3.1 Plasticity of life history traits in response to
elevated temperature and their correspondence with plasmotype diversity
We wished to examine the effects of plasmotype diversity on barley
phenotypic plasticity including growth, productivity and photosynthesis
rhythmicity while growing plants under ambient vs. high temperatures.
Based on considerations of maximal inclusions of genetic diversity we
performed a set of crosses between 11 wild barley accessions and one
cultivated variety to achieve reciprocal hybrids (RH) pairs with few
genotypes missing to achieve diallel (see Methods).
The days to flowering (DTF) was almost identical under HT and AT
(DTF=-109.9 ±5.6 and 111.73 ±4.97 days, respectively) (Figure1a ). Unlike DTF, the vegetative dry weight of the plants were
significantly affected by the heat, with change from mean of 11.3 gr to
16.4 gr between AT and HT, respectively (Figure 1b ). Similar to
DTF, and unlike the significant effects of the thermal environment on
the vegetative traits, the reproductive traits were less affected; For
spike dry weight (SpDW), there was not a significant difference between
environments (Figure 1c, raw data are presented in TableS2 ) (7.13 ±2.2 and 7.35 ±3.16 gr, respectively).
The reciprocal nature of the hybrids allowed us to group the F1
genotypes into different plasmotype subpopulations and different male
parent subpopulations (representing the nucleotype). One-way ANOVA for
each of these two divisions of the hybrids indicated a larger percentage
variation explained (PVE) by the nucleotype (male donors) in comparison
to differences between plasmotype (female donors) for a few traits
(Table 1 ). For example, for the ASDW under HT the nucleotype
factor explained 41% of trait variation (PVE=41%) vs. PVE=27% by the
plasmotype. For most life history traits, however, we found higher
variation explained by the plasmotype than by the nucleotype under both
temperatures (AT and HT): for PH, PVE=39% vs. 30% and 33% vs. 21%
under AT and HT, respectively. Higher variation explained by the
plasmotype than nucleotype was true also for reproductive output, e.g.,
SpDW, which showed higher variance between plasmotypes under AT
(PVE=35% vs. 21%) and to a lesser extent under HT (PVE=23% vs. 19%
between plasmotype and nucleotype contributions).