"9117","12","archive","16",,,"disk0/00/00/91/17","2015-11-09 09:15:30","2015-11-18 10:52:04","2015-11-09 09:15:30","thesis",,,"show",,,,"","","","","","","","","","",,,,"Pushpavalli","R","","","","","","","Vadez","V","","","","","Rao","M V","","","Bharathidasan University (Tiruchirappalli)","",,,,,"","","Bharathidasan University (Tiruchirappalli)","India","Physiological and genetic deciphering of water,
salinity and relative humidity stress in chickpea
(Cicer arietinum L.)","submitted","s1.1","D4","crp1.4","restricted",,,"Water stress, Salinity, Phenology, Quantitative trait,mapping, pollen germination, Atmospheric, flowering, seed",,,"Chickpea (Cicer arietinum L.), an important cool-season, food legume
crop, is known to be sensitive to several abiotic stresses: drought, salinity
and heat. The yield losses caused by these stresses are accounted to 6.4
million tonnes (t)/ year on global production. To improve any existing
cultivar and harness the genetic regions involved in the tolerance it is
important to understand the genetic and physiological mechanisms that
underlie any tolerance. The objectives of this study were to (i)
understanding the effect of either water deficit or salt stress on the
reproductive biology of genotypes know to contrast for either salt or
drought stress and (ii) construction of genetic map and identification of
QTLs and candidate genes for salinity tolerance in 188 RILs derived from
the ICCV 2 × JG 11 cross.
In the water deficit study conducted in two consecutive years, ten
genotypes with contrasting yields under terminal drought stress in the
field were exposed to a gradual, but similar, water stress in the
glasshouse. Nine parameters related to yield were recorded in wellwatered
plants (WW) and in water-stressed plants (WS) when the level of
deficit was mild (phase I), and when the stress was severe (phase II). The
WS treatment reduced seed yield, seed and pod number, but not flower +
pod + seed abortion percentage or 100-seed weight. The controlled
drought imposition in glass house conditions revealed genotypic
differences inthe sensitivity of the reproductive process to drought. The
seed yield differences in chickpea were largely related to the capacity to
produce a large number of flowers and to set seeds, especially when the
degree of water deficit was mild.
In the salinity experiments, fourteen genotypes of chickpea (Cicer
arietinum L.) were used to study yield parameters, and eight genotypes
were selected for ion analysis after being grown in soil treated with 0 mM
and 80 mM NaCl, to assess any possible relationship between salt ion
accumulation in different plant tissues and yield reduction. Salinity
delayed flowering and the delay was greater in sensitive than tolerant
genotypes under salt stress. Filled pod and seed numbers, but not seed
size, were associated with seed yield in saline conditions, suggesting that
salinity impaired reproductive success more in sensitive than tolerant
lines. The delay in flowering was associated with higher concentrations of
Na+ in the laminae of fully expanded young leaves (R2=0.61) and old
green leaves (R2=0.51). Na+ accumulation in leaves was associated with
delayed flowering that in turn could have played a role of the lower
reproductive success in the sensitive lines.
In QTL mapping for salinity tolerance, yield and components were
assessed in 188 recombinant inbred lines (RILs) derived from cross ICCV
2 × JG 11, in soil treated with either 0 mM NaCl (control) or 80 mM NaCl
(salinity) over two consecutive years. Salinity significantly (P<0.05)
affected almost all traits across years. The mean yield reduction under
salinity compared to control was around 40% across years. A genetic
map was constructed using 56 (SSR, SNP) polymorphic markers. The
QTL analysis revealed two key genomic regions on CaLG05 (28.6 cM) and
on CaLG07 (19.4 cM) that harboured QTLs for salinity tolerance
associated traits. Two major QTLs for higher yield in the salinity
treatment (explaining 12 and 17% of the phenotyping variation) wereidentified within the two key genomic regions. Comparison with already
published chickpea genetic maps showed that these regions conferred
salinity tolerance across two other populations and the markers can be
deployed for enhancing salinity tolerance in chickpea. Based on gene
ontology annotation 48 putative candidate genes responsive to salinity
stress were found. Most of them were believed to be involved in achieving
osmoregulation under stress conditions.
In the relative humidity stress study, five genotypes that contrasting for
yield under heat stress were studied. The plants were grown in three
different vapor pressure deficit conditions (2.5, 3.0, 3.4 kPa) where the
temperature was maintained constant (30°C) and the RH varied as 40,
30, 20% respectively. Genotypic variation found for almost all traits
across treatments. The traits seed number and seed weight differentiated
tolerant and sensitive group significantly at VPD conditions 2.5 and 3.0
but not in 3.4 kPa. Seed size was unaffected under 2.5 and 3.0 kPa VPD
regimes but did get reduced upto 45% under 3.4 kPa treatment
compared to 2.5 kPa treatment. The lowest RH treatment, even under
fully well-watered condition, as any other abiotic stress reduced yield.
Thus, it is important to consider the effect of low RH and the
mechanisms behindits tolerance and sensitivity in future heat tolerance
studies. The pollen viability or pollen in vivo germination was unaffected
in this study.
All the four studies have revealed that certain parameters can be used for
achieving water deficit, salinity and relative humidity stress tolerance in
future chickpea improvement programs.","2015","submitted",,,,,,,,"199",,,,,,,"Bharathidasan University,Tiruchirappalli, Tamil Nadu","Department of Plant Science Center of Excellence in Life Sciences","phd",,,,,,,,,"",,"","",,"","",,,,,,"",,,,,,,"",,,,,"",,,,,"","",,,,,"","",,,,,
"9117",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,"Vadez","V","","","ICRISAT (Patancheru)",,,,,,,,"ICRISAT (Patancheru)",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,