reactive oxygen species production could potentially cause the observed germination and seedling growth reductions. The osmotic effects by mannitol solution on germination as well as growth and physiology at a level of ?0.57 and ?0.45 bar, respectively, demonstrated that the results from aqueous plant extracts were partially induced by the osmotic potential on and above those levels. Overall, the relative strength of inhibition on measured parameters was the highest in leaf extract, followed by rhizome, root, stem, and inflorescence. Root exudates of P. australis also had negative impacts by reducing germination and growth of plant. High-performance liquid chromatography (HPLC) analysis revealed gallic acid, a potent phytotoxin, as a major compound with an order of leaf >inflorescence>rhizome>root>stem.     

紫茎泽兰叶片水浸液对蚕豆的化感效应

外来入侵植物可以通过淋溶、自然挥发、根系分泌和植株凋落物分解等途径向周围环境释放化感物质,抑制伴生植物的生长、发育。该研究以不同浓度紫茎泽兰(Eupatorium adenophorum)叶片水浸液处理蚕豆(Vicia faba)种子,研究紫茎泽兰叶片水浸液对蚕豆根尖细胞微核、染色体畸变、细胞凋亡、蚕豆幼苗叶片叶绿素和N含量、光合生理特性、生物量的影响。结果表明:(1)紫茎泽兰叶片水浸液处理显著抑制蚕豆根尖的伸长和细胞的有丝分裂,并诱导蚕豆根尖细胞染色体畸变和细胞微核的产生,有丝分裂指数随着叶片水浸液浓度增加而减小,根尖细胞微核率随叶片水浸液浓度增加而增大,高浓度叶片水浸液处理对蚕豆根尖细胞的凋亡及坏死有明显影响。(2)紫茎泽兰叶片水浸液处理引起蚕豆幼苗叶片的叶绿素和N含量显著降低,并导致蚕豆幼苗最大净光合速率和生物量的显著下降。总之,紫茎泽兰叶片水浸液可能引起蚕豆根尖的氧化损伤和抑制根尖的伸长,且叶片水浸液的抑制作用呈现一定的剂量效应。紫茎泽兰叶片水浸液对蚕豆根尖的损伤和抑制作用可能影响了植株对氮素的吸收,进而对蚕豆幼苗光合生理表现以及生物量积累产生显著负面效应。     

Allelopathy and the allelothathic activity of a phenylpropanol from cucumber plants

The growth inhibitory effect of cucumber (Cucumis sativus L.) plants after crop harvested was investigated. Aqueous methanol extracts of the cucumber plants inhibited the growth of roots and shoots of cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), ryegrass (Lolium multiflorum L.), timothy (Pheleum pratense L.), crabgrass (Digitaria sanguinalis L.), Echinochloa crus-galli (L.) Beauv and Echinochloa colonum (L.) Link, and increasing the extract concentration increased the inhibition. These results suggest that cucumber plants may possess allelopathic activity. The aqueous methanol extract of cucumber plants was divided into ethyl acetate and aqueous fractions, and the growth inhibitory activity of ethyl acetate fraction was greater than that of aqueous fraction. Thus, ethyl acetate fraction was further purified and a main allopathically active substance in the fraction was isolated and determined as (S)-2-benzoyloxy-3-phenyl-1-propanol by spectral data. This substance inhibited root and shoot growth of cress seedlings at concentrations greater than 10 μM, and the concentration required for 50% inhibition of root and shoot growth was 21 and 23 μM, respectively. These results suggest that (S)-2-benzoyloxy-3-phenyl-1-propanol may contribute to the growth inhibitory effect of cucumber plants and may play an important role in cucumber allelopathy. Thus, cucumber plants may be potentially useful for weed management in a field setting. An erratum to this article can be found at     

The effect of ethylene, octanoic acid and a plant-derived smoke extract on the germination of light-sensitive lettuce seeds

