Improving blast resistance of maintainer line DRR 9B by transferring broad spectrum resistance gene Pi2 by marker assisted selection in rice.

Hybrid rice technology offers great promise to further enhance rice production and productivity for global food security. Improving hybrid rice parental lines is the first step in developing heterotic rice hybrids. To improve resistance against blast disease, a maintainer line DRR 9B was fortified with a major broad-spectrum blast resistance gene Pi2 through marker-assisted selection. The rice blast caused by Magnaporthe oryzae is a major disease and can cause severe yield losses upto 100%. The NILs of Samba Mahsuri namely BA-23-11-89-12-168 possessing Pi2 was utilized as a donor parent. The PCR-based molecular marker tightly linked to Pi2 gene was used for the foreground selection at BC1F1 generation. The molecular marker tightly linked to the major fertility restorer gene Rf4 was used for negative selection (i.e., selection of plants possessing non fertility restoring alleles) at BC1F1 generation to identify maintainer lines. The positive plants with Rf4 gene were added to the restorer pool for restorer line development. At each stage, MAS for Pi2 coupled with stringent phenotypic selection for agro-morphological and grain quality traits were exercised. At BC1F3 generation, one hundred families were screened against blast disease at uniform blast nursery (UBN) and selected resistant lines were advanced to next generations. In the BC1F5 generation plants were subjected to agro-morphological evaluation for yield and yield-contributing traits. The selected plants at BC1F5 generation were crossed with DRR 9A to assess the maintainer ability of blast resistance lines and for further CMS line conversion for hybrid rice breeding for developing blast resistance rice hybrids.

Marker-assisted improvement of the elite restorer line of rice, RPHR-1005 for resistance against bacterial blight and blast diseases.

This study was carried out to improve the RPHR-1005, a stable restorer line of the popular medium slender grain type rice hybrid, DRRH-3 for bacterial blight (BB) and blast resistance through marker-assisted backcross breeding (MABB). Two major BB resistance genes, Xa21 and Xa33 and a major blast resistance gene, Pi2 were transferred to RPHR-1005 as two individual crosses. Foreground selection for Xa21, Xa33, Pi2, Rf3 and Rf4 was done by using gene-specific functional markers, while 59 simple sequence repeat (SSR) markers polymorphic between the donors and recipient parents were used to select the best plant possessing target resistance genes at each backcross generation. Backcrossing was continued till BC2F2 and a promising homozygous backcross derived line possessing Xa21+ Pi2 and another possessing Xa33 were intercrossed to stack the target resistance genes into the genetic background of RPHR-1005. At ICF4, 10 promising lines possessing three resistance genes in homozygous condition along with fine-grain type, complete fertility restoration, better panicle exertion and taller plant type (compared to RPHR-1005) were identified.

Development of Gene-Pyramid Lines of the Elite Restorer Line, RPHR-1005 Possessing Durable Bacterial Blight and Blast Resistance.

RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the experimental hybrids derived by crossing the gene-pyramid lines of RPHR-1005 with APMS6A (the female parent of DRRH-3), showed heterosis levels equivalent to or higher than DRRH-3. The results of present study exemplify the utility of MABB for targeted improvement of multiple traits in hybrid rice.

Evaluate the Effect of Commercially Available Denture Cleansers on Surface Hardness and Roughness of Denture Liners at Various Time Intervals.

