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28 November 2015, Volume 22 Issue 6 Previous Issue    Next Issue
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Identification and Cloning of Tillering-Related Genes OsMAX1 in Rice Xiu-mei Wang, Yue-yang Liang, Ling Li, Chang-wei Gong, Hai-peng Wang, Xiao-xi Huang, Shuang-cheng Li, Qi-ming Deng, Jun Zhu, Ai-ping Zheng, Ping Li, Shi-quan Wang 2015, 22(6): 255-263.  DOI: 10.1016/S1672-6308(14)60307-3 Abstract ( )   HTML ( )   PDF (776KB) ( )   Tillering is an important agronomic trait which has a direct impact on plant type and grain yield. Strigolactones are a class of important phytohormones regulating rice tillering. ATMAX1 is an important gene involved in strigolactone biosynthesis through encoding the protein P450 in Arabidopsis. Based on sequence BLASTp, we identified five homologous genes of ATMAX1 in rice, i.e., OsMAX1a, OsMAX1b, OsMAX1c, OsMAX1d and OsMAX1e. Among them, OsMAX1a and OsMAX1e showed stable and high expression in rice tissues. In addition, we observed that OsMAX1a and OsMAX1e can rescue the branched phenotype and the influences caused by MAX1 mutation in Arabidopsis. Moreover, the expression of OsMAX1a and OsMAX1e can respond to phosphate deficiency and different phytohormones, especially GR24, a strigolactone analogue. Therefore, it is concluded that OsMAX1a and OsMAX1e are involved in the biosynthesis of strigolactones and regulated rice tillering.

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Genetic Dissection of Low Phosphorus Tolerance Related Traits Using Selected Introgression Lines in Rice Chao Xiang, Jie Ren, Xiu-qin Zhao, Zai-song Ding, Jing Zhang, Chao Wang, Jun-wei Zhang, Augustino Joseph Charles, Qiang Zhang, Yun-long Pang, Yong-ming Gao, Ying-yao Shi 2015, 22(6): 264-274.  DOI: 10.1016/S1672-6308(14)60306-1 Abstract ( )   HTML ( )   PDF (1036KB) ( )   To dissect the genetic basis of low phosphorus tolerance (LPT), 114 BC2F4 introgression lines (ILs) were developed from Shuhui 527 and Minghui 86 (recurrent parents), and Yetuozai (donor parent). The progenies were tested for 11 quantitative traits under three treatments including normal fertilization in normal soil (as control), normal fertilization in barren soil and low phosphorus stress in barren soil in Langfang, Hebei Province, China. Moreover, the ILs were investigated at the seedling stage using nutrient solution culture method in greenhouse in Beijing, China. A total of 49 main-effect quantitative trait loci (QTLs) underlying yield related traits were identified in Langfang, and their contributions to phenotypic variations ranged from 6.7% to 16.5%. Among them, 25 (51.0%) QTLs had favorable alleles from donor parent. A total of 48 main-effect QTLs were identified for LPT-related traits in Beijing, and their contributions to phenotypic variations ranged from 7.7% to 16.6%. Among them, 21 (43.8%) QTLs had favorable alleles from donor parent. About 79.6% of the QTLs can be detected repeatedly under two or more treatments, especially QTLs associated with spikelet number per panicle, spikelet fertility and 1000-grain weight, displaying consistent phenotypic effects. Among all the detected QTLs, eight QTLs were simultaneously identified under low phosphorus stress across two environments. These results can provide useful information for the genetic dissection of LPT in rice.

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Comparative Study on Growth Performance of Transgenic (Over-Expressed OsNHX1) and Wild-Type Nipponbare under Different Salinity Regimes Kahrani Ishak Nurul, Sulaiman Zohrah, U. Tennakoon Kushan 2015, 22(6): 275-282.  DOI: 10.1016/S1672-6308(14)60301-2 Abstract ( )   HTML ( )   PDF (554KB) ( )   Transgenic Nipponbare which over-expressed a Na+/H+ antiporter gene OsNHX1 was used to compare its growth performance, water status and photosynthetic efficiency with its wild type under varying salinity regimes. Chlorophyll content, quantum yield and photosynthetic rate were measured to assess the impact of salinity stress on photosynthetic efficiency for transgenic and wild-type Nipponbare. Effects of salinity on water status and gas exchange to both lines were studied by measuring water use efficiency, instantaneous transpiration rate and stomatal conductance. Dry shoot weight and leaf area were determined after three months of growth to assess the impacts of salinity on the growth of those two lines. Our study showed that both lines were affected by salinity stress, however, the transgenic line showed higher photosynthetic efficiency, better utilization of water, and better growth due to low transpiration rate and stomatal conductance. Reduction of photosynthetic efficiency exhibited by the wild-type Nipponbare was correlated to its poor growth under salinity stress.

