This document summarizes research on developing transgenic crops with improved tolerance to salinity and drought stress and enhanced nutritional quality. It describes how genes like OsMYB6, IPT, and MCM6 were introduced into rice, tobacco, and pea plants via genetic engineering to increase their tolerance to salt and drought. Transgenic sugarcane with the AVP1 gene also showed improved tolerance. Additionally, it discusses efforts to biofortify crops like bananas, potatoes and wheat to increase their vitamin, mineral and micronutrient content through metabolic engineering and breeding.

1. Transgenic crops tolerating
salinity and drought stress and
improvement in Nutrional
quality.
NAME:- ISHAN VINAY SHAH
CLASS:- MSc1
SAP NO:- 40504210007
ROLL NO.:- C006

2. Introduction
 What are transgenic crops?
A transgenic crop is a genetically modified
organism (GMO). Transgenic indicates that a
transfer of genes has occurred using recombinant
DNA technology. Generally, a transgenic crop
contains one or more genes that have been inserted
artificially either from an unrelated plant or from
different species altogether.

3.  High salinity and drought are two major stress factors that can seriously affect
plant growth, development, and crop yield.
 Sessile and they keep evolving.
 When plants are exposed to drought and salinity stress, a series of genes are
activated or inhibited, and the products of these genes may either further control
the expression of downstream genes or directly protect plants from stress
damage.
 AP2/ERF, MYB, NAC, WRKY, bZIP, and bHLH- transcription factors
 MYB transcription factor
 MYB proteins have been identified in various plant species (e.g., rice, soybean,
Arabidopsis, sweet orange) through the genome-wide analysis method.

4.  Plays a significant role in regulatory networks
that involve in the whole process of plant
growth and development.
E.g. MusaMYB31 in bananas, DcMYB6 in purple
carrots, EsMYB9 in Epimedium
 Numerous studies have suggested that MYB
proteins are also involved in regulating plant
responses to abiotic stress.
 Overexpression of TaODORANT1 enhances
resistance to drought and salt stress in
transgenic plants.
 PbrMYB21 gene plays a positive role in drought
tolerance partly due to the modulation of
polyamine synthesis by regulating the ADC
expression.
 The CaMYB85 protein confers drought and salt
tolerance via increasing the expression of stress-
responsive genes in transgenic Arabidopsis.

5. Rice (Oryza sativa)
 Rice (Oryza sativa) is a monocotyledonous
model plant and a staple crop for most of the
world’s population.
 However, rice is more sensitive to drought and
salt stress than other cereals such as barley,
wheat, and rye.
 We speculated that overexpression of OsMYB6
might increase the resistance of transgenic
plants to drought stress.

6.  The performance of 2-week-old
wild-type and transgenic plant
seedlings was explored in nutrient
soil and vermiculite (1:3)
underwater deficiency conditions.
 No significant difference seen
before the drought stress
treatment.
 After 25days:
Wild type: severe dehydration, wilting,
only few green leaves were seen
Transgenic type: still healthy and
green.
Growth retardation in both, but more
pronounced in wild type

7.  High rate of Proline accumulation is seen in the transgenic crops.
 REL & MDA content were more in wild type after drought stress
 CAT & SOD increased in both after drought stress but significant increase in transgenic plant.
 Overexpression of OsMYB6 in rice can increase the resistance of transgenic plants to drought
stress.

8.  NaCl stress rapidly activated OsMYB6 expression, showing that OsMYB6 might play an
important role in response to salinity stress.
 At seedling stage rice was supplemented with 150mM of salt sol. For 6 days after 6 days:
Wild-type plants showed fewer green leaves, and more severe leaf rolling and wilting, whereas
transgenic plants displayed more green leaves and less leaf wilting and rolling.
Compared with the wild-type plants, the transgenic plants exhibited a lower REL, lower MDA
content, higher proline content and higher CAT and SOD activities.
Results showed that overexpression of OsMYB6 can also increase the resistance of transgenic rice
to salinity stress.

9. Tobacco plant (Nicotiana tabacum)
 Introduction into tobacco of isopentenyl transferase (IPT)
from Agrobacterium tumefaciens via Agrobacterium-mediated
transformation is reported.
 Arabidopsis thaliana
 Ectopic IPT overexpression IPT under the control of the stress-
inducible rd29A promoter resulted in significantly enhanced
tolerance to salt stress.
 The leaves of transgenic tobacco plants showed significantly
prolonged chlorophyll retention times under a 2-week salt-
stress treatment
 In contrast, the leaves of the non-transformed plants (wild type)
gradually senesced under the same condition.

10.  MDA increased during stress period
 Superoxide dismutase increased during stress period
 These results indicate that enhanced reactive oxygen species scavenging capability may play a
significant role in acquiring tolerance to abiotic stress.

11. Pea plant (Pisum sativum)
 The MCMs provide DNA unwinding function during DNA
replication.
 Since MCM proteins play an essential role in cell division and
most likely are affected during stress conditions therefore their
overexpression in plants may help in stress tolerance.
 MCM6 is upregulated with salinity and cold stress but not
with ABA, heat & drought stress.
 MCM6 overexpression driven by a constitutive cauliflower mosaic
virus-35S promoter in tobacco plants confers salinity tolerance.

12.  T1 transgenic plants were not affected by salinity stress. Only Na+ gets conc. In the older leaves
and seeds do not get affected.
 T1 transgenic plants maintained significantly higher levels of leaf chlorophyll content.
 Hence, it suggest that DNA replication machinery can be exploited for promoting stress tolerance
in crop plants.

13. Sugarcane (Saccharum
officinarum)
 Glycolyte
 Severly affected by salt and drought stress
 Arabidopsis Vacuolar Pyrophosphatase (AVP1)
gene
 Agrobacterium
 Application of acetosyringone, cefotaxime,
kanamycin, and co-cultivation period for
successful transformation.
 77.5% regenration was achieved on MS media

14.  A longer and more profuse root
system was observed in
transgenic plants in comparison
with control plants
 Concomitantly, only transgenic
plants were able to withstand
higher NaCl salt stress as well as
the scarcity of water thus,
showing tolerance against salinity
and drought stresses.

15. Nutritional quality of
transgenic crops
 Nutritional improvement efforts in
potatoes (Solanum tuberosum)nutrient
concentration increase and anti-nutrient
decrease.
 In the Banana21 biofortification program,
which aims to increase pro-vitamin A
content (and iron in the future) in cooking
banana, which is a staple food in Uganda.
 Biofortification strategies to enhance B-
vitamin in crops using metabolic
engineering or breeding are presented.

16.  Lyons reviews the approaches used for agronomic
biofortification of crops with iodine (I) and selenium
(Se) in major crops, with a special focus on wheat.
 Integration of a naturally Ca-rich crop like finger
millet into global biofortification programs could be
a good starting point to alleviate human Ca
malnutrition.

17. Webliography
 1. https://www.frontiersin.org/articles/10.3389/fpls.2019.00168/full
 2. https://link.springer.com/article/10.1007/s11105-011-0337-y
 3. https://link.springer.com/article/10.1007/s11103-011-9758-0
 4. https://link.springer.com/article/10.1007/s12033-013-9695-z
 5. https://www.frontiersin.org/articles/10.3389/fpls.2019.00738/full