BACKGROUND AND OBJECTIVE: Chemical cleansing by denture cleansers is first choice for denture plaque control. The most common problems while using denture cleansers are hardening, porosity, odor sorption, water sorption, solubility, and colour change, bacterial and fungal growth. Chemical cleansing procedures have been found to have an effect on the physical and mechanical properties of denture liners. Thus, this study was conducted to evaluate the effect of commercially available denture cleansers on surface hardness and roughness of acrylic and silicon based denture liners at various time interval. METHOD: Two autopolymerising denture liners Kooliner (acrylic) and GC reline soft (silicon) were tested with two commercially available denture cleansers, polident and efferdent plus. Total of 120 specimens were prepared and all the specimens were divided into six groups based on the relining materials and denture cleansers used. Surface hardness and surface roughness was tested using Shore A durometer and profilometer respectively at the end of day 1, day 7, day 30 and day 90. All the specimens were stored in artificial saliva throughout the study. Cleanser solution was prepared daily by adding Polident and Efferdent plus denture cleanser tablet into 250ml of enough very warm (not hot) water. Acrylic and silicon liner groups were cleansed in a solution of denture cleanser and water for 15 minutes daily, rinsed with water and stored in artificial saliva at room temperature. The data was analyzed with one way ANOVA and independent t-test. RESULT: The acrylic soft lining showed gradual hardening and increase in surface roughness after immersion in denture cleanser and also with time. Acrylic liner material showed maximum hardness and roughness with Polident followed by Efferdent plus and water (control group). Silicone lining material showed a slight difference in hardness and roughness between the test group and control group. There was a slight increase in hardness in all the groups with time. Very slight increase in mean surface roughness of all the silicon liner groups from day 1 to day 90 was observed. A statistically significant change was noted between and within the all silicon liner groups on day 7, day 30 and day 90. CONCLUSION: The average surface hardness and surface roughness were lower in silicon liner material than acrylic liner material. Maximum surface roughness was noted by Polident followed by Efferdent Plus and Water for both acrylic liner group and silicon liner group.

Neck mestastasis from unknown origin-results of planned primary surgery and post-operative radiation therapy.

Ninety-two patients with metastasis of unknown origin were studied between 1986 and 1997 at Kidwai Memorial Institute of Oncology, India. Treatment included planned primary radical neck dissection followed by radiotherapy. Sixty-seven patients completed our multimodal therapy. Thirty-eight of these patients had a median follow-up pf 35.7 months. Nine patients had a median follow-up of 8.3 months. Twenty patients were lost in follow-up after completing the above protocol. Twenty-five patients did not comply with prescribed therapy. Of the followed up patients 78.9% were disease free. The failure rate was 21%, which comprised of regional failure in 16% and liver metastasis in 5%. Primary manifested at base of tongue in 2 patients. In a third world cancer center like ours, advanced neck disease and unreliable follow-up mandate multimodal therapy to be instituted at the first instance. Manifest primaries should be treated on individual basis.

Functional laryngeal surgery - critical determinants of successful rehabilitation.

This study addresses the functional outcome and rehabilitative process in 30 partial laryngectomies carried out for laryngeal (22) und hypoorpharyngeal (8) cancers at the department of H/N Surgery, The kidwai Memorial Institute of Oncology. Bangalore, India from 1985-1995, Special emphasis is directed towards post-surgical convalescence after various partial laryngeetomy techniques which include 6 vertical laryngectomies (V L / VPL). 17 supraglottic laryngectomies (SG L), and 7 supracricoid laryngectomies with Cricohyoidepexy (CHP). Rehabilitative success was measured with respect to the ease of dccannulation, resumption of normal deglutition and speech analysis - both objectively using standard speech analytical equipment in a speech laboratory and subjectively using the services of blinded judges to score recorded speech of patients. The speech analysis indicate that past SGL speech was the superior most followed by V L and C H P in that order. Aspiration was deemed as minimal and inconsequential after V L/VPL followed by CHP;and SGL, in the order of severity;the extended modifications to resect the arytenoid and / or basE of tongue and / or piriform fossa faring worse than classic standard technique.

Vocal rehabilitation after gastric transposition. The critical overview.

Re-establishment of effective communication following laryngopharyngo esophagectomy and gastric transposition requires thorough knowledge and flexibility of introducing the entire range of communication options. This study describes our experience with eleven patients of gastric transposition who attended intensive speech therapy and developed gastric speech using different method of speech producing and attaining various levels of proficiency. Application of digital pressure is one of the most effective technique for production of satisfactory and intelligible voice in gastric transposition cases who fail to develop speech by inhalation method.