Overexpression of the Barley Nicotianamine Synthase Gene HvNAS1 Increases Iron and Zinc Concentrations in Rice Grains

In humans, iron (Fe) and zinc (Zn) deficiencies result in major worldwide health problems. Transgenic technologies to produce Fe- and Zn-biofortified rice varieties offer a promising potential solution. Nicotianamine, the precursor of phytosiderophores, chelates Fe²⁺ and Zn²⁺ and plays an important role in transporting these metals to both vegetative and reproductive organs within the plant. Our objective was to increase Fe and Zn contents in rice grains by overexpressing the barley nicotianamine synthase gene HvNAS1. HvNAS1-overexpressing transgenic rice showed increased HvNAS1 expression and subsequent increases in endogenous nicotianamine and phytosiderophore content in shoots, roots, and seeds. Fe and Zn concentrations in polished T₁ seeds from transgenic plants increased more than three and twofold, respectively; Fe and Zn concentrations also increased in both polished and brown T₂ seeds. These results suggest that the overproduction of nicotianamine enhances the translocation of Fe and Zn into rice grains.     

Introgression of Gene for Non-Pollen Type Thermo-Sensitive Genic Male Sterility to Thai Rice Cultivars

For the two-line hybrid rice system, pol en sterility is regulated by recessive gene that responds to temperature. The recessive gene controlling thermo-sensitive genetic male sterility （TGMS） is expressed when the plants are grown in conditions with higher or lower critical temperatures. To transfer tgms gene（s） control ing TGMS to Thai rice cultivars by backcross breeding method, a male sterile line was used as a donor parent while Thai rice cultivars ChaiNat 1, PathumThani 1, and SuphanBuri 1 were used as recurrent parents. The BC2F2 lines were developed from backcrossing and selfing. Moreover, the simple sequence repeat （SSR） markers were developed for identifying tgms gene and the linked marker was used for assisting selection in backcrossing. The identification lines were confirmed by pol en observation. The results showed the success of introgression of the tgms gene into Thai rice cultivars. These lines will be tested for combining ability and used as female parent in hybrid rice production in Thailand.     

Production of Two Elite Glutinous Rice Varieties by Editing Wx Gene

The waxy gene(Wx) in rice, which encodes the granule bound starch synthase enzyme, is responsible for amylose synthesis. Glutinous(sticky) rice has little or no amylose that can be used in various applications, such as brewing. In this study, knockout of the Wx gene with CRISPR/Cas9 technology was conducted in two elite japonica rice lines, Huaidao 5(HD5) and Suken 118(SK118), aiming to develop elite sticky rice varieties. We achieved six homozygous T_0 plants with more than 200 bp deletion in the Wx gene, as well as 36 wx-HD5 and 18 wx-SK118 homozygous transgene-free plants in the T_1 generation. The seeds of all the mutants were white and opaque, similar to those of sticky rice, and contained only 2.6%–3.2% amylose. Results of scanning electron microscopy showed that the quality of rice did not change. In conclusion, we successfully developed two elite sticky rice varieties.     

Development of Marker-Free Transgenic Cry1Ab Rice with Lepidopteran Pest Resistance by Agrobacterium Mixture-Mediated Co-transformation

Cry1Ab gene was transformed into four rice varieties, Zhejing 22, Zhejing 27, Jiahua 1 and Xiushui 63 mediated by Agrobacterium-mixture co-transformation. Rice genotype had an important effect on callus induction and transformation efficiency. Different mixtures of Agrobacterium strains (EHA105 and EHA101) contained Hpt and Cry1Ab genes resulted in different frequencies of resistant calli. There was no correlation between the frequency of transformants with the ratio of the Agrobacterium strain mixture contained Hpt and Cry1Ab genes. A total of 509 transgenic plants were obtained from the four rice varieties, and 272 T₂ progenies were analyzed for Cry1Ab and Hpt genes. PCR analysis revealed that 412 regenerated plants were Hpt positive (80.94%), 62 plants were also Cry1Ab co-transformants (15.05% in total frequency), and 42 plants among the 272 T₂ progenies were Cry1Ab positive but Hpt negative. This suggests that marker-free transgenic plants could be produced by co-transformation mediated by mixed Agrobacterium strains with the selectable marker gene and target gene. Southern blot analysis of five independent marker-free T₂ transgenic lines co-transformed from Zhejing 22 showed that Cry1Ab gene had been inserted into rice genome with a single copy. The transgenic plants showed significantly stronger resistance to lepidopteron than the non-transgenic plants under no application of insecticides against lepidopteron.     

