Rice leaf inclination2, a VIN3-1ike protein, regulates leaf angle through modulating cell division of the collar

As an important agronomic trait, inclination of leaves is crucial Ior crop architecture and grain yields. 10 understand the molecular mechanism controlling rice leaf angles, one rice leaf inclination2 （1c2, three alleles） mutant was identified and functionally characterized. Compared to wild-type plants, lc2 mutants have enlarged leaf angles due to increased cell division in the adaxial epidermis of lamina joint. The LC2 gene was isolated through positional cloning, and encodes a vernalization insensitive 3-like protein. Complementary expression of LC2 reversed the enlarged leaf angles of lc2 plants, confirming its role in controlling leaf inclination. LC2 is mainly expressed in the lamina joint during leaf development, and particularly, is induced by the phytohormones abscisic acid, gibberellic acid, auxin, and brassinosteroids. LC2 is localized in the nucleus and defects of LC2 result in altered expression of cell division and hormone-responsive genes, indicating an important role of LC2 in regulating leaf inclination and mediating hormone effects.

Generation of selectable marker-free soft transgenic rice with transparent kernels by downregulation of SSSⅡ-2

The amylose content(AC) of rice endosperm starch varies from 0 to 35%,and is associated with rice cooking and eating quality.Soft rice has low AC,generally between 6% and 15%,and its eating quality is high whether it is consumed hot or cold.However,the appearance quality of current soft rice cultivars needs to be improved,especially opaque endosperm.Conventional genetic engineering has improved some agronomic traits of soft rice varieties,but not endosperm appearance.In the present study,a RNAi construct of the soluble starch synthase Ⅱ-2(SSSⅡ-2) and the hygromycin phosphotransferase(HPT) gene were introduced into an elite japonica rice variety,Kangtiaowuyunjing(KWY8) by co-transformation.Several selectable marker-free(SMF) transgenic lines were obtained,and SSSⅡ-2 expression was significantly downregulated in selected transgenic lines,resulting in lower AC of the endosperm.The physicochemical properties of the transgenic rice kernels,including gel consistency(GC) and rapid visco analyzer(RVA) profile,differed significantly from those of wild-type rice and were similar to those of a soft rice variety,Nanjing 46(NJ46).These findings indicate that the cooking,eating,and processing qualities of transgenic rice are comparable to those of NJ46.However,the transgenic rice endosperm retained a transparent appearance under low-moisture conditions.Thus,SMF SSSⅡ-2 RNAi rice provides a resource for breeding soft rice with transparent endosperm.

Changes in Protein Content and Chitinase and β-1,3- glucanase Activities of Rice with Blast Resistance Induced by Ag-antibiotic 702

[Objective] The paper was to explore the effect of rice blast resistance induced by Ag-antibiotics 702 on protein content and chitlnase and β-1,3-glucanase activities in rice. [ Method] At the fourth leaf stage of Luliangyou 996, 15 μg/mL Ag-antibiotic 702 was sprayed, while Validamycin and distilled wa- ter were sprayed as positive control and negative control, respectively. All treatments were inoculated with spore fluid of Magnaporthe grisea at 48 h post spraying, and the rice inoculated with only distilled water was used as blank control. The enzymes activities （endochitinase, exochitinase and β-1,3-glucanase） and total pro- tein content in rice leaves were determined every 24 h within 168 h post spraying. [ Result] Compared with the blank control, the rice inoculated with spore fluid of M. grisea could significantly increase the total protein content and the activities of β-1,3-glucanase and chitinase. The induction effect of Ag-antibiotics 702 exceeded that of Validamycin treatment. And the changes in activities of β-1,3-glucanase and chitinase had obvious synchronicity. [ Conclusion] Ag-antibiotic 702 can significantly improve the total protein content and the activities of β-1,3-glucanase and chitinase, thus enhancing the resistance to rice blast.

Improving grain appearance of erect-panicle japonica rice cultivars by introgression of the null gs9 allele

The panicle architecture and grain size of rice affect not only grain yield but also grain quality,especially grain appearance.The erect-panicle(EP)trait controlled by the qpe9-1/dep1 allele has been widely used in high-yielding japonica rice breeding,but usually accompanied with moderate appearance of milled rice.The null gs9 allele shows a good potential for improving grain shape and appearance.However,GS9 and qPE9-1/DEP1 loci are tightly linked,and their interaction is unclear,which obviously restricts their utilization in modern rice breeding.In the present study,comparative analyses of protein and mRNA levels revealed that GS9 and qPE9-1 function independently.Three nearisogenic lines(NILs)carrying various allelic combinations of these two loci,NIL(gs9/qpe9-1),NIL(GS9/qPE9-1)and NIL(gs9/qPE9-1),in the EP japonica cultivar 2661(GS9/qpe9-1)background were developed for genetic interaction analysis.GS9 and qPE9-1 had additive effects on determining grain size,and the null gs9 allele could decrease grain chalkiness and improve grain appearance without affecting plant and panicle architecture in EP japonica cultivars.Additionally,introgression lines(ILs)developed in another released EP japonica cultivar Wuyujing 27(WYJ27)background showed the same additive effect and the feasibility of utilizing the gs9 allele to improve grain appearance quality in high-yielding EP cultivars.This study provides an effective strategy for rice breeders to improve rice grain appearance in EP japonica and related cultivars.