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Proline and Glutamine Improve in vitro Callus Induction and Subsequent Shooting in Rice Pawar Bhausaheb, Kale Prashant, Bahurupe Jyoti, Jadhav Ashok, Kale Anil, Pawar Sharad 2015, 22(6): 283-289.  DOI: 10.1016/S1672-6308(14)60300-0 Abstract ( )   HTML ( )   PDF (597KB) ( )   This study was conducted to evaluate the effects of proline and glutamine on in vitro callus induction and subsequent regeneration and to develop a reproducible and highly efficient plant regeneration protocol in four rice genotypes, viz. Pawana, Jaya, Indrayani and Ambemohar. Considerable variation in response to plant growth regulators and amino acid supplements used was observed in all the four genotypes. Medium supplemented with proline and glutamine was shown to be superior to medium without proline and glutamine. The best callusing from mature embryo was observed on Murashige and Skoog (MS) medium supplemented with 2.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D), 500 mg/L proline and 500 mg/L glutamine. Shoot induction was higher in the callus obtained from medium supplemented with 500 mg/L proline and 500 mg/L glutamine. The highest shoot regeneration frequency (83.2%) was observed on MS medium with 2.0 mg/L benzylaminopurine, 0.5 mg/L 1-naphthaleneacetic acid, 500 mg/L proline, and 500 mg/L glutamine in the callus obtained from MS medium supplemented with 2.0 mg/L 2,4-D, 500 mg/L proline and 500 mg/L glutamine. Among the four genotypes, Pawana has the highest regeneration efficiency (83.2%), whereas the regeneration efficiency of the rest three rice genotypes was in the range of 32.0% to 72.3%. This optimized regeneration protocol can be efficiently used for Agrobacterium mediated genetic transformation in rice.

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Development and Characterization of Elite Doubled Haploid Lines from Two Indica Rice Hybrids Rukmini MISHRA, Gundimeda Jwala Narashima RAO, Ravi Nageswara RAO, Pankaj KAUSHAL 2015, 22(6): 290-299.  DOI: 10.1016/S1672-6308(14)60301-2 Abstract ( )   HTML ( )   PDF (912KB) ( )   Despite significant yield advantage over inbred rice, the adoption rate of hybrid rice in India is very low due to the high seed cost and poor quality of the produce. To alleviate the problem, we initiated a doubled haploid (DH) breeding approach to develop new lines from two elite indica rice hybrids (CRHR5 and CRHR7) through rapid fixation of homozygosity in the recombinants. In vitro culture of the rice anthers resulted in 243 and 186 fertile DH lines of CRHR5 and CRHR7, respectively. Flow cytometric and pollen fertility analyses confirmed the DH ploidy status of the regenerations. Morpho-agronomic evaluation revealed 100% uniformity and stability for all the characters in the DH lines of both hybrids. Nineteen promising DH lines of each hybrid were advanced to A2 generation for yield evaluation. The yield levels of the DH lines ranged from 5 097–6 965 kg/hm2 for CRHR5 and 5 141–7 235 kg/hm2 for CRHR7, which were at par or higher than the parental hybrids. Physico-chemical characterization and cooking quality analyses revealed significant and acceptable values for grain length and width, alkali spreading value, amylose content and water uptake ratio of the selected DH lines. Three DH lines, CR5-10, CR5-49, CR5-61 from CRHR5, and four DH lines, CR7-5, CR7-7, CR7-12 and CR7-52 from CRHR7, showed significant grain yield and quality characteristics and have been recommended for multi-location trials for subsequent release as new indica doubled haploid rice varieties.

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Development and Identification of Novel Rice Blast Resistant Sources and Their Characterization Using Molecular Markers J. S. Rama Devi S., Singh Kuldeep, Umakanth B., Vishalakshi B., Renuka P., Vijay Sudhakar K., S. Prasad M., C. Viraktamath B., Ravindra Babu V., S. Madhav M. 2015, 22(6): 300-308.  DOI: 10.1016/S1672-6308(14)60308-5 Abstract ( )   HTML ( )   PDF (652KB) ( )   To develop and characterize introgression lines for leaf and neck blast resistance, 326 introgression lines were developed using various accessions of six different AA genome wild species in the genetic background of elite Indian varieties like PR114 and Pusa 44 and were screened for blast resistance. Stringent phenotyping coupled with genotyping using gene based markers led to the identification of four resistant introgression lines, which showed promising resistance and do not possess any of the tested genes. Furthermore, multi-location screening confirmed the field resistance of the four introgression lines to both leaf and neck blast. Molecular characterization of these introgression lines using genome-wide simple sequence repeat markers revealed the presence of small percentage of wild Oryza genome introgrssion. So these lines can be used for mapping and identification of novel leaf and neck blast resistance genes. Thus, these four introgression lines can be considered as new genetic resources for blast resistance.