Bacterial blight (BB) and fungal blast diseases are the major biotic constraints that limit rice productivity. To sustain yield improvement in rice, it is necessary to developed yield potential of ...the rice varieties by incorporation of biotic stress resistance genes. Tellahamsa is a well-adapted popular high yielding rice variety in Telangana state, India. However, the variety is highly susceptible to BB and blast. In this study, simultaneous stepwise transfer of genes through marker-assisted backcross breeding (MABB) strategy was used to introgress two major BB (Xa21 and xa13) and two major blast resistance genes (Pi54 and Pi1) into Tellahamsa. In each generation (from F.sub.1 to ICF.sub.3) foreground selection was done using gene-specific markers viz., pTA248 (Xa21), xa13prom (xa13), Pi54MAS (Pi54) and RM224 (Pi1). Two independent BC.sub.2 F.sub.1 lines of Tellahamsa/ISM (Cross-I) and Tellahamsa/NLR145 (Cross-II) possessing 92% and 94% recurrent parent genome (RPG) respectively were intercrossed to develop ICF1-ICF.sub.3 generations. These gene pyramided lines were evaluated for key agro-morphological traits, quality, and resistance against blast at three different hotspot locations as well as BB at two locations. Two ICF.sub.3 gene pyramided lines viz., TH-625-159 and TH-625-491 possessing four genes exhibited a high level of resistance to BB and blast. In the future, these improved Tellahamsa lines could be developed as mega varieties for different agro-climatic zones and also as potential donors for different pre-breeding rice research.
JGL1798 (Jagtial Sannalu) is a high yielding fine grain variety released for Telangana state, India, and highly susceptible to two major rice diseases, bacterial blight (BB) and blast. To improve ...JGL1798 for BB and blast resistance, two bacterial blight resistance genes (
xa13
and
Xa21
) derived from improved Samba Mahsuri (B95-1) and one blast resistance gene (
Pi54
) from NLR145 have been introgressed using marker-assisted backcross breeding (MABB) method. Foreground selection was carried out in two independent backcross-derived progenies JGL1798 X B95-1(C
5
) and JGL1798 X NLR145 (C
6
) using three gene linked markers viz., xa13 promoter, PTA248, and Pi54MAS. To achieve maximum genome recovery of recurrent parent, background selection was carried out among the gene positive plants at each backcross generation and identified backcross lines having high genome recovery of recurrent parent. Pyramiding three genes into one background, marker-assisted backcrossing was continued until BC
2
generation and an intercross was made between highest genome recovery plants, i.e., C
5
-BC
2
F
1
-23and C
6
-BC
2
F
1
-4. The six triple heterozygous positive ICF
1
plants confirmed for the presence of
xa13
,
Xa21
, and
Pi54
genes in heterozygous condition. These plants were screened with polymorphic SSR markers and the ICF
1
24 plant possessing maximum percentage (90%) of recurrent parent genome was selected, selfed and 2216 ICF
2
plants were obtained and evaluated during kharif, 2013. A total of 862 plants were genotyped possessing the target resistance genes in homozygous condition. Among those, 11 homozygous plants, the ICF
2
-4-12 lines possessing the highest genome recovery (92.3%). The identified 11 introgressed lines displayed higher level of resistance to bacterial blight and blast with good agro-morphological traits, grain yield, physical, and cooking quality characters similar to that of JGL1798.
Intercropping groundnut with sorghum at a 3:1 ration has given lower AUDPC (1018) with a mean pod yield of 1868 kg/ha, and was found significant in reducing the PBND (34.2%) compared to sole ...groundnut (AUDPC of 1545 mean pod yield of 1407 kg/ha, 52% PBND). In groundnut intercropped with pulses, groundnut + redgram (5:1) was found to be effective in reducing PBND to an extent of 10% and recorded higher equivalent pod yield of 2236 kg/ha with 1014 AUDPC compared to sole groundnut (AUDPC 1078, 63.44% PBND; mean pod yield of 1663 kg/ha). The higher incidence of PBND was recorded in the treatments involving greengram, blackgram and soybean and it was also reflected in realising higher values of AUDPC.
We report here the first successful transfer of T-DNA of
Agrobacterium tumefaciens carrying the genes coding for β-glucuronidase (
uidA), green fluorescent protein (
gfp) and hygromycin ...phosphotransferase (
hpt) to the nuclear genome of the green alga
Chlamydomonas reinhardtii. The transformation frequency (which was based on hygromycin resistance phenotype) was 50-fold higher than that of the glass bead transformation. Molecular and genetic analyses performed on transformants revealed the stable nuclear integration and expression of transgenes. The simplicity of
Agrobacterium-mediated gene transfer and the high transformation frequency as well as the precision of T-DNA integration will enable further molecular dissection of this important model organism to understand basic plant metabolic processes as well as to exploit the system for biotechnological applications.
The HCV NS5B RNA dependent RNA polymerase plays an essential role in viral replication. The discovery of a novel class of inhibitors based on an N,N-disubstituted phenylalanine scaffold and ...structure−activity relationships studies to improve potency are described.
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