Genetic basis and adaptive implications of temperature-dependent and temperature-independent effects of drought on chickpea reproductive phenology

Abstract

Water deficit often hastens flowering of pulses partially because droughted plants are hotter. Separating temperature-independent and temperature-dependent effects of drought is important to understand, model and manipulate phenology. We define a new trait, drought effect on phenology (DEP = difference in flowering time between irrigated and rainfed crops), and use FST genome scanning to probe for genomic regions under selection for this trait. Owing to the negligible variation in daylength, variation in phenology with sowing date was attributed to temperature and water; hence, genomic regions overlapping for early- and late-sown crops would associate with temperature-independent effects and non-overlapping genomic regions would associate with temperature-dependent effects. Thermal time to flowering was shortened with increasing water stress quantified with carbon isotope composition. Genomic regions on chromosomes 4, 5, 6, 7 and 8 were under selection for DEP. An overlapping region for early and late sowing on chromosome 8 revealed a temperature-independent effect with four candidate genes: BAM1, BAM2, HSL2 and ANT. The non-overlapping regions included six candidate genes: EMF1, EMF2, BRC1/TCP18, BZR1, NPGR1 and ERF1. Modelling showed DEP reduces the likelihood of drought and heat stress at the expense of cold stress. Accounting for DEP would improve genetic and phenotypic models of phenology.

Linking phenology, harvest index and genetics to improve chickpea grain yield

“…The practical meaning of a low DLc is that the impact of daylength regulating flowering time is restricted to early sowings and/or high latitudes, whereas its impact may be insignificant in low latitudes and/or late sowings (Vadez et al, 2013), as evidenced by the small differences in flowering time of the six late sowings across sites and years. This partly explains the undervalued role of daylength modulating flowering time in other studies (Li et al, 2022;Singh et al, 2021).…”

“…The notion of a species-specific critical period for seed production is central to both fitness in nature (Darwin, 1859) and crop production in agriculture (Li et al ., 2022). Growth conditions during this developmental period modulate grain number, which is the main source of variation in yield (Sadras, 2021).…”

“…Phenology is more complex and less understood in chickpea than in other pulses and cereals (Singh et al ., 2021). In addition to temperature and daylength (Roberts et al ., 1985), soil water availability also affects chickpea phenology (Chauhan et al ., 2019; Li et al ., 2022; Singh and Virmani, 1996). Warm temperatures, long days and water deficit hasten chickpea’s rate of development, with interactions among these environmental factors, and genotype-dependent variation in the response (Daba et al ., 2016; Richards et al ., 2020; Siddique et al ., 2000).…”

Relationships of frequencies of extreme low temperatures with grain yield of some Australian commercial chickpea cultivars

“…However, variation in thermal time targets for flowering (Table 3), which are used for predicting flowering time in different environments, could make prediction somewhat tricky. This variation in the thermal time target for flowering seems to be because flowering is modulated by soil water in addition to photoperiod and temperature (Li et al 2022;Chauhan et al 2019). The strong negative relationship of PostFFr and LTDF with the day of sowing (Fig.…”

Bread and hummus: trait connectance and correlation pleiades in grain crops

“…g ., below 0.5 for time to flowering and below 0.4 for podding from parent-offspring correlations (Anbessa et al ., 2006). Whereas daylength and temperature are drivers of phenological development in both wheat and chickpea, soil factors such as moisture and salinity also modulate phenological development of pulses (Li et al ., 2022; Lizarazo et al ., 2017); a larger environmental component of the phenotypic variance can therefore account for the lower heritability of phenological development in chickpea and its associated higher connectance. In both crops, connectance of yield was at the higher end of the range (Fig.…”