Importance of pre‐anthesis anther sink strength for maintenance of grain number during reproductive stage water stress in wheat

Abstract. Gametogenesis in rice (Oryza sativa L.), and particularly male gametogenesis, is a critical developmental stage affected by different abiotic stresses. Research on this stage is limited, as flowering stage has been the major focus for research to date. Our main objective was to identify a phenotypic marker for male gametogenesis and the duration of exposure needed to quantify the impact of heat stress at this stage. Spikelet size coinciding with microsporogenesis was identified using parafilm sectioning, and the panicle (spikelet) growth rate was established. The environmental stability of the marker was ascertained with different nitrogen (75 and 125 kg ha -1 ) and night temperature (22 C and 28 C) combinations under field conditions. A distance of -8 to -9 cm between the collar of the last fully opened leaf and the flag leaf collar, which was yet to emerge was identified as the environmentally stable phenotypic marker. Heat stress (38 C) imposed using the identified marker induced 8-63% spikelet sterility across seven genetically diverse rice genotypes. Identifying the right stage based on the marker information and imposing 6 consecutive days of heat stress ensures that >95% of the spikelets in a panicle are stressed spanning across the entire microsporogenesis stage.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A phenotypic marker for quantifying heat stress impact during microsporogenesis in rice (Oryza sativa L.)

Jagadish

Craufurd

Shi

et al. 2014

“…In maize under water stress, functional reversion analysis by sucrose feeding (see Boyer and McLaughlin 2007) confirmed the role of glucose in floral abortion and identified a cell wall and a soluble invertase among the few genes controlling sugar uptake by the ovary. In wheat, Ji et al (2010) observed a difference in storage carbohydrate accumulation in drought-sensitive and drought tolerant wheat. Interestingly, genotypic variation for WSC accumulation in the stem, mainly fructans, is well established in wheat (Rebetzke et al 2008;Dreccer et al 2009) and consistent with different levels of expression in fructan metabolism enzymes (Xue et al 2008).…”

mentioning

confidence: 91%

“…Under drought, carbohydrate metabolism enzymes play a crucial role in grain set in tolerant maize germplasm (Boyer and McLaughlin 2007) and pollen viability in wheat (Ji et al 2010). In maize under water stress, functional reversion analysis by sucrose feeding (see Boyer and McLaughlin 2007) confirmed the role of glucose in floral abortion and identified a cell wall and a soluble invertase among the few genes controlling sugar uptake by the ovary.…”

mentioning

confidence: 99%

More fertile florets and grains per spike can be achieved at higher temperature in wheat lines with high spike biomass and sugar content at booting

Dreccer

Wockner

Palta

et al. 2014

Abstract. An understanding of processes regulating wheat floret and grain number at higher temperatures is required to better exploit genetic variation. In this study we tested the hypothesis that at higher temperatures, a reduction in floret fertility is associated with a decrease in soluble sugars and this response is exacerbated in genotypes low in water soluble carbohydrates (WSC). Four recombinant inbred lines contrasting for stem WSC were grown at 20/10 C and 11 h photoperiod until terminal spikelet, and then continued in a factorial combination of 20/10 C or 28/14 C with 11 h or 16 h photoperiod until anthesis. Across environments, High WSC lines had more grains per spike associated with more florets per spike. The number of fertile florets was associated with spike biomass at booting and, by extension, with glucose amount, both higher in High WSC lines. At booting, High WSC lines had higher fixed 13 C and higher levels of expression of genes involved in photosynthesis and sucrose transport and lower in sucrose degradation compared with Low WSC lines. At higher temperature, the intrinsic rate of floret development rate before booting was slower in High WSC lines. Grain set declined with the intrinsic rate of floret development before booting, with an advantage for High WSC lines at 28/14 C and 16 h. Genotypic and environmental action on floret fertility and grain set was summarised in a model.

“…Drought during the pre-anthesis stage of reproductive development has a dramatic effect on grain number (Fig. 1a-c;Bingham 1966;Fischer 1973;Ji et al 2010). Even short, mild water stress periods at the young microspore stage of pollen development (Fig.…”

Section: Drought Stressmentioning

confidence: 99%

Yield stability for cereals in a changing climate

Powell

Ravash

et al. 2012

Self Cite

131

Abstract. The United Nations Food and Agriculture Organisation (FAO) forecasts a 34% increase in the world population by 2050. As a consequence, the productivity of important staple crops such as cereals needs to be boosted by an estimated 43%. This growth in cereal productivity will need to occur in a world with a changing climate, where more frequent weather extremes will impact on grain productivity. Improving cereal productivity will, therefore, not only be a matter of increasing yield potential of current germplasm, but also of improving yield stability through enhanced tolerance to abiotic stresses. Successful reproductive development in cereals is essential for grain productivity and environmental constraints (drought, cold, frost, heat and waterlogging) that are associated with climate change are likely to have severe effects on yield stability of cereal crops. Currently, genetic gains conferring improved abiotic stress tolerance in cereals is hampered by the lack of reliable screening methods, availability of suitable germplasm and poor knowledge about the physiological and molecular underpinnings of abiotic stress tolerance traits.