The effects of an aqueous plant-derived smoke extract, octanoic acid and ethylene on germination of light-sensitive Grand Rapids lettuce seeds were investigated. The smoke extract brought about a concentration dependent increase in germination and a complete inhibition of germination at high concentrations. Octanoic acid could not induce germination. Ethylene at concentrations over 5 L L^–1 increased lettuce seed germination, but not to the same degree as smoke. Aqueous smoke in combination with ethylene showed a synergistic effect on germination at suboptimal smoke concentrations. At high smoke concentrations the effect of ethylene was almost completely inhibited. Octanoic acid in combination with ethylene brought about a higher level of germination than with ethylene alone, but only at the highest concentration of octanoic acid tested (1 mM). Standardized hexane and dichloromethane-partitioned smoke extracts and octanoic acid were subjected to TLC separation. The R _f -fractions in the smoke lanes showing activity in the lettuce seed bioassay did not correspond to the R _f -value of octanoic acid. As aqueous smoke can withstand autoclaving and can be separated by TLC and HPLC without loosing activity it is unlikely that the activity of aqueous smoke is linked to ethylene. It thus appears that the active compound in smoke is neither octanoic acid nor ethylene.Abbreviations TLC thin layer chromatography - HPLC High performance liquid chromatography     

Allantoin Alleviates Seed Germination Thermoinhibition in <i>Arabidopsis</i>

Allantoin as the metabolite of purine catabolism can store and remobilize nitrogen for plant growth and development. However, emerging evidence suggests it also contributes to plant tolerance to stress response through altering abscisic acid (ABA) and reducing reactive oxygen species (ROS) level. 1-CYS PEROXIREDOXIN (PER1) is a seed-specific antioxidant that enhances seed longevity through scavenging ROS over-accumulation. High temperature (HT) suppresses seed germination and induces seed secondary dormancy, called as seed germination thermoinhibition. However, the mechanism that allantoin and PER1 regulate seed germination thermoinhibition remains unknown. In this study, we reported that allantoin treatment enhances seed germination under HT stress. Consistently, the aln mutants displayed higher seed germination, as well as more accumulation of endogenous allantoin, than that of wild-type control. Further biochemical and genetic analyses showed that allantoin reduces ABA content under HT, and allantoin targets PER1 to efficiently scavenge HT-induced ROS accumulation, meanwhile, the function of allantoin requires PER1 during seed gemination thermotolerance. Collectively, our finding proposes a novel function of allantoin in enhancing seed germination tolerance to HT, and uncovers the underlying mechanism by which allantoin regulates seed germination through altering ABA metabolism and PER1-mediated ROS level under HT stress.     

Activation of an oxidative burst is a general feature of sensitive plants exposed to the air pollutant ozone

Ozone exposure stimulates an oxidative burst in leaves of sensitive plants, resulting in the generation and accumulation of hydrogen peroxide (H₂O₂) in tobacco and tomato, and superoxide (O₂^–?) together with H₂O₂ in Arabidopsis accessions. Accumulation of these reactive oxygen species (ROS) preceded the induction of cell death, and both responses co‐occurred spatially in the periveinal regions of the leaves. Re‐current ozone exposure of the sensitive tobacco cv. Bel W3 in closed chambers or in the field led to an enlargement of existing lesions by priming the border cells for H₂O₂ accumulation. Open top chamber experiments with native herbaceous plants in the field showed that Malva sylvestris L. accumulates O₂^–? at those sites that later exhibit plant cell death. Blocking of ROS accumulation markedly reduced ozone‐induced cell death in tomato, Arabidopsis and M. sylvestris. It is concluded that ozone triggers an in planta generation and accumulation of H₂O₂ and/or O₂^–? depending on the species, accession and cultivar, and that both these reactive oxygen species are involved in the induction of cell death in sensitive crop and native plants.     

Titanium Dioxide Nanoparticles Promote Root Growth by Interfering with Auxin Pathways in <i>Arabidopsis thaliana</i>

TiO₂ nanoparticles (nano-TiO₂) are widely used in the world, and a considerable amount of nano-TiO₂ is released into the environment, with toxic effects on organisms. In the various species of higher plants, growth, including seed germination, root elongation, and biomass accumulation, is affected by nano-TiO₂. However, the underlying molecular mechanisms remain to be elucidated. In this study, we observed that nano-TiO₂ promoted root elongation in a dose-dependent manner. Furthermore, we found that nano-TiO₂ elevated auxin accumulation in the root tips of the auxin marker lines DII-VENUS and DR5:: GUS, and, correspondingly, quantitative real-time PCR analysis revealed that nano-TiO₂ increased the expression levels of auxin biosynthesis- and transportrelated genes. GFP fluorescence observation using transgenic PIN2-GFP indicated that nano-TiO₂ promoted root growth by inducing PIN2 accumulation. Thus, we propose that nano-TiO₂ promote root growth in Arabidopsis thaliana by altering the expression levels of auxin biosynthesis- and transport-related genes.     