Transgene Stacking and Coordinated Expression of Plant Defensins Confer Fungal Resistance in Rice

Transgenic rice with cleavable chimeric polyprotein and single-protein gene constructs placed under the control of single maize ubiquitin promoter were generated by Agrobacterium tumefaciens-mediated transformation. The polyprotein precursor consists of a leader peptide and two different antimicrobial proteins (AMPs), Dm-AMP1 and Rs-AFP2, from the seeds of Dahlia merckii and Raphanus sativus, respectively. These genes were linked by a 16 amino acid Ib-AMP linker peptide region isolated from the seeds of Impatiens balsamina. Average expression of Dm-AMP1 and Rs-AFP2 was 8.35?±?0.56 and 8.1?±?0.6 2 g/mg of total soluble proteins in the leaf extracts of transgenic plants. Plants transformed with polyprotein construct showed significantly improved disease resistance against Magnaporthe oryzae and Rhizoctonia solani by 90% and 79%, respectively, as compared to untransformed plants. The plants transformed with polyprotein construct were more resistant to M. oryzae compared to plants transformed with control single-gene constructs of Dm-AMP1 and Rs-AFP2. The chimeric polyprotein was cleaved and present in equimolar concentration in transgenic rice and the individual AMPs were secreted into the extracellular space. The results of in vitro, in planta, and microscopic analyses suggest that chimeric polyprotein expression has the potential to provide broad-spectrum disease resistance in rice.     

Infection of Early and Young Callus Tissues of Indica Rice BPT 5204 Enhances Regeneration and Transformation Efficiency

A rapid and reproducible method to develop transgenic plants with enhanced transformation efficiency using Agrobacterium has been developed for the elite indica rice variety BPT 5204. Different rice calli aged from 3 to 30 d were co-cultivated with pre-incubated Agrobacterium suspension culture （LBA4404： pSB1, pCAMBIA1301） and incubated in dark for 3 d. Based on the transient GUS gene expression analysis, 6-day-old young calli showed high transformation frequency followed by 21-day-old ones. Thus, both 6-and 21-day-old calli were used for assessing the stable transformation efficiency. It was observed that the 6-day-old young transformed calli showed about 2-fold higher regeneration frequency when compared with 21-day-old calli. The transformation efficiency was enhanced for young calli to 5.9% compared with 0.8% of the 21-day-old calli. Molecular and genetic analysis of transgenic plants （To） revealed the presence of 1-2 copies of T-DNA integration in transformants and it follows Mendalian ratio in T1 transgenic plants. From the present study, it was concluded that the development of transgenic rice plants in less duration with high regeneration and transformation efficiency was achieved in BPT 5204 by using 6-day-old young calli as explants.     

Increase in Iron and Zinc Concentrations in Rice Grains Via the Introduction of Barley Genes Involved in Phytosiderophore Synthesis

Increasing the iron (Fe) and zinc (Zn) concentrations of staple foods, such as rice, could solve Fe and Zn deficiencies, which are two of the most serious nutritional problems affecting humans. Mugineic acid family phytosiderophores (MAs) play a very important role in the uptake of Fe from the soil and Fe transport within the plant in graminaceous plants. To explore the possibility of MAs increasing the Fe concentration in grains, we cultivated three transgenic rice lines possessing barley genome fragments containing genes for MAs synthesis (i.e., HvNAS1, HvNAS1, and HvNAAT-A and HvNAAT-B or IDS3) in a paddy field with Andosol soils. Polished rice seeds with IDS3 inserts had up to 1.40 and 1.35 times higher Fe and Zn concentrations, respectively, compared to non-transgenic rice seeds. Enhanced MAs production due to the introduced barley genes is suggested to be effective for increasing Fe and Zn concentrations in rice grains.     

