The polymorphisms of Waxy (Wx) microsatellite and G-T single-nucleotide polymorphism (SNP) in the Wx gene region were analyzed using simplified techniques in fifteen rice varieties. A rapid and reliable electrophoresis method, MetaPhor agarose gel electrophoresis (MAGE), was effectively employed as an alternative to polyacrylamide gel electrophoresis (PAGE) for separating Wx microsatellite alleles. The amplified products containing the Wx microsatellite ranged from 100 to 130 bp in length. Five Wx microsatellite alleles, namely (CT)10, (CT)11, (CT)16, (CT)17, and (CT)18 were identified. Of these, (CT)11 and (CT)17 were the predominant classes among the tested varieties. All varieties with an apparent amylose content higher than 24% were associated with the shorter repeat alleles; (CT)10 and (CT)11, while varieties with 24% or less amylose were associated with the longer repeat alleles. All varieties with intermediate and high amylose content had the sequence AGGTATA at the 5′-leader intron splice site, while varieties with low amylose content had the sequence AGTTATA. The G-T polymorphism was further verified by the PCR-AccI cleaved amplified polymorphic sequence (CAPS) method, in which only genotypes containing the AGGTATA sequence were cleaved by AccI. Hence, varieties with desirable amylose levels can be developed rapidly using the Wx microsatellite and G-T SNP, along with MAGE.
The duration of flight by Nilaparvata lugens (Stil) of tropical origin from field and laboratory populations was studied. Field insects (from the third generation on rice) flew longer and more readily than laboratorybred insects. The longest recorded flight, of 10'75 h, was by a female from the field. Laboratory-reared insects performed poorly even after only one generation in the laboratory. Flights that were started in the morning lasted longer than those started in the afternoon. Lift production varied between individuals and during a continuous flight. Individuals flying for over 150 min tended to produce more lift for a longer proportion of the flight than those flying for less than 10 min. The pattern of lift production appeared to be similar in successive flights, except in those following very long flights when the insect appeared to be exhausted. There was no tendency for the first flight to be the longest. Up to 28% loss of body weight was recorded (in a flight lasting 512 min) during flight. The results indicate that individuals from tropical field populations of N. lugens have the capacity for long range migration.
In 2000, agriculture contributed 13% to the national gross domestic product of Malaysia. The country of 23 million people has created a competitive program coordinated by the Ministry of Science, Technology and the Environment, research institutions, and universities to undertake biotechnology research in several areas. Intensified research efforts are under way on oil palm, rubber, rice, papaya, and orchids. Although the most progress has been made in rice and papaya, no transgenic crop is ready for field trials. Nonetheless, preliminary steps have been taken to prepare for the trials, and detailed testing protocols are being developed.
While it is crucial for developing countries like Malaysia to achieve self-sufficiency in rice (Oryza sativa L.), it is equally critical to be able to produce high-quality rice, specifically fragrant rice, which demands are often met through importation. The present study was aimed at developing high-yielding fragrant rice, in a timely and cost-effective manner. A marker-assisted backcross (MABC) approach was optimised to introgress the fragrance gene (fgr) into two high-yielding Malaysian varieties, MR84 and MR219, within two years utilising less than 50 molecular markers. Coupled with phenotypic screening, one single foreground marker (fgr-SNP) and 48 background markers were selected and utilised, revealing recovery of at least 90% of recurrent parent genome (RPG) in merely two backcross generations. Collectively, the yield potential of the developed BC2F2 lines (BLs) was higher (P > 0.05) than the donor parent, MRQ74, and similar (P < 0.05) to both the recurrent parents, MR84 and MR219. In addition, some of the developed BLs showed good grain quality, such as having long grain. We believe that this is the first report comprising the validation and utilisation of the single functional marker system (fgr-SNP) in introgressing the fgr gene into different rice varieties.
Five citrus species namely Citrus reticulata, C. aurantium, C. grandis, C. madurensis and Murraya paniculata were assessed for tolerance by grafting and vector transmission tests toward Ca. L. asiaticus-Terengganu isolate. This study was conducted in an insect-proof glasshouse for a period of six months. Results of this study showed that seedlings of M. paniculata, and C. grandis showed no HLB symptoms six months after inoculation period. They were also showed negative results by polymerase chain reaction (PCR) test and recorded the lowest percentage of reduction rate of plant height and plant biomass. Based on our findings, proved that these two citrus species were resistance to huanglongbing (HLB) or citrus greening infection. However, C. aurantium was showed high tolerance to HLB infection with the trees exhibited mild leaf mottling and green vein and the infected seedlings recovered after 3-4 months after treated with fertilizer. However the pathogen was detected by PCR test in the recovered seedlings. C. reticulata and C. madurensis were very susceptible to HLB infection. Inoculated seedlings showed severe HLB symptoms such as leaf mottling and yellowing, leaf green vein, leaf defoliation, twigs dieback within six months after inoculation. The inoculated seedlings started showing the first symptoms within three months after inoculation. Infected seedlings were also showed positive results with PCR
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