Mapping and Functional Analysis of LE Gene in a Lethal Etiolated Rice Mutant at Seedling Stage

An EMS(ethy methanesulfonate)-induced lethal etiolated(le)mutant obtained from the rice variety Zhongjian 100 was characterized by lethal etiolated phenotypes,with significantly reduced levels of chlorophyll a,chlorophyll b,total chlorophyll,and carotenoids.Additionally,the mutant displayed a significantly decreased number of chloroplast grana,along with irregular and less-stacked grana lamellae.The le mutant showed markedly diminished root length,root surface area,and root volume compared with the wild type.It also exhibited significantly lower catalase activity and total protein content,while peroxidase activity was significantly higher.Using the map-based cloning method,we successfully mapped the LE gene to a 48-kb interval between markers RM16107 and RM16110 on rice chromosome 3.A mutation(from T to C)was identified at nucleotide position 692 bp of LOC_Os03g59640(ChlD),resulting in a change from leucine to proline.By crossing HM133(a pale green mutant with a single-base substitution of A for G in exon 10 of ChlD subunit)with a heterozygous line of le(LEle),we obtained two plant lines heterozygous at both the LE and HM133 loci.Among 15 transgenic plants,3 complementation lines displayed normal leaf color with significantly higher total chlorophyll,chlorophyll a,and chlorophyll b contents.The mutation in le led to a lethal etiolated phenotype,which has not been observed in other ChlD mutants.The mutation in the AAA+domain of ChlD disrupted the interaction of ChlDle with ChlI as demonstrated by a yeast two-hybrid assay,leading to the loss of ChlD function and hindering chlorophyll synthesis and chloroplast development.Consequently,this disruption is responsible for the lethal etiolated phenotype in the mutant.

Regulation of phytohormones on root primordium initiation and adventitious root formation in the etiolated shoots of Paeonia suffruticosa'Yinfen Jinlin'

Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mech- nisms of the adventitious rooting and the regulation of rooting processes are the principles and techniques of plant propagation and improvement. Microstructures and fluctuations of phytohormones in the adventitious rooting were studied with the etiolated soft- wood shoots of Paeonia suffkuticosa ＇Yinfen Jinlin＇. There are no pre-primordia in the shoots of the cultivar. Adventitious roots are produced in five stages： shoot selection, primordium initiation, primordium growth, conducting tissue differentiation and root protru- sion. Primordia initiated in the cortex. The contents of the endogenous hormones, IAA, ABA and GA, were 5.842, 0.873 and 1.043 nmol·g^-1 FW on the bases of shoots, respectively. CTKs which included isopentenyl adenine （iPA）, zeatin riboside （ZR） and dihy- drozeatin riboside （DHZR） were 0.949, 0.695 and 2.034 nmol·g^-1 FW, respectively. DHZR is active among CTKs. The ratio of IAA to GA, CTK and ABA clearly increased at the stage of primordium initiation, while they showed low levels at the stages of primor- dium growth. The ratios were restored at the shoot levels at the stage of root protrusion. IBA provoked primordia initiation in the cortex, the vascular cambium, the pith and even in the callus induced on the base of shoots. ]AA levels in the treated shoots increased gradually to its highest level （three times of control） at the stage of conducting tissue differentiation. The ratios of IAA to GA, CTK and ABA clearly decreased at the stage of primordium initiation. The ratio of IAA to ABA is regulated at 10：1.

Overexpression of OsPIL15, a phytochrome-interacting factor-like protein gene, represses etiolated seedling growth in rice

Phytochrome-interacting factors （PIFs） regulate an array of developmental responses ranging from seed germi- nation to vegetational architecture in Arabidopsis. However, information regarding the functions of the PIF family in monocots has not been widely reported. Here, we investigate the roles of OsPIL15, a member of the rice （Oryza sativa L. cv. Nipponbare） PIF family, in regulating seedling growth. OsPIL15 encodes a basic helix-loop-helix factor localized in the nucleus. OsPIL15-OX seedlings exhibit an exaggerated shorter above- ground part and undeveloped root system relative to wild-type seedlings, suggesting that OsPIL15 represses seedling growth in the dark. Microarray analysis combined with gene ontology analysis revealed that OsPIL15 represses a set of genes involved in auxin pathways and cell wall organization or biogenesis. Given the important roles of the auxin pathway and cell wall properties in controlling plant growth, we speculate that OsPIL15 represses seedling growth likely by regulating the auxin pathway and suppressing cell wall organization in etiolated rice seedlings. Additionally, exposure to red light or far-red light relieved growth retardation and promoted seedling elongation in the OsPIL15-OX lines, despite higher levels of OsPIL15 transcripts under red light and far-red light than in the dark. These results suggest that light regulation of OsPIL15 expres- sion is probably involved in photomorphogenesis in rice.

