VII. Flowering time
As stress response is correlated with flowering, the genetics of flowering and its
temporal variations can be utilized in a breeding fruit crop. The gene MdTFL1
targeting the same phenotype has been used for a silencing study, and its role for
controlling flowering has been discovered in apple (Flachowsky et al. 2012). Even
from a major class of genes, few putative genes have been characterized that express
sufficiently the control miRNA responsible for the transition state, that is, vegetative
to floral initiation (Jia et al. 2017).
VIII. Drought stress
Longer drought spells occurring frequently in the subtropical environment before
flowering hamper the flower to fruit conversion and ultimate production potential.
The genetic potential of drought-tolerant crops can be exploited to develop tolerant
cultivars in the crop of interest. Under drought conditions a plant always finds a
strategy to avoid stress. It may change its physiology accordingly by reducing
stomatal conductance and changes in root system architecture, reducing life cycle
and early flowering in this circumstance and also maintaining some compatible
solutes, that is, osmotic adjustment strategies (Blum 2017) in the vacuole.
Maintaining physiological stasis under the affected water potential of the plant and
carbon gain measured through photosynthesis activity can be considered for breeding climate-smart fruit crops (Jimenez et al. 2013). MdMYB88 and MdMYB124
genes have been reported to be associated with adaptive drought tolerance in apple
that maintains the plant water level under stress conditions (Geng et al. 2018).
Various major transcription factors related to drought tolerance mechanisms such
as MYB, MYC, NAC, NAM, bZIP, and DREB are reported for drought tolerancebased differential regulation (Argarwal and Jha 2010).
IX. Salinity stress
Salinity stress is one of the problems of major arid and semiarid regions. Various
frequent flashes of rain and subsequent inundation at the coastal belt cause a stress
that impacts the crop and is also withstood by the crop plant by channelizing extra
salt at the vacuoles. Genes such as LEA5, glutathione S-transferases, and SOD have
been identified to be associated with salt-induced oxidative stress (Beeor-Tzahar
et al. 1995).
(b) Adaptation through management practices
I. Use of rootstock
Rootstocks have an important role in successful establishment of plants into wide
environmental and soil conditions. Most fruit crops are propagated vegetatively
using rootstock tolerant to different abiotic stresses such as salinity, drought, iron
chlorosis, and flooding (Irenaeus and Mitra 2014). In grapes, Dogridge is used for
drought and salinity tolerance. Sharad Seedless grafted on Dogridge rootstock
showed maximum water use efficiency (Satisha and Prakash 2006). Juglans hindsii
rootstock is used in walnut for tolerance to waterlogged soils.
92
T. Sarkar et al.
As stress response is correlated with flowering, the genetics of flowering and its
temporal variations can be utilized in a breeding fruit crop. The gene MdTFL1
targeting the same phenotype has been used for a silencing study, and its role for
controlling flowering has been discovered in apple (Flachowsky et al. 2012). Even
from a major class of genes, few putative genes have been characterized that express
sufficiently the control miRNA responsible for the transition state, that is, vegetative
to floral initiation (Jia et al. 2017).
VIII. Drought stress
Longer drought spells occurring frequently in the subtropical environment before
flowering hamper the flower to fruit conversion and ultimate production potential.
The genetic potential of drought-tolerant crops can be exploited to develop tolerant
cultivars in the crop of interest. Under drought conditions a plant always finds a
strategy to avoid stress. It may change its physiology accordingly by reducing
stomatal conductance and changes in root system architecture, reducing life cycle
and early flowering in this circumstance and also maintaining some compatible
solutes, that is, osmotic adjustment strategies (Blum 2017) in the vacuole.
Maintaining physiological stasis under the affected water potential of the plant and
carbon gain measured through photosynthesis activity can be considered for breeding climate-smart fruit crops (Jimenez et al. 2013). MdMYB88 and MdMYB124
genes have been reported to be associated with adaptive drought tolerance in apple
that maintains the plant water level under stress conditions (Geng et al. 2018).
Various major transcription factors related to drought tolerance mechanisms such
as MYB, MYC, NAC, NAM, bZIP, and DREB are reported for drought tolerancebased differential regulation (Argarwal and Jha 2010).
IX. Salinity stress
Salinity stress is one of the problems of major arid and semiarid regions. Various
frequent flashes of rain and subsequent inundation at the coastal belt cause a stress
that impacts the crop and is also withstood by the crop plant by channelizing extra
salt at the vacuoles. Genes such as LEA5, glutathione S-transferases, and SOD have
been identified to be associated with salt-induced oxidative stress (Beeor-Tzahar
et al. 1995).
(b) Adaptation through management practices
I. Use of rootstock
Rootstocks have an important role in successful establishment of plants into wide
environmental and soil conditions. Most fruit crops are propagated vegetatively
using rootstock tolerant to different abiotic stresses such as salinity, drought, iron
chlorosis, and flooding (Irenaeus and Mitra 2014). In grapes, Dogridge is used for
drought and salinity tolerance. Sharad Seedless grafted on Dogridge rootstock
showed maximum water use efficiency (Satisha and Prakash 2006). Juglans hindsii
rootstock is used in walnut for tolerance to waterlogged soils.
92
T. Sarkar et al.