Exploration and Validation of the Potential Downstream Genes Underlying ipa1-2D Locus for Rice Panicle Branching

In recent years,some super hybrid rice varieties were bred with strong culms and large panicles,which are mainly contributed by the ipa1-2D locus.A gain-of-function allele of OsSPL14 is the ipa1-2D and it can greatly increase the panicle primary branch number.However,the key downstream genes mediating this trait variation are not fully explored.In this study,we developed high-quality near-isogenic lines(NILs)with a difference of only 30 kb chromosomal segment covering the ipa1-2D locus.Using the NILs,we explored the impact of ipa1-2D on five sequential stages of early inflorescence development,and found that the locus can greatly enhance the initiation of primary branch meristems.A transcriptomic analysis was performed to unveil the downstream molecular network of ipa1-2D,and 87 genes were found differentially expressed,many of which are involved in metabolism and catalysis processes.In addition,transgenic lines of overexpression and RNA interference were generated to shape different levels of OsSPL14.They were also used to validate the expression variation explored by transcriptome.Based on the gene annotation,twelve potential downstream targets of ipa1-2D were selected,and their expression variation was confirmed by qRT-PCR analysis both in NILs and transgenic lines.This research expands the molecular network underlying ipa1-2D and provides novel gene information which might be involved in the control of panicle branching.We discussed the potential function of identified genes and highlighted their values for future function exploration and breeding application.

Effects of Different NH_4^+/NO_3^- Ratio and Water Condition on Physiological Characteristics of Rice Seedlings

[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4＋ /NO3- ratio and different water condition. [Method] Under the hydroponic condition in laboratory, 3 NH4＋/NO3- ratios （0/100, 50/50 and 100/0） and 2 water conditions （＋PEG,-PEG） were designed for Fengliangyou 7203. [Result] The root-canopy ratio of rice seedlings increased under any of the NH4＋/NO3- ratios and water conditions. Under water stress, the root-canopy ratio of rice seedlings changed most greatly at the NH4＋/NO3- ratio of 0/ 100; the overall water potential of rice seedlings reached the lowest at the NH4＋/ NO3- ratio of 100/0; and the changes of water potential and xylem flow pH were relatively stable at the NH4＋/NO3- ratio of 50/50. Under the condition of no water stress, the growth of rice seedlings was best at the NH4＋/NO3- ratio of 50/50, followed by the NH4＋/NO3- ratios of 0/100 and 100/0. [Conclusion] This study will pro- vide a basis for understanding the relationship between water potential and xylem flow.

Field Evaluation of Growth and Yield of Two Local Rice Varieties (Tox-728-1 and Madjitolngar) in Response to Indogenous Mycorrhizal Inoculation in South-Chad

This study was carried out to find out how dependent are two local rice varieties (Magitolngar and Tox-728-1) to inoculation with selected endogenous arbuscular mycorrhizal fungi (AMF) in a field where they were isolated. The multi-indigenous endomycorrhiza spores previously isolated and identified were the active ingredient in the production of bioinoculants used for this purpose. Spores massively multiplied from the rhizosphere of each rice variety in each of the four locally collected soils substrates were harvested to constitute 08 AMF inoculants (Kema = T1;Lama = T2;Latox = T3;Ndjatox = T4;Koloma = T5;Kolotox = T6;Ndjama = T7;Ketox = T8). These inoculants were field tested on the two rice varieties at Kelo, under a complete randomized block design, comprising 10 treatments (8 inoculants, 01 positive control = T9, 01 negative control = T10), each of which was repeated thrice. The analysis of data indicates that AMF-inoculated plants were taller, developed more tillers/plant, and produced more rice grains/panicle than non-AMF-inoculated plants for both studied rice varieties. The rice variety Madjitolngar yielded more grains (7.5 t/ha) than the Tox-728-1 variety (5.8 t/ha). Moreover, inoculants Koloma (T1), Latox (T3) and Kolotox (T6) on the one hand, Koloma (T1) and Ketox (T8) on the other hand, were best suited for the improvement of growth and yield of the rice varieties Madjitolngar and Tox-728-1 respectively, tested under field conditions at Kelo. In this study, the two rice varieties have shown a dependency to endomycorrhizal symbiosis at Kelo, and therefore, an industrial-scale production of efficient endomycorrhal inoculants is necessary to sustainably boost the productivity of this important crop in Chad.

Biological control of rice disease and insect by chitinase-producing bacterium X2-23

Enriched by the-medium containingchitin and cell wall of Phizoctoniasolani AG-1,a bacterium X2-23 withhigher chitinase activity was isolatedfrom 166 chitinase-producing bacteria.It could distinctly inhibit the fungi