Central Rice Research Institute Annual report...2011-12

30 BC 1
F 1
embryos were inoculated successfully in ¼
MS medium. The crossability (%) ranged from 0.33-0.42.
The seeds of F 4
, F 5
and BC 1
F 2
and BC 2
F 2
generations of
the cross Naveen/O.nivara, Lalat/O. nivara were collected
for next generation testing. New crosses have
been effected using female parents such as Savitri with
male parents such as O. nivara (AC100476, AC100374).
More than 10 promising selections were made of which
CR2892-14-3, CR2892-21-5, CR2892-30-1-1 were having
desirable plant type with high degree of tolerance
to drought.
The BC 1
F 1
hybrids of O. sativa cv. Savitri/O.
brachyantha were backcrossed with recurrent parents
employing embryo rescue technique with hormonal
treatments before and after pollination. Out of over
10,000 pollinations, 12 BC 2
F 1
hybrids recovered following
embryo rescue and were grown in pots. The chromosome
numbers of BC 2
F 1
plants ranged from 24 to 36.
Three plants were 24 normal but differed from each
other as well as from the normal disomic sibs in several
morphological and reproductive features including
slow growth habit. Sibs with 25 chromosomes were isolated.
One disomic plant exhibited moderate resistance
(MR) against yellow stem borer (YSB).
Studies on Gene Flow from Cultivated
to Wild Species
Detection of gene flow using anthocyanin
pigmentation of rice as morphological marker
A field experiment on gene flow from cultivated rice
O. sativa ‘Crossa’ (as pollen source) to wild rice O.
nivara (pollen receiver), was conducted during the wet
season of 2011. The purple plant color of ‘Crossa’ was
used as morphological marker. The ‘Crossa’ plants at
the centre were surrounded by plants of O. nivara in a
square design at every meter distance from the source
up to 10 meters. The mature seeds of the receiver plants
were allowed to shatter and fall in the same field to
grow naturally in the next wet season on its own. It
was expected to get purple hybrids from the 3 rd
year on and the extent of which will be an index
of gene flow.
Tracing of gene flow using CMS lines
and molecular markers
A field experiment was conducted to study
the gene flow of rice in the wet season of 2011
using the CMS line as pollen receiver and rice
varieties ‘Lalat’ and ‘Tapaswini’ with gene pyramids
of Xa5, Xa13 and Xa21 series as pollen
source in a square design. This method was designed
to provide a double check on pollen flow
from the designated source. The percentages of
fertile spikelets, representing the pollen flow in
the CMS lines were highest at 5 m than those at 10 m.
There were also differences in the percentage of fertile
spikelets with different directions studied. The highest
percentage of pollen flow, in terms of % of fertile spikelets
was 2.74% in north-east direction at 5m distance
followed by 2.4 %, 2.14 %, in north, and north-west
direction, respectively. The lowest pollen flow of 0.71%
was observed in eastward direction. Overall, the pollen
flow values were found to vary with different distances
and directions.
Improving Biochemical/Physiological
Efficiency of Varieties
Transformation of rice variety Naveen using
NADP-Malate dehydrogenase
Rice variety Naveen was transformed with NADP-
Malate dehydrogenase using seed derived callus. Surface-sterilized
seeds were allowed to germinate and
cultured on 2N6 media for four weeks; callus was harvested
and further cultured on 2N6 media for 10 days.
The Calli were then incubated for 20 minutes in bacteria
re-suspended (OD 600
=1.0) in AAM media, drained,
dried on sterile filter paper and then co-cultured with
bacteria (S. meliloti) for seven days on 2N6AS media.
After co-culture, rice calli were assayed for GUS activity
and transferred to selective media (2N6TCH) for four
weeks and proliferating calli were selected and transferred
to regeneration media (RGH6). Shoots arising
from calli on regeneration media were transferred to
rooting media (½ MSH media: ½ strength MS major, MS
minor salts, N6 vitamins; 10 g l -1 sucrose, 2.5 g l -
1
Phytagel, pH 5.8, 50 mg l -1 hygromycin-B). After root
formation, plants were transferred to soil for further
analysis (Fig. 3).
Rice plants transformed with maize MDH
34 CRRI ANNUAL REPORT 2011-12