Seed Priming Improves Agronomic Trait Performance under Flooding and Non-flooding Conditions in Rice with QTL SUB1

Farmers in South East Asia are adopting rice crop establishment methods from transplanting to direct wet or dry seeding as it requires less labour and time and comparatively less energy than transplanting.In contrast to irrigated condition,in rainfed lowland,direct seeding is a common practice.Early flooding controls weeds but decreases seedling establishment in direct seeded rice.Anaerobic germination is an important trait to counteract damages caused by early flooding.Management options which can help in crop establishment and improve crop growth under flooding might remove the constraints related to direct seeding.The investigation was carried out with two near isogenic lines Swarna and SwarnaSub1.Swarna-Sub1 is tolerant to submergence whereas Swarna is susceptible.Seed priming was done with water and 2% Jamun(Syzygium cumini) leaf extract,and it improved seedling establishment under flooding.Acceleration of growth occurred due to seed pretreatment,which resulted longer seedling and greater accumulation of biomass.Seed priming greatly hastened the activities of total amylase and alcohol dehydrogenase in Swarna-Sub1 than in Swarna.Swarna-Sub1 outperformed Swarna when the plants were cultivated under flooding.Weed biomass decreased significantly under flooding compared to non-flooding conditions.Seed priming had positive effects on yield and yield attributing parameters both under non-flooding and early flooding conditions.     

Identification and Fine Mapping of Heading Date Related Mutant Gene in Rice

A rice heading-date-related mutant was isolated from a 60 Co-γ-ray-induced mutation pool of Zhejing 22,a conventional japonica cultivar in Zhejiang Province,China.The mutant was characterized by a delayed heading date of almost 20 d longer than the wild type plant.Genetic analysis revealed that the mutation was controlled by a single nuclear-encoded recessive gene that was designed as HD(t)(heading date tentatively).To isolate the HD(t) gene,a map-based cloning approach was employed using 479 F 2 mutant individual plants derived from the cross between the hd(t) mutant(japonica) × Zhenshan 97(indica).Finally,the HD(t) gene was mapped to an approximate 53 kb region between the insertion and deletion(InDel) markers of 10-61W and 10-66W on chromosome 10.According to the genome sequence of Nipponbare,the target region contains 11 annotated genes.It is helpful for future cloning of HD(t) gene based on this fine mapping results.     

Testing of Rice Stocks for Their Survival of Winter Cold

Rice cultivation is considered to be initiated by vegetative propagation of sprout from wild perennial stocks. To test whether any presently cultivated rice cultivar can survive the winter cold or not, rice stocks of several cultivars including indica and japonica types were placed in a shallow pool from October to April in 2015–2016 and 2016–2017. During the coldest period of the winter, the bases of the stocks were placed 5–6 cm below the surface of water, where temperatures ranged from 3 ℃ to 5 ℃, while the surface was frozen for two or three times and covered with snow for a day. Only one cultivar, Nipponbare, a japonica type, survived the winter cold and regenerated sprouts in the end of April or early May. A possibility to develop perennial cultivation of rice or perennial hybrid rice is discussed.     

杂交香稻新品种内优航148高产栽培技术

总结了杂交籼稻新品种内优航148在各地示范种植的表现,并从播种育秧、大田移栽以及田间的肥水管理与病虫害防治等方面介绍了杂交稻内优航148高产栽培的关键技术要点。     

超高产杂交水稻培矮64S/E32和两优培九剑叶对高温的响应

 以汕优63为对照，研究了新育成的两个超级杂交水稻组合培矮64S/E32和两优培九的高温耐受特性。结果表明高温引起了光合效率降低，加重了光合光抑制。光化学、光合电子传递最适温度在28℃左右，光合碳同化的最适温度在35～40℃。高温下通过PSⅡ线性电子传递的能力几乎丧失（下降96.7%～100%），而PSⅡ光化学效率下降较少（8.8%～210%）,暗示PSⅡ光合线性电子传递过程比光化学能转化对高温更敏感。超级杂交稻比对照汕优63更耐高温，其机理可能如下：一是因为超级稻在高温时有更迅速的类胡萝卜素积累，增加其抗氧化能力，减少了因过剩激发能积累引起活性氧产生、积累并伤害光合细胞；二是因为超级稻高温下有高效的叶黄素循环热耗散途径可以耗散过量的激发能； 三是因为超级稻在高温下有稳定的光合功能和较强的光合效率，较高的热稳定蛋白含量。     