黄顶菊茎叶浸提液对白菜和水稻幼苗化感作用的初步研究

研究了不同浓度的黄顶菊茎叶浸提液对白菜和水稻幼苗的化感作用.结果表明:黄顶菊茎叶浸提液显著地抑制了白菜和水稻幼苗的根长和苗高,降低了白菜和水稻的根系活力,提高了丙二醛含量,并且增大了受体细胞膜透性,使细胞内含物外渗,导致电导率值增高;同时,黄顶菊茎叶浸提液对白菜和水稻的过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性均有显著的抑制作用,导致受体对外界不良环境的抵抗力降低.由此可见黄顶菊通过影响植物体内的一系列生理过程,降低植物对环境的抗胁迫能力,使受体植物的生长发育受到抑制,从而表现出强烈的化感作用.综合各项指标可以看出,白菜较水稻对黄顶菊化感作用较敏感.     

Allelopathic effect of <Emphasis Type="Italic">Nepeta meyeri</Emphasis> Benth. extracts on seed germination and seedling growth of some crop plants

In order to evaluate the allelopathic potential of Nepeta meyeri Benth., the effects of aqueous extracts (0.125, 0.25, 0.5, 1, 2.5 and 5%) prepared from roots and leaves of N. meyeri were studied on the seed germination and seedling growth of several economically important crops (barley, wheat, canola, safflower, and sunflower). Both the root and leaf extracts of N. meyeri caused a general phytotoxic effect on the seed germination and seedling growth of barley and sunflower at all concentrations. However, both the root and leaf extracts significantly increased the seedling growth of wheat, especially at the lower concentrations 0.125, 0.25 and 0.5%, whereas the higher concentrations had a neutral effect. The seed germination and the seedling growth of canola and safflower were also generally improved by both extracts, especially at lower concentrations. However, these advantages were not observed at higher concentrations, at which the extracts mostly had a phytotoxic effect on canola and safflower. The Allelopathic activity of N. meyeri depended on whether the extract was derived from the leaf or root parts of the plant. The maximum allelopathic effect occurred with leaf extracts. The results demonstrate that the aqueous extracts from N. meyeri have allelopathic potential and should be evaluated as an allelopathic species, presenting a risk or advantage to seed germination and seedling growth of crop or weed plants.     

Phenotype Analysis and Fine Mapping of the Male Sterile Mutant <i>ms10</i> in Rice (<i>Oryza sativa</i> L.)

There is a positive correlation between fertility and yield, and the decrease of fertility is bound to a greatly reduced crop yield. Male sterile mutants can be used in hybrid rice. Therefore, rice male sterility has an important value in research and application, and the study of related mutants is also very vital. The mutant ms10 (male sterile 10) reported in this study was induced by ethyl methane sulfonate (EMS) in the indica maintainer line Xinong 1B. There was no significant difference between the ms10 and wild type in the vegetative growth stage. However, in the reproductive growth stage, ms10 showed that the plant became shorter, the anther became smaller and the color became lighter, and finally showed the phenotype of male sterility in comparison to the wild type. I₂-KI staining showed that the pollen was malformed and only a little was active. Scanning electron microscopy observation showed that the exine waxy layer of the ms10 anther decreased, suggesting that the protective effect on pollen was decreased. This may be one of the reasons leading to the phenotype of male sterility. Finally, the pollen showed shrinkage and collapsed, and the structure of germinating pore cover disappeared. This may be the result of sterility. Genetic analysis showed that the male sterility phenotype of the mutant was controlled by a single recessive nuclear gene. MS10 was mapped between the molecular markers IND37 and IND51 on chromosome 4, with a physical distance of 178.6 kb. These results lay the foundation for further studies on MS10.