Abstract
Drought stress induced pollen sterility is a detrimental factor reducing grain number in wheat. Exploring the mechanisms underlying pollen fertility under drought conditions could assist breeding high-yielding wheat cultivars with stress tolerance. Here, by using two Chinese wheat cultivars subjected to different levels of polyethylene glycol (PEG)-induced drought stress, possible links between pollen fertility and stress tolerance were analyzed under different levels of drought stress at the young microspore stage. In both cultivars, higher grain number reduction was observed under condition of lower water availability. Overall, the drought tolerant cultivar (Jinmai47) exhibited less grain number reduction than the drought sensitive cultivar (Shiluan02-1) under all stress conditions. Compared with Shiluan02-1, Jinmai47 exhibited superior physiological performance in terms of leaf photosynthetic rate, ear carbohydrate accumulation, pollen sink strength, pollen development and fertility under stress. Moreover, Jinmai47 showed a lower increase in endogenous abscisic acid in ears than Shiluan02-1. Furthermore, higher levels of superoxide dismutase (SOD) and peroxidase (POD) activities were also found in the drought tolerant cultivar Jinmai47 under PEG stress, compared with the drought sensitive cultivar Shiluan02-1. Changes in these physiological traits could contribute to better pollen development and male fertility, ultimately leading to the maintenance of grain number under drought stress.
Highlights
Drought stress is a detrimental abiotic factor that limits crop productivity and quality worldwide (Barnabas et al, 2008; Daryanto et al, 2016)
The effects of drought stress on drought tolerant and sensitive wheat cultivars were evaluated by investigating reproductive structures, photosynthetic related parameters, protective enzyme levels, abscisic acid (ABA) level, ABA homeostasis-associated gene expression and agronomic traits
The data presented here highlights the importance of tapetum and pollen development in drought stress adaptation, with insights into the possible physiological mechanisms contributing to the maintenance of reproductive fertility and yield stability in the drought tolerant cultivar
Summary
Drought stress is a detrimental abiotic factor that limits crop productivity and quality worldwide (Barnabas et al, 2008; Daryanto et al, 2016). Grain number potential in cereals is determined during the early development stage prior to anthesis (Sreenivasulu and Schnurbusch, 2012) Drought stress at this stage significantly affects the development of the floral meristem and can cause a reduction of spikelet initiation and abortion of developing florets (Dolferus et al, 2011). It has been shown that drought stress and moderate water-deficit stress at this stage of development can dramatically reduce grain number (Saini et al, 1984; Dorion et al, 1996; Ji et al, 2010), which has been linked to pollen sterility during the early reproductive stages (such as YM), whereas ovary fertility remained unaffected (Ji et al, 2010)
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