ELUCIDATION OF MOLECULAR MECHANISMS GOVERNING COLD TOLERANCE DURING REPRODUCTIVE STAGE IN CHICKPEA (Cicer arietinum L.)
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Date
2018-10
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CSKHPKV, Palampur
Abstract
Description
Low temperature induced flower abortion in chickpea (Cicer arietinum L.), an important food
grain legume in India, is the major cause of reduced yields in winter sown chickpea in India.
However, exact causes of flower abscission by cold stress (CS) in chickpea, especially the
impact of CS on male gamete development are largely unknown. Similarly, flower
development and anther/pollen development in chickpea are also not known. In the present
study, flower development stages (12 stages; stages 7-18) and anther/pollen development
stages (11 stages; stage 4-14c) were identified in chickpea. A user friendly criterion based on
flower length and flower stage to estimate anther stage was also described. In addition to this,
the causes of aberrations in male gamete formation in cold-susceptible genotype GPF2 were
also investigated under CS (4°C and 9°C). The abortion of flowers at early flower stages was
due to disruption of microsporogenesis, microgametogenesis, tapetum degeneration and
anther dehiscence, whereas abortion of older flowers was due to reduction in pollen viability,
ovule viability, stigma receptivity and pollen load on stigma. Male and female reproductive
organ development as well as flower development under CS in GPF2 was compared with
(cold-tolerant) ICC 16349 genotype. The studies revealed that 4°C temperature was too low
for expression of cold-tolerance in chickpea and evaluation of cold-tolerance in chickpea
should be carried out at 9°C. At 9°C, the growth of plants, flowers, anthers and gynoecium
was better in ICC 16349 than that in GPF2. The molecular mechanisms of anther
development in cold-tolerant ICC 16349 under CS were also investigated. ICC 16349 anthers
under CS maintained normal carbohydrate pool (reducing sugars, non reducing sugars and
starch), whereas GPF2 anthers failed to do so. Apart from carbohydrates, the antioxidant
enzymes glutathione reductase and ascorbate peroxidase also appeared to contribute to cold
tolerance in ICC 16349 anthers. Higher levels of proline in ICC 16349 anthers under CS were
due to increased transport of proline to anthers as evident from higher expression of
transporter of proline called PT 1. Further studies using whole genome transcriptomics are
expected to elucidate other genes involved in cold tolerance by chickpea anthers.
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