优质稻宜优673在新罗区再生能力表现及高产栽培技术

文章根据龙岩市新罗区气候特点及宜优673品种特征、再生能力表现及配套栽培技术进行了探讨,以期形成宜优673在新罗区发展再生稻的高产配套栽培技术,利于大面积推广应用。     

Tolerance of longer-term partial stagnant flooding is independent of the SUB1 locus in rice

Longer-term partial stagnant flooding, particularly when it occurs following transient complete submergence causes severe damage to modern rice varieties. Progress was made in developing varieties tolerant of complete submergence through transfer of the Submergence-1 (SUB1) gene into popular varieties. However, SUB1 may not be effective under partial stagnant flooding (SF), as the new varieties may not elongate and continue growth when fully or partially submerged because of the SUB1-mediated suppression of elongation. We tested a set of rice genotypes, including a pair of near-isogenic lines (NILs), Swarna and Swarna-Sub1, under either SF or SF following complete submergence of 12 d. Swarna-Sub1 had higher survival and yield than Swarna following 12 d of submergence, but survival and grain yield of all lines decreased substantially when SF of 15-30 cm followed complete submergence, with the sensitive lines experiencing greater reductions in growth and yield. This suggests the importance of combining SUB1 with tolerance of SF in areas where both stresses are expected during the season. Swarna and Swarna-Sub1 are more sensitive to long-term partial SF than IR49830 and IR42 because of their short stature, and Swarna-Sub1 showed slightly higher reduction in tillering than did Swarna when subjected to deeper SF alone, possibly because of further inhibition of elongation by SUB1 if induced in submerged tissue. The results suggest that tolerance of these genotypes to SF depends less on SUB1 introgression and more so on the genetic background of the recipient genotype, with better performance of the genotypes that are inherently taller, such as IR42 and IR49830. The SUB1 donor landrace FR13A and its derivative breeding line IR49830 had better survival and relatively less reduction in grain yield under SF following complete submergence and under longer-term partial SF, indicating that these genotypes may have genes other than SUB1 for submergence and SF tolerance. For better adaptation to prolonged SF, SUB1 should be introgressed into genotypes that tolerate partial SF through better tillering ability and taller shoots, because SUB1 may not be effective in shorter genotypes, as it promotes survival of submerged plants by hindering shoot elongation to conserve energy reserves. Varieties combining tolerance of prolonged SF with SUB1 will have broader adaptation in flood-prone areas and greater impacts on yield stability.     

水稻植株在二化螟为害后的生理变化

研究了不同类型水稻品种在二化螟为害后植株体内的一些生理变化,包括叶绿素含量、根系活力和钾元素吸收能力。不同水稻品种在主茎受二化螟为害形成枯心后,分蘖的叶绿素含量均降低,但与健康植株相比无显著差异。常规杂交稻汕优63和超级杂交稻两优培九在主茎枯心过程中根系活力显著增强,而粳稻秀水11枯心后根系活力反而显著下降。采用86Rb标记示踪原子法研究了在二化螟为害后水稻根系对土壤中钾的吸收能力的变化,发现秀水11主茎枯心24 h和48 h后分蘖中铷的含量比健康植株分别降低了5.23%和47.5%,说明对钾的吸收能力下降,而汕优63和两优培九分蘖中铷的含量分别比健康植株增加了2.91%和14.36%、21.3%和15.9%,即对钾的吸收能力提高。     

抗除草剂基因导入培矮64S实现杂交水稻制种机械化的初步研究

 利用农杆菌介导的高效遗传转化技术，成功地将Bar基因转入两系杂交稻的不育系培矮64S。转基因植株具有明显的Basta抗性，分子检测进一步证明Bar基因已整合到水稻染色体上。模拟制种的成功，表明机械化制备杂交水稻种子是可行的。讨论了实现机械化制备杂交水稻种子所需解决的各种问题。