Biochemical Characterization of Soluble Acid and Alkaline Invertases from Shoots of Etiolated Pea Seedlings

Soluble invertase was purified from pea （Pisum sativum L.） by sequential procedures entailing ammonium sulfate precipitation, DEAE-Sepharose column, Con-A- and Green 19-Sepharose affinity columns, hydroxyapatite column, ultra-filtration, and Sephacryl 300 gel filtration. The purified soluble acid （SAC） and alkaline （SALK） invertases had a pH optimum of 5.3 and 7.3, respectively. The temperature optimum of two invertases was 37 ℃. The effects of various concentrations of Tris-HCI, HgCI2, and CuSO4 on the activities of the two purified enzymes were examined. Tris-HCI and HgCI2 did not affect SAC activity, whereas 10 mM Tris-HCI and 0.05 mM HgCI2 inhibited SALK activity by about 50%. SAC and SALK were inhibited by 4.8 mM and 0.6 mM CuSO4 by 50%, respectively. The enzymes display typical hyperbolic saturation kinetics for sucrose hydrolysis. The Kms of SAC and SALK were determined to be 1.8 and 38.6 mM, respectively. The molecular masses of SAC shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting were 22 kDa and 45 kDa. The molecular mass of SALK was 30 kDa. Iso-electric points of the SAC and SALK were estimated to be about pH 7.0 and pH 5.7, respectively.

Rejuvenation and Adventitious Rooting in Coppice-Shoot Cuttings of <i>Tectona grandis</i>as Affected by Stock-Plant Etiolation

The effect of stock-plant etiolation on adventitious rooting of single-node leafy cuttings (SNCs) made from coppice shoots from different age groups of donor plants were investigated for teak (Tectona grandis Linn. f.). When donor plants age were 1-, 2-, 3-, 4-, and 5-year-old, they were coppiced and maintained in the dark for etiolation, while a parallel set was kept in normal light in an open environment. After 20 days, coppice shoots were made into SNCs which were cultured under intermittent mist for rooting. Stock-plant etiolation significantly increased percent rooting, shoot and root length, and number of roots per SNC, but callusing at the base of SNCs decreased. Etiolated SNCs have shown 71.7% rooting, whereas for controls (non-etiolated), the response was 41.7%. The effect of aging on callusing, rooting and sprouting of etiolated and non-etiolated coppice shoots cuttings varied widely. Aging of donor plants decreased rooting and sprouting capability in SNCs and increased callusing at the base of etiolated cuttings. The results showed that stock-plant etiolation in 1-, 2-, 3-, 4-, and 5-year-old donor plants hastened rooting potential by rejuvenation of coppice shoots.

Asexual Propagation of Sheanut Tree (<i>Vitellaria paradoxa</i>C.F. Gaertn.) Using a Container Layering Technique

In spite of the economic potential of the sheanut tree (Vitellaria paradoxa), its domestication still has not been achieved due to the long juvenile period of seed propagated plants and the absence of a reliable vegetative propagation method. Three experiments were conducted by using a modified container layering technique to investigate the effects of season (rainy and dry season), light treatments (etiolation and natural light) and indole 3-butyric acid (IBA) on root formation in juvenile and mature sheanut trees. The effect of light treatments on the internal conditions such as level of sugars (soluble, insoluble and total sugars) and total free phenols in layered sheanut shoots was also considered. Rooting was generally lower in the mature trees (27.9%) compared to that in juvenile 4 year-old plants (40.9%). Etiolation increased the levels of total sugars and phenols in shoots of 4-year-old plants and mature fruit bearing trees, but this increase did not significantly enhance rooting in both the juvenile and mature sheanut trees. The container layering technique holds promise as a method for the asexual propagation of sheanut planting material. Roots formed using this method looked healthy and were vertically orientated giving layered shoots a better chance at survival.

Research on the Peanut Leaf Etiolation Prevention and Film Mulching Effect in Hubei Province

The possible nutrient problems existing in leaf etiolation,the influence of film mulching on the yield of peanut and benefits of balanced fertilization were analyzed. The results showed that the deficiency of nutrient elements was not main limiting factor in leaf etiolation of peanut in Hong'an. Deep trench,film mulching,liming and organic manure could be used to prevent leaf etiolation. The film mulching could increase the yield of peanut by improving the rate of germination and seedling,the number of branches and full pod,and it was beneficial to playing the effect of balanced fertilization.

REMCO Established

A joint venture named Rare Earth Magnet Com-pany(REMCO)was set up by Baotou Steel and RareEarth Company of China and Bankhouse Group ofUSA.The ceremany of signing the agreement be-tween the two sides was held in Huhehot,capital cityof Inner Mongolia July 27,1992.China holds ap-proximately 80% of the world total rare earth re-sources,and rare earths are now an important compo-nent in making advanced magnets.It is the intentionof the two sides to form an equal partnership in whichChina would share with the United States the