Analysis of randomly isolated cDNAs from developing endosperm of rice (Oryza sativa L.): evaluation of expressed sequence tags,and expression levels of mRNAs

Using a cDNA library prepared from poly(A)⁺ RNA from 10-day-old rice endosperm, partial nucleotide sequences of randomly isolated clones were analyzed. A total of 153 (30.6%) out of 500 cDNA clones showed high amino acid identity to previously identified genes. There was significant redundancy in cDNAs encoding prolamine and glutelin. About 21.0% of the cDNA clones were found to code for seed storage protein genes. Consequently, 37 independent genes were identified. Using cDNA clones encoding glutelin, prolamine, seed allergen, -1,4-glucan branching enzyme, glycine-rich RNA binding protein, metallothionein, non-specific lipid-transfer protein and ubiquitin conjugating enzyme the accumulation of mRNA during rice seed development was compared. Genes associated with seed storage protein and starch biosynthesis were expressed according to expected developmental stages. Glycinerich RNA binding protein genes as well as metallothionein-like protein genes were highly expressed in developing seeds, but low in leaves of whole plants.     

Inheritance of gusA and neo genes in transgenic rice

Inheritance of foreign genes neo and gusA in rice (Oryza sativa L. cv. IR54 and Radon) has been investigated in three different primary (T₀) transformants and their progeny plants. T₀ plants were obtained by co-transforming protoplasts from two different rice suspension cultures with the neomycin phosphotransferase II gene [neo or aph (3) II] and the -glucuronidase gene (uidA or gusA) residing on separate chimeric plasmid constructs. The suspension cultures were derived from callus of immature embryos of indica variety IR54 and japonica variety Radon. One transgenic line of Radon (AR2) contained neo driven by the CaMV 35S promoter and gusA driven by the rice actin promoter. A second Radon line (R3) contained neo driven by the CaMV 35S promoter and gusA driven by a promoter of the rice tungro bacilliform virus. The third transgenic line, IR54-1, contained neo driven by the CaMV 35S promoter and gusA driven by the CaMV 35S.Inheritance of the transgenes in progeny of the transgenic rice was investigated by Southern blot analysis and enzyme assays. Southern blot analysis of genomic DNA showed that, regardless of copy numbers of the transgenes in the plant genome and the fact that the two transgenes resided on two different plasmids before transformation, the introduced gusA and neo genes were stably transmitted from one generation to another and co-inherited together in transgenic rice progeny plants derived from self-pollination. Analysis of GUS and NPT II activities in T₁ to T₂ plants provided evidence that inheritance of the gusA and neo genes was in a Mendelian fashion in one plant line (AR2), and in an irregular fashion in the two other plant lines (R3 and IR54-1). Homozygous progeny plants expressing the gusA and neo genes were obtained in the T₂ generation of AR2, but the homozygous state was not found in the other two lines of transgenic rice.     

Rice scutellum induces Agrobacterium tumefaciens vir genes and T-strand generation

For successful transformation of a plant by Agrobacterium tumefaciens it is essential that the explant used in cocultivation has the ability to induce Agrobacterium tumour-inducing (Ti) plasmid virulence (vir) genes. Here we report a significant variation in different tissues of Indica rice (Oryza sativa L. cv. Co43) in their ability to induce Agrobacterium tumefaciens vir genes and T-strand generation, using explants preincubated in liquid Murashige and Skoog (MS) medium. An analysis of rice leaf segments revealed that they neither induced vir genes nor inhibited vir gene induction. Of different parts of rice plants of different ages analysed only scutellum from four-day old rice seedlings induced vir genes and generation of T-strands. We observed that the physical presence of preincubated scutella is required for vir gene induction. Conditioned medium from which preincubated scutella were removed did not induce the vir genes. Scutellum-derived calli, cultured for 25 days on medium containing 2,4-D, also induced virE to an appreciable level. These results suggest that scutellum and scutellum-derived calli may be the most susceptible tissues of rice for Agrobacterium-mediated transformation.     

Brassinosteroid-induced rice lamina joint inclination and its relation to indole-3-acetic acid and ethylene

Brassinosteroid (BR)-induced rice (Oriza sativa L.) lamina joint (RLJ) inclination and its relationship to indole-3-acetic acid (IAA) and ethylene were investigated using BR isolated from beeswax. The effect of BR on RLJ inclination was time- and concentration-dependent. Etiolated lamina were more sensitive to BR than green lamina. The BR-induced inclination was accompanied by increased lamina fresh weight, total water content, free-water content, proton extrusion and ethylene production, and decreased bound-water content. Lamina dry weight was not changed. The inclination was due to greater expansion of the adaxial cells relative to the dorsal cells in the lamina joint. This response was caused by BR and/or BR-induced signal(s) that were transported from the leaf sheath to the leaf blade. Both BR-induced RLJ inclination and ethylene production were inhibited by cobalt chloride (CoCl₂), an inhibitor of ACC oxidase. BR-induced inclination was much higher than that of IAA, and was inhibited by high concentration of 2,3,5-triiodobenzoic acid (TIBA), an inhibitor of IAA transport. A synergistic effect was observed between BR and IAA. These results suggest that the effects of BR on RLJ inclination and pulvinus cell expansion may be resulted from BR-increased water potential and proton extrusion in the lamina. The BR-induced RLJ inclination may involve the action of ethylene but may be independent of IAA.Abbreviations BR brassinolide or brassinosteroid(s) - IAA indole-3-acetic acid - TIBA 2,3,5-triiodobenzoic acid - RLJ rice lamina joint     

Effect of long term feeding of rice bran oil upon lipids and lipoproteins in rats

The effects of feeding two levels of rice bran oil (RBO) on the growth, lipid parameters, and fatty acid composition of the plasma and liver of rats (Wistar strain) were compared with those produced on animals which had been fed the same levels of peanut oil (PNO). The control animals were fed synthetic diets containing 5 and 20% peanut oil (PNO) and the experimental groups were fed similar diets, containing the same level of rice bran oil (RBO). There was no significant difference with respect to the organ weights between the control and the experimental groups. In general, groups fed 20% oil gained more weight than groups fed 5% oil. The animals which received rice bran oil in their diet had, in general, comparatively lower levels of cholesterol, triglycerides and phospholipids. On the other hand, animals receiving 20% rice bran oil in their diet, showed an increase of 20% in high density lipoproteins (HDL-C), within 18 weeks (p<0.05), when compared to the animals fed with peanut oil. Similarly, low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein cholesterol (VLDL-C) were lower in RBO-fed groups, than in the PNO-fed groups. There was, however, no significant differences in the cholesterol/phospholipid (C/P) ratio of the two groups. Analysis of plasma and of liver fatty acids indicated, in a general way, the type of fat consumed. There were no significant difference in the P/S ratio, nor any in the oleic/linoleic, oleic/stearic, palmitoleic/palmitic, oleic/palmitic, and oleic/palmitoleic ratios. Furthermore, levels of saturated (SAFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identical in both the groups. Thus, our results suggest that feeding a high level of rice bran oil (RBO) has no deleterious effect on the growth and blood lipid profile of rats.Abbreviations PNO peanut oil - RBO rice bran oil - HDL-C high density lipoprotein cholesterol - LDL-C low density lipoprotein cholesterol - VLDL-C very low density lipoprotein cholesterol - SAFA saturated fatty acids - MUFA mono-unsaturated fatty acids     

Expression of betaine aldehyde dehydrogenase gene and salinity tolerance in rice transgenic plants

Betaine as one of osmolytes plays an important role in osmoregulation of most high plants. Betaine aldehyde dehydrogenase C BADH) is the second enzyme involved in betaine biosynthesis. The BADH gene from a halophite, Atriplex hortensis, was transformed into rice cultivars by bombarment method. Totally 192 transgenic rice plants were obtained and most of them had higher salt tolerance than controls. Among transgenic plants transplanted in the saline pool containing 0.5% NaCl in a greenhouse, 22 survived, 13 of which set seeds, and the frequency of seed setting was very low, only 10% . But the controls could not grow under the same condition. The results of BADH ac-tivity assay and Northern blot showed that the BADH gene was integrated into chromosomes of transgenic plants and expressed.     

籼稻的抗冷性与亲本的关系

四个籼稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）品种幼苗经１℃黑暗或光照２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １处理后,抗冷的“桂山矮选３”比不抗冷的“青华６ 号”幼苗存活率高,其子代是以“桂山矮选３”为母本的比“青华６ 号”为母本的存活率较高。抽穗期剑叶经光照低温处理１２、２４ 和３６ ｈ 后,光合作用是“桂山矮选３”和以“桂山矮选３”为母本的子代比“青华６ 号”和以“青华６ 号”为母本的子代下降较少。呼吸作用是前者比后者在处理１２ ｈ 时有明显升高现象。荧光参数Ｆｖ／Ｆｏ和Ｆｖ／Ｆｍ比值在处理２４ ｈ 时前者比后者下降明显,但在常温下恢复则是前者比后者明显较快。自然低温（寒露风）对叶绿素荧光的影响亦有相似的规律。对水稻后代的抗冷性倾向于母本进行了讨论     

Genome characterization of glucose-isomerase-producingStreptomyces sp. NCIM 2730: detection of sequences homologous to a rice repeat sequence

Restriction analysis of the genomic DNA from a high glucose/xylose-isomerase-yieldingStreptomyces sp. NCIM 2730 revealed a number of distinct bands on a background smear, indicating the occurrence of repeated DNA sequences in the genome. Optical renaturation analysis indicated that 25% of the genome comprised rapidly reannealing sequences with a copy number of 50 and a kinetic complexity of 3×10³. Hybridization of theStreptomyces genomic library with theStreptomyces DNA, supported the estimate of the repetitive DNA content derived from the re-association kinetics of the DNA. Hybridization of DNA from three differentStreptomyces species with a rice repetitive DNA probe revealed the presence of homologous sequences, which is a unique finding.M.S. Ghatge was and V.V. Deshpande and P.K. Ranjekar are with the Division of Biochemical Sciences, National Chemical Laboratory, Pune -41108, India; M.S. Ghatge is now with the Department of Microbiology & Molecular Biology, The University of Kansas Medical Center, 36th and Rainbow Blvd, Kansas City, Kansas - 